From the ABC 7 Weather team

Unprecedented Quiet Start to Tornado Season

March 24, 2015 - 05:40 AM
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Zero. None. Nada.  That's how many tornadoes have been recorded in the United States so far this March.

Preliminary Tornado Count 2015

March tends to be a busy time for severe weather forecasters, but so far not only have there been no tornadoes this month, there hasn't even been a watch issued.  According to Warning Coordination Meteorologist Greg Carbin at the Storm Prediction Center in Norman, OK where watches are issued, it is unprecedented.

Source: Storm Prediction Center

Carbin says this has never happened since the Storm Prediction Center has been keeping records dating back to 1970.  Typically there will have been dozens by this time of the year.  On average, 130 tornadoes are recorded from January through mid to late March. This year there are 28 preliminary reports from January and February combined. That's 10 percent of average.

U.S. Tornado Trends

Most severe weather this time of the year happens in the south. But, tornadoes can and have occurred in any month of the year in Virginia and Maryland. 

March Severe Weather Probabilities

Why has there been such a lack of tornadoes?  You can thank the chilly temperatures in the east for one thing.  We've had a persistent pattern that has not allowed much moisture, heat or instability from the south to clash with cooler arctic air from the north. 

On average Virginia will see 18 tornadoes a year and Maryland will experience 10.  Most of those tornadoes occur between April and September. 

Tornado Climatology by State

Will the quiet start to the season continue?  Perhaps for at least the short term. cooler than average temperatures are expected to continue in the east into early April. However, weather patterns can change quickly. April and May are typically the busiest months of the year for tornadoes. Just because it's quiet now, doesn't necessarily mean that there will be a correlation of low tornado counts through the end of June.  In fact, the Storm Prediction Center has issued a slight risk of severe storms for both Tuesday and Wednesday. 

Severe Weather Outlook Tuesday

While we're not expecting any severe storms in the D.C. region this week, we could hear a few rumbles of thunder on Thursday and there could be some gusty winds with those storms. 

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Snow showers and flurries possible overnight into Tuesday AM

March 23, 2015 - 03:06 PM
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Snow fell in parts of the Midwest this morning and will continue to move to the south and east this evening into tonight. Early tomorrow morning, the weak disturbance will move into the D.C. area bringing the chance for some light snow showers or flurries. Here's more on what you can expect.

The system is currently moving out of Indiana and into the Ohio Valley. Areas such as Chicago picked up 1 to 5 inches of snow but the disturbance will continue to move into areas of dry air as it moves south and west towards the Mid Atlantic. The dry air it will encounter will act as a hindrance, evaporating much of the snow before it makes to the surface.

Stormscan showing snow entering the Ohio Valley this afternoon

Clouds will increase tonight but you should begin to see some clouds increasing on the horizon at sunset. Skies will be cloudy overnight and snow showers will move into the Appalachian Mountains around midnight. It will take areas east of the mountains longer to saturate, so many locations across the D.C. area won't even see any snow, but locations north and west will saturate faster and will have the chance for some light snow.

Forecast low temperatures Tuesday morning

Temperatures will be below freezing in the outlying suburbs west of D.C. and near or slightly above freezing in the D.C. Metro. Road temperatures should stay above freezing for the most part but some locations west of the Blue Ridge may experience a dusting IF snow falls heavy enough. The best chance for this would be in Washington County, MD, the Panhandle of VA and into the Shenandoah Valley in VA on lesser traveled roadways.

Potential Snowfall Accumulations (On the grass!)

While this is strictly model output, I do think there is the potential for a dusting in a few spots north and west of D.C. Tuesday morning. This will not be a big deal for the morning rush hour but it will definitely be interesting to see after the Vernal Equinox!

Just to remind you, March 25th of 2014 featured 1.7 inches of snow at Reagan National and 3.8 inches of snow at Dulles Airport, so it could be worse.

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Spring Has Sprung: The Vernal Equinox Friday

March 20, 2015 - 04:45 AM
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It's here!  Spring!  Astronomical spring arrives on Friday at 6:45pm, the vernal equinox.

And how welcome the season is after such a cold and snowy February. Unfortunately, Spring doesn't necessarily bring with it milder temperatures. The average high today is 59F but it appears temperatures today won't get out of the 40s!

The equinox occurs at the point when the sun crosses the celestial equator from South to North. The image above and below help to visualize this.

(http://earthsky.org/)

At the equinox, the geometric center of the Sun crosses the equator and this point is above the horizon for 12 hours everywhere on Earth.  Now when we think about the equinox, we often think about equal hours of daylight and darkness. The word equinox comes from the Latin word "aequus" meaning "equal" and "nox" meaning "night". Although it's close, there are actually a few more minutes of daylight on the equinox than darkness. Monday we had 12 hours of daylight and 12 hours of darkness.  Sunrise on Monday, March 17, 2012 was 7:16 AM and sunset was at 7:17 PM. So you may be asking, why wasn't Monday the equinox?

Well, it all comes down to that exact point when the center of the sun crosses the equator.  Sunrise and sunset occur when the top of the sun, not the center, is on the horizon.  That's why there are actually a few more minutes of daylight on the equinox.  Also, the earth's atmosphere refracts, or bends, light from the sun.  So, the top of the sun appears to be above the horizon when it is actually below the horizon. 

(http://calgary.rasc.ca/index.htm)

Today (Friday) we'll have a little over 12 hours of daylight (12 hours and 8 minutes), whereas Tuesday had 12 hours of daylight and darkness. From here on out, up until the summer solstice, we'll gain 2 hours 44 minutes of daylight.

The growing daylight and higher sun angle help promote warmer days.  Unfortunately, it can sometimes be a slow process in these transition months. Case in point, this March. The average high for the middle of March is about 55°. By the end of the month, the average high will be 61°.  The extended forecast starts out seasonable and then get a little warmer than average; however, another dip in temperatures for early next week. 

Happy Spring!

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Update: Snow possible for the 1st day of spring

March 18, 2015 - 11:29 AM
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The vernal equinox (i.e. spring) is Friday, so you would think we have seen the last of the wintry weather. Unfortunately or fortunately, depending on how you look at it, that is not the case!

