From the ABC 7 Weather team

Odds of a White Christmas for Washington D.C.

December 11, 2014 - 02:42 PM
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Are you dreaming of a white Christmas? Okay, let me be honest. After a few days of just a cold rain, I am ready for some snow—and right in time for Christmas. So, what are the chances we can see a white Christmas around the WJLA viewing area?

 

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According to this map put together by the National Climatic Data Center, there is about a 11% -25% chance that there will be at least 1.00” of snow on the ground on December 25th. To break it down, there about a 15% chance of that scenario unfortunately for most of the WJLA viewing area (the data in this map is based on the historic probabilities measured over the last 3 decades from 1981/2010). “This dataset contains daily and monthly normal of temperatures, precipitation, snowfall, heating and cooling degree days, frost/freeze dates and growing degree days calculated from observations at approximately 9,800 station operated by NOAA’s National Weather Service.” (NCDC)

Our local National Weather Service Office has done some incredible research in this category. They found that since 1888, there were only 19 occurrences with measurable snow on the ground already from a previous snow storm OR measurable snow fell on Christmas Day. That on average is about once every 6 or 7 years or 15%.

So you’re telling me we have a chance?! (Inset Dumb and Dumber quote here). Well yes, albeit a small one. The last time we had snow ON Christmas Day was in 2002 when we received a whopping 0.2” at Reagan National Airport. Think about it this way, measurable snow (at least 0.1” of snow) has only fallen on the City of D.C. ON Christmas Day 10 times in the past 130 years. Therefore, on average, snow falls on Christmas Day every 13 years or around 8%.


Check out these stats from the National Weather Service in Sterling (full report here):


“In the past 20 years there have only been two Christmases that had snowfall: 1993 and 2002. Both years featured just a fraction of 1.00”. Furthermore, there were only two years in the past 40 that had 1.00” or more of snow on the ground on Christmas. They were during the very cold December of 1989 when nearly 2.00” f snow was on the ground from previous snowfall that month. More recently in 2009 we had 7.00” still on the ground from the first of our major snowstorms that record setting winter. All 7.00” of that snowpack on Christmas 2009 melted by the next morning (as temperatures rose into the mid-40s).


Of note, 18 years ago in 1993, in a span lasting less than 30 minutes in the evening, 0.2” of snow fell with upwards of 1.00” falling in the western suburbs. That quick bust of snow on Christmas night in 1993 caused severe travel problems. Much of the snow melted on contact with paved surfaces as temperatures were just above freezing at the time the snow feel. However, an arctic cold front swept in just after the snow ended. Any water remaining on roads and sidewalks from melted snow quickly flash froze into a thin layer of ice which caused gridlock and treacherous travel that night.

Precipitation of any sort (rain included) is much easier to come by of course. Fifty-one Christmases have had measurable precipitation. That translates to about a 36% probability of measurable precipitation or roughly on in every three years. “


So with snow falling ON Christmas Day averaging every 13 years and last time we saw snow on Christmas Day was 2002, we may have to wait until 2015 to see some snow fall ON Christmas Day. Usually the typical Christmas Day consists of a morning low of 30 degrees with daytime highs rising into the mid-40s. History also tells us that is it partly cloudy on Christmas Day.

Last year, temperatures were fairly cold in Washington D.C. with some snow flurries on Christmas Eve and as well as the 26th of December. We topped out around the freezing mark (official temperature recorded AT DCA on December 25th was 32 degrees in 2013). Last year was the coldest Christmas since 2004 (high temperature of 31 degrees).

Nothing in the works yet as far as precip or temperatures as we are waaaaaay too far out but as always, we will continue to keep an eye on it as we get closer to the 25th.

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Coastal Storm Brings Wet Weather Beginning Monday Night

December 7, 2014 - 05:58 PM
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It's been a grey start to December, but we finally saw a nice, clear day today.  This was the first fully sunny day since November 21st!  Soak up the sun early tomorrow morning because clouds will quickly thicken, as our next weather system approaches the area.

A developing area of low pressure, off the coast of the Carolinas, will increase cloud cover through the day Monday.  With the clouds, temperatures will only reach the mid 30s by the afternoon.  Here is a look at forecast highs on Monday.

Forecast Highs Monday

Both the morning and evening commutes will be dry, with wet weather from the coastal storm arriving after 8 PM.  Temperatures won't fall much overnight Monday into Tuesday, in fact, temperatures may actually climb a few degrees with an easterly wind component.  Check out our local simulation of radar at 10 PM Monday (1st image below) and 6 AM Tuesday (2nd image).

Local RPM Model Monday 10 PM
Local RPM Model Tuesday 6 AM

This model depicts all rain, which seems to be the trend among most guidance.  As the coastal low tracks farther north Tuesday, there may be a brief transition to snow late Tuesday night well NW of D.C.  Little to no accumulation is expected.  In fact, by Tuesday at 8 PM the coastal storm will be greatly impacting New England.  Here is a simulation of the coastal storm at 8 PM Tuesday.

