From the ABC 7 Weather team

Archive for January 2014

Numerous chances for wintry weather in D.C. next week

January 31, 2014 - 02:05 PM

First things first, if you haven't done it yet, I'm not sure you'll want to get your car washed this weekend. I know, they look terrible, and the salt is probably corroding everything under your car, but Sunday night into Monday looks messy, as does Tuesday night into Wednesday, and possibly again towards the end of next week!

Here's the set up. For once this winter (not really, but it feels this way) there is a trough over the west coast and ridging over the east coast. This will allow for milder temperatures this weekend to rise near 50 degrees each day.

500mb vorticity plot for Sunday showing disturbances over Texas and off the coast of California

A few disturbances will begin to line up along the west coast, with one settling into Texas Sunday while the other moves in behind it off the coast of California. Those are the two culprits which will bring precipitation to the region Monday and Wednesday of next week.

Sunday Night into Monday System

Even the first storm has a considerable amount of questions to it as Sunday is expected to be in the 50s, which will lead to warm surface temperatures and the potential for rain at the onset of precipitation.

There is also the question as to just how far north the precipitation will be as other guidance is hinting it may pass a little farther south. Finally, some guidance even depicts the possibility of a rain-snow mix through the area with milder hanging on a little longer.

12Z ECMWF 6hr precip and MSLP for Monday depicting system one moving through the region

As the disturbance moves into the region, colder air will begin to filter in as a cold front is expected to pass east of the region Sunday afternoon. Behind the front, cooler air will settle in, but at this time once precipitation starts, it still may be warm enough for rain. The second problem which we may need to account for are much warmer ground temperatures, meaning if snow were to fall how much would actually stick?

Probability of >1" snow from Sunday morning to Monday Morning (our best chance will be Monday morning through Monday early afternoon)

We'll keep a close eye on this system as it has the potential to be a more typical D.C. type light snow maker, with highest snow totals located northwest of D.C. and much less in the D.C. Metro and points southeast. This system bears keeping an eye on this weekend as it may lead to delays or even closings on Monday.

Tuesday Night into Wednesday System

Nope, we're not done yet..and it's only Tuesday. The next system is expected to develop in the Plains and Mississippi Valley region next Tuesday before moving through the Ohio Valley. You may be thinking to yourself, "But Alex, it's headed west of the mountains, doesn't that mean it will be too warm on the East Coast?"

12Z GFS Model depicting MSLP and 6hr precipi for next Tuesday night into Wednesday morning

That may be the case, but in this scenario that's drawn out at the moment, high pressure is expected to move over the area Monday night into Tuesday and move northeast over New York and New England late Tuesday, allowing for a nice feed of cool, dry air into the region. Unfortunately, it's looking like a nice set up for cold air damming and the potential for a wintry mix or icing situation.

At this time, it's way too early to tell exactly what to expect from this system as its energy is currently located over the Pacific Ocean. Regardless, it's ruining another car wash opportunity by putting precipitation in the middle of the week.

Late Week Blizzard?

Haha, I HAD to write that. It's funny when my friends ask me about these kind of things and I have no clue what they are talking about. Weather models and imagery just flies around the web these days, but not everyone that uses it is actually a meteorologist. I am pretty sure a lot of this came from a post a hobbyist posted to his facebook page for fun and it spiraled out of control from there.

WPC forecast surface map indicating high pressure over D.C. next Friday but low pressure developing in the Gulf near Texas

There's a chance for precipitation possibly next Friday through Sunday, but right now that's about as much as I can tell you. If you were one of my best friends I would tell you the same thing, ask them.

All I know as I would hurt my own credibility to go out on a limb and take a wild guess as to whether to expect a snowstorm next weekend. Besides, we have two other systems I need to concentrate on first!

Enjoy the mild weekend.

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Groundhog Day 2014: What Will Phil Predict?

January 31, 2014 - 05:00 AM

While there are so many sophisticated short-range and long-term forecast models that help meteorologists identify weather patterns to make predictions, one special forecaster gets his turn in the spotlight this weekend.

The annual Groundhog Day prediction from Gobbler’s Knob in Punxsutawney, Pa., is Sunday! This is when we find out if winter is history or Mother Nature will deal us six more weeks of cold and snow.

Groundhog Day has been a tradition in the U.S. since the 1800s (which is when weather records began as well). The date is always February 2 --- why you ask? That day is the midpoint between the winter solstice (shortest day of the year) and the spring equinox (a nice balance of 12 hours of daylight and 12 hours of darkness). The first official trek to Gobbler’s Knob in Punxsutawney, Pa., happened February 2, 1887.

Groundhog Day 2005 in Punxsutawney, Pa.

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Light blanket of snow for parts of the D.C. area

January 29, 2014 - 12:45 PM

The highest snowfall totals in the area were 6.7" in Ridge, MD in St. Mary's County and 6.5" in Lusby, MD in Calvert County. Southern Maryland (Charles, Calvert and St. Mary's Counties) was hit the hardest last night, with snowfall reports of 2.5" to 5" commonplace.

Snowfall Reports from Tuesday Night

Other areas in and around D.C. and points westward saw the general coating to an inch that was expected, and it fell at a time when little disruptions occurred. Anything is better than seeing what happened in Atlanta and parts of Alabama. Did that remind anyone of our commutageddon we had a few years ago?

Snow in Lusby, MD from Tammy Sampson Benninghoven

Reagan National recorded 0.9" of snow last night, which gets the snowfall totals for the winter up to 8.1". This is now 3" more than the last two winters combined! Dulles and BWI Thurgood Marshall only recoded a couple tenths of an inch of snow, but each airport still has above average snowfall for the winter so far.

Milder air will settle back into the region by Friday into the weekend with highs in the 40s Friday and near the 50 degree mark Saturday and Sunday.

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Winter Weather Advisory for parts of the D.C. area

January 28, 2014 - 03:06 PM

We'll go ahead and start off this blog by saying there was a very slight chance for light snow southeast of D.C. yesterday. We mentioned the best chance was over Southern Maryland and the Eastern Shore, but as of today some of the latest guidance is showing snow as far north and west as the D.C. Metro.

Winter Weather Advisory south and east of D.C.

While we're not expecting heavy snow, with temperatures as cold as they are, anything that falls is expected to stick not only to the grass, but also the area roadways. A Winter Weather Advisory has been issued for areas southeast of D.C. in Maryland and Virginia for the potential of a few inches of snow from 5pm tonight through 6am Wednesday.


A trough of low pressure is expected to push the best forcing through the D.C. area tonight through early tomorrow morning. Light snow is expected to begin around 5pm tonight through much the area (best chance D.C. and points east) and continue to fall through the early morning hours. Snow should end earlier closer to the D.C. Metro (possibly 3-4am) than the Chesapeake Bay (closer to 5-6am).

