From the ABC 7 Weather team

Archive for January 2015

Winter Weather Moving In Sunday Night

January 24, 2015 - 08:54 PM
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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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A Series of Storms Headed Towards Us For the Weekend-Latest Details

January 23, 2015 - 12:43 PM
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Well here we go! A storm system that continues to approach us out of the southwest arrives this evening and will end by Saturday afternoon. A winter weather advisory (purple) is in effect this evening through tomorrow with the exception of Stafford, Spotsylvania, King George and the majority of Southern Maryland and a Winter Storm Warning is in effect for Winchester, VA, Morgan and Berkeley Counties in West Virginia and Washington County, MD.

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If your commute takes you to the southwest of the region tonight, you may want to try to scoot out a little on the early side given Friday traffic …and with added precipitation , we all know too well what kind of headaches that can cause. I wouldn’t be surprised if any sporting events (basketball, wrestling matches, etc) at area high schools are canceled given the going forecast, so please be prepared for that.

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We are looking at mainly rain to start as it moves in from the southwest to the northeast. There will be some snow mixed in and some pockets of wintry mix across the region as well. However, temperatures will still be relatively warm as the precipitation moves in. We will need to keep a constant eye on temperatures because of course, that will determine the type of precipitation as we move forward during the evening and late evening hours.

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Caption: Surface temperatures around 7 p.m. Friday evening. Notice all temperatures around the region are above freezing.

Rain showers, moderate to heavy at times, around D.C and areas south will continue through the overnight with snow and a mix to the north and west – that’s again where we can find the heaviest accumulation of snow.

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By the time daybreak comes around, we could see a changeover to snow for D.C. and areas north as temperatures drop to the lower 30s. There could be some sleet mixed in as well.

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When it’s all said and done we anticipate a trace to perhaps a slushy inch around the D.C. metro area with a few inches possible north and west of town.

I do believe travel will be impacted overnight into the first half of Saturday. Again, if your commute takes you anywhere north and west of D.C., that is where we are going to find the highest amounts of snow.
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All precipitation should be out of here as we go through the early afternoon hours on Saturday. Winds will pick up and we may even see some clearing as we continue into Saturday night. However, that will not last long. Our next system will be knocking on our door Sunday night into Monday morning.

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Caption: Sunday evening through Monday morning could see some rain change to snow with some snow accumulation on the ground by early Monday morning.


 

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Storm headed towards Washington D.C. right in time for the weekend

January 22, 2015 - 01:04 PM
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Welcome to winter. Finally it has arrived and finally we have something to talk about. A conveyor belt of systems are moving this way from different directions. Let’s take one at a time and first concentrate on the one Friday night into Saturday (the next after that will be Sunday night into Monday).

Most of the day Friday will turn out just fine. With a chilly start in store for Friday morning, we will start off with sunshine before clouds increase through the day. Temperatures on Friday will top out in the lower to mid 40s. While we are experiencing this in the D.C. region, a storm is getting organized moving through the deep South.

Thursday, a developing system moving out of the four-corners area and into the southern Plains is bringing lots of rain to Texas and eventually the deep South. On Friday, an area of low pressure will form along the northern portion of the Gulf of Mexico, eventually traveling north and east headed towards the Mid Atlantic.

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 Above Image Credit (Blacksburg NWS)

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Caption: Rain through the Deep South will eventually spawn a low off the VA coast as it moves towards the Mid Atlantic Friday.

As this low travels to the Mid Atlantic, it will eventually transfer its energy off the coast of Virginia Beach Saturday morning. In addition to that, there is a weak area of high pressure across the Mid Atlantic as well; therefore, we will have a feed of some relatively cold air filtering into the region but not arctic air and not a lot of it.

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As this low travels to the Mid Atlantic, it will eventually transfer its energy off the coast of Virginia Beach Saturday morning. In addition to that, there is a weak area of high pressure across the Mid Atlantic as well; therefore, we will have a feed of relatively cold air filtering into the region but not arctic air.

ZZZZZCaption: Area of low pressure off the coast of Virginia Saturday morning.