Surface Features Tuesday at 8 PM

This will be a predominately rain event for us with the greatest snow potential over interior New England.  Check out forecast snowfall accumulations by Thursday afternoon.  Areas shaded in pink could receive over 10" of snow.

WxBell GFS Forecast Snow Total By Midday Thursday

The area of low pressure will get cut-off from the jet stream midweek and will spin freely over New England through at least Thursday.  That means added clouds for us Wednesday and Thursday with possible light rain and snow showers. 

There are still uncertainties to the forecast, since the coastal storm has yet to develop.  The Stormwatch weather team will continue to update the forecast, as new information becomes available. 

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More unsettled weather for the weekend ahead

December 3, 2014 - 05:34 PM
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The pattern doesn't appear like it will change anytime soon after bringing nearly an inch of rain to parts of the region Monday night into Tuesday and clouds on Wednesday. Thursday should experience a lull in the action, just in time for the National Christmas Tree Lighting, which Chief Meteorologist Doug Hill will be out live broadcasting tomorrow evening.

At this point we are expecting some sunshine in the morning hours followed by afternoon clouds as the next system pushes in from the west. A few models have depicted the chance for a few showers late tomorrow night into Friday morning, but this should be a low probability at this point with the best chance south and west of D.C.

Water Vapor image with tomorrow's disturbance and Saturday's disturbance

Looking west, an area of low pressure has been bringing inches of rain to parts of California over the past few days. A bit of energy and associated moisture has spun off this system and will help bring clouds to our region Thursday afternoon through Friday night.

Thursday rainfall totals as of 5pm for parts of California

Another area of energy will push into Southern California tonight into Thursday morning. This disturbance will move across the U.S. and into the Mid Atlantic this weekend, increasing chances for rain Friday night into the day Saturday.

Precipitation forecast for Friday through Saturday evening

Beyond Saturday, there are stark differences in model depictions, with a few models spinning up additional areas of low pressure off the east coast and socking the region in clouds and precipitation Sunday and Monday, and another completely clearing the region out Sunday with sunshine and mild temperatures. We will get a much better handle on this forecast in the next 12-24 hours but at this point are content on keeping the rain chances in for Sunday and again Monday.

Forecast precipitation Saturday through Monday Evening

 

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

December 1, 2014 - 03:27 PM
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A cold front will sweep through the region on Monday afternoon/evening. Temperatures will fall behind the front, eventually ending up in the 30s for overnight lows!

Cold front will move through Monday afternoon/evening bringing a threat of isolated showers and dropping temperatures.


Eventually that front will stall just to the south of the region. An area of low pressure will ride along the front Monday night into Tuesday bringing precip with it. At the same time, high pressure will move front the Great Lakes region to the New England area. Eventually this evening, our winds will shift to the north and east bringing moisture and cooler air off the Atlantic Ocean and right into our area. What happens is, that moisture banks up against the mountains to our west creating a “cold air damming” affect or CAD. This set up generally makes forecasting that much more difficult, especially when determining precipitation types because that colder air will slide right under the warm air aloft which would make the precip type more of that of a wintry mix (freezing rain/sleet).

Winter Weather Advisory from 1am Tuesday to 1am Wednesday

Just around daybreak and into the morning commute, we will start to experience some spotty sleet and freezing rain, mainly north and west of D.C. (Loudoun County and Central and Western Montgomery County and points northwest). Inside the beltway, along I-95 and areas to the south and east, this event mainly looks like a very cold rain event but I can’t rule out some isolated pockets around D.C. of the wintry mix.

This is NOT looking like a major event but since it comes for the morning rush, there could be some problems (as there tends to be, even if it is just plain rain). And we are really not expecting that much to accumulate at all, perhaps just a glaze in some areas. Surface road temperatures, especially around the D.C. area, are above freezing so just like last Wednesday, any frozen precip that falls will have a hard time sticking. However, north and west of town on some rural roads, elevated surfaces (bridges and overpasses) and even exits could have some slick spots.

In-house model of Tuesday morning (rain = green, wintry mix = pink)


Again, I do not think this is going to be a huge event but I don’t want it to take anybody by surprise when our temperatures do not make it out of the 30s tomorrow (considering we are around 70 in a lot of the area on Monday).

Warm air will start to erode the shallow layer of cold air and any wintry mix will turn to plain rain by the afternoon hours. Most of the precipitation should move north around the kickoff of the evening commute but I do expect there to be some drizzle and fog around the region – there could even be some freezing drizzle at the high elevations). Temperatures rebound into the lower 50s on Wednesday but another bout of precipitation could be on the horizon for Friday.

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Wintry Mix Possible Monday Night Into Tuesday

November 30, 2014 - 07:00 PM
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The first of December, and the start of meteorological winter, will be unseasonably warm.  Our average high this time of year is 52°.  After topping out in the 60s today, we'll climb back into the 60s tomorrow with a warm southwesterly breeze.  Here are forecast highs for the eastern half of the U.S. Monday.

Forecast Highs Monday

While we'll enjoy one more warm day, notice temperatures behind the cold front to our west.  Highs will only reach single digits and 20s in the Midwest.  That airmass will filter in late Monday night into Tuesday. 

