As one winter storm exits, another is forecast to enter by early Tuesday morning, making for the possibility of more delays, cancellations and additional travel complications.
A Winter Storm Watch is in effect everywhere besides Southern Maryland as well as Stafford and Spotsylvania Counties in Virginia.
Areas to the southeast are expected to mix in a bit more of the way of rain and sleet so accumulations will be limited in those locations, thus not hitting the 5" or greater Winter Storm Watch criteria.
At this point, our team is thinking a more general 2" to 5" will be possible tomorrow, with the highest amounts just to the west of D.C. where snow should be the primary precipitation type with colder air available.
I like the graphic from the National Weather Service below showing the probability of greater than 4" of snow in a given area. For the D.C. Metro it only stands at 40-50%.
At this point it appears that snow will begin in the morning hours during the rush hour and continue through the early afternoon. Precipitation may start as a mix in the D.C. Metro and points east but should change over to snow the rest of the day. This will of course create more travel headaches, and delays and cancellations will be likely.
The National Weather Service is discussing the potential for a banding feature to set up somewhere just west of the D.C. area that could bring the potential for heavier snow in isolated locations. At this point, I think it's a little difficult to say exactly if this feature will happen or where exactly it will be.
Heavy snow band northwest of D.C. Sunday
We saw the same kind of feature yesterday north and west of D.C. where very heavy snow fell from Winchester north to Hagerstown and east to north of Baltimore. We'll be monitoring radar trends tomorrow to try and stay on top of it. With that being said, there's an outlying chance of some locations seeing 5" or more.
Another note is most of the roadways are wet right now and will continue to be wet through tomorrow morning.
Area roadways are currently above freezing and should be tomorrow morning, leading to the majority of snow in the morning to melt on contact. Snow will need to become moderate or heavy to overcome the warm roads in order to pile up.
Snowfall totals may be reached but you might not notice it if the roads aren't as bad!
We'll of course be on air and online all day so tune in tonight at 5, 6 and 11 p.m. and tomorrow starting at 4 a.m. (if you happen to be up that early!) to see if there are any changes to the forecast!
7:36pm: Very wet in D.C. along Columbus Circle in front of Union Station. Bands of moderate rain have caused standing water. Fortunately, temperatures are above freezing, so it's just wet. Farther north and west, ice is a major concern.
7:25am: The rain train continues, but will gradually taper off over the next several hours. Any freezing rain will transition to rain, as temperatures slowly climb above freezing.
6:45am: Moderate rain falling in the District. West of I-95 freezing rain is still being reported. Here's a radar image depicting the mixed precipitation across the metro area.
4:25am: Temperatures downtown are now above freezing (34 degrees), but freezing rain is still an issue west of the District. The moisture train continues with precipitation possible through early afternoon.
11:25 pm: Last blog post tonight. It will rain most of the night, across most of the area. BUT the temperature trend is encouraging especially south and east of DC. As soon as temperatures reach 33 degrees, no more ice will form. The problem is it may take until after sunrise tomorrow for that to occur across the entire region. Don't be surpised to hear some sleet and a clap of thunder overnight. The highest ice accumulations willoccur north and west of DC where temperatures will stay below freezing the longest. Jacqui and Eileen will start our coverage on ABC 7 at 4:30 Monday morning...just 5 hours from now. And by the way. model guidance suggest we may see more snow on Tuesday with the next system moving in. Be safe out there!
10:40 pm: As the heavier rain returns, we have noticed icicles forming on the branches of the sycamore trees along Lynn Street just outside our studio windows here in Rosslyn. This rainfall rate does not accrete as quickly as steady very light rain or drizzle does. As long as temps stay below 32 ice will build up. And rain will continue all night long. We expect a slow rise in temepratures but many areas north and west of DC may stay below freezing for most of the overnight hours. That is not good.
9:50 pm: The leading edge of the next precipitation area has arrived here in Arlington. There have been reports of lightning and thunder along with some sleet. The rain will get heavier in places at times for the rest of the night. Additional icing likely and significant icing in those areas that remain more than a degree below freezing. In time, we expect to see some rise in surface temperatures. But it will be a long, icy and nasty night.
9:05 pm: The 9 pm observation at Reagan Nat'l Airport rose 1 degree to 32 degrees. The temperature at BWI rose by 1 degree to 30 degrees. At least some temperatures are trending upwards. More icing as the next batch of rain arrives. Improvement only when temps go up to 33 degrees. Could happen overnight if some heavier downpours bring some warmer air down to the surface. This will take longer the farther north and west you are from DC.
8:06pm: The leading edge of the next batch of freezing rain is moving rapidly from southwest to northeast. It has now reached Harrionsburg. The rain stretchessouthwestward to North Georgia, Alabama and Mississippi.Icing will develop quickly and continue until temperatures rise above freezing. And in many areas that may not happen until after sinrise Monday morning.
