From the ABC 7 Weather team

Archive for February 2013

Potential for snow less likely in the D.C. area (Afternoon Update)

February 13, 2013 - 04:00 PM

Wednesday Late Afternoon Update:

With widespread temperatures in the low to mid 40s, scattered showers, and road temperatures in the 40s, we don't think this system will be much of an issue for the D.C. Metro or even points north and west at this time. There have been a few reports of flurries or snow showers at the onset of precipitation in the Shenandoah Valley, but otherwise, it's been all rain out there.

The main energy is still expected to push through the area later this evening between 5pm and 8pm, and showers will continue to be possible. There is still the slight chance for a few light snow showers, mainly north and west of the D.C. Metro closer western Loudoun and Frederick Counties and points west. Higher elevations will have a much better shot of seeing light snow. Here is a look at the 4km NAM model for 8pm tonight, showing the potential for a few flakes west of the Blue Ridge.

4km NAM forecast for 8pm this evening (WeatherBELL Models)

As far as the D.C. Metro is concerned, a few flurries may be possible around 8 or 9pm tonight, but we wouldn't be entirely surprised if precipitation never changes back to snow before ending. 

Previous Discussion Below

Wednesday Morning Update (Adam Caskey): The latest guidance is not looking good for snow lovers.  As of now, it looks as though temperatures will be a little too warm for much snow to fall across the abc7 viewing area later today.  That said, minor accumulations are still expected north and west of Washington, D.C.  As for the metro area, the most likely scenario is a light frosting of snow on some grassy areas by late in the evening.  A breakdown of the snow odds for the D.C. metro is shown here:

Metro Area Snow Odds

I think our Microcast (shown below) has a pretty good handle on the situation, but it may be underestimating snow amounts in the hills west and northwest of Washington.  As usual, higher elevations will have more snowfall potential, so 1-2" is possible in the hills just west and northwest of D.C. including but not limited to parts of Loudoun, Fauquier, Frederick and Washington Counties.  We'll have another update close to noon as the rain begins, so check back to see if anything changes.

Microcast Model

An area of low pressure will move into the area on Wednesday bringing with it the chance for rain as well as the chance for snow. With temperatures in the 50s today ahead of the system, we think much of the area will not see much in the way of accumulation. Some areas may receive a couple of inches, with the highest potential for accumulating snow well north and west of the D.C. Metro.

HPC Probability of >= 1" Snow

Above is a look at the latest probabilities for greater than or equal to one inch of snow from the Hydrometeorological Prediction Center which is fairly close to what we are thinking. This gives about a 40-50% chance for an inch of snow in the D.C. area, though we think that would mainly be on the grassy surfaces given the rain at the onset of precipitation and the warmer ground temperatures. There is a much higher likelihood (80-90%) of accumulating snow north and west of D.C., particularly in the higher elevations towards the Blue Ridge and even areas such as northern Montgomery County.

Our current thought is that precipitation will begin in the form of light rain or sprinkles tomorrow morning during the latter part of the commute (9-10am). More steady rain should continue for the D.C. Metro and points south and east through the afternoon hours, with the potential of a couple tenths of an inch. Rain will changeover to snow by the afternoon hours north and west of D.C., where colder air will filter in as the low passes just south of the area. We think this will mainly occur along and west of the Blue Ridge first, but then also changeover in Frederick, MD and northern Loudoun and Montgomery counties as well.

4km NAM for 7pm Wednesday evening (WeatherBELL Models)

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Blizzard of 13: How much snow really?

February 11, 2013 - 04:30 AM

I admit I'm a bit weird and grew up loving weather. Here is an example and a fun calculation of why. 

This is a great satellite picture taken on Sunday at about noon of snow covered New England and the Northeast from the TERRA satellite, thanks to the great MODIS today site at the University of Wisconsin.