Expected Snowfall Totals

Our forecast:  While light snow may accumulate up to a dusting in D.C., slightly higher amounts are expected south and east of D.C. We are confident in an inch or more snow accumulating in parts of Charles, Calvert and St. Mary's Counties. Isolated amounts to 2 or 3 inches will be possible closer to the Chesapeake Bay. The Advisory from the NWS even indicates the potential for up to 5 inches of snow in spots, though it looks like at this point in time that would be on the high end.

Oddly enough, this is about as opposite as you can get from the majority of winter storms that affect the D.C. area where areas north and west are hardest hit.

6z 4km NAM Model Forecast Snowfall (Courtesy: WeatherBell Models)

Model Guidance:  Above is a look at the 6z 4km NAM Model Snowfall Accumulations through Wednesday morning. Showing model output for snowfall isn't one of my favorite things but I wanted to show this just to give you an idea of where heavier snow is expected. Areas south and east definitely have the best chance for accumulating snow.

This model also only depicts a snow ratio of 10:1, which means for every inch of rain, 10 inches of snow would fall. The ratios should be much higher since it is so cold, so expect ratios closer to 15 or 20:1, meaning a dry, light snow, not wet, heavy snow. This snow should be sweepable.

NWS Products:  The local NWS office puts out a few winter products that are often quiet helpful to people such as emergency management officials. Below is a look at the 90th percentile snow totals, or basically a look at what would happen if this storm reached close to its maximum potential. Still only a few inches of snow are possible in D.C. but up to 5 inches would be possible in extreme Southern Maryland. Do not focus on this map as there is only a 10% chance of this occurring, hence the 90th percentile of accumulating snowfall.

Maximum snowfall potential for the D.C. area

Below is a look at the probability of greater than 1" of snow falling in the D.C. area. This product is developed by the National Weather Service Baltimore/Washington office. As of this morning, a 30% chance for greater than an inch of snow is possible in D.C. where it rises to 60% in southern Maryland.

Probability of greater than 1" of snow


Slick spots will develop tonight on area roadways and travel will become difficult southeast of D.C. Luckily Calvert County schools are already closed tomorrow for a teacher work day but other school closings may be possible by tomorrow morning. Winds shouldn't be a big concern with this system, but they will become breezy at times tomorrow around 10 to 15 mph keeping chills in the teens.

Snow will come to an end tomorrow morning, the sunshine will return and temperatures will be *slightly* warmer in the mid to upper 20s on Wednesday. Milder air should return by the weekend, though with highs back in the 40s expected Saturday and Sunday.

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The Arctic Express arrives Again!

January 27, 2014 - 08:33 AM

Here we go AGAIN! Yep. Our 4th “Polar Plunge” of the month. Today’s arctic cold front will usher in another brush with single digits and wind chill temperatures below zero.

 Wind Chill Advisory

The good news is that this latest round will not be the coldest for the D.C. area of the month nor the longest. Starting this afternoon, temperatures will begin dropping through the 30s. A wind chill advisory is in effect starting at 1a.m. Tuesday through 10a.m. The feel factor will reach -5 to -10 at times. It will stay cold and breezy on Tuesday with high temperatures near 20 in The District, but mid Teens in the suburbs. Tuesday will be the coldest day of the week. But, Wednesday won’t be much better. Highs in the mid 20s. We should break the freezing mark Thursday and a reversal in the jet stream pattern will bring 40+ by the end of the week!!

 Jet Stream Late Week

So, let’s take a look at what we’ve seen for January so far. First of all, despite the extreme temperatures, no record lows have been broken at Reagan National Airport.  However, we did have the coldest high temperatures in decades.  If we count today, this is only the 6th date our temperature has reached the freezing mark or better. And when you average the highs and lows, we end up at 33 degrees for the month, that’s three degrees below the average.

 January Statistics

Our first brush with arctic air and below average temperatures came January 3rd and 4th. We picked up just shy of 2” of snow and our temperatures dropped into the teens. It seems tolerable compared to what came next. Our coldest temperatures of the season arrived January 6th-8th. We recorded a low temperature of 6 degrees on the morning of January 7th at Reagan National Airport. The record at Dulles was broken with a low of only 1 degree.  And a few spots West dipped below zero (not including the wind chill which was much lower). The next touch with arctic air arrived January 21st. This was the longest stretch of subfreezing temperatures that lasted through the 24th.

 Snow in Tyson's Corner, January 21st

It was also our biggest winter storm of the season bringing 4-10" of snow across the region.  Our 4th and yes, final blast starts this afternoon and lasts into Thursday. But thankfully (for those of you that hate the cold) the month will end on a warmer note. Right now our forecast high for January 31st is 40 degrees. While that is still below the average high for the date in the mid 40s, it is above freezing. And, if you care, the Groundhog will be making his spring outlook on Sunday.

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Cold start, cold end to January 2014 in Washington D.C.

January 23, 2014 - 04:24 PM

I thought it would be fun to print out a few monthly climate data sheets from the National Weather Service and show them to Adam Caskey this afternoon. I hid the location of one and asked him based of the recorded temperatures through the month for him to guess where the location was. Based on the temperatures in the teens, 20s and 30s overnight and highs in the 30s to low 40s during the day, he guessed somewhere in the Central Plains such as Tulsa, Oklahoma. Turns out I was showing him Anchorage, Alaska.

Anchorage is running over 10.5 degrees above normal this month as well as much of the state. Fairbanks, which has seen temperatures as low as -41°F twice this month is still running over 12 degrees above normal. Meanwhile, the D.C. area is running slightly below normal currently, looking to end the month a few degrees below normal. This is all due to the pattern aloft, steering milder air over the Western U.S. and Alaska and keeping the Midwest and East Coast in a cold pattern.

12Z GFS 250mb Jetstream forecast for Thursday evening

Looking at the GFS pattern above, this gives you a hint why temperatures have been like this for much of the month. Taking a look at the U.S., you can see a wave extending from Canada through the Midwest eastward to New England.

This "U" shape in the jet stream is called a trough in the atmosphere. The West Coast north to Alaska has been experiencing just the opposite for much of the month, which is called a ridge.

850mb Temperature Normalized Anomalies (Courtesy: WeatherBell Models)

The "troughiness" for the eastern half of the country has made for much colder than average temperatures as cold air has been continually steered out of Canada whereas milder air has been stuck and centered over the Pacific and north into Alaska.

The graphic above gives an idea of this with temperatures 2 to 3 standard deviations above the mean near Alaska and 2 to 3 below the mean in the D.C. area. With the persistent jet over much of North America, there was really only a period of 5 days in the month when the pattern changed.

When that happened, temperatures in D.C. soared into the 50s and 60s from the 11th-15th, whereas Fairbanks experienced 5 days with low temperatures below -16°F, two of which hit -41°F!