5:32pm: The Winter Storm Warning has been extended to include D.C., Arlington and Alexandria in VA, Prince Georges Co. and Anne Arundel Co. in MD. The National Weather Service is anticipating the next round of precipitation to be a period of moderate to at times heavy freezing rain.
Up to a quarter of freezing rain is possible, which would make for major icing on trees, power lines and roadways. Major travel disruptions would be possible tonight and into Monday morning.
5:06pm: Be very careful out there tonight, quite slippery!
4:30pm: Light sleet and freezing rain is expected to end over the next few hours, with a large break expected until closer to bedtime. When the next batch of precipitation enters, it should either be in the form of rain or freezing rain and rain. Temperatures are still hanging in the upper 20s to lower 30s and we will be monitoring them closely.
2:48pm: Ice is now beginning to accumulate on elevated surfaces and may soon begin (if it hasn't already) to accumulate on trees, bridges and overpasses and even the road surfaces. Snow is still clinging to life in Loudoun and Frederick Counties and points northwest into the Shenandoah Valley.
2:07pm: Snow has changed over to sleet now in Arlington, VA and has also changed over south and east of D.C. Here is the current surface observations as of 2pm. Dulles Airport is now reporting sleet mixing in as well as Fort Belvoir and Quantico in VA. Areas will continue to change over to sleet and freezing rain through the afternoon and evening.
1:04pm: Snow has been reported mainly north and west of the red line (though coverage is spotty in Southern Maryland, any reports are welcome!). Snow has been continuing through the D.C. Metro and heavy snowfall continues to be reported in the western suburbs including Martinsburg, Leesburg as well as places just to the north of Baltimore along I-95.
A few areas south of D.C. such as Culpeper and Orange are reporting light sleet as well. A transition to sleet and freezing rain should occur during the next few hours from southeast to northwest. Some locations in Southern Maryland may change over to rain but not until later this afternoon and evening.
Surface Observations as of 1pm
12:47pm: Mike Stinneford west of Front Royal is now reporting close to 4" of snow.
11:54am: Frederick, MD has been reporting very heavy snowfall, but our very own Ron Riley just reported a change to sleet in southeastern Frederick County. This is a picture from Bryan Schuerman along I-70 in Frederick. Very poor conditions on the roadways.
11:42am: Very heavy snowfall is falling in the Shenandoah Valley north and east to Frederick County, MD. We have reports of 3 inches or more in various locations, along with very poor visibility and covered roadways along I-81 and I-70. I've circled the area with the heaviest snow band in yellow.
Heavy snow band
11:08 a.m.: We held a quick Google Hangout to update everyone on the current situation. Check out a replay of Alex Liggitt's forecast.
10:50am: Mike Stinneford near Front Royal, VA sent in this nice snow video. About 2 inches has fallen there so far.
10:11am: Here are the first snow reports coming in across the region to the National Weather Service. In addition, we have seen many reports of over an inch along and west of the Blue Ridge and upwards of a half inch in the western suburbs of D.C.
9:54am: Snow has been sticking to the roadways west of D.C. This was a look at Reston Parkway around 9am. Please tweet me any pictures or share them to our Stormwatch 7 Facebook page wall so we can share them.
9:27am: Here is the latest storm timeline from Jacqui Jeras. Snow will change over to sleet and freezing rain closer to lunch time. Icing may be up to a quarter of an inch west of D.C. with lesser amounts for the Metro and points east to the Chesapeake Bay.
Here is an updated timeline of today's weather for the D.C. Metro.Freezing rain holds on West of I-95 into the a.m. pic.twitter.com/AYIXVFXaA4
9:18am: Adam Caskey is now reporting snow grains in Arlington. This could be part of the first signs of a changeover as it means there is a warmer layer somewhere aloft. Snow is still being reported west of D.C. and freezing rain is now being reported in St. Mary's County, MD.
9:06am: Check out the "Misery Map" from flightaware.com. Already reporting massive delays at Dulles Airport and delays still common in Dallas and have spread to New York City. Not a great day to be traveling!
8:30am: Here is the atmospheric sounding from this morning at Dulles Airport, showing cold air extending from the surface and no warm layers aloft just yet signaling all snow to start the day. Once warm air gets into the region aloft, precipitation will begin changing to sleet and freezing rain.
8:27am: Snow is now being reported at the National Weather Service office in Sterling too!
7:40am: Here's a look at the storm total ice forecast from the National Weather Service. Ice is worse than snow or sleet as it can cause massive traffic problems and can also cause trees to fall and possible power outages due to the weight of the ice on the surfaces.
A half inch of snow already just west of Front Royal.
7:22am: A few reports are already coming in, with some sleet starting in Fredericksburg and some light snow being reported in the Shenandoah Valley. Mike Stinneford took this picture from his mountain home in the Blue Ridge where a dusting has already fallen.
6:47am: The stage