From the ABC 7 Weather team

Archive for category Seasonal January 2015

Winter Weather Advisory, Winter Storm Warning Monday

January 25, 2015 - 05:11 PM


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The Stormwatch 7 weather team has been working together a lot today trying to figure out the forecast over the next 24 to 36 hours. Our main thought is that this is a two-part system. The first being a clipper moving through the region tonight into Monday morning, and the second being the development of a coastal low which will take over tomorrow afternoon off the Delmarva and rapidly intensify as it moves into the northeast tomorrow night. Here is the latest.

The D.C. Metro is under a Winter Weather Advisory from 2am Monday morning through 6pm Monday evening. Areas of rain are already beginning to enter the western portions of the area and will continue to spread east overnight. Temperatures are still well above freezing and even eclipsed the 50 degree mark earlier today so will need to cool drastically overnight. Temperatures will cool into the 30s tonight into Monday morning, and rain will begin to change to snow late tonight closer to the Mason-Dixon line, and eventually to snow closer to the D.C. Metro tomorrow morning.

At this point, we think precipitation will change over to snow around the morning commute or towards the tail-end of the morning commute. Even IF precipitation changes over earlier, surface temperatures should still be just above freezing, so snow should be able to melt on contact with the roadways everywhere from eastern Loudoun, Montgomery and points east.

Locations that have seen colder air longer will have the chance for some accumulation on the roadways. Those regions include northern Loudoun and Montgomery Counties and points west. The highest likelihood will be in the warning area for Frederick Co. (VA), the Panhandle of WV and Washington Co. (MD) and points west.

The clipper's energy will transition to the coast Monday afternoon and light snow will continue to be possible throughout the day once it transitions from rain. The low is forecast to rapidly intensify off the east coast tomorrow evening into tomorrow night and race up the east coast.

When this happens, some heavier snow bands may be able to set up along and east of I-95 while the system is gaining strength off the coast. This will be the second part of the storm and another chance for disruptive snowfall in the D.C. Metro.

Currently, a Winter Storm Watch is posted along the Chesapeake Bay and points east Monday evening through Tuesday morning. There is a potential for 2-5 inches of snow in those areas along the Bay, with drastically more possible farther north and east along the Delmarva and into the northeast.

If the banding sets up a little farther west, the D.C. Metro or areas east including Charles, Prince Georges and north to Howard and Baltimore will have the potential for 2-5 inches of snow as well. Right now, there is a fair amount of uncertainty and we will have to follow the radar trends as the storm develops.

The D.C. Metro will have the potential for 1 to 3 inches of snow, with more north and west in some of the higher elevations as well as north to Baltimore and the Mason Dixon line. Regions south of D.C. such as Culpeper to Stafford and points south will have the chance for the least amount of snow from both portions of the storm.

This is a very difficult forecast and we will be doing our very best to keep you updated with the very latest information. Be sure to follow our facebook and twitter accounts and be sure to watch Eileen Whelan tonight on Newschannel 8 and ABC 7 News at 11pm. Jacqui Jeras will be live starting at 4am on ABC 7 News tomorrow morning and Newschannel 8 with Brian van de Graaff will start at 5am with the latest updates. Be prepared for delays, closings and travel disruptions through Tuesday morning.


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Winter Weather Moving In Sunday Night

January 24, 2015 - 08:54 PM

One system moves out and yet another is on its heels.  An Alberta clipper is diving out of Canada and is currently over the northern Plains.  This clipper will continue it's trek southeastward and will bring snow to parts of our area by dinner time Sunday.

The National Weather Service has issued a Winter Storm Watch for northwestern parts of the ABC 7 viewing area from 9 PM Sunday through 9 PM Monday.  A winter storm watch is issued when 5", or more, of snow is possible.

Clouds will increase Sunday with a rain/snow mix beginning around dinner-time (6 PM) in our far northwestern zones.  As temperatures fall, precipitation will transition to all snow after midnight.  Snow will fill in across the rest of the area overnight Sunday.  Here's our in house computer simulation at 7 AM Monday.  Blue=snow.  Pink=mix. Green=rain.

Snow showers will greet you Monday morning with school closings and delays likely.  Good Morning Washington will begin at 4 AM Monday and will have all of that information. 

Temperatures will stay in the lower 30s Monday with light snow showers continuing throughout the day.  There is still inconsistency within the models, but at this time, I think our StormWatch 7 futurecast model has a good handle on preliminary snowfall totals.