The cold front will slide through late Monday bringing a slight chance of rain showers by the Monday evening commute.  Here's our in-house computer simulation of rain and clouds at 5 PM Monday.

Local Futurecast 5 PM Monday

Temperatures will fall into the 30s and 40s overnight Monday.  An area of low pressure will develop along the cold front and will keep precipitation around through the day Tuesday.  With colder air at the surface, and aloft, the potential arises for wintry weather.  These are forecast temperatures Tuesday morning.  Notice temperatures will be in the upper 30s in the D.C. Metro with low 30s, freezing or below, west of the I-81 corridor.

WxBell Forecast Temperatures 7 AM Tuesday - European Model

This is one of those tricky forecasts in determining precipitation type; however, it will likely impact your Tuesday AM commute to some degree.  Here is one model simulation of precipitation type Tuesday morning.  Green is rain, blue is snow, pink is freezing rain, and orange is sleet.

WxBell GFS Precipitation Type 7 AM Tuesday

Fortunately, the precipitation totals will be light.  If any snow, ice accumulates, it will be far NW.  Remember, temperatures will be in the 60s the day before, so ground temperatures should remain above freezing.  Here's a forecast ice accumulation graphic by the Weather Prediction Center.  The highest likelihood (50% and higher) of any ice accumulation is in our far NW suburbs and west of I-81.

Weather Prediction Center Ice Accumulation Probability by 7 PM Tuesday

This will not be a major winter event by any means, but it may create a slow go on the roads Tuesday morning.  The StormWatch weather team will continue to monitor the weather situation and update you with new information as it becomes available.

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Washington Weather Extremes on Thanksgiving Day

November 30, 2014 - 05:00 PM
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The year is quickly drawing to a close and the holidays are now in full swing. While many beg for a white Christmas, do you know we’ve had our fair share of white Thanksgivings in the past? Remember warm turkey days when you could host a game of kickball or football without the chill of late November weather? What about the coldest Thanksgivings when a cup of hot cocoa went well with your turkey meal?

Here is a list of the top warmest, coldest, snowiest and wettest Thanksgiving Days in the nation’s capital.

Top 7 Warmest                              Top 6 Coldest Mornings
1. 77 degrees – 2007                        1. 18 degrees - 1902
2. 75 degrees – 1979 & 1933            2. 19 degrees - 1903
3. 73 degrees - 1927                         3. 21 degrees - 1930 & 1894
4. 72 degrees – 1896                        4. 22 degrees - 1892         
5. 71 degrees – 1987                        5. 23 degrees - 1938, 1905 and 1901
6. 69 degrees – 1973 & 1966            6. 24 degrees - 1917 and 1895
7. 68 degrees – 1968 

Top 5 Snowiest                               Top 5 Wettest
1. 1.9" - 1989                                      1. 1.15" - 1971
2. 1.0" - 1971                                      2. 0.96" - 1916
3. 0.6" - 1912                                      3. 0.93" - 1935 
4. 0.5" - 1938                                      4. 0.91" - 1945 & 1886 
5. 0.2" - 1901& 1898                           5. 0.77" - 1938 & 1966

Although the Thanksgiving weekend is drawing to a close on the warm side, much more seasonal weather is just around the corner next week. For more on the forecast, click here.

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Snow in the D.C. area Wednesday; Send your pictures!

November 26, 2014 - 09:58 AM
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LIVE DOPPLER  |  HD CAMERAS  |  WARNINGS & ADVISORIES

Tweet us your pictures so we can share them on air!

@DougHillABC7    @SteveRudinABC7    @JacquiJeras    @ABC7Brian  @alexliggitt    @LaurynRicketts    @EileenABC7    @DevonLucie

1:07pm: Snow is beginning to taper off in spots already but light precipitation will continue to fall over the next few hours. Any additional accumulations will be very light in nature and no additional accumulations are expected on the roads with temperatures mainly above freezing.

You can find the latest snowfall reports here

Snow in Berkeley Springs, WV from Chuck Marsh

11:25am Update:  The transition to snow has occurred across the majority of the D.C. Metro. Heavy snow is being reported across much of the metro which has caused visibilities to plunge to a quarter of a mile in spots. The Dulles Toll Road recently reported some slushy road conditions in spots and crews have been dispatched to treat the roadways. Here's a look at the latest Doppler radar image.

Live Super Doppler Radar as of 11:30am

We are still thinking snow will end later on this afternoon closer to 3pm west of D.C. and 4pm around the Metro.

10am Update: Rain will continue to be likely along and east of I-95. Wet snowflakes will mix in at times with a better chance for flakes closer to Noon through the early afternoon hours.

Areas west of I-95 will continue to see wet snow, with the potential for rates of a half on an inch to an inch per hour in some locations. Current temperatures are mainly above freezing at the surface, so snowfall rates will need to be heavy in order for accumulations on the road surfaces.

We have been seeing many areas still experiencing accumulating snow on the roads, even as close as Leesburg, VA. We will continue to keep you posted with the latest snowfall totals, where it is and when it will end. As of now, snow and rain looks to end by 3 or 4pm this afternoon.