The National Weather Service has issued a Winter Weather Advisory for areas northwest (in purple) and a Winter Storm Warning (pink) for Washington, Morgan, and Alleganyy counties in MD and Berkeley county WV.  A winter weather advisory indicates light snowfall could impact road conditions.  A winter storm warning is issued when heavy snow is expected and will likely cause travel impacts.  Elevation will play a huge role in this system with the highest accumulations farther NW. 

NWS Watches

The moisture is creeping in from the south, as you can see from this surface map.

ZZZZZ

The system should arrive during the overnight hours Thursday into Friday morning. Temperatures will be above freezing, but the air is dry, and as the moisture begins to fall, there will be some cooling of the air mass and wintry precipitation.

In House Model 6AM simulation of Snow

At this point, the Stormwatch 7 team cannot promise that we will see accumulating snow in the immediate metro area, but it is not out of the question.  Here's the latest StormWatch7 team's thinking:

Latest model guidance suggests around an inch of snow around the beltway with several inches possible farther north and west. I think we are in luck though because the local roadways are mild, which is a good thing. That means that even with an inch of snow possible, the amount we can really actualize (how much can accumulate) on the ground is minimal. I predict a scenario where a light coating could develop in mainly grassy areas. This setup lends itself to being an elevation-dependent situation. Meaning those who are hilltops and ridges have a greater likelihood of a couple of inches of accumulation and the potential for snow to make for slippery roadways.

As warmer air overspreads through the day, we all change over to a cold rain before it finally tapers off Friday night. The question remains though what, if any impact this may have on the region and in particular for the morning rush.  So here are the key points for now and we urge you to check back here for updates as we get new information. 

ZZZZZ

 As always, stay with the StormWatch7 weather team for more!

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Daylight Saving Time Sunday morning

March 6, 2015 - 04:14 PM
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It's that time of year again when you have to again wake up in the dark but at the same time experience a longer period of daylight in the evening. We enter Daylight Saving Time Sunday morning at 2am.

Sunrise on Saturday is at 6:32am and it sets at 6:07pm. Feel free to sleep in Sunday morning, as it will still be dark after 7am with sunrise at 7:31am. Personally I love having the extra hour of daylight in the evening hours instead with the sun setting Sunday at 7:08pm.

This is also a great time to change your batteries in your smoke and carbon monoxide detectors. IAFF will thank me for passing that along!

Sunrise and Sunset times Saturday and Sunday

As far as adding daylight to the mix, D.C. will experience 11 hours and 35 minutes of daylight Saturday, but in just 11 days there will be 12 hours of daylight.

Looking ahead, there will be 12 hours and 36 minutes of daylight by March 31st and over 13 hours of daylight by April 10th. That should be enough to look forward to for a little while. Enjoy the milder weekend!

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Winter Weather Thursday in D.C.

March 5, 2015 - 04:30 AM
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LIVE RADAR  |  HD CAMERAS  |  CLOSINGS  |  WARNINGS

Please tweet pictures or reports to..

@AlexLiggitt @JacquiJeras  |  @LaurynRicketts  |  @EileenABC7

@ABC7Brian @SteveRudinABC7  |  @DevonLucie

6:43PM: The live blog is about wrapped up for the night. Accumulating snow has ended across the region, with record daily snows at Dulles and Reagan Airports.

Tonight, low temperatures will fall into the single digits in the suburbs to low teens inside the beltway. Anything that isn't shoveled will freeze solid by tomorrow morning. Highs tomorrow should approach the 30 degree mark but with mostly sunny skies and a higher March sun angle, there should still be plenty of melting.

Temperatures should move into the 40s Saturday and 50s Sunday. Have a good night, enjoy the snow and stay warm!

5:46PM: Snowfall totals across the area have mainly been in the 4" to 10" range, with the highest north and west of D.C.

Here is the latest snowfall report list from the National Weather Service

5:14PM: Snow will gradually end over the next hour with a few flurries remaining through the evening. Reagan National recorded 4.6" for the day breaking the record of 4.4" from 1888.

3:16PM: The back edge of the snow is beginning to show up on Live Doppler Radar along the I-81 corridor. Light snow or flurries may continue to persist there but should taper off over the next hour.

Snow should begin to taper in the D.C. Metro around 5pm and closer to the Bay by 6pm. Patches of flurries or light snow showers may be possible through the early evening.

2:41PM: Sorry for the hiatus! The back edge of the snow is finally starting to show up on our StormWatch 7 Super Doppler. The heaviest snow is now south and east of D.C. and will continue to be there through the remainder of the event.

That being said, there is still moderate to heavy snow in D.C.  I expect another few inches around the D.C. Metro before the snow ends closer to 5pm or 6pm this evening.

Roads have a lot of slush on them right now, which will more than likely freeze solid in many places overnight with lows in the single digits to low teens. Record lows are expected to be broken at Dulles Airport and BWI Airport tomorrow morning.

12:09PM: A mesoscale discussion for heavy snow was again issued for the D.C. area concerning heavy snow banding continuing to push through the Metro and eventually south through the evening hours. As areas to the south and east haven't experienced as much snow yet, they aren't out of the woods yet and measureable snow is still expected.

11:25AM: The heaviest snow bands remain just north and west of D.C. and appear like they will move into the D.C. Metro over the next hour. Snowfall rates of 1 to 2 inches per hour will be possible.

Snow still looks like it will come to an end closer to 5pm or 6pm this afternoon. Here is a link to the latest snowfall totals.

10:43 AM:  Heaviest snowfall shaded in green.  Snowfall rates of 1" an hour in these locations.  This includes you, in Leesburg, Great Falls, Poolesville, Gaithersburg, and Rockville.

Live Super Doppler

9:57AM: Please, please, please try to beat this picture... It's amazing.

Finley seems to be enjoying the snow today!

9:23AM: You can check out the area roadways at the sites below.

Virginia: http://www.511virginia.org/

Maryland: Coordinated highways action response team

9:04AM: Sampling of current snowfall reports across the region...

Dulles Airport: 1.0"

Berryville, VA: 0.9"

Leesburg, VA: 0.5"

Herndon, VA: 0.7"

Inwood, WV: 2.0"

Columbia, MD: 0.7"

Hagerstown, MD: 0.7"

8:48AM: The Storm Prediction Center placed the D.C. area under a discussion which focuses on the likelihood for heavy snowfall this morning through the afternoon. Snowfall rates of an inch per hour or more will be possible through the day.