12 GFS 850mb temperatures for Thursday evening

I thought this depiction of 850mb temperatures would help drive this point home to give you a nice idea of how these airmasses have been interacting. Looking at the graphic of the 250mb jet stream at the top of this post corresponds nicely to where the areas of cold and mild air are located. The ridging out west can easily be seen as well as the trough over the eastern half of the U.S.

Looking forward in time, unfortunately this pattern doesn't appear like it will be breaking down in January. There are hints the pattern may change and become more zonal (jet stream travels more west to east in nature) by the beginning of February. Time will tell if that forecast persists.

7-Day Outlook

Until then, expect Friday to experience high temperatures nearly 20 degrees below average, the weekend to feature another round of snow showers with temperatures only in the 30s, and next week to start out with 3 straight days only in the 20s. Who else is waiting for January to hit the road?

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Washington D.C. area snow Tuesday

January 21, 2014 - 07:10 PM



10:06PM: Here's a sampling of the snowfall totals in the D.C. area so far.

8:26PM: Here are some of the latest snowfall totals from the National Weather Service office.

3 miles NW Frederick, MD: 10.0"

2 miles SE Westminster, MD: 10.3"

North Beach, MD: 5"

2 miles N Columbia, MD: 7.2"

1 mile ENE Gaithersburg, MD: 8.3"

Damascus, MD: 8"

Laurel, MD: 5.3"

Baileys Crossroads, VA: 5.2"

Alexandria, VA: 4"

Winchester, VA: 8"

Berryville, VA: 7.7"

Centreville, VA: 6"

Herndon, VA: 5"

Dulles International Airport: 7.1"

Ashburn, VA: 6.8"

Leesburg, VA: 7"

Linden, VA: 7"

Martinsburg, WV: 8.7"

7:39PM: Snow will continue to taper off through the next hour or two in the city and by 11pm closer to the Bay. Feel free to track Doppler Radar to watch the last few bands move through your neighborhood!

It's been a fun day watching the snow, but I don't think anyone is looking forward to the extreme cold tomorrow morning with lows in the single digits in much of the area. Chills will be below zero throughout the region and high temperatures Wednesday are only expected to reach the teens.

7:23PM: Here's a nice loop of this last moderate to heavy snow band moving through the region right now. Enjoy this final snow before it ends later tonight!

7:12PM: Some warnings have been cancelled by the NWS as this final snow band pushes east of the Blue Ridge.

Winter Storm Warnings cancelled west


6:15PM: A moderate band of snow will continue to push to the east over Montgomery, Loudoun, Fairfax into the District and eventually eastward over the next hour. This will allow for additional snowfall accumulations before the end of the event.

Snow should begin to end in the western suburbs around 8pm and closer to 10pm around the Metro.

6:14PM: Here are some of the latest snowfall reports from the National Weather Service. Some areas in Frederick County, MD are reporting over 9 inches!




5:28PM: Here's a good find from Adam Caskey on the effectiveness of road salt from the Wisconsin Department of Transportation.

"Q. What are the limitations of road salt?
The minimum practical application range for salt is a pavement temperature of 15-20°F and above. While salt will melt snow and ice down to a pavement temperature of -6°F, it can melt over five times as much ice at 30°F as at 20°F. Thus the effectiveness of salt is sensitive to small differences in pavement temperature. Counties will attempt to apply only the amount required for temperature, time and use. Too little and the roadway will refreeze, too much is a waste of money and resources.

When the pavement temperature drops below 15°F the effectiveness of salt is decreased significantly. At these lower temperatures, the county highway departments will typically cease straight salt applications and begin adding other chemicals to the salt such as calcium chloride or magnesium chloride that will lower the freezing point even further.

Wind conditions must also be considered when deciding on whether to apply salt or other de-icing agents. As the temperatures drop and the snow becomes dryer, the wind can begin to blow the snow across the pavement. If there is a chemical residue left on the pavement from a previous salt application, blowing snow can be attracted to the residue and stick to the pavement creating hazardous conditions that would not have existed if no de-icing agents were previously applied. This is why counties are sometimes reluctant to apply salt or chemicals when the pavement temperatures are below 15°F. The effectiveness of salt can also be affected by the type of pavement. For example, salt works better on new asphaltic (blacktop) pavements than on tined concrete pavements.



The salt being used today typically includes other ice melting de-icing agents to increase its effectiveness at lower temperatures and to help it better adhere to the pavement. Adding other de-icing agents to the salt also reduces the number of applications needed. WisDOT is always looking for new ways to reduce the amount of chlorides needed to return the roadways to safe winter driving conditions. Sometimes counties use sand and other abrasives at lower temperatures to improve friction on the roadway. Abrasives have no ice melting properties and thus their use is limited."

5:10PM: Latest snow fall total map across the region




4:15PM: Bethesda, MD at 9AM (left) vs 3PM (right)....Thank you Suzanne Matwyshen-Gillen!




4:00PM: Winter Storm Warnings still posted across the region (until 11PM) and the Wind Chill Advisory kicks in at 6PM





3:45: This is what to expect as we continue with the snow 


2:42pm: Here are some of the latest snowfall reports across the region with much lower snowfall totals being realized south and west of D.C. Up to 5 inches of snow has been seen in Frederick Counties in MD and VA, Loudoun has seen 4 inches

At this time, snowfall amounts look to be less than the original forecast in the D.C. Metro and points south. Areas north and west still look like they will see 6-10 inches of snow. The Metro itself has a better possibility of 3 to 5 inches of snow and areas south up to 3 inches.

1:15pm: Here's a great comparison of the roads changing in just 15 minutes in D.C. Snow is really beginning to stick on the roads in the D.C. Metro and points northwest.

1:11pm: Snow in Frederick, MD from twitter.

12:49pm: Snowfall totals so far from the National Weather Service Baltimore/Washington Office.

Westminster, MD (Carroll County): 4.8"

Walkersville, MD (Frederick County): 4.5"

Germantown, MD: 2"

Berryville, VA (Clarke County): 3.3"

Stephens City, VA (Frederick County): 2.9"

Purcellville, VA: 2.8"

Herndon, VA: 1.1"


11:43am: Area roads are starting to become covered. Please tweet me or let us know on facebook how your roads are faring!

11:40am: Not a good day to be flying. Many delays and cancellations across the northeast today.

11:25am: A Mesoscale Discussion has been placed over parts of the D.C. area including the Metro for heavy snowfall potential. Snowfall rates up to 1-2" per hour will be possible through the afternoon.

Mesoscale Discussion area for Heavy Snow


10:57am: Winds tonight will be around 10 to 20 mph with gusts to 35 mph at times. This will make it feel like it is below zero at times. Wind Chill Advisories are posted for the majority of the area with chills from 5 to 15 below zero and even lower in the western surburbs.