The clipper will transition to a strong coastal storm and will be a major snow storm over the Northeast.  Strong NE winds will kick up Monday with the deepening area of low pressure.  That means some blowing snow showers Monday, which could result in reduced visibility.  Check out the 988 mb low, forecast by the GFS model, by 8 PM Monday.

WeatherBell Computer Models - 18z GFS

It's still uncertain the exact track of the low, which will have an impact on snowfall accumulations in the area.  You'll want to stay with the StormWatch7 weather team throughout the day Sunday for additional weather updates, as new information becomes available. 

Regardless, expect a snowy Monday morning commute with delays and closings likely. 

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Another clipper headed for the D.C. area Wednesday (Update)

January 20, 2015 - 10:30 PM


Temperatures have dropped into the upper 20s to lower 30s across the region late this evening and should pretty much hang here for the majority of the night. Low pressure associated with the clipper system is still over the Midwest but will reach the D.C. area by tomorrow.

Looking at some of the latest data, we're still expecting much of the same with light snow and even some rain beginning in the morning hours. At this point, I would only expect a few flurries in the early morning between 6am and 8am. The more steady and possibly even heavier precipitation appears like it will move through the region between 11am and 4pm.

Snow appears more likely north and west of D.C., with a mix of rain and snow closer to the Metro, and more rain than anything else south of D.C. Travel problems appear likely during this time, and schools may be delayed, cancelled or even let out early because of this. If not, it may be a mess on some of the area roadways during the early afternoon.

If you're working tomorrow and commuting anywhere north and west of D.C., remember travel problems will be likely for the afternoon and evening rush, so plan accordingly. We will of course be updating the forecast and following the system as it pushes through the region so will have updates on air throughout the day.

Road temperatures in and around the Metro will have a chance to warm so may be marginal at or near freezing. This could allow for some melting, but areas north of D.C. may not be as lucky and may possibly experience accumulations due to heavier snowfall rates.

Forecast temperatures Wednesday in D.C. (Courtesy: NWS)

With this system, temperatures will be around the freezing mark, so a mix between rain and snow will be likely. Current forecasts tonight even bump temperatures up a few degrees after sunrise which will help the road temperatures. Be sure to monitor road conditions at the links below.

Current Road Surface Temperatures in Maryland

Virginia Road Conditions and Cameras

As far as snowfall totals are concerned, we still think the heaviest accumulations will be north and west of D.C. where more cold air is available. Here is a look at our snowfall map.

Snowfall Forecast for Wednesday

The D.C. Metro will have the potential for up to an inch or so of snow. Areas north and west including northern Montgomery, Loudoun, the Panhandle of West Virginia to the Mason-Dixon will have the chance for 1 to 2 inches of snow. Areas closer to the Mason-Dixon will actually have a chance for 2 to 3 inches of snow, especially norther Frederick into Carroll and north of Baltimore and points east.

Winter Weather Advisory for the D.C. Metro and points north and west Wednesday

A Winter Weather Advisory has been posted for the D.C. Metro and points north and west from 6am to 6pm tomorrow. Areas west of the Blue Ridge have the Advisory starting at 4am and continuing until 6pm. We will continue to have the very latest on ABC 7 News and NewsChannel 8 starting at 5am tomorrow.

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Chance for light snow or wintry mix Wednesday morning for the D.C. area

January 13, 2015 - 11:17 AM

Latest guidance has changed some over the past 12 to 24 hours to start depicting a better chance for light snow or a light wintry mix across parts of the D.C. area.

The system appears to have the same timing as last week's clipper which crippled the morning commute in the D.C. Metro, but this time around, the best chance for measurable precipitation looks to be south and east of D.C.

Snow and Wintry Mix Potential

Above is a look at our first guess, with light snow possible from around 4am to lunch time in the D.C. Metro. Regions south and east of D.C. may experience a longer duration, with precipitation beginning earlier and ending later tomorrow afternoon.

We have a low to medium confidence in this system as this has been slow to show up in the models. With temperatures forecast to be in the 20s tomorrow morning, even light snow will have the potential to stick to the area roads and treatments may not have much of an effect.

Advisories and Winter Storm Watch south of D.C.