Please keep sending your pictures in via Facebook and Twitter!

7:58 AM:

66 eastbound at Markham. Sleet and snow mix- very slick!

ZZZZZ

 

 

 

7:49 AM:  Dulles Greenway snow covered and looking very slick in Ashburn - Loudoun county.  Thanks, Dave Johnson, for sending this!  Keep your pictures coming! #DMVSnow

Dave Johnson - Dulles Greenway - Ashburn, VA

7:32 AM:  Snow Emergency Plan in place for Howard, Carroll, Frederick, and Washington counties per MD State Highway Administration.  Roads are already snow covered in these areas.  Road and travel condition will only get worse over the next several hours.

MD State Highway Administration

7:15 AM update:

The rain to sleet to snow line is getting closer to D.C. metro area! Tune into www.wjla.com/weather for the latest radar!

ZZZZZ

 Hourly:

ZZZZZ

 

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Thursday Snow: Impact, Timing, Totals, and Could it Change?

March 4, 2015 - 07:58 AM
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Here we go again. It seems every week in February and now into March we've had school closings, delays and disruptive snow or ice. A winter storm warning is now in effect for most of our area Thursday. 

Winter Storm Warning

Today is a dreary one with nothing but plain old rain. Temperatures will warm up and help melt our leftover snow. The changes will start overnight. Cold air will advance into the region and meet up with the stream of moisture that stretches all the way from the Northeast to Mexico! 

Water Vapor Satellite NOAA

Here is a timeline of the transition and when we expect snow across the region. It will start happening while you are sleeping. Areas north and west could wake up to a little snow on the ground, but don't be shocked if it's not accumulating yet until around sun up in the metro. Longer south of town.

Rain to Snow Timeline

The heaviest snow will be in the morning through midday. It tapers off late afternoon/early evening. Snowfall totals will range with the heaviest snow north of D.C. and lighter amounts to the south. Here is the latest Stormwatch7 forecast.  

Stormwatch7 Snow Forecast

COULD IT CHANGE? 

Yes. The key thing to watch is how quickly cold air rushes in tomorrow and how much moisture will still be in place when that happens. A prolonged period of sleet or wintry mix would require us to shave down the numbers.  At the same time, snow bands will likely set up somewhere across the region and could bring a slightly higher burst for bigger numbers. Our forecast reflects the most likely totals and why we always give you a range of numbers. If you are "shopping around" comparing forecasts, make sure you note that source. There are a lot of maps floating around on social media from people that do not have a meteorology background. No matter the numbers, the impact will be significant. School closings are likely. Government closing.. probably. You can check the latest on this link. Travel will be bad through much of the day Thursday with snow covered roads and poor visibility at times. Flights will get cancelled. The later in the day your flight, the more likely you will get out as snow should ease late day or early evening.  If you are winter weary, check out our 7day forecast!  A nice break over the weekend into next week.

 

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Plan Ahead for Slick Spots This Evening but Light and Widespread

March 3, 2015 - 11:31 AM
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WINTER WEATHER ADVISORY NOW CANCELED FOR A GOOD PORTION OF THE REGION

ZZZZZ

Not impressed. Yes, I can hear the keyboard typing with comments now but this is how the weather rolls in D.C. –once you think you nailed the forecast – things have to go ahead and change. We always have to keep an eye on the latest data because of this fact (and this is also why we wait just a little while longer to put out snow totals).


I’ll just come out and say it – although there will be slick spots out there this afternoon and tonight, anything we get will be fairly widespread and pretty light. We are really dry out there and temperatures are rising. The precipitation will be delayed slightly because it is evaporating before it even hits the ground. Considering it will take longer to moisten the atmosphere, temperatures will continue to rise.

ZZZZZ

I would still plan ahead for some light icing during the evening commute and use caution but I believe a good majority of the roads around the D.C. metro area and south will just be wet with some light rain. However, please watch for the regular spots – bridges, overpasses, underpasses and exit ramps for a better chance of some light glaze. (Don’t worry – the StormWatch7 team will continue to update through your evening commute to get your home safely).


Temperatures will rise overnight and we will have some spotty rain showers during the overnight hours. More scattered showers will move in through the day tomorrow as temperatures move on up to the lower 50s in spots! Rain could be heavy at times which could lead to some flooding around the region (rain plus melting of the existing snowpack).

We are still on point to see some snow/sleet move in on Wednesday after midnight as a cold front will unleash more arctic air upon us for Thursday. In fact, temperatures drop on Thursday from the 30s and into the 20s (winds will pick up as well making it feel like the teens and single digits). Any sleet will then turn to snow showers and those are forecast to hang around for much of the day on Thursday which means accumulating snow around the region. It is too early to push out snow totals so please don’t buy into the hype on the internet just yet (look how quickly things changed today). If I had to go out on a limb right now, I would count on delays and cancelations on Thursday as the way things look now. However, we will update you with snow totals early Wednesday morning with all the latest information!

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Get Ready for a Bumpy Ride- Rollercoaster of Weather this Week

March 2, 2015 - 10:52 AM
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Alright March – stop it. This is where we should begin to look forward to spring: days are getting longer, next Sunday Daylight Saving Time begins, it is actually the beginning of meteorological spring, etc. However, you give us one day this week that will feel like spring-wedged between days that we have winter weather activity. C’mon March!

This week will be a roller coaster ride so get ready. The forecast is subject to change (as always) but I want to give you an outline of what to expect. The reason for the change is that there are a lot of timing issues that we will have to watch. For example – how much ice could we accumulate on Tuesday evening before warm air takes over? That is an example of just one of the questions we have this week but bear with me and just keep an eye on the forecast. Here is what you can expect in the very least.

After some decent melting through the day on Monday as temperatures climb through the 40s, we will once again have some icy spots tonight with overnight lows forecast to drop into the teens and 20s. We will start off on the mostly clear side tonight with high pressure slipping east from the Midwest. However, clouds will be on the increase towards daybreak Tuesday.


TUESDAY


The first half of Tuesday looks fine (besides some morning icy spots). Temperatures will move into the mid-30s through the day ahead of our next system. A warm front will slide in from the south and west through Tuesday night as high pressure scoots off the Mid Atlantic coast.