With all that being said, we can expect precipitation to move into the region late Friday evening moving from the Southwest to the North and East and moving out by Saturday afternoon. There are still some inconsistencies in models but the spread is decreasing with each run. We are still concerned about timing, track and the depth of cold air across the region.

It does look like we could see a mixed bag of precipitation ranging from snow, rain, freezing rain and sleet. We are not talking about big totals, but we are talking about enough precipitation to disrupt traffic through the area and areas north. This storm will eventually become a nor’easter as it travels up the eastern seaboard. Any bigger snow totals would of course be north and west of D.C. with more of a rain event for areas to the south, through central Virginia and southern Maryland. There is going to be a fine line with temperatures and the type of precipitation that will fall across any area. Just know to plan ahead and keep it here! We will continue to keep you updated.

After we get through this storm, we will have to watch for another clipper type system on Sunday night into Monday. Just fasten your seat belt, it could be a bumpy ride as we continue through the 2nd half of January.

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

January 20, 2015 - 10:30 PM
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TUESDAY NIGHT FORECAST UPDATE

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
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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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After a Calm Weekend, Prepare for a Dicey Monday AM Commute

January 10, 2015 - 12:05 PM
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Are you ready for possibly another messy commute? As if Monday’s aren’t terrible enough, this upcoming Monday, we will have to watch for some areas of freezing rain falling around the region, right in time for the morning drive.

High pressure that will bump up our temperatures slightly up on Sunday will head off the east coast. An area of low pressure will be pushing out of the Great Lakes region on Sunday night. It will eventually move into the New England area through Monday all while dragging a cold front eastward along with it. There is also a weak area of low pressure over Texas. The interaction between these pressures will allow for moisture to flow in from the Gulf and right into the Mid Atlantic.

 

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 Caption: Moisture headed to the D.C area on Sunday night at 8 p.m. from the southwest. This will eventually move into the region overnight Sunday into Monday morning.

As moisture moves into the region, we will have to keep a close eye on temperatures at the surface. Daytime highs on Sunday should reach into the upper 30s with increasing clouds through the day. However, overnight, temperatures will fall below freezing and may stay there at the time precip begins. Since the low levels will still be on the cold side (and forecast to be below freezing in most places) and with warmer air above the surface due to a southwesterly flow aloft, we are mainly looking at a freezing rain event for our region.

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 Caption: Temperatures at 7:00 a.m. on Monday morning should be just below or right around the freezing mark. Therefore, we will have to keep a very close eye on temperatures vs. timing of the precip on Monday morning.

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Caption: At 7 a.m. on Monday morning, this model showing a good chance of freezing rain falling across the area (pink).

 Any freezing rain will gradually turn to a plain cold rain as temperatures move up and top out in the upper 30s for Monday since there is no real source for cold air streaming into our region. The changeover to plain rain is expected through the mid-morning hours but again, the freezing rain in the morning will definitely be a concern with minor icing on the roadways (not expecting that much in accumulation of ice).


Rain will gradually end Monday evening but the cold air returns. Tuesday’s highs will only reach into the upper 20s/lower 30s behind the cold front. So pack your patience once again for Monday morning, you may need it.

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Tuesday's Snow Forecast and Perception Versus Reality

January 7, 2015 - 08:41 AM
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A school bus struggles to navigate snow-covered roads in Arlington. Photo: Eric Mensh

Public perception of a forecast is all that really matters. I have to admit that the forecast and what happened wasn’t a perfect match, but it was right on for the two most important factors of timing and impact. The snow totals fell short.  The storm started on time as advertised and created gridlock on area roads.

Despite this, there were many comments on social media stating that people weren’t expecting the snow to be a problem around Washington, D.C. on Tuesday morning. In particular, I’m talking about school authorities. As a meteorologist, I was surprised that some schools chose not to at least delay classes yesterday based on the best information available at 5 a.m. This was even before it was clear the heaviest band of snow was setting up right along the I-66 corridor.

As a parent, I was concerned about my daughter taking the bus five miles down winding, snow-covered roads to her school (my son is a walker, so no problem there). In addition, (full disclosure here, my kids go to Fairfax County Public Schools) I was confused as to why my county changed the calendar to build in as many at 15 snow days and yet chose to stay open. Many parents were outraged and expressed their opinions on Twitter. Soon the hashtag #closeFCPS was trending on Twitter worldwide.