10:42am: Temperatures are expected to fall into the single digits tonight with lows near zero in the western suburbs. Here is a look at the forecast temperatures from the 4km NAM courtesy of

4km NAM Forecast low temperatures Wednesday morning (WeatherBELL Models)

10:22am: 2" of snow is being reported so far in Frederick County, VA from the NWS Baltimore/Washington office.

10:13am: Snow is causing slick roads already west of D.C. This picture of a crash was taken near Purcellville, VA by our very own reporter Richard Reeve.

9:56am: The Flightaware Misery Map is showing big time delays and cancellations in Chicago, New York City and Washington D.C. from the weather. Definitely check or call before heading to the airport today!

9:48am: Nice snowfall so far in Winchester, VA.

Winchester Snow from Lauren Torbett

9:34am: Snow coming down in Cumberland, MD. Already covering the roads!


9:18am: This is our latest forecast for snowfall today. A heavier band of 6-10" appears possible north and west of D.C. with slightly lower amounts for D.C. and points south and east. You can already see a heavier band setting up northwest of the city and we think those will be the hardest areas hit by this system.

9:12am: Here's a look at the snow so far in Ijamsville, MD on our HD WeatherBug camera.

Ijamsville High School in Frederick, MD

9:00am: Snow is beginning to move into the region this morning with the heaviest pushing into Loudoun and Frederick Counties right now. Be sure to check out the HD cameras above as snow is entering the region. The ground is already white in Berryville, VA and Frederick, MD.

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Biggest Snow of the Season Tuesday

January 20, 2014 - 10:23 AM

Follow Lauryn on Facebook and Twitter (as well as the StormWatch7 Page) for continuous information!

Update: 8:30AM - Of course now expecting more as the snow begins to move into the region.....tune in to our StormWatch 7 Radar - Right now in terms of accumulations we are expecting -

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There could be upwards of 10" towards the PA line, less south of the DC metro area.


Also - Wind Chill Advisories begin tonight!

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This will move on out of here by the time we head into the late evening hours - 10PM



Today: I guess you could call it the calm before the storm. A very mild day out there today as temperatures rise into the upper 40s/low 50s! This will be well above our average temperature of 43 degrees! Then we head into tomorrow. That’s when we will face some problems, snow problems.

A Winter Storm Warning has been posted for the entire region beginning early tomorrow morning and continuing through tomorrow evening.


There is a good chance that we could see some accumulating snow for everybody around the region and probably the best chance we have seen yet this winter. So what is going on?

Another piece of energy moving in from Canada (remember the “clippers”) will head southeast today out of the northern plains and through the Ohio Valley. While this is going on, a frontal system will drop through the region crossing the area tonight. The piece of energy slipping into the region will join with the front and eventually cause an area of low pressure to form off the coast along the front through the day tomorrow. That low will move northeast, just off of the east coast line.

Lows tonight will drop into the 20s and then pretty much stay in the 20s (below freezing) for tomorrow. Therefore, there is no question that the snow will stick. Snow will begin to impact the region starting early tomorrow morning from the west (most likely around 7AM). The snow will continue to spread eastward and reach the DC metro area anywhere from 9AM-11AM. At this point, current thinking is anywhere from 3”-5” of snow around the area with some locally higher amounts (these could be subject to change). Since it will be fairly dry, the snow will be of the fluffy nature which can tend to pile up quickly.

This graphic below the percentages (on the left) that we could see at least 4.00” of snow across the region. Mostly about a 60% shot. We do believe that it will be slightly more in total accumulation (3”-6”) to the north and west and then also more south and east of the DC area once the storm forms off the coast (4”-8”).

Weather Prediction Center

Not only are we worrying about the snow falling, we are going to have some breezy conditions through the day tomorrow. Northwest winds anywhere from 10-20 mph with bring wind chills down into the single digits, mainly for the afternoon hours. This will also cause blowing snow around the region as the heaviest of snow will fall during the afternoon hours. Snow will come to an end by the time we head into Tuesday night but winds will stay put at least through the first part of Wednesday dropping wind chills Wednesday morning to below zero.

Tomorrow morning will not be quite as bad as tomorrow afternoon so even with that being said, I do believe there will be some cancellations for schools and office buildings. Keep it here as we continue to tweak the ongoing forecast, but for the most part-get prepared to see some snow!

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Progressive DC winter pattern continues; next snow chance Tuesday

January 19, 2014 - 09:07 PM

The jet stream, or zone of strong upper-level winds that guides weather systems across the U.S. has shown a bit of a “kink” or trough in the Mississippi Valley to the East with a persistent ridge in the West so far this winter. This pattern favors fast-moving but frequent storm systems that don’t bring large quantities of precipitation. It also hasn’t favored a major coastal storm; the kind that bring Washington’s biggest snows.

upper-level pattern

This week coming up shows signs that the Eastern trough will dig far south once again (noted by the big dip across the Great Lakes). Typically in a transition pattern (from above average temperatures as seen today and will again on Monday to much below average temperatures by Wednesday) a storm forms.

upper-level pattern

The latest data catch onto a snow potential once again in Washington. Low pressure in Alberta Canada will ride the jet stream winds into the Midwest and then the Mid-Atlantic, bringing a swath of light snow along its journey.

Known as an “Alberta Clipper,”this low will likely bring a light, fluffy snow on Tuesday during the day. The latest data suggest about an inch or two will fall in Washington with higher totals expected south of the city in central Virginia (mainly south of Interstate 66) and southern Maryland. However, snow will accumulate all the way north to the Mason-Dixon Line where  accumulation will be lighter. This could be just enough snow to warrant a Winter Weather Advisory from the National Weather Service for Tuesday.


upper-level pattern

Since temperatures will be in the 20s and the entire atmospheric column will be well-below freezing, the snow will likely stick on many surfaces once it begins. The light, fluffy snow will cause a few slippery spots for commuters.

In its wake, a cold blast will arrive from the Arctic. As a matter of fact, by Wednesday morning, wind chills will range from 0 to minus-10 degrees from the Shenandoah Valley to the Blue Ridge foothills to the lower single digits in the nation’s capital.

Temperatures will only recover into the teens and lower 20s on Wednesday. The following is a list of daily record cold maximum temperatures that could go by the wayside in the Wednesday cold blast.

upper-level pattern

Stay tuned to ABC7 for updates on the early week snow potential and midweek chill and when you are away from the internet or the TV, stay with WTOP, 103.5 FM, around the clock for weather updates on the 8’s.

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Additional snow chances and return of arctic cold air

January 16, 2014 - 04:02 PM

Light snow fell across parts of the region Wednesday night into Thursday morning, and additional systems will soon follow. Another disturbance will move into the area Friday night into Saturday morning, and a following clipper will move through Saturday night into Sunday morning.