ZZZZZ

There will be plenty of clouds around and cold air in place at the surface. Precipitation will begin to fall from the southwest to the northeast after the lunch hour into the early afternoon. It looks to start off as maybe some snow but a quick transition to sleet and freezing rain.

Warm air will eventually filter in from the south and west but the question remains: when can that warm air win out at the surface? At that point, we will begin to see a transition to rain as temperatures actually go up Tuesday night into Wednesday. However, at this point, expect some icy accumulation for the evening commute on Tuesday.

ZZZZZ

Caption: Probability of 0.01” or more freezing rain/ice accumulation through 1 a.m. Wednesday morning. D.C. has a 50%-60% chance of 0.01” or more of ice accumulation through 1 a.m. Wednesday. Chances of that happening increase north and west of D.C.


WEDNESDAY


This is the most spring like day we will experience this week. Temperatures will shoot into the 50s as the D.C. region will be in the warm sector. However, there will be some scattered rain showers around throughout the day.

There could be a decent amount of rain coming down in areas so we will have to watch for potential localized flooding throughout the region as the snow pack that is left begins to melt. I do not expect widespread flooding but at least the potential for again, some more localized flooding.

ZZZZZ

WEDNESDAY NIGHT INTO THURSDAY


A strong cold front will then slowly move through the region and cold air will begin to move back in from the north and west. An area of low pressure will form and ride along the front after it sweeps through our region and sags to the south and east of the D.C. area. This will give us a chance of some wet snow Wednesday night into Thursday morning. In fact, there could be some accumulating snow around by Thursday morning. Temperatures on Thursday will only rebound into the lower 30s, not far off from our overnight low on Wednesday night of around 30 degrees. Any snow will move out during the morning with arctic high pressure pushing in. Expect a breezy day on Thursday as winds pick up.

High pressure will stick around Friday and Saturday giving us sunshine and gradually warming temperatures. Plan ahead and keep it here for the latest forecast as we continue to tweak it!

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Another Round of Wintry Weather

March 2, 2015 - 10:27 AM
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Alright March – stop it. This is where we should begin to look forward to spring: days are getting longer, next Sunday Daylight Saving Time begins, it is actually the begin of meteorological spring, etc. However, you give us one day this week that will feel like spring-wedged between days that we have winter weather activity. C’mon March!

This week will be a roller coaster ride so get ready. The forecast is subject to change (as always) but I want to give you an outline of what to expect. The reason for the change is that there are a lot of timing issues that we will have to watch. For example – how much ice could we accumulate on Tuesday evening before warm air takes over? That is an example of just one of the questions we have this week but bear with me and just keep an eye on the forecast. Here is what you can expect in the very least.

After some decent melting through the day on Monday as temperatures climb through the 40s, we will once again have some icy spots tonight with overnight lows forecast to drop into the teens and 20s. We will start off on the mostly clear side tonight with high pressure slipping east from the Midwest. However, clouds will be on the increase towards daybreak Tuesday.

TUESDAY

A Winter Weather Advisory is in effect from Tuesday morning through the evening hours across the D.C. area. This is to cover the potential for light icing through the day. It may actually start as a brief period of snow and sleet before changing to freezing rain.

Winter Weather Advisory in effect for the entire D.C. area Tuesday


The first half of Tuesday looks fine (besides some morning icy spots). Temperatures will move into the mid-30s through the day ahead of our next system. A warm front will slide in from the south and west through Tuesday night as high pressure scoots off the Mid Atlantic coast.

NOAA

There will be plenty of clouds around and cold air in place at the surface. Precipitation will begin to fall from the southwest to the northeast after the lunch hour into the early afternoon. It looks to start off as maybe some snow but a quick transition to sleet and freezing rain.

Warm air will eventually filter in from the south and west but the question remains: when can that warm air win out at the surface? At that point, we will begin to see a transition to rain as temperatures actually go up Tuesday night into Wednesday. However, at this point, expect some icy accumulation for the evening commute on Tuesday.  

 

Probability of .01" or more of ice accumulation through 1a.m. Wednesday

WEDNESDAY

This is the most spring like day we will experience this week. Temperatures will shoot into the 50s as the D.C. region will be in the warm sector. However, there will be some scattered rain showers around throughout the day. There could be a decent amount of rain coming down in areas so we will have to watch for potential localized flooding throughout the region as the snow pack that is left begins to melt. I do not expect widespread flooding but at least the potential for again, some more localized flooding.

River Flood Outlook


WEDNESDAY NIGHT INTO THURSDAY

A strong cold front will then slowly move through the region and cold air will begin to move back in from the north and west. An area of low pressure will form and ride along the front after it sweeps through our region and sags to the south and east of the D.C. area. This will give us a chance of some wet snow Wednesday night into Thursday morning.

In fact, there could be some accumulating snow around by Thursday morning. Temperatures on Thursday will only rebound into the lower 30s, not far off from our overnight low on Wednesday night of around 30 degrees. Any snow will move out during the morning with arctic high pressure pushing in. Expect a breezy day on Thursday as winds pick up.

High pressure will stick around Friday and Saturday giving us sunshine and gradually warming temperatures. Plan ahead and keep it here for the latest forecast as we continue to tweak it! 

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More Winter Weather Headed Our Way for Sunday

February 27, 2015 - 05:43 PM
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The pattern persists with another weekend system that's expected to affect the region, but as opposed to last weekend where it snowed on Saturday, this storm is forecast into Sunday. There are some similarities, but also some notable differences with this system compared to this last one. A similar cold air mass is already in place with lows in the teens, and highs only in the 20s to near freezing, but that's even a bit above the air mass last weekend where we experienced record cold. This next storm track is also riding the "Southern Stream," located in Texas right now and will move closer to the region on Sunday but will set-up just west of the Mid-Atlantic instead of moving completely south of the region. The strength of the high pressure also associated with the cold air is also very strong which could influence the track of the system, and is of similar strength to this past significant snow event.

The overall picture to take away from this weekend's forecast is to plan ahead in taking care of errands or other tasks on Saturday rather than Sunday. The latest information points to mostly wintry precipitation on Sunday, before an eventual changeover to all rain overnight Sunday into early Monday morning.