 

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UPDATE: Chances of Season's First Snowfall and Forecast Totals

November 25, 2014 - 07:44 AM
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Today will be a fabulous weather day to travel if you have the ability to adjust your plans at all. All signs are leading to a major travel headache for D.C. and throughout the Megalopolis for Wednesday all day long. We are officially on Stormwatch now. Here are the latest warnings and advisories for our area.

Winter Storm Watch
The pink area is under a warning and most likely to have the heaviest snowfall totals that could reach 6" or more. In the advisory snow will only be a few inches. As new information from computer models continue to pour in, we still have some variations on the solution, so it makes for a tricky one. No big surprise, this is D.C.  Let's start with timing. Here is a look at the most recent Futurecast7 model of the start of rain, transition to snow and sharp ending.
ABC7 Futurecast

The models depict a cold rain to start, mix by late morning, with some hovering or the transition line around I-95 and then ending with snow.

Here are the big three things that you need to know:

METRO:

1)  Starts as rain before dawn, changes to rain/snow mid-late morning, finishes as snow before evening commute.

2) Little-to-no accumulation is expected inside beltway, mainly just wet Roads. If snow rate is heavy enough, up to a slushy 1/2" or inch possible. Watch for slick spots after dark temperatures start around 40 and end just above freezing. Fairfax and Montgomery Counties may see 1-2".

3) Heaviest precipitation will be between 10 a.m. and 3 p.m.

Impact for Potomac Highlands and Mountains:

1) May start as wintry mix or snow in the morning.

2) Snow totals are likely 3-6" with isolated spots getting more.

3) Hazardous roads much of the day. Ending mid-afternoon, but slick spots will stay unless roads are treated.

Challenge: Temperatures. Through the duration of the storm, temperatures are currently forecast to be above freezing in the close-in metro. We've been very warm the past few days, so snow will melt on contact for a while.  There is no arctic air in place, but the storm will create it's own cold. How much is still somewhat in question. Bottom line is that confidence is moderate on this storm and these forecast totals could go up or down still.  Here is my latest forecast snow totals map.

ABC7 Snowfall Forecast Wednesday

Make sure you join ABC7's Stormteam of meteorologists today from Noon-6:30 p.m. on Facebook.  We will take your questions in a live Q & A session about the storm and travel across the country.

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Coastal Storm with Big Travel Impact Imminent for D.C. on Wednesday

November 24, 2014 - 08:15 AM
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It seemed unlikely last week, but now it is almost certain that D.C. will see a strong storm on Wednesday that will bring the first snowfall of the season. The timing couldn't be worse for Thanksgiving travelers. There are still many elements that have to come together. Here is what we know right now.

A cold front will pass our region tonight and stall just to our east in the Atlantic Ocean. Low pressure will develop near the Carolinas Tuesday night into Wednesday morning and head up the coast. It will pull in colder air from the northwest and moisture from the Atlantic to make a travel headache for millions of Americans from D.C. to New England. All of the weather computer models have predicted that there will be a strong coastal storm, but they differ on the exact track. This means it is still uncertain where the rain/snow line is and how much snow could accumulate.

Possible Computer Model Storm Tracks

What can we expect in the D.C metro? Right now, I expect temperatures to be in the 40s when we wake up on Wednesday, leading to the onset of precipitation as a cold rain. As temperatures drop, it will transition to snow in the afternoon. Because of the borderline temperatures at the surface and warm ground with today's record heat, it is going to be tough to get snow to accumulate on roads inside the beltway.  Minor accumulations are possible on grassy areas, but the snow rates will have to be very heavy for that to happen.

Potomac Highlands/Blue Ridge/Mountains:  Temperatures are key here too with upper 30s possible to start the day as moisture moves in. A rain/snow mix is possible to start with before transitioning to snow by late morning or early afternoon. With falling temperatures and elevation, snow will likely accumulate here. It's too soon to put numbers on this, but we may need a whole hand to count the number of inches that accumulate. As temperatures drop further after sunset, roads will become icy.

Computer models are showing a very wide range of possible accumulations. We will have a better idea Tuesday morning so stay tuned for snow band maps. Here is a look at a probability graphic of 1" of snow or more accumulating from Wednesday morning through Thursday morning.

Percentage of Probability of 1" of Snow or More- NOAA

The storm will exit late Wednesday or very early Thursday morning with wrap around snow showers in the mountains. The rest of Thursday will be clear and cold with highs in the upper 30s to lower 40s. A good day to turn on the oven and cook a bird and stay indoors.  The rest of the holiday weekend is looking calm and cool.

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Warming Up on Monday but Uncertainty Comes Mid-Next Week

November 21, 2014 - 02:33 PM
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Get ready for a warm up-and I believe that is something we can all latch on to given the bitterly cold air more normal for January that moved into our area of the last week. However, after some evening rain on Sunday, we will warm up nicely on Monday – into the lower 70s in some spots!