Each of these systems have the potential to bring flurries and light snow, but it may not add up to anything other than a dusting on the grass.

GFS 500mb Vorticity Forecast for Saturday morning

Above is a look at the mid-level pattern, with the bright yellow, orange and magenta colors denoting areas of energy and lift in the atmosphere. For more technical information on 500mb weather plots, check out this site.

On the model forecast above, a trough is depicted over the Eastern U.S. Energy associated with that system will push through Friday night into Saturday morning.

Our current thought is that light snow will fall across the region with up to a dusting to a half inch possible mainly in the western portions of the viewing area. Areas at higher elevations will have the potential for up to an inch. Snow will come to an end by Saturday morning and gusty winds and cooler temperatures in the 30s will settle into the region during the day.

The next system on the model forecast above can be seen over the Dakotas moving in to Minnesota. This system will continue to push southeast south of the Great Lakes and eventually into the Mid Atlantic by Sunday morning. An additional chance for light snow will be possible Saturday night into Sunday morning.

ECMWF Predicted Snowfall through Sunday afternoon (Courtesy: WeatherBELL Models)

We're sorry if you're snow lovers, but both of these systems will have rather low levels of moisture involved so precipitation is expected to be light. One model shown above is showing the chance of a quarter to a half inch of snow east of the Blue Ridge and more in the higher elevations to the west. Ski spots in the mountains have the best chance for measurable snow, so it may be a good weekend if you're headed out that way!

Snowshoe Mountain Resort Cam

Beyond this weekend, an additional chance for snow lies on Tuesday, but there are more questions than answers on that system right now and if anything it appears like it would be light. We'll update you as confidence increases.

850 Temperatures next Wednesday

Temperatures look to be the bigger story next week. Monday should be the warmest day of the week with highs in the upper 40s. Beyond that, the arctic plunge appears to return, with highs in the 30s Tuesday, and possibly only in the 20s next Wednesday and Thursday.

Related Blog: Coldest January's on Record in D.C.

Below is a look at the ECMWF forecast model 2-m temperatures next Wednesday morning. If you can't see the tiny numbers, they are in the teens in the suburbs and 20s closer to town. Not quite as cold as earlier this month when it bottomed out in the single digits, but still quite cold!

(Courtesy: WeatherBELL Models)

Cold air may hang around for a while too, with chilly conditions expected next weekend and another strong cold push possible the following week. We don't want to get too far ahead of ourselves here but we wanted to outline the possibility of another cold air outbreak returning to D.C. next week.

Here is a look at the Climate Prediction Center's 6-10 Day Outlook, showing an 80% probability for colder than normal temperatures from next Wednesday through Sunday. I would call those pretty good odds. Be sure to have your cold gear ready next week!

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Coldest Januaries on record in D.C. history

January 16, 2014 - 03:45 AM

January is typically the coldest month of the year with a normal temperature around 36°F, which is about 3°F colder than the next coldest month of February. The D.C. area has seen some very cold Januaries, and this month seemed like it would begin to challenge some of the coldest on record with below average temperatures in 7 of the first 10 days of the month and some of the coldest temperatures recorded in 20 years.

With four days in a row now recording 50 degrees or warmer, an extremely cold January doesn't appear likely. Even with the chance of more colder than normal temperatures next week, it just won't be cold enough to even make the top 10 coldest Januaries in the D.C. area.

Above is a look at the top ten coldest January's in D.C. The coldest averages 23.7°F for the month! That is the mean temperature for the month, which is the average of all the high temperatures of the month plus the average of all the low temperatures for the month divided by two. I took a look at the top three coldest months as I wanted to know what each was like compared to what D.C. experienced last week.

Related Blog: 102nd anniversary of record cold in D.C.

As a reminder, the temperature dropped to 11°F, 6°F and 13°F last Monday, Tuesday and Wednesday, respectively. That was very cold compared to the past few years, but nothing compared to the coldest months.

January 1940 - 3rd coldest January on record in D.C.

1940 featured some extremely cold temperatures, with only three days at or above 40°F. One of those days reached 55°F, the highest temperature recorded for the month. That January recorded nineteen days with high temperatures below 32°F, and five days with single digit low temperatures. Twenty-two days featured low temperatures below 20°F. Even if it dropped below 20°F for the rest of the month this year, that would only add up to twenty-one days!

January 1893 - 2nd coldest on record

1893 was downright cold. Oddly enough it didn't feature as many days with high temperatures below 32°F (16) as 1940, and had more days with highs above 40°F than 1940, but it was the extreme cold that really mattered.

From Jan. 10-22, 1893, there were ten days with low temperatures below 10°F. Two of the ten were below zero, including -5°F on the 14th, and -6°F on the 18th. Six of those day time high temperatures only reached the teens. Compare that to our coldest day last week which hit 21°F at Reagan National. All six of those days with highs in the teens occurred within an 8 day period. That's cold!

January 1918 - Coldest on record

1918 was just plain consistently cold. Like 1940, nineteen days featured high temperatures at or below 32°F. You know it's going to be a bad month when low temperatures start off with 1°F on the 1st, 10°F on the 2nd, 4°F on the 3rd, and 2°F on the 4th. Sheesh!

The highest temperature for the month was only 50°F, and only three days recorded high temperatures above 40°F. The difference between 1918 and 1940 were the low temperatures. 1940 featured four days with low temperatures above 30°F, whereas 1918 recorded its highest low temperature for the month at 30°F.

If you think back to Tuesday morning, it hit 41°F, which is two degrees shy of the normal high temperature for the day. Yes, 2014 won't be close to any kind of record breaking cold.

(Side note: For the history of where weather observations were taken, please consult this document)

Below is a look at the official 1893 January monthly climate summary which was sent to me with help from the National Weather Service office in Sterling, VA. Thanks for your help!

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102nd Year Anniversary of Record Cold

January 14, 2014 - 05:57 AM

If you thought last Tuesday was cold, imagine what it felt like in 1912.

Baltimore dipped to a record 3 degrees last Tuesday, but during a historic 1912 cold snap, the Charm City set a record low of -2 degrees on Jan. 14. The high temperature both on Jan. 13 and 14, 1912 only reached 11 and 20 degrees respectively, marking the coldest daytime highs for those days. Records at BWI Thurgood Marshall go all the way back to 1871.

Meanwhile, Dulles reached a record low of 1 degree last Tuesday and a record cold high temperature of 18 degrees that same day. For January 13 and 14, the records only date back to 1970 and 1981.

Keep in mind, though, that Dulles wasn’t an official reporting station until 1963, so there is no recollection of how cold the temperature was here in the 1912 outbreak.