How much snow do you think is there?  Let's calculate it.  Here are the "Blizzard of '13" snow totals:


Here's the total melted precipitation for the last two days from this great NWS site over the Northeast:


This entire region has an area of about 180,000 square miles.  Let's say roughly 1 inch of precipitation fell over that area from the 2-day blizzard.  Certainly Boston, Hartford, Providence, New York CIty and Portland, Maine got 20 to 30 inches of snow, or 2 to 3 inches liquid.  Let's be conservative and estimate about 1 inch of melted snow for the Northeast. 
We know 1 inch of rain per square mile is about 17 million gallons of water.  So 12 inches of snow (1 inch of  rain) over 180,000 square miles gives us about 3 trillion gallons of water, and at 8 pounds of water per gallon, about 10 billion tons of snow from the blizzard.
This doesn't even include the snow that fell on the ocean and melted.
So, let's imagine if all of that snow that fell from the "Blizzard of '13" was piled on the National Mall in Washington, D.C.

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Areas of light snow in the D.C. area Friday morning

February 8, 2013 - 02:39 PM

The strong winter storm that is affecting the northeast actually ended up dropping a couple inches of snow in parts of the D.C. area this morning. I actually woke up at 2 am this morning in Arlington and saw some light sleet, but in the higher elevations west of the city, and even lower areas just east of the Blue Ridge, there was enough cold air available for light snow.

Susan McVeigh from Bull Run Mountain

Here are some of the light snowfall totals from this morning from the latest National Weather Service statement. Madison, Culpeper and Fauquier Counties in Virginia had some of the higher snowfall totals, with 5 inches reported in Reva (Culpeper), 4.5 inches in Haywood (Madison) and 3 inches in Opal (Fauquier).

Valerie Waters from The Plains, VA

A few other areas reported an inch or less, but looking at our HD WeatherBug cameras, much of the snow melted already as temperatures have climbed above freezing.

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Blizzard of '78: Being There

February 8, 2013 - 04:00 AM

The monster storm that will be hitting New England Friday and Saturday (Blizzard Warnings up) is being compared to be possibly as great a storm as the famous "Blizzard of 78".  I was in Boston in the early years of my broadcast meteorology career and did have some "period" sport coats. 


The "Blizzard of 78"  was (and still is)  the greatest, most powerful, most devastating winter storm I have ever seen, forecast or experienced!!  The storm was likened to a winter hurricane and indeed a satellite picture (early GOES) of the storm does show similar structure to a hurricane and even had an eye.


One of my great on air bloopers of all time happened only a few weeks before the blizzard.  What many forget is Boston was hit by a huge snow storm in January, 1978 - 22".


After that storm ended, big mouth Ryan told folks in Boston, "Remember this storm well, we won't see a storm this big for a long time".  A "long time" turned out to be 3 weeks.  This was what the Boston beltway -Rt 128 looked like days later. 


Compared to today's very accurate and detailed weather "models" or simulations of the atmosphere based on physics and mathematics, the weather models in 1978 were fairly crude.  There was no Internet, no Doppler radar and much of the critical weather information came through old facsimile machines, paper maps and teletypes. 


I was working with legendary Boston meteorologist Bob Copeland 


We and the local National Weather Service office in Boston were very confident that the February 78 storm would be a big storm, "Heavy Snow Warnings" and "Near Blizzard Conditions".  But it was a real blizzard.  The evening and night before the storm hit, I forecast snow of 18" which I thought was pretty bold at the time.   A foot and a half of snow.  I missed by about 18".  Here is the snow fall from that historic storm.


Bob and I did have radar.  But it was a radar image that came from an old NWS radar south of Boston as a small scanned image. We  could barely make out the image,  we sure could not show  that on local TV news.  We could see what looked like a wall approaching and watched the teletype weather observations and reports from New York and Long Island and could see what was coming. Indeed  It turned out to be a wall of snow.  We watched out the window on the afternoon of February 5, 1978 as the visibility went from a few miles to 1/4 mile in minutes.  The snow would not end for 36 hours!  Look at the weather map 36 hours after the snow started. 