Currently, there aren't any advisories in the D.C. Metro area itself, but places south of Richmond east to the Tidewater and south into North Carolina have the potential for light to moderate icing. Some locations are forecasting an inch to two tenths of an inch of ice through the day tomorrow. It is our guess that these advisories will spread north this afternoon and we will update you if they do.

Our team doesn't want to take any risks with this system since the same modeling that handled the Clipper very well last week is depicting the same light snow scenario for tomorrow morning. With the timing, the cold air in place, and the light precipitation again expected, we don't want to see a repeat of last week, so please plan accordingly and if you need to be at work tomorrow be sure to allow for extra time to get to your destination.

The system itself is much different from the clipper that moved through last week. The forcing doesn't appear to be quite as strong, and upper-level dynamics don't look as favorable with a weaker jet, but the potential still exists.

As always, this will be an evolving weather system and we will be here throughout the day delivering the very latest information.

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Snow overachieves in parts of D.C. area Tuesday

January 6, 2015 - 09:46 AM


A potent Alberta clipper pushed through the region at the absolute wrong time this morning, dropping measurable snow across the D.C. Metro. Timing was about perfect as far as the modeling was concerned but snowfall totals have definitely been more than the 1 to 2 inches that was forecast. We thought there would be a few pockets of 3 inches as of yesterday evening, but some spots received up to 5 inches west of D.C. in Loudoun and Warren Counties!

The combination of the timing, the cold and more snow than expected made for a terrible commute this morning as pre treatments didn't work and plows couldn't get to work until a few inches of snow fell, leading to white roads across the area.

With the cold temperatures in the 20s and teens this morning, it appears snowfall ratios were higher than expected, so it will be good to see what the ratios were when the event is over. Snow is already beginning to taper off from west to east, with the back edge moving into the Metro as of 10am.

Live Super Doppler Radar as of 10am

Patches of flurries and light snow showers will be possible through the early afternoon but additional accumulating snow west of D.C. doesn't appear likely.

Here is a preliminary snowfall total list from the National Weather Service in Sterling, VA. The highest are listed below. Please tweet me @alexliggitt your snow totals and any pictures you would like to see on air.

Front Royal, VA: 5.3"

Middleburg, VA: 5"

Aldie, VA: 4"

Reston, VA: 3.1"


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Snow may snarl the Tuesday morning commute

January 5, 2015 - 02:09 AM

It's been a bit of a snow drought so far this season with only a trace reported at Reagan National Airport. As of this blog, we have a snow deficit of 3.3" and a deficit of 3.1" at Dulles. However, we should put a dent in that tomorrow with a good chance of around an inch of snow in the Capitol City.  It's not much, but it would be the first measurable snow this year. When you sync that up with the morning commute, it often means trouble on the roads. An Alberta Clipper will dive through the Midwest today and arrive in the Mid-Atlantic before dawn Tuesday. Here is the latest ABC 7 snow futurecast model to show the timing of the snow.

Snow Starts Before Dawn

A clipper is a fast moving system. Temperatures in all layers of the atmosphere will support nothing but snow. However, since it moves pretty quickly, accumulations will stay light. The snow is expected to develop in D.C. between 4 a.m. and 6 a.m. Snow showers will continue until about noon. Areas north and west of the city could see around 2" with around 1" downtown. Southern Maryland will get just a trace of snow.  Here is our ABC 7 computer model snowfall prediction through Tuesday evening.

ABC 7 Futurecast Snow Totals

And here is what the ABC 7 Stormwatch team of meteorologists is predicting.

Stormwatch7 Team Forecast

Good Morning Washington will go on the air early at 4 a.m. to give you the latest information to help you through this inconvenience. Set your alarm early for that and also to give you extra time to navigate the roads.

The winter weather doesn't stop with the snow on Tuesday. Following the clipper will be bitter cold arctic air. It will be the coldest so far of the season. It will have been almost a year since we've experienced temperatures this cold. Thursday morning will be the worst of it with temperatures in the low teens downtown and many spots north and west will drop into the single digits. Here's a look at the GFS computer model temperatures on Thursday morning.

Model Map WeatherBell

Highs on Thursday afternoon will only reach the mid 20s. Temperatures will slowly warm up this weekend into the 30s. Make sure you have the Stormwatch7 app downloaded for live radar and updated blogs and conditions this week. you can download it here. Also, I will be tweeting through the morning drive and broadcasts. Follow me @JacquiJeras.

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