What’s more impressive is that the 1912 cold wave set a Maryland low temperature record. Oakland, Md., (located at approximately 2,398 feet in the Allegheny Mountains of far western Maryland) dropped to -40 degrees to set the state’s all-time record low temperature.

The cold weather pierced the nation’s capital as well. While Reagan National didn’t set any cold records last week, it sure did in the 1912 outbreak!

The official reporting station for Washington dropped to a record minus-8 degrees on January 13, 1912 and -13 degrees the next morning. Even more impressive, the high of 8 degrees on Jan. 13, 1912 pushed Washington into the record books for the coldest daytime high ever registered. That temperature was then matched again on Jan. 19, 1994.

courtesy Barbara M. Watson NWS

The bitter blast chilled many other locations in the Washington area. Hagerstown, Md., dropped to a record -27 degrees on Jan. 13, 1912, establishing the city’s coldest low temperature on record. Frederick dropped to -21 degrees while Rockville registered -10 degrees. Even Salisbury was below zero degrees at -4 degrees.

The weather data was sparse in the early 1900s with maps showing much less detail than with today’s technology. However, notice the huge Arctic high pressure centered across the Mid-Atlantic just as this outbreak was in full throttle.

The high came straight down from northern Canada into the Mid-Atlantic, the ideal track for our region to get the brunt of a record cold blast.

courtesy of NOAA Central Library Data Imaging Project

In addition, the 1912 outbreak came at just the right time in winter to set these records. Mid-January is traditionally Washington’s coldest period. From now through Jan. 24, the average high is 43 degrees and average low is 28 degrees, the coldest averages for the calendar year and winter season.

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Alberta Clippers to have collision course with D.C. this week

January 13, 2014 - 08:27 AM

Polar Vortex is so last week.

This week we’ll be talking all about the Alberta Clipper, or the “Clipper” for short. Chances are pretty good you’ve heard of this one before.

This week we will have at least two clippers move across our area, bringing chances of precipitation and shots of chilly air to follow them.

Computer Model Forecast of Clippers

So, what is an Alberta Clipper and how will it impact our weather?

Alberta Clipper

An Alberta Clipper is a fast moving winter storm that develops from the Canadian province of Alberta. This area of low pressure tracks along with the jet stream from Albert to the Upper Midwest, through the Great lakes and usually moves off the coast in the Mid-Atlantic.
Since these systems move pretty quickly - they're named clipper after sailing ships - the snowfall they bring with them tends to only amount to a few inches at most. But, they can usher in frigid temperatures on the back side along with gusty winds.
The first clipper arrives Wednesday afternoon and will bring some rain and snow to the D.C. area. Our ABC7 Futurecast model shows the chance of both late in the day.

Wednesday Rain/Snow on Futurecast

Right now, we expect little to no accumulation, but temperatures will drop about 10 degrees. The second clipper arrives late Friday and this one packs more of a punch. Temperatures will be much colder after it’s passage on Saturday.
Here's the European model solution for Saturday afternoon temperatures.

WeatherBell ECMWF Model

However, we don’t expect to squeeze out much moisture on Friday, just a few flurries. It's still early in the week, so the timing and precipitation expectations could change between now and then.  The ABC7 Stormwatch Team will keep you up to date.

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Heavy rain likely Saturday in the D.C. area; Flood Watch Issued

January 10, 2014 - 11:19 AM

Parts of the D.C. area may receive up to 2 inches of rain and possibly even higher amounts in isolated areas. A Flood Watch has been posted for the majority of the D.C. Metro from Saturday morning through Saturday evening for areas below shaded in dark green.

Rain appears like it will continue on and off the remainder of today, but the heaviest activity is expected tomorrow closer to lunch time. Temperatures are also expected to warm through the remainder of today, into tonight and continue to warm ahead of the front tomorrow.

High temperatures may reach the 60 degree mark ahead of the front tomorrow.

Forecast precipitation from the WPC through Sunday morning

Above is a look at the forecast precipitation from the Weather Prediction Center. The shaded area in purple are precipitation totals of 1.5 inches to 2.5 inches.

A widespread heavy rain is anticipated from the southeast north into North Carolina, the Mid Atlantic and Northeast. The I-95 corridor will be hit hard from Virginia through the northeast so travel conditions will be poor.

Courtesy: WeatherBELL Models

The timing of the front brings some of the heaviest rainfall through the D.C. area around lunch time. Above is a look at the 4km NAM forecast for Saturday at 1 p.m., bringing heavy rain to the Metro.

Checking some of the latest forecast atmospheric soundings, it appears some gusty winds and possibly even a few rumbles of thunder will be possible as there will be a little elevated instability across the region.

The Storm Prediction Center has issued a Slight Risk for severe storms over much of the Southeast including the I-95 corridor. Storms will develop in a very unstable airmass ahead of the cold front and will have the potential for gusty winds and possibly even a few isolated tornadoes.

This outlook included extreme Southern Maryland, the Northern Neck, and the Eastern Shore, so if you are traveling in those areas stay tuned to the latest forecasts and keep and eye out for rapidly changing weather conditions.

Rainfall totals around the D.C. Metro as of now are forecast to be heaviest southeast of D.C., with upwards of 2 inches of rain possible. Flooding doesn't appear to be a huge concern at the moment, but ponding of water and minor flooding of streams and creeks still may be possible.

Remember: if you come up to high water across the roadway, please turn around and try to find another route. Below gives an idea of how much rain the 4km NAM model is predicting for the D.C. area by Saturday night.

4km NAM forecast precipitation by Saturday night (Courtesy: WeatherBELL Models)

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Wintry mix for Friday morning commute?

January 9, 2014 - 05:20 PM

What a week it's been between the record cold temperatures Tuesday, associated with the Polar Vortex, to the possibility of a wintry mix Friday. At least temperatures have been on the upswing.

This next disturbance will move into the region overnight Thursday and early Friday morning. Temperatures will be right around freezing, so freezing rain and snow are possible. Unfortunately, the timing will coincide with the morning rush. This morning, wintry precipitation is falling over the south and Midwest.

A Freezing Rain Advisory has been posted for the majority of the D.C. area besides the Southern Maryland counties of Calvert and St. Mary's. The advisory begins at 11pm tonight for zones to the southwest of D.C. and at 3am Friday closer to the D.C. Metro. The advisory runs through 9am Friday.

This moisture will track northeast throughout Thursday. As warmer air moves into the mid and upper levels of the atmosphere, freezing rain will be a concern with surface temperatures at or slightly below freezing. Take a look at our in-house computer simulation of temperatures and precipitation tomorrow morning.