Bob and I were working together 24 hours (several hours off each) and shared a motel room just across from Channel 5.  At the first height of the storm, about 2AM, I headed off to the motel, which was also near many TV and radio transmitter towers west of Boston.  The lightning and thunder was continuous. . . .and scary.  Snow was horizontal, falling at 2-3" per hour and lightning and  thunder!  I have never experienced or seen anything like that late night since.  The storm not only crippled any traffic but the high tides and storm surge devastated many towns facing Massachusetts Bay.


We worked for 3-4 days straight.   Neither of us got home for days.  There were 3-5000 cars abandoned in the area in impassable snows.   


The storm reduced neighborhoods along the Massachusetts Bay to ruble with the combination of hurricane winds, high tides and what would have been a storm surge for a hurricane.  Almost 300 lives were lost including many people who died of carbon monoxide poisoning or cold and were lost on the Boston Beltway Rt 128 with no emergency workers able to reach and rescue people .  The storm was indeed a monster.  I finally got home to my safe family 3 days later and measured 48" of snow in my yard.  I was lucky.  Everyone was fine.  It was the greatest and worst snowstorm I have every seen, experienced and forecast.  I love snow but not storms that destroy like this "Blizzard of 78" and I sure hope not like this coming "Blizzard of 13" for New England. 

For much more and all the credits here is a terrific resource from the NWS Boston office.

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New England Braces for a Major Winter Snowstorm

February 7, 2013 - 04:52 PM

New England is bracing for a historic winter snowstorm.  Between one and three feet of snow is possible and, on top of it, winds could gust to 65mph at times.  Blizzard warnings are in effect much of New England, including Long Island, Harford, Boston, and Portsmouth. 

Check out the latest snowfall accumulation maps from the Boston forecast office.  The heart of the storm will impact northern Rhode Island and eastern Massachussetts.  Over 2 feet of snow could fall in the areas shaded in white.

The coastal storm is in its early stages of development.  The storm system, currently over the southeast U.S. will rapidly intensify, as it moves up the coast.  The low will then then merge with energy from a weather front, currently over the Midwest, and explode off the coast of New England.

This is going to be a snowstorm of epic proportion that will go into the records and will rival the Blizzard of '78.  More updates to come.

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Winter Weather Advisory for Parts of the D.C. Aarea Friday

February 7, 2013 - 04:11 PM

A potent winter storm is heading for the northeast, but the same system will move through the D.C. Metro before intensifying off the east coast tomorrow evening. A Winter Weather Advisory is in effect for areas west of the D.C. Metro including Loudoun and Fauquier Counties in Virginia and Frederick County in Maryland and points to the west. Below is a graphical look at the current advisories posted for the D.C. Metro.

So what should you expect when you wake up tomorrow morning? As far as the D.C. Metro and points east, rain will be the likely form of precipitation with up to a quarter of an inch or more of precipitation along and east of I-95.  The heaviest rainfall totals will fall over the Eastern Shore with up to 3 inches possible along the coast.

Farther north and west, in the advisory area, temperatures will be close enough to freezing where sleet, freezing rain, and some wet snow will be possible very early tomorrow morning.  Accumulations will be little to none, but it could cause a few slick spots for the Friday morning commute.  After about 8am, temperatures in the northwest suburbs should climb above freezing and a transition to a chilly rain will occur.  Here's one simulation of temperatures tomorrow morning at 3am. 

18z HighRes NAM

As the coastal low intensifies off the New England coast late tomorrow night, colder air will filter in and north winds will pick up.  It will feel like winter!  Also, some wrap around snow bands will move through late tomorrow afternoon and evening, but little to no snow accumulation is expected.  The image below shows snowfall totals through 4am Saturday with a tenth of an inch of snow predicted over D.C. and slightly higher amounts north of Washington.  The highest snowfall totals, as usual in this area, will occur over the high spots

The confidence with this forecast is fairly high.  New England will certainly get the brunt of this storm and it will go in the history books, for sure. 