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Caption: Temperatures warm to around 70 degrees on Monday

However, a cold front will sweep on through on Monday night into Tuesday morning and that will gradually bring an end to our mini warm up. Tuesday should be a fairly quiet day as temperatures will still top out in the mid to upper 50s with sunshine however, as we head into Wednesday, we could see some changes.
Since this is several days away, the forecast confidence is low for mid next week but given it is one of the busiest travel days of the year, I want to go ahead and tell you what we’re looking it. Temperatures will continue to fall below normal on Wednesday and Thursday (Thanksgiving)-most likely topping out in the mid to upper 40s.
ZZZZZ

The frontal system that passes through the area on Tuesday morning will stall out off the eastern seaboard. The models are hinting at an area of low pressure forming along the stalled frontal boundary and moving north along it. The question will remain: how close to the coast can that area of low pressure get? If we see a shift westward, then we could have some rain/snow along the eastern seaboard on Wednesday (D.C. area included). However, if it keeps veering out to sea, there is a good chance of not seeing anything expect a dry day here. Obviously this will be something we continue to watch as we head into next week.

As far as the rest of the U.S. is concerned for travel, there are no major storms across the region mid-next week. There could be a clipper system that dives southeast out of northwestern Canada that could bring some light snow showers to the Great Lakes region and Upper Plains (this could include any Chicago airports) – however, any snow associated with that looks to be light.

Until then, just enjoy the weekend and we’ll keep an eye on the weather!

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Voracious sunspot could impact us on Earth

November 20, 2014 - 10:22 AM
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When the sunspot faced Earth last month it was the largest one on record in nearly a quarter century. What impacts could it have on us and is there anything we can do to prepare for it? Check out my one-on-one interview with NASA Solar Astrophysicist Dr. Alex Young.

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Record cold across the D.C. area Wednesday morning

November 19, 2014 - 11:07 AM
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Record lows were broken at both Dulles and BWI Marshall last night. Dulles broke the record of 20F set back in 1990 by 7 degrees as the location plunged to 13F this morning. BWI Marshall broke its record of 20F set in 1936 as they dropped to 19F this morning. Reagan National, which hasn't broken any record lows between November and March since 1996 was close, but still failed to break the record of 18F this morning as it only fell to 22F.

Record Lows at Dulles and BWI Marshall Wednesday morning

 A number of other records were broken across the country this morning as well. Here are a few cities that also broke or tied low temperature records. You can find a bigger list of all kinds of records from the NWS here.

Elkins, WV: 12F (Old record 14F-1990)

Richmond, VA: 18F (Tied 1936)

Philadelphia, PA: 20F (Tied 1936)

Morgantown, WV: 16F (Old record 19F-1989)

Charleston, SC: 23F (Old record 27F-1949)

Savannah, GA: 26F (Old record 27F-2008)

Jacksonville, FL: 27F (Old record 28F-2008)

New Orleans, LA: 31F (Tied-1946)

While it was freezing in the central and eastern U.S., the opposite is happening in parts of Alaska, with record highs broken in both Anchorage and Nome yesterday.

Temperatures will begin to moderate tomorrow as they settle back into the mid 40s, but another brief cold push is expected Friday before a milder weekend ahead. Just to put this cold in perspective, today will be the earliest day with highs below 40 degrees at Reagan National since 1996. Basically, this is the coldest it's been this early in the season in 18 years. I don't think anyone I've spoken to has missed the cold!

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Arctic Blast Brings Record Challenging Temperatures Tonight and Wednesday

November 18, 2014 - 08:49 AM
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Today's bitter arctic blast brought us the coldest air of the season so far and beats last week's cold by about ten degrees. D.C. dropped down into the 20s for the first time and wind chill temperatures were down in the the teens and even single digits in a few spots.

Lows this Morning

Believe it or not, our high temperature actually happened at midnight with 42 degrees and then plummeting temperatures through sunrise. This afternoon will recover a bit, but temperatures only warm a few notches in the low to mid 30s. That is more typical of January temperatures! And it isn't just the temperatures making it feel unreasonably cold. Gusty winds will keep our wind chill factor in the 20s all day long. Wind gusts will reach 25 to 30mph at times. Here's a look at ABC7's computer model forecast wind chill temperatures this afternoon.

Forecast Wind Chill this Afternoon

The wind will diminish after sunset, so that will help, but clear skies means a cold night ahead. Record lows are in jeopardy tonight. The record low for Dulles is 20. I'm expecting to meet or just break that record. Reagan National's record low is 18, and I think we'll miss that by just a few.

Lows Wednesday Morning

Additional records may be set Wednesday afternoon. Highs will only reach the low to mid 30s. We could have the coldest high temperature on record for the date. Here at the stats for that.

Record Cold Highs Wednesday?

By Thursday, we start a slow recovery with temperatures back in the 40s. A dry cold front will pass our area, but won't bring the temperatures down too much more on Friday. For those of you hating on the cold, we'll reach near average temps in the mid 50s late this weekend and should easily top 60 on Monday. The warmer temperatures won't stop there.

 

6-10 Day Temperature Probability

The 6-10 day outlook has much above average temperatures for the Mid-Atlantic and that should last into the first part of December. Hang in there!