So, what happened? I wrote a blog on Monday morning that you can find at this link. The headline is “Snow may snarl the Tuesday morning commute.” The StormWatch 7 Team was predicting snow to begin between “4 a.m. and 6 a.m.” and that “snow showers will continue until about noon.” The snow began at 4:52 a.m. at Reagan National. I also sent out tweets with this information.

In each of my weather forecasts on the air, I emphasized that the morning commute would be ugly. I said that while this isn’t a big storm, it will be a big impact while everyone tries to get to work at the same time as the snow is coming down. Heck, around here, just a little rain can make for a bad commute.

The Totals: This is where the message interpretations were likely different. Our forecast snow bands map was short of what fell in the major metro area due to a narrow band of heavier snow. I had most of D.C. in the same color band as southern Maryland in the Trace to Around 1” category. While Northwest D.C. along with Fairfax, Loudoun, and Montgomery Counties in the 1-2” range. While I mentioned the potential for a few spots with higher totals for banding, it's nearly impossible to predict where that sets up.  Here is that map we used to forecast snow totals before the storm.

Snowfall Forecast

  Obviously this is short of the final tallies you can find on this map.

Final Snowfall Reports via National Weather Service

I’m certainly not above criticism and improvement on my forecast. I take full blame for missing the higher snowfall totals. On this one, I’ve learned to watch the snow/liquid ratio more closely and to do a better job warning people about snow banding that can bring higher totals.
At Reagan National we had 2.4” of snow. If you melt that down, it equals .20” of liquid. That’s a 12/1 ratio. At Dulles, 4.2” of snow melted down to .28” of liquid which is a 15/1 ratio. On average, 10" of snow will equal 1" of liquid. This time around, it was a light, fluffy snow due to drier air and cold temperatures.
My main disappointment comes with finding that some people didn’t think the IMPACT message was clear. Even after admitting officials were wrong to keep school in session yesterday in Fairfax County their wording still blamed the weather or the forecast, not themselves.
“We apologize for the difficulties the weather caused this morning," the county's statement read. "Please know that significant area government entities were coordinating at a very early hour. The decision was made with the best information we had very early this morning. Needless to say, the conditions were far worse than anticipated." 
Maybe there was a bit more snow than expected, but the impact was as advertised. The right decision made with the best information available would have been to close schools for the day.

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Snow overachieves in parts of D.C. area Tuesday

January 6, 2015 - 09:46 AM
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LIVE DOPPLER RADAR  |  HD CAMERAS

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
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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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Happy Perihelion Day!

January 4, 2015 - 06:23 PM
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Ok, so this might be a geeky scientist’s way of celebrating a celestial event (I guess you can call it).

Today marks the ONE day out of the year when the Earth makes its closest approach to the Sun, even though the clouds blocked its rays in D.C.

To put the universe in perspective, the Earth has an elliptical shaped orbit around the Sun. Every year in the beginning of January, the Earth reaches its closest point to the Sun. Today at 1:36 a.m. EST is when that point was reached.

The Earth was 3 million miles CLOSER to the Sun than it will be in July when the Earth is opposite its position to the Sun or farthest from it. This year, that day, called Aphelion, is July 5th (so a reason for another celebration following Independence Day, right?). The exact time this farthest away point from the Sun is reached will be 3:41 p.m. EDT! The Earth will then be 94.5 million miles from the Sun as opposed to early January’s distance of 91.4 million miles.

Earth's distance from the Sun

Since the Northern Hemisphere (all land and ocean north of the Equator) is tilted away from the Sun’s direct rays in January, we still experience winter  despite the "closeness" to the warm Sun. In July, the opposite is true. The Northern Hemisphere is tilted TOWARDS the Sun's direct rays, so despite being 3-million miles farther from the Sun, we still experience summer.

Perihelion isn’t ALWAYS January 4th but it’s always in the very beginning of January. Similarly, Aphelion is not always on July 5th. For a list of dates through 2020, click here.

 

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