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Historic Snowstorm?: Now a Blizzard Watch

February 6, 2013 - 04:38 PM

More and more the storm that is just beginning to form in the Gulf will become a major snow storm for New England.  Jacqui gave a great overview of this storm earlier today.  The storm will see the convergence of a weak storm moving from the west, merging with a strong storm/wave from the southeast and becoming a "monster" for New England.  Our regional Futurecast nicely captures this sequence in the next two days. 


A blizzard watch is now out for the Boston area. 


  One of the great tools for forecasting these storms is not any 1 model or simulation of the atmosphere but the ensemble or the simulation of a number of "models".  Here is the output of an ensemble from earlier today looks like from the great site at PSU.  Not a big threat for us and that red line well to our north suggests any precipitation here  would be rain, not snow  


And here is the ensemble output of total precipitation for the Northeast by Saturday. 


Have friends in Boston and other areas of New England?  The dark red region is 3" of precipitation or, if it comes about . . . close to 30" of snow!!  Tell your New England friends to get ready and for snow lovers here in the D.C. area . . .well you could still get a flight tomorrow to Boston.  But be prepared to be there for many days.


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Coastal storm developing for Friday

February 6, 2013 - 09:59 AM

Some excited buzz in the weather world and snow lovers today as confidence is growing that a major nor'easter could hit at the end of the week. At the time of this writing, an area of low pressure is developing along the Gulf of Coast. In addition, a weaker storm in the Northwest is tracking along the northern branch of the jet stream. The two are expected to come together off the mid-atlantic coast on Friday and potentially dump as much as 20" of snow in parts of New England before the end of the weekend. That's the snow lovers version. And hey.. what about us in D.C? As often is the case, the DMV will be on the edge of the storms and due to timing, the precipitation type is iffy, at least at the start of the storm. Here's a look at the GFS forecast for Friday midday.

GFS Computer Forecast Friday Midday

It shows a tightly wound low pressure off the Virginia Coast. And here is the European version of the storm for Friday early evening.

European Computer Forecast Friday Evening

The models are similar in positioning and intensity, so confidence in this becoming a big impact storm for New England is growing. But for us, there is less confidence at this moment. The precipitation should arrive overnight Thursday and into the wee hours of Friday... around 2 a.m. (give or takea few). A wintery mix at onset is most likely, especially north and west of D.C. with a transition to rain later in the morning. Rainfall amounts could reach a half an inch depending on the exact time the rain starts and just how close the low develops to the coastline. The computer models are keeping us pretty warm overall with temps near the freezing mark on Friday morning, and warming into the mid to upper 40s later. 

Forecast Temperatures Friday Morning

The computer models tend spill out numbers that trend warmer than the usual outcome in similar situations. I think the air will cool as it moistens up before the actual precipitation falls. So I do have some concern just 30 miles or so outside of the city for dicy conditions Friday morning. The coastal storm will last through the day for our area with breezy conditions to go along with the rain. As the low travels up the coast it will have a major impact on New England. Boston will be the hardest hit city in the Megalopolis with 8-12"+ possible. Here's the forecast snowfall totals at this time from their local NWS office. 

Boston Snow Forecast Friday

As for totals for all the the northeast, I think this map from AccuWeather has a good handle on it. 

Northeast Snowfall Forecast Accuweather

Stay tuned for forecast changes on this developing storm. Confidence is medium for D.C. right now. I expect to fine tune timing and precipitation type in the coming 36 hours.


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It's National Weather Person's Day!

February 5, 2013 - 03:33 PM

You plan your day around the weather.  Do you need an umbrella?  Is it a good day to head to the pool?  Is there a risk for severe storms?  Or is another snowmaggedon heading our way? 