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Chilly Rain Monday Then Bitter Blast Tuesday

November 16, 2014 - 04:47 PM
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Grab the umbrella and rain coat Monday morning and allow for some extra time for the AM commute.  Rain, and even some sleet, started falling Sunday evening and rain will continue, on and off, through late Monday afternoon.  Even though there were reports of sleet at the onset of precipitation, temperatures will remain above freezing for the duration of the wet weather, so it will be an all rain event.

Here's a radar simulation at 7 AM Monday.  Notice the wide shield of rain overhead.  Expect extra delays for the morning rush, so be prepared.

The rain is coming from an area of low pressure currently over the deep south.  This low will track northeastward overnight and tomorrow bringing ample moisture.  Between .75-1.00" of rain is expected.  Here's a larger view of our weather story.

The bulk of the moisture should be out of the region by the evening commute.  Winds will begin to shift out of the NW drawing in another very cold airmass.  Temperatures will tumble quickly Monday night into the lower 30s.  The gusty winds should help dry the roads, but icy spots are possible Tuesday morning.  Even during the afternoon, highs will struggle to reach the freezing marks in spots.

Temperatures will be nearly 20° colder than average for this time of year.  And it's not just us dealing with the bitter cold.  The map below shows the temperature departure from average.  The blue and purple colors indicate temperatures 20-30° below average. 

WxBell GFS Output

If the cold wasn't enough, winds will be howling between 25-35 mph Tuesday.  That means wind chills will be in teens and 20s during the day.  Here's an hourly forecast of the "feels like" temperature on Tuesday.

Winds will gradually diminish late Tuesday night, but the cold air sticks around Wednesday with highs, again, in the mid 30s.  Temperatures will rebound slightly by the end of the week and into next week, but will still be well below our average of 58°.

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Fun Weather Facts: Just How Cold & Snowy Has It Been?

November 15, 2014 - 06:35 PM
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*A total of 28.5% of the U.S. is currently covered by snow compared to 5.8% last year at this time.

Current Snow Depth
Current Snow Depth

*In the last 11 years, only November 2012 comes closest to snow coverage seen so far this month when 20.1% of the Lower 48 was covered by snow.

Current Snow Depth
Current Snow Depth
*Snowfall coverage (snow extent in thousands of square kilometers) across North America in September was the highest since records began in 1966 and eighth highest in October.
Current Snow Depth *Snowfall coverage (snow extent in thousands of square kilometers) in northern Asia (Eurasia) last month was the second highest since records began in 1966.
Current Snow Depth *In the last 24-hours, there was a 103 degree temperature spread across the U.S. The high Friday hit 84 at Death Valley, CA and today’s morning low was -19 in Jordan, MT & Dunn Center, ND..

*There have been more cold record highs set this month in the U.S. than warm record highs.

Current Snow Depth *Lake Superior (largest of the Great Lakes) and Lake Michigan’s water temperatures are below average; the remainder of the Great Lakes currently are seeing near average water temperatures.

Be sure to get the latest forecast for the Washington area by clicking here.

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A Cold Wet Rain Could End as Snow on Monday

November 14, 2014 - 12:46 PM
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If you didn’t think the cold weather was here with yesterday’s daytime high temperatures topping out in the 40s, I am sure you were reminded how winter has paid us an early visit with the first flakes of the season Thursday evening. Not everybody saw the light flurries; some people experienced some sleet as well! Any precipitation last night quickly changed to rain but it was a reminder that this forecast is more reminiscent of a December or January forecast as opposed to a mid-November forecast. Either way, we will have yet another reminder of winter paying us an early visit as we start off the next work week.

Winds will continue to die down through the evening so we are expecting light winds during the overnight. Light winds and clear skies means those temperatures are going to drop.

ZZZZZ

Caption: Overnight lows Friday overnight

We will start off on the chilly side on Saturday as arctic high pressure builds right overhead. Temperatures will manage to make it into the low to mid 40s. So if you are headed to College Park on Saturday night, watch for temperatures falling through the lower 30s during the Maryland/Michigan State game. Clouds will increase on Sunday ahead of our next system with temperatures warming to around 50 degrees! That means we are looking good for the Redskins vs. Tampa Bay game at Fed Ex – just some clouds but remaining dry.

After midnight on Sunday, all bets are off. An area of low pressure will move out of the Gulf of Mexico and to the northeast along a cold front. It will gain some energy from a few disturbances moving out of the Great Lakes region as well as the Midwest.

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We could see a little wintry mix at the onset after midnight on Sunday well north and west of D.C. but this is mainly going to be a cold rain event for the WJLA viewing area all day on Monday with the influence of warm air at all levels of the atmosphere. And FYI, it will most likely rain both during the morning AND evening commutes.

 

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Caption: Monday afternoon, snow stays well west with rain (green) around the region.

As that low moves off the coast into the evening hours, there is a chance the rain could quickly change to some light snow as cold air surges in from the west. Not expecting any accumulation around the D.C. area as that low will quickly move to the north and east, taking the precipitation with it.
After the precip moves out Monday night, another arctic high pressure will move in advancing even colder air into the region. Daytime highs on Tuesday and Wednesday may not make it out of the 30s!