Timing: Forecasts are showing precipitation entering the region as early as Sunday morning, and lasting all day. Right now in the Storm Watch 7 forecast department, we're holding off the onset to around midday in the immediate D.C. metro.

Precipitation Type: Possible snow at onset, then a melt layer that will change the snow to sleet, possibly changing to freezing rain by afternoon, then finally changing to all rain late Sunday into early Monday.

The Dirty Details

This winter system is still about 2 days away, and is currently located in Texas.

Satellite / Radar at 4PM Today

Forecasts are in pretty good agreement in moving in precipitation some time on Sunday:

12z NAM Forecast Courtesy: Weatherbell
12z GFS Forecast Courtesy: Weatherbell
12z ECMWF Forecast Courtesy: Weatherbell

The biggest forecast problems to resolve will be exactly what type of precipitation will occur, amounts, duration, and air temperatures closest to the ground. This is a graphic forecasting what could fall over the D.C. metro by late morning. If this forecast were to happen, then sleet would fall over the area.

NAM 12z Atmosphere Temperature Forecast

This graphic is a forecast by afternoon showing that freezing rain would be most likely to occur over the metro.

NAM 12z Atmosphere Temperature Forecast

Our Futurecast forecast shows possible snow at onset early Sunday morning.

Weather Central Futurecast Forecast

Later into the mid-morning hours, it depicts a mix of wintry precipitation that would most likely in this case be mainly sleet.

Weather Central Futurecast Forecast

Futurecast then shows the possible mix of wintry weather, that in this case would most likely be freezing rain, or ice that would build up on trees, power lines, your car, the sidewalk, and untreated roads.

Weather Central Futurecast Forecast

Summary: The overall picture is turning more towards a significant wintry event on Sunday that will impact travel conditions. Our advice at this point, is to plan on running errands or getting in activities on Saturday as Sunday is beginning to show the potential for a day that would be very difficult traveling on regional roads.

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More Snow for Another Morning Commute!

February 25, 2015 - 02:17 PM
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A major storm system tracking from the south will brush the D.C. region with some minor snow accumulation. However, timing is everything and this snow, like many others this season, will fall during the overnight and through the morning rush hour. Here is the latest:

An area of low pressure will track out of the Gulf of Mexico tonight and off the eastern coast of the Carolinas by tomorrow morning.

 

ZZZZZ

 

Expect snow to spread through our region beginning late tonight through central Virginia and continuing to move northward through the overnight. Temperatures overnight are forecast to drop anywhere from the mid teens to the mid-20s so any snow that we get will immediately stick to the ground, making overnight travel slick in a lot of the region.

Considering this storm system will track south of the region, most of the heaviest snow accumulation will be south of the D.C. metro area. Winter Weather Advisory has been issued for the region beginning tonight and continuing through the first part of tomorrow.

ZZZZZ

The impact will absolutely be greater south so if your travels take you south of the D.C. metro area, past Richmond and even Charlottesville on Thursday, stay alert:

ZZZZZ

Winter Weather Advisories and Warnings for the Southern United States.

Again, we are looking at significant totals the farther south you head. However, even with minimal totals around the D.C. area, the timing of this will have this biggest impact. This is the current thinking for area snow totals as of Wednesday afternoon:

ZZZZZ

I do believe there will be some delays and even closings tomorrow. Snow will continue through the morning commute and taper off through the day. Temperatures will only make it to near 30 degrees on Thursday so there may even be slick spots for the evening commute.


The StormWatch7 team will continue to update you with any changes but this is the current thinking. Just plan ahead for the morning commute and travel safely. Also be advised that we are stepping closer to Spring each day-Daylight Savings Time begins next Sunday, March 8th!

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Stay Alert: Possible Snow on Thursday Morning

February 24, 2015 - 02:49 PM
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Old Man Winter is really getting it all in as we truck along this February. After a relatively quiet season, winter has perked up during this month and this Thursday morning is no exception.

We are keeping our eyes peeled for some snow possible during the Thursday morning commute. Monday, it seemed like this system was going to stay far enough south that it would only brush our southern tier counties with some light snow showers/flurries. Now, the system has inched northward, making snow more likely across the region.

An area of low pressure will track from the Gulf of Mexico on Wednesday and head northeast. It will eventually scoot off the southeastern seaboard on Thursday.

ZZZZZCaption: Euro model showing the area of low pressure in the northern Gulf of Mexico on Wednesday night. Courtesy of Weatherbell.
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Caption: GFS model showing the area of low pressure moving off the coast overnight Wednesday into Thursday spreading snow northward through Virginia. Courtesy of Weatherbell.

It will certainly be cold enough for snow. Although temperatures are forecast to be above freezing on Wednesday (nearing 40 degrees), temperatures will fall overnight Wednesday into Thursday and only rise to near the 30 degree mark on Thursday.

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Caption: With temperatures values on the left hand side (ranging from -10 to 50 degrees) the output from various models (different color lines) shows that temperatures will stay mostly below the 30 degree mark on Thursday. The black line the mean taken from all the data displayed. Courtesy of Storm Prediction Center.

While it is too early to talk about snow totals, the impact with just even a minimal amount of snow could and will create hazardous driving conditions on Thursday morning. Considering this is a southerly storm, areas south of D.C. have a better chance of receiving accumulating snow. Once again, this is something we will need to monitor as the track of the low could shift over the next 24 hours, changing our forecast.

At this time, the Weather Prediction Center gives the D.C. metro area about a 30% chance of receiving an inch or more of snow while Fredericksburg has about a 40% chance. Again, the farther south you travel, the better chance you will have to encounter snow.

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With road temperatures still on the cold side, this will stick quickly. This is just a heads up however; we will continue to update you through Wednesday on any changes in the forecast. Just keep thinking spring…only 24 days away.

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D.C. snowstorm Saturday

February 21, 2015 - 01:26 PM
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LIVE DOPPLER  |  TEMPERATURES  |  WARNINGS & ADVISORIES

9:39pm: The changeover to rain across the area is almost complete. But many parts of the region still have surface temperatures below freezing. This means the rain is freezing on contact when it falls .And now you have a real-time description of what freezing rain is.

During the balance of the night, at different rates, at different times, in different areas, surface temperatures will rise above freezing and that trend will continue through the day tomorrow. But until all areas are several degrees above freezing, icy roads, sidewalks and parking lots will continue to be a major impediment to drivers and pedestrians.