Whenever you need an answer to these questions, you turn to a weatherperson.  Today, February 5th, is National Weather Person's Day.  The day commemorates John Jeffries, one of the first American weather observers.  John Jeffries, born February 5th, 1744, began taking weather measurements in 1774 in Boston.  Jeffries also took the first weather balloon observation in 1784. 

John Jeffries

Since then, the study of weather and climate has evolved greatly and better forecasting tools and techniques are available to provide increasingly more accurate short term and long range weather forecasts.  Meteorology and climatology are still growing sciences, but forecasts continue to improve on a daily basis. 

Don't forget to recognize the forecasters who prepare you for daily weather, the "big storms", and an ever changing climate.  

Cheers to the incredibly large and talented Stormwatch 7 Weather Team:

Doug Hill, Bob Ryan, Jacqui Jeras, Adam Caskey, Brian van de Graaff, Steve Rudin, Devon Lucie, Alex Liggitt, Eileen Whelan, Dave Zahren, Lauryn Ricketts, Chad Merrill, Mike Stinneford, and Ryan Miller.

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Phil Says An Early Spring! But How Accurate Is The Groundhog?

February 5, 2013 - 05:00 AM

So Punxsutawney Phil didn't see his shadow, which means an early spring... but does it really?  How accurate is this groundhog? 

NOAA put together a great table of Phil's forecast vs. the U.S. National Temperature for February and March dating back to 1888.  Check it out.


Now Phil's been predicting the spring forecast for quite some time.  In fact, he's the oldest weather person in the books!  The Groundhog Day tradition has been around since the 18th century.  It's an ancient celebration of the midpoint between the winter solstice and spring equinox.  Groundhog day occurs every year on February 2nd.  Legend has it that fair weather is a foreshadowing of a stormy and cold second half to winter. 

When Phil emerges from his hole, after a long winter's sleep, on February 2nd if he sees his shadow, Phil thinks it's an omen, and returns to his hole for six more weeks of winter.  If Phil does not see his shadow, he takes it as a sign of an early spring and stays above ground.  

Phil has predicted an early spring this year, but according to NOAA's research, Phil's not getting the forecast correct, as often, especially in the most recent years. 

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D.C. snow forecast: the "clipper craze" continues

February 4, 2013 - 09:09 AM

Here's a stat for you: Reagan National Airport (DCA) has recorded at least a trace of snow in 8 of the past 12 days.  This amounted to a mere 1.3 inches at the airport because of the weak nature of the clipper systems causing the snow.  Dulles received 2.4 inches in that time.  Today should be the fourth consecutive day with snowfall as yet another clipper slides into town, and Tuesday should mark five days in a row.

The "clipper craze" started back on January 23rd and continues through tomorrow as two more weak systems speed through Washington with a dusting to light coating of snow.  The first is expected Monday evening with areas of light snow into Monday night. 

Accumulations should be under an inch in the metro area and for most of the abc7 viewing area, but just over an inch is possible closer to Frederick, Hagerstown, Martinsburg, Winchester and areas in between.  Also, as usual, the western facing slopes of the Potomac Highlands should get 5 to 8 inches due to topography and elevation (That's you Frostburg, MD). 

Then the second clipper sneaks through Washington on Tuesday night, but as of now, we're just expecting flurries to a dusting of snow.  It looks like the clipper craze will come to an end by midweek with highs in the 40s and rain possible by Friday.

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The Wild Week, And Month, of Weather That Was

February 2, 2013 - 05:00 AM

It was a wild January with temperature roller coasters, heavy rain, the first snow of the season, for some, and a true arctic blast.

With all of the ups and downs, the month ended 4.3 degrees above average.  Precipitation was below average by 0.28", but nearly half of the rain this January, at Reagan National, came from the end-of-the-month soaker with a strong cold front.

Satellite & Radar composite from January 30, 2013

Now other parts of the region received MUCH more rain with that same system, in fact, over the monthly rainfall at Reagan National.  I tapped into our WeatherBug network to find the highest rainfall totals from the January 30-31st rain storm. 