Good news is, the Climate Prediction Center has our temperatures moving back towards normal (mid to upper 50s) by Thanksgiving week so there is an end in sight!

 

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The 1987 Veterans Day Snowstorm remembered

November 11, 2014 - 11:20 AM
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Above is some footage from Fox 5 during the 1987 Veterans Day Snowstorm. Thanks to Capital Weather Gang for finding this and I hope you all enjoy watching my friend Sue Palka discuss the storm. Notice that it reached the 60s the day before and the forecast was for highs in the 50s with scattered light rain. Let's just go ahead and hope this scenario doesn't repeat itself any time this Winter!

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Arctic cold front moves through D.C. midweek

November 10, 2014 - 12:23 PM
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Enjoy the mild temperatures while they last this afternoon through Wednesday, as unfortunately they won't hang around much longer. Conditions will remain very quiet and mild through Tuesday.

Wednesday will continue to be mild but a strong cold front is expected to enter the region, with gusty winds up to 20-25 mph and cooling temperatures through the afternoon and evening. After highs in the mid 60s Wednesday, morning low temperatures should be in the 20s and 30s by this Thursday.

Comparison of forecast 850mb temperatures this evening (left) and Thursday evening (Right) Courtesy: College of Dupage Models

For the tail end of the work week into the weekend, temperatures should hang in the 40s. The current forecast depicts highs in the upper 40s Thursday, low to mid 40s Friday and mid to upper 40s for the weekend. There is a chance the 50 degree mark may be reached on Sunday ahead of another cold push returning temperatures in the 40s possibly Monday through Friday of next week.

ECMWF Forecast Temperature Anomaly Friday afternoon (Courtesy: WeatherBell Models)

While this isn't statistically qualifying as extreme cold, it will be unseasonably cold for this time of year with highs forecast to be on the order of 10 to 15 degrees below average. In addition, Reagan National is yet to record a high temperature below 50 degrees this fall, and hasn't experienced a prolonged period of sub 50 degree days since March 24-26 when highs topped out at 43, 36 and 39 degrees and 1.7" of snow fell during the time period.

Speaking of snow, there has been talk about the potential for some flakes in the forecast over the past few days. As of our current forecast, the best possibility will be Thursday night into Friday morning mainly south and east of the city as a weak area of low pressure develops off the Virginia/North Carolina coastline. The best possibility to see any flakes would be closer to the Middle Peninsula of Virginia and points south and east. This system looks moisture-starved and too far east to affect the D.C. Metro at this time.

500mb heights and vorticity forecast for Sunday showing the next trough and energy allowing for the next better chance for precipitation (Courtesy: College of Dupage Models)

A stronger area of low pressure looks to develop for the latter part of the weekend on Sunday bringing with it an additional chance for precipitation, but at the moment it appears to be in the wet variety rather than white. We will of course keep you informed throughout the week of any forecast changes.

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Cold Air Headed Our Way after Remnants of Nuri Hits Alaska

November 7, 2014 - 12:01 PM
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After a windy Friday, we will settle nicely through the 50s for the weekend. The weekend forecast looking great! We may have a few clouds and a sprinkle here or there Saturday evening into Sunday morning, but for the most part, we are looking at sunshine!

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Nice weather will continue into the beginning of next week as a weak area of high pressure moves into the region. Temperatures will rebound back into the low 60s for a period of time before another cold front pushes through the region by mid next week. After that, big changes are on the way to our area.


Remember that Super Typhoon Nuri that I was harping about in my last blog? Well it is barreling down on the western coast of Alaska and the Bering Sea as it has now formed into a cold core low that is a very powerful storm. Most likely, one of the most powerful storms we have seen in 2014 and one of the most powerful storms to hit Alaska in decades. This storm could actually be a record breaker in that it could break the lowest atmospheric pressure recorded in Alaska. The old record was 925mb (millibars) that was measured in October of 1977 in the Dutch Harbor (off the southern coast of Alaska).

 

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Alaska will take a brutal hit from this storm this weekend with hurricane force winds, very high seas and heavy precipitation. As it stalls out during the end of the weekend and into early next week in the central Bering Sea, it will weaken significantly knocking down the odds of a large coastal flood event of the mainland of Alaska. However, this storm will have an effect on our weather around the continental United States as it causes a ripple effect for the jet stream.


Okay, let’s all calm down about a polar vortex (yes, I am talking about my friends around the country in the media). THE POLAR VORTEX IS ALWAYS THERE! I want to face palm myself every time I hear that (which has been about 40 times on social media and on TV in about 30 mins on this Friday morning). Here is a simple reminder:

 

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With that being said, yes we are going to get chilly towards the end of next week. Why? Well in simplest terms – behind a cold front that will cross through mid-week, a strong arctic high will build across the region and this little blast of chilly air is most likely due from the remnants of Super Typhoon Nuri as that storm will continue to pump warm air into the atmosphere in the western North America, surging cold air down across the United States.

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Cold air will filter out of the northern plains and continue to trek into the Midwest at the beginning of next week. As we head into the end of the work we and once that frontal system moves through and high pressure slides eastward across the United States, we are looking at temperatures around the D.C. area below average for this time of year.