Conditions will be much improved by sunrise when temperatures will be above freezing across the entire region. So until then, our advice is simple. Unless you absolutely must venture out…stay off the roads tonight. And as an unwelcome bonus, many areas will be dealing with areas of fog overnight, as well.

5:42pm: It appears the transition has occurred for the majority of the region with sleet and freezing rain now mixing in with the snow. At this time, some locations are still seeing snow but as we head into the next few hours, more sleet and freezing rain is expected.

Some of the latest guidance (which I'm not even sure why I'm bringing up since it's been pretty terrible today) is thinking temperatures will get closer to freezing by 9pm or 10pm. It has reached the mid to upper 20s in D.C. and the 30 degree mark in the far southern parts of the viewing area. At this point I think guidance isn't too far off and temperatures should make the freezing mark prior to midnight.

By tomorrow morning, temperatures should be in the mid to upper 30s and rise into the 40s by lunch time. Highs Sunday should still reach the low to mid 40s.

5:03pm: We are finally getting some reports of a change to sleet in areas such as Winchester, Bristow in Virginia and a change to freezing rain in Southern Maryland.

Most areas west of I-95 have recorded snowfall totals around 6 inches or more. Here is the latest preliminary snowfall totals list from NWS Sterling.

4:11pm: Snow is continuing to be the primary form of precipitation and should continue to be so over the next few hours. We're expecting the transition to sleet and freezing rain closer to 7pm now, and a transition to rain will happen closer to 9pm or later. 

Surface temperatures have reached the mid 20s around D.C. and have pushed closer to the 30 degree mark south of D.C. near Fredericksburg and Southern Maryland. St. Mary's County in MD has already seen a transition to sleet and areas in the Northern Neck.

This transition should slowly but surely move north into the D.C. area over the next few hours. We'll be keeping a close eye on temperatures!

For some of the latest snowfall totals, see the NWS Sterling, VA Public Information Statement here.

 

Some of the latest snowfall reports

2:20pm: Meteorologist Steve Rudin and myself just took a stroll outside to make a quick facebook video post. You can find it here.

1:55pm: Areas of heavy snow continue along and just west of I-95. Locations in western Fauquier and Loudoun Counties are experiencing a lull in the precipitation.

The heaviest snowfall currently extends from Culpeper north to Prince William, Fairfax and Montgomery Counties.

1:36pm:  Roads across the D.C. area are snow covered with the worst conditions north and west of the city. I recently talked to Chief Meteorologist Doug Hill who said he hasn't even seen a flake of snow in Southern Maryland, so this will be a very sharp cut off of a storm!

Below is a look at I-66 east around 11am. Conditions have deteriorated quickly.

MD Road Cameras

VA Road Cameras

This was a look at eastbound I-66 near East Falls Church Metro at 11am

1:30pm:  Areas of snow will continue to fall over the next few hours before changing over to sleet and freezing rain we think around 4-7pm. Currently, temperatures are getting into the upper 20s and low 30s south and east of town, where little to possibly even no snow is possible in Southern Maryland.

Areas north and west of D.C. have already received 3 to 4 inches of snow and will continue to see additional accumulations through the afternoon.

Latest Snowfall Accumulations

 

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Snow, Ice, and Freezing Rain Saturday

February 21, 2015 - 08:00 AM
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LIVE DOPPLER RADAR  |  HD CAMERAS  |  CURRENT TEMPS

Snow is already beginning to enter the western parts of the region, with reports of it sticking to the roadways as of 8:30am in Winchester, VA and points west along the Shenandoah Valley. Snow will continue to move to the east into the immediate D.C. Metro area later this morning. Snow appears to be the predominant precipitation type through the afternoon, until milder air filters in overhead and changes the type to sleet and eventually freezing rain.

Winter Storm Warnings are in effect until Sunday morning for Montgomery and Loudoun Counties and points west. A Winter Weather Advisory is in effect for D.C. and Fairfax and points south and east. The higher snowfall totals will be likely in the warned areas.

Current Warnings and Advisories

Taking a look at our local futurecast below, the expectation continues to be a changeover to sleet and freezing rain as warmer air moves in overhead. As you can see in the image below, surface temperatures should still be in the 20s late this afternoon, so anything that falls will still be either frozen in the form of sleet or will freeze on contact with surfaces in the form of freezing rain.

Temperatures should finally move above freezing after sunset, probably closer to 9 or 10pm. By that time, rain is expected to take over and continue through Sunday morning. Temperatures should continue to rise through the overnight hours and into Sunday. Highs Sunday should top the 40 degree mark, hopefully helping melt the ice and at least some of the accumulated snow.


Below is a look at our snowfall forecast from yesterday. Looking at some of the latest guidance, we think this map still works but there is the potential for an additional inch or two in the western 3-6" band, and an additional inch in the 1-3" band around D.C.

This is one of those occasions where we don't really want to stress snowfall totals, as it will be the effects that really matter. Snow will start, but we are equally as worried about the change to sleet and freezing rain. Depending on how long the freezing rain lasts, there could be a coating of ice on top of everything later this evening into tonight.

Our main recommendation would be to NOT TRAVEL this afternoon into tonight if at all possible.


The StormWatch7 weather team will be here throughout the day with the latest updates. Please be sure to send us any pictures or video and we'll be sure to share it!

Follow the team on Twitter!

@DougHillABC7  |  @EileenABC7  |  @alexliggitt  @LaurynRicketts

@SteveRudinABC7  |  @ABC7Brian  |  @DevonLucie  |  @JacquiJeras

@MetMattRitter

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Record Cold Temps Likely Broken and Dangerous Wind Chills Tonight!

February 19, 2015 - 08:47 AM
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There's no sugar coating it; it is mighty cold. The arctic air is here and it gets worse before it gets better. Today actually "looks" nice outside with nothing but sunshine this morning. But don't be fooled by appearances! A few clouds and flurries are possible this afternoon as the core of the cold air moves in. Temperatures will stay in the teens in the D.C. area today. But it will feel like -5 to +5 through much of the day. A wind chill advisory is in effect now through 10 a.m. on Friday. 