Rainfall totals January 30-31st

Ahead of that front, we had our warmest temperatures of the month.  The highest temperature of the month at Reagan was 72° on the 30th. No record at DCA, but Dulles' high of 72° broke the previous record of 70° back in 2002.   Keep in mind, our average high for the beginning of January is 43° and by the end of the month 44°. 

Not only did it feel like April in January, it also felt like the Midwest with a bitter blast that plunged into the region on the 22nd.  For four consecutive days, the temperature never climbed above freezing.  The lowest temperature over the entire month at Reagan was 15 degrees on the 23rd.  That was the coldest it had been in nearly 4 years.  The lowest temperature before then was on January 17th, 2009 with a low of 8 degrees.

And with the arctic air mass came some of the first snow of the season.  Snowfall in D.C. was 0.9", but there were certainly some higher amounts across the region.  Average January snowfall is 5.6", so this month was certainly well below average. 

Brianne Carter

We begin the month of February with unseasonably cool temperatures and snow.  Will this be the a colder and snowier than average month?  It's way too early to tell.  Looking back at January, there was a little bit of everything!  I guess we'll just have to wait and see.

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Road Salt: Too Much or Safe?

February 1, 2013 - 04:31 PM

The timing of  when to apply road salt to area roads, and how much to apply is always a tricky decision.  This morning was another example, of many this winter, of only a little snow really  caused only  a few problems in a metropolitan area of 3-4 million drivers.  But the timing was terrible.  Even for a "dusting" to 1" 


The light fluffy snow started around 5AM and was over around DC by 8AM.  In D.C. another 0.2" of snow and the total for the winter is now "only" 1.2".  Road crews had pretreated most major area roads and the dusting to 1" didn't cause major widespread problems.  The the question is are we over salting, or pretreating roads and using too much salt before ANY snow?  We had this recent poll. 


Many folks think we are using too much salt.  So far just in D.C. about 10,000 tons of salt have been applied to roads.  That works out to about 8,000 tons of salt per inch of snow.  This is what K street looked like after a dusting last week.  


White, salt covered streets probably insure maximum safety, but all the rain early this week washed that salt into area streams and rivers and eventually into the Cheseapeak Bay.  What do you think?  Should area transportation officials try and minimize the use of salt, especially if the forecast is only a "50% chance of light snow" or there may only be a dusting?  All of us just drive slower and carefully and don't try to go 60 mph on slippery roads?  What's the balance between safety, local government responsibility and ending even an average winter with almost 1 million tons of road salt from the entire region, being added to area waterways and the Bay.  Difficult decisions-what do you think?


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VIDEO: Spectacular "real time" moonrise

February 1, 2013 - 01:30 PM

In his own words, photographer Mark Gee explains how he captured this awesome moonrise.

"Full Moon Silhouettes is something that I’ve wanted to capture for over a year now. The video is a real time capture of the moon rising over the Mount Victoria Lookout in the capital city of Wellington, New Zealand. On the evening of January 28th, 2013, after a lot of planning and many failed attempts, I finally managed to pull it off.

There were numerous factors I had to consider and get right to capture the footage. The weather, moon phases and finding a suitable location where I could actually get the moon rising directly over the lookout. Finally it all came together – I found the perfect location, and the weather in Wellington was amazing! Luckily there were people watching the moonrise from the lookout. I didn’t know what to expect with the performance of everyone up there, but I couldn’t have directed it better myself, even though they had no idea I was filming them. I shot 8 minutes of footage between 9.14 PM and 9.22 PM and the finished edit shows about the first three minutes of that.

Technically, getting the shot was quite difficult. I about a mile away and there was no room for error. I only had one chance of getting the shot right on the night. Thankfully it all came together, and what I ended up with was this wonderful performance of total strangers silhouetted against the full moon as it rose above the lookout."

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