 

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Caption: Cold air filters out of the Northern Plains on Tuesday afternoon.

 

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Caption: Cold air slides to the east coast by Friday as an Arctic High travels eastward across the United States.

Our average temperature towards the end of next week will top out in the upper 50s; however, we will most likely fall into the 40s by the end of next week. So we are not too chilly but chilly enough to take notice! And just a note, we have generally already fallen into the 40s in the D.C. area by this time so we have some work to do to catch up!

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Super Typhoon Nuri and How It Can Effect D.C. Weather

November 5, 2014 - 04:15 PM
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How much are you enjoying this taste of spring in November? Or would you rather like to keep your winter jackets on with cold air over us? Well, this is the first time I can honestly say we can make everyone happy with the weather forecast. For at least the next 10 days as we get a taste of both mild air and cool air thanks to the remnants of an incredible storm that will reshape near the western coast of Alaska by Friday.

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Caption: NASA’s Aqua satellite captured a visible picture of Typhoon Nuri on November 4th at 11:10p.m. EST as clouds (newly developed thunderstorms) replace the original eyewall.

In the short term, expect rain to roll across the region Wednesday night continuing through the first part of Thursday as a cold front finally works its way through the region. There will be another cold front that will swing through Thursday evening that could produce a few more isolated showers but for the most part, we will just be concerned with the winds and the cool air that will follow the front on Thursday night.


By Friday, temperatures will only rise into the 50s for daytime highs after only topping out in the upper 60s/lower 70s for the last few days.

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We look to stay in the 50s before another warm up into the 60s by the middle of next week followed by another cool down by the end of next week: a rollercoaster of temperatures if you will. And of course, this sounds like something we speak of almost every single month, no matter the season. However, for this forecast – there is an interesting addition to the puzzle. That piece of the puzzle is about 805 miles south of Tokyo, Japan today.

Super Typhoon Nuri is one heck of a storm. This is one of the most impressive and most powerful cyclones that has developed in the western Pacific in 2014. Not only did this storm reach the equivalent of a category 5 hurricane but it kept winds going at 180 mph for at least 24 hours with a minimum pressure recorded of 910mb!

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Wednesday afternoon, Typhoon Nuri moved to the northeast at 12 mph weakening as it migrates to the east of Japan entering into an area with pretty high vertical wind shear, ripping it apart as it travels. It is also moving into colder water, cutting off its moisture and supply feed. However, with that being said, the eventual remnants of Nuri will continue to move through open waters and towards the western coast of Alaska and the Bering Sea, reintensifiying as it navigates to the north and east becoming a storm-force cold core area of low pressure.

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Caption: The European Model shows the strong area of low pressure off the coast of Alaska with a forecast barometric pressure of 920mb.

By the time it reaches the Bering Sea and the western Alaska, the pressure is forecast to drop from about 970mb on Thursday night to between 918mb and 922mb on Friday night (the lower the pressure means the more intense the storm). In fact, the lowest pressure storm (obviously we are not talking about a tropical storm here) observed in the Bering Sea was on October 25th, 1977 where a storm by the Dutch Harbor (the islands the roll southwest off the southern part of Alaska) dropped to 925mb in pressure! *To give you a little comparison: the minimum barometric pressure of Hurricane Katrina’s second landfall was 920mb – which is the third strongest to make landfall*


(For all the weather nerds out there *I am obviously one so I welcome you with open arms*: The extreme drop in pressure will be due to the very cold air at the surface interacting with the warm air from Nuri aloft. This will make for a fast-moving wind surrounded by slower moving air that will eventually create a bombing out or an extreme deepening of that low-dropping the pressure rapidly).


Since this is such a powerful and impressive storm, we are talking about hurricane force winds for Alaska on both Friday and Saturday as well as seas that could reach more than 45 feet with abundant precipitation! Good news is that this low will weaken steadily through the end of the weekend and the middle of next week as it drifts slowly to the east.


However, all this energy has to go somewhere and generally when we see these types of situation, we can see effects across portions of North America as that energy gets pulled into the North Pacific jet stream. All in all, as the storm moved through the open waters of the Pacific, on its way to Alaska, it was already doing its deed and amplifying the longwave pattern downstream across North America. And what does that mean exactly? Well the remnants of Nuri will impact our weather forecast across the continental United States


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Caption: As the remnants of Nuri effects Alaska, we cool down quite a bit on the eastern seaboard with heavy snow and much cooler temperatures expected in the northern plains.

And back to our rollercoaster temperatures here on the east coast. While we are warming up here over the last few days with high pressure pumping in some nice southerly air, we will be cooling down as a front dives our way for Thursday. We look to stay cool through the weekend before yet another frontal system comes through on Saturday into Sunday. Warming up into mid next week, we cool down once again by the end of next week.


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Caption: A look a daytime highs possible next Friday are significantly cooler around the D.C. area.

While I think we will see minimal effects here in Washington D.C. that anybody will just chalk up to “regular weather changes,” it is very interesting to think that everything is connected in the weather world. A storm in the western Pacific could eventually impact our weather no more than 10 days later.

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