Wind Chill Advisory until 10 a.m. Friday

Tonight and early Friday will be the coldest time period. Wind chills will reach the double digits below zero as shown here on our Stormwatch7 Futurecast. 

Futurecast Wind Chills Friday Morning

Apparent temperatures that cold can be dangerous and cause frostbite and hypothermia. You can use our Stormwatch7 app to check the temperature and wind at your house. Then use this handy chart from the National Weather Service to calculate how long it will take to get frostbite. 

Wind Chill Chart

I expect it will take less than 30 minutes Friday morning. Make sure pets are indoors tonight and tomorrow morning. Also, please check on the kids at the bus stop to make sure they are picked up on time. I think there will be plenty of 2 hr delays Friday morning at least! Those buses have a hard time starting in these conditions. Records are likely to be broken as well. Here are the forecast low temperatures tomorrow. 

Caption

I think we will at least meet the record at Reagan National, but it is less likely at Dulles. Here are the record temperatures for February 20th.  

Records to Beat Friday

Winds will relax a bit by late Friday morning, and the feels like temperature will reach the teens in the afternoon. Check out this graphic stating if we stay below 20 today and tomorrow at Reagan National, Dulles, and BWI it will be the coldest two days in 20 years!! 

Coldest in 20 years?!

The cold is no fun, but we're going to try anyway! Eileen Whelan will be out with the Storm Chaser Friday morning with a bunch of items to freeze during Good Morning, Washington from 4:30 a.m. - 7 a.m. Ever wanted to know how long it will take to freeze a banana? Do you have an idea that she should try? Make sure you message her on her Facebook page here or on the WJLA Facebook page here. If you don't like this cold, the good news is that temperatures will warm up this weekend. The bad news is that another storm is heading our way. Still working out the details and timing, but I expect some snow and/or freezing rain on Saturday late to make for bad travel conditions. Temperatures should warm up overnight into Sunday to change it all to rain.  Highs on Sunday will top 40 degrees... free car wash to get rid of all of that salt! Stay tuned to the Stormwatch 7 Weather Team as there will be updates on the weekend forecast.

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The Snow Has Ended but Maybe More to Come?

February 17, 2015 - 06:13 AM
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The snow will continue to come to an end today as the area of low pressure that tracked to the south of us last night, moves out to sea, off the coast of Virginia and North Carolina. We received a fine mist of snow, heavy at times, starting yesterday afternoon and continuing through the morning. While snow totals were slightly below what was anticipated, we still got the most snow we have seen yet this season.


Here are some snow totals so far (however, we are waiting for the final tallies to come in as some of these are from the early overnight hours).

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With the snowpack on the ground all across the region, temperatures today will only rise through the 20s. We will get some sunshine this afternoon but with that temperature not getting above freezing, we are not going to experience much melting. Of course there will be icy spots through the day and evening by tomorrow morning as temperatures fall into the teens once again tonight.


We will start with some sunshine on Wednesday but ANOTHER arctic cold front will slide through on Wednesday afternoon/evening. This will kick up winds slightly, bring temperatures down through the afternoon and also bring a chance for some snow showers/flurries. We will have to watch for a chance for some heavier lines of snow to form (think back to Saturday night), so of course this is something that we will have to monitor as the day moves on tomorrow. Also, since the temperatures will be below freezing during the afternoon, anything that falls will stick so there could be some hazardous travel by Wednesday’s evening commute.

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Caption: The StormWatch7 FutureCast shows snow moving through the region during the late Wednesday afternoon, into the early evening.

Arctic air will infiltrate our area once again on Thursday with temperatures not getting out of the teens! It will continue to be a little breezy on Thursday so wind chills once again will be right around zero for much of the day.

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Everything You Need To Know About Our Snow Storm

February 16, 2015 - 12:00 PM
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Finally! Snow lovers, your dream has come true. A system moving into the region will bring the best chances of snow that we have seen all this season. With cold, dry air in place, expect snow to start moving into the area this afternoon.

A Winter Storm Warning (pink) is in place for much of our area. This starts this afternoon/evening (depending on your location) and continues until noon on Tuesday. There is also a Winter Weather Advisory (purple) for Washington County, MD, Berkeley and Morgan Counties in West Virginia.

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An area of low pressure will track out of the Deep South today and into the Carolinas overnight bringing snow with it. That low will eventually track off the coast on Tuesday morning but not before it brings up some good snow totals.

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Caption: Area of low pressure will track out of Texas Monday morning and continue through Alabama on Monday night. It will then scoot off the coast of Virginia by Tuesday morning.


The snow will spread into the area from the WSW to the ENE through the afternoon and into the early evening (with areas north and east of D.C. the last to see the first flakes). Temperatures today are stuck in the teens to around 20 degrees, so we are definitely cold enough for some snow and good news is, we will not have the windy conditions that we have seen for past few days. That is great because we are expecting a pretty dry snow across the region and if we were to have gusty winds (which we will not-winds will be on the light side), the snow will be much lighter to blow around in turn, bringing visibilities down.

The snow to liquid ratio could be 15:1 or even higher through this event. That means this snow will be a dry snow with little liquid content. There will be lots of air pocket between the snow crystals as it accumulates making it fluff up even more. Unfortunately, this is not good snowball making snow.
Here is what we are expecting across the region:

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The heaviest snow will remain south of Quantico Marine Corp Base and south of Culpeper through Fredericksburg and beyond. The D.C. metro area, west to the Shenandoah Valley and continuing east to Annapolis could receive 5” to 8” of snow. Areas well north towards the Mason Dixon line will get more of a break with this storm, forecast to receive 3” – 5”.

Light snow will continue to move in through the second half of Monday with the heaviest snow falling overnight. The heaviest snow will move in through about 10p.m. tonight and continue about daybreak tomorrow morning. If you are commuting this afternoon, just know, there will be some light snow around.

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Everything will begin to taper off by early Tuesday morning and should all be out by mid-morning Tuesday. There could be a few light snow showers lingering on Tuesday but we are not expecting any additional accumulation with these. There could even be a little more sunshine by Tuesday afternoon! Temperatures on Tuesday will top out from the mid to upper 20s. We will have another arctic front move through on Wednesday, bringing some more snow showers with it.