As warmer temperatures work in from the south through the early to mid morning, all precipitation will quickly change to rain. Here's another simulation of precipitation type at 9 and 11 a.m. Friday. In a two-hour span, the precipitation changes to rain. Remember, this is one simulation, so we'll have to watch temperatures closely.
Penn State e-wall

Ice accumulations, if any, will be very light. In fact, look at this product from the Weather Prediction Center. This image below shows the probability of ice accumulations of less than 0.01 inches. The D.C. metro has a 5-10 percent probability of a light coating, with higher probabilities farther west.

Weather Prediction Center

As the warm front lifts farther north, and winds shift out of the south, temperatures will climb, believe it or not, into the upper 50s to low 60s by Saturday afternoon! Take a look a the surge of southerly warmth ahead of the next cold front.

College of DuPage

This front will bring another round of wet weather for the day Saturday. The heaviest rain will slide in late Saturday afternoon and will be out of here by Sunday morning. Stay with the StormWatch7 weather team for the latest in winter weather developments.

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Polar Vortex, Record Cold, and Dangerous Wind Chill

January 7, 2014 - 11:13 AM

We've been warning you since last week that an arctic blast would chill you to the bone in D.C. this morning, but just how bad did it get?

Unofficial Morning Lows

Temperatures plunged into the single digits across the area, but it was the wind chill that was painfully cold. Here is a sampling of the coldest unofficial readings I could find across the region.

Wind Chill Temperatures

Keep in mind that elevation played a role in the -40s in Garrett County, Maryland. So, were records broken as advertised? Yes, and No. Here is a look at the standing records before today:

This morning, Reagan National dropped down to 7 degrees and the automated observing system at Dulles Airport dipped to 1 degree at 7:32a.m. which breaks the old record of 8 degrees set in 1988. A few notes on both of these... The record on the climatology report for D.C. was actually set back in 1884, when the Weather Bureau took observations on G Street, not at Reagan National.

It's the coldest air we've experienced since 1996 when we all did "The Macarena" dance to keep us warm. (Thanks to my colleague Bob Van Dillen at HLN for this reminder). It had our own ABC7 Good Morning Washington Storm Chaser7 Meteorologist Eileen Whelan all bundled up in the elements this morning reporting how the brutal cold made her face feel "stiff" and showing us how to dress in these extremes.

Eileen loving life this morning

So WHY is it so cold you ask? I'm sure you've heard the term "Polar Vortex" by now. It is trending on social media and has been misused over and over the past few days. In the most simplistic terms, the polar vortex is a circulation in the upper atmosphere that originates near the poles. This is NOT a new term for meteorologists.

The polar vortex has always been there. In the winter time, it can become very strong and will sink south from the pole. Right now, the polar vortex is over the northern Great Lakes and a "piece" of it entered the northern U.S. It is he winds that circulate around this atmospheric phenomenon that help draw arctic air into this U.S. where millions of people live. Here is a great graphic put together from the National Weather Service in New York to help explain.

Polar Vortex Explainer from the NWS in New York City

And you can click on this link if you really want to "weather geek-out" with me.

The cold air has made its way across the entire eastern half of the U.S, including Florida. This is a big deal because it hasn't happened to this extent in almost two decades. People have died from this cold in the Midwest where the wind chill has been -40 to -50+ Records have been broken this morning from New York to Alabama. Here's a look at preliminary numbers.

Record Lows this Morning

Why did the Polar Vortex get so far south? It is likely due to natural variations in the atmosphere, and we can't peg a singular event on climate change, if you're wondering. If you hate the cold, we're stuck in it today with a wind chill advisory through 6p.m. for the metro area. We should finally get above freezing by Thursday. Believe it or not, temps will actually warm above average this weekend.

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Watch Out Washington D.C. Cold Spell-Moving in Today

January 6, 2014 - 11:30 AM

And here we go. The weather is about to get dangerously cold as we continue through your Monday. A very strong arctic cold front swept through the region this morning unleashing cold air into the Mid-Atlantic in the wake of its passage. Here was a look at temperatures as the cold front marches east at 9:00AM this morning. Through the day today, temperatures will drop and the winds will kick up due to the front exiting the region and high pressure building into the area. 


Eventually, a prolonged period of gusty winds will ensue, moving west sustained at 15-25 mph and gusting up to 35 mph. Unfortunately these winds will stick with us through Tuesday evening so bitter cold conditions will remain in our forecast for the next 30+ hours. Considering the temperatures will drop into the single digits tonight and barely make it into the mid-teens tomorrow, we have to talk about wind chill values. Wind chill advisories and wind chill warnings are in place across the listening area.


Here is one model’s interpretation of wind chill values at 8PM tonight. Wind chill values will start to slip below zero west of the DC area (along the I-81 corridor) this afternoon and by the evening hours, DC will start to slip below zero for wind chill values. The coldest period for all locations will likely come afternoon midnight and stick with us through early tomorrow morning. Most, if not all locations will stay below zero for the wind chill factor through the day on Tuesday and winds will continue to be gusty.


This is some of the coldest air we have seen in sometime. Taking you back to January 1994, on the 19th of that year, temperatures dipped down to 8 degrees for a daytime high with an overnight low of -4 degrees. Since then, the closest we have been to being THAT cold was February 4th, 1996 when temperatures in Washington, D.C. were at 17 for a daytime high and 9 for an overnight low. There is a good chance that some local airports could break temperature records, mainly daytime high records on Tuesday but we will come very close to breaking the record lows for Tuesday at both Dulles and Reagan National Airport.


Our forecast low for the DC area Monday night into Tuesday is 9 degrees, so we will be very close to the record low of 5 degrees in DC (set in 1884). By the time we head through the day on Tuesday, daytime highs should only reach about 15 degrees which could break a record from 1878 with a temperature of only 18 degrees. By Tuesday night into Wednesday, wind will start to calm as high pressure centers itself over the Carolinas and temperatures will begin to go up on Wednesday to around 30 degrees. There IS light at the end of the tunnel though! Temperatures should be well above normal by the end of the weekend! We are talking possibly mid-50s in spots! So, make sure to bundle up over the next 30 hours and brace yourselves for some of the cold air we have seen in two decades.

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Major Arctic Blast Heading for D.C.

January 5, 2014 - 06:17 PM

The weather is known for extremes, especially in the height of summer and winter months and what is coming down the pike early next week is no exception. An Arctic cold front chopping through the Tennessee Valley is quickly heading east this evening. Temperatures are dropping quickly in the front’s wake with rain changing to snow across Kentucky, southern Indiana and Ohio.


To provide insight into how cold the air mass is behind the Arctic front, the lowest temperature in the lower 48 states this morning was -40 degrees in Babbitt and Embarrass, Minn. “To every action there is an equal and opposite reaction,” according to Sir Isaac Newton’s Third Law of Motion. Therefore, ahead of the front, with southerly winds, temperatures will warm overnight instead of drop inside the Capital Beltway.