 

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High-Impact Snow Eyes Washington

February 15, 2015 - 06:55 PM
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So far this winter, Washington has picked up 3.7 inches of snow, a far cry from the average seasonal snow to-date of 11.8 inches. Quickly, the 8 inch snow departure will get made up with an early week storm.

DC Snow Drought

Low pressure developing in the southern Plains on the heels of the Arctic front that moved through the region Saturday evening will move into the Mid-South Monday before quickly sliding into the Carolinas early Monday and then transitioning to the southeastern Virginia coast.

Typically, the heaviest snow falls in a 50-mile band about 150 miles northwest of the low pressure’s track. Therefore, the bull’s eye for heavy snow in the Mid-Atlantic will be up to Interstate 66 in northern Virginia.

Honing in on amounts, the liquid equivalent will likely be 0.50 inch. In a traditional sense, 0.50 inch would yield 5 inches of wet snow. Since the temperatures through the atmosphere will be very cold, the same liquid amount will yield a higher snow ratio. Instead of 10:1 (0.10 inch producing 1 inch of snow), the ratio will be closer to 20:1. Therefore, the same amount of liquid-equivalent will yield snowfall amounts in Washington of about 7 to 8”.The snow will, therefore, be dry and powdery in nature.

There are pros and cons with a dry snow. First, given the recent Arctic outbreak, surface temperatures are below freezing, so the snow will be able to stick to most roadways as soon as it begins. Even treated roads will be slippery in spots (near the shoulders and lane divides, especially).

Snow will likely begin a few hours prior to Midnight Tuesday and end during the morning rush. Since most accumulation will occur at night, there’s no benefit to solar radiation peeking through the clouds to help to warm roadways and provide an extra melting boost at the storm’s onset. This is another reason the snow will be a high-impact snow; it will cause slippery travel once it begins.

Snow Impacts

However, fluffy snow is easier to remove from driveways and sidewalks. Five to 8 inches of dry snow amounts to about one-fourth of the weight of 5 to 8 inches of wet snow. Therefore, while travel will become difficult, shoveling the snow will be a far easier process. Unlike the recent New England blizzard, winds will be lighter in the Metro area as the snow falls, so visibility won’t be limited by blowing and drifting.

Snow Impacts

Crews will be able to keep up with the snow and not have to worry about drifting quickly closing already cleared roads. Since the snow will be falling overnight, crews won’t have interference from the normal flow of travel to keep the roads cleared. However, the Tuesday commute will still be treacherous since most of the accumulation will have occurred by the time most folks head back to work following the holiday weekend.

Stay with ABC7 for the latest weather forecast and WTOP Radio for around-the-clock weather information.

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Dangerous Winds and Temperatures Headed Our Way

February 13, 2015 - 01:58 PM
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It is going to get dangerously cold around the region this weekend. Not only are we going to have some of the coldest temperatures we have seen in over a year across the region, but the bone chilling winds chills are going to be the main culprit in this big chill. So grab a loved one this Valentine’s Day weekend and hunker down inside because it is going to be brutally cold outside.

Today is almost a practice day because by the time we get to Sunday, it will feel a lot colder. Winds will continue to diminish as the time ticks away on this Friday. Clear skies today will continue into the evening with just a few clouds building in overnight. Temperatures tonight will still fall into the teens but winds will be light so there will be not much of a wind chill.

Saturday, winds will shift out of the south as high pressure scoots off the coast. That will push our temperature to around 40 degrees! There will be some sunshine to start but that will be short-lived as another arctic cold front approaches the area increasing the clouds cover across the region.

ZZZZZCaption: High pressure off the coast will bring temperatures to near 40 degrees by Saturday afternoon. Snow showers expected tomorrow afternoon and evening.

Expect some snow showers to move into the area through the afternoon and into the evening on Saturday. There could be some minor accumulation in spots, especially if we get a heavy band that sets up. We are thinking a coating to around 1” of snow accumulation possible around the area. However, if we get a heavy band that sets up, that could be a little more and any of the heavier accumulation looks to be north and west of D.C.

*Note: When I mention “north and west” of D.C. generally I am speaking of western Loudoun county, northwestern Montgomery county and continuing north and west of those areas*

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Caption: The Weather Prediction Center probability for 1.0” or more of snow. The district has a 10%-20% chance of see 1.0” or more of snow while those chances increase north and west of D.C.

So if you are headed out for any Valentine’s Day festivities, might want to keep an eye on our radar and the roads because there absolutely could be some slick spots out there with some minor snow accumulation.

Winds will increase through the afternoon turning from the south to the northwest as the front plows through the region. By Saturday night, winds will be gusting up to 50mph/60 mph in spots!

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Caption: High Wind Watch is in effect for the region from 6 p.m. Saturday evening until 12 p.m. Sunday afternoon.

With winds of this speed, we will certainly have to watch for the impact they may cause. This could be downed trees, possibly power lines leading to power outages. Also, it may make it tough to drive, especially high profile vehicles.

Temperatures will fall into the single digits and teens for overnight lows Saturday into Sunday. That means wind chills will be well below zero for much of the region.

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Caption: A wind chill watch is in effect for areas shaded in dark blue on Sunday from midnight until noon.

Wind chill readings in these watch area could be 20 to 30 degrees BELOW zero (especially higher elevations). These absolutely will lead to hypothermia and frost bite if you are outside for a prolonged period without the proper dress. Wind chills not in the watch area are still forecast to be below zero for much, if not all of Sunday.

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Caption: Forecast wind chill values on Sunday morning at 7 a.m.

For those who want to know how we calculate wind chills and frostbite times click here for more info. However, here is a chart you can use on your own to figure out.

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Sunshine will stay for Sunday but those winds aren’t going anywhere. Temperatures will only top out near 20 degrees in D.C. with most of the region staying in the teens. We could challenge some records on Sunday as well for air temperatures! The lowest daytime high on record in D.C. and BWI is 18 degrees, both set in 1943. The lowest daytime high at Dulles is 22 degrees set in 1979.

Winds will finally calm early Monday morning. President’s day is looking a lot better in terms of winds (they will be in the 5-10mph range) but it will still be chilly. Temperatures will stick in 20s with some sunshine to start and more clouds filling in later.

So enjoy this weekend but try not to spend too much time outside – which should give you an excuse to stay inside with your Valentine.

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