The warmest temperatures, with 40s and 50s expected, will immediately precede the cold front, which will arrive right during the morning commute. The temperatures will quickly drop in the band of rain that will be followed by a transition to snow in the front’s wake between 6 a.m. and 9 a.m. The front will also transport gusty winds to the surface, with gusts approaching 40 mph.

Allow yourself extra time for the morning commute as the snow, although it won’t last more than 30 minutes or so, could quickly accumulate on secondary roads, parking lots and untreated surfaces. The snow will fall quickly, likely overcoming the rate of melting on warm surfaces (since temperatures will have warmed into the 40s and 50s prior to the front’s arrival).

A mix of several different model runs (called an ensemble solution) below shows a period of snow is likely following the front but accumulation would be less than one-half inch. This solution looks logical since rain is changing to snow immediately behind the front in the western Tennessee Valley and Midwest tonight.

snow potential

The core of the coldest air will arrive Monday night into Tuesday. Following a day with falling morning temperatures and steady afternoon temperatures, readings will plummet by sunset into Tuesday morning. Wind Chill Watches have been posted along the Blue Ridge into the Shenandoah Valley. These watches will get upgraded to warnings with wind chills expected to drop below minus-20 degrees, making for life-threatening conditions overnight Monday. Inside the Capital Beltway, wind chills will drop to minus-5 degrees.

The following are the records in jeopardy Tuesday and Wednesday. Several of these records, specifically for Dulles International and BWI Thurgood Marshall Airport, have been standing since 1988.


Dressing in layers (long-sleeved shirt, sweater, winter coat, for instance) is the best way to trap body heat (provides more insulation than one heavy layer) and stay warm if you must venture out in the cold weather. Most heat escapes through the head, so wear a warm hat and cover all extremities to prevent frostbite. Also, be sure to keep faucets dripping and open cabinet doors to keep pipes from freezing and busting. Keep pets inside and check on the elderly.

Temperatures will finally moderate by Wednesday. Click here for the latest 7-day forecast.

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First the east coast blizzard, now extreme cold

January 3, 2014 - 11:30 AM

The highest snowfall totals in the D.C. area were centered all around the city but the heaviest fell along and north of a line along I-66 and I-50. Up to 4.5 inches of snow fell across areas such as Loudoun, Frederick (MD) and even east of D.C. in Calvert and Anne Arundel Counties where snow lasted the longest.

Snow total map from NWS Sterling, VA

Above is a look at the map view. You can find the full report here from the NWS Sterling Office. Snowfall totals were a couple inches greater than we expected but that was about it. With our forecast in the 1-3" range, I think we did alright as I personally was expecting less closer to D.C. but temperatures weren't as warm as forecast and less rain mixed in. Always a lesson to be learned in each winter scenario in D.C.

Other areas along the east coast had moderate snow such as New York where 6" or greater seemed common. You can find the snowfall reports for the New York City area here.

The Boston area got the brunt of the system, with up to 2 feet in Essex County, MA. Here is the snowfall report for Boston.

The concern today through tonight is the cold. Winds have diminished enough that the Wind Advisory was cancelled, but not before wind gusts reached the upper 40s in the D.C. area and up to 64 mph at Wintergreen Mountain in VA. Below is a nice look at a graphic put together by the NWS in Sterling.

Lows tonight will be some of the coldest temperatures in over a year at Reagan National. In fact, I was compiling some statistics on twitter earlier this morning and realized it will be cold, but the duration of the cold won't be as long as it was only a year ago.

If lows tonight fall below 15 degrees, which is a high possibility, it would be the coldest night since March 3rd when it dipped to 14 degrees at Reagan National. There were also back-to-back nights in January in 2009 on the 16th and 17th that fell to 11 degrees and 8 degrees, so it could always be worse!

Forecast 4km NAM low temperatures tonight (Courtesy: WeatherBell Models)

Above is a look at the forecast 4km NAM low temperatures tonight, forecast to be in the single digits in the outlying suburbs and teens around D.C. The snow cover on the ground, coupled with light winds and clear skies overnight may help temperatures drop even more, so at this time we think the coldest air in about 5 years will be realized. I would probably hold off that morning run until the afternoon if possible.

850mb Temperatures and Winds next Tuesday per the GFS model

Not to steer you further into depression if you hate the cold, but an even stronger cold push is forecast for early next week, with low temperatures possibly in the single digits in the D.C. Metro come Tuesday morning! We will be keeping a close eye on that system as well as high temperatures next Tuesday may only reach the teens. Winter is here.

How serious is next weeks cold spell? Serious enough that the National Weather Service office for Minneapolis and St. Paul, MN (Twin Cities) already put out a full page graphic to warn about the impending dangerous cold. I hope no one is planning to travel to the Midwest early next week.

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Northeast Winter Storm: DC Impact

January 2, 2014 - 07:38 AM
Snow began accumulating quickly in Bealeton. Photo: Rob Glenn

The New Year is starting off with tranquil weather conditions in the Nation's Capital.... but, that is all about to change. 

A strong coastal storm will develop later today and will pound the Northeast with snow and wind.  As of Thursday morning, moisture is streaming in from the Gulf and a cold front is dropping in from the Midwest.  Check out the water vapor imagery depicting these features.


The two systems will essentially merge later today and a strong coastal low will develop. Watch the progression from our in-house computer model.

The low rapidly intensifies overnight off the New England coast.  That is when the winds will really start to pick up across the region.

This will be a major winter weather storm for much of New England and the interior northeast.  Snowfall totals will get close to a foot in some areas, and with gusty winds, near whiteout conditions will be likely, making travel a nightmare. 

Blizzard warnings are in effect due to the snow and wind anticipated on Long Island and Cape Cod.  Check out all the winter watches and warnings across the region.

For us in D.C., this will be a minimal impact storm.  Snowfall totals will range from around an inch in the district (a trace over southern Maryland, if that) to around 2 inches in northern Maryland.  That is where a winter weather advisory is in effect

Here's a simulation of snowfall totals for our area.  I think some of these totals are a tad high, but gives you and idea of the slightly higher totals the farther north you go.

The precipitation will start later Thursday afternoon/evening, as light rain and will then transition to light snow.  Light snow will continue overnight, as temperatures fall into the 20s. 

By Friday morning's commute, the snow will be over, but the cold and wind will be the big story.  Here's a timeline for later today through tomorrow morning.

Temperatures Friday morning will be in the 20s, but with gusty northerly winds, wind chill values will be in the single digits and teens throughout the day.  Here's a look at forecast wind chills for tomorrow at 6 a.m.

By the upcoming weekend, temperatures start to moderate a bit.  But another winter storm could bring some rain and snow to the region by Sunday.  Once we get through Thursday's storm, we'll hash out the details on the weekend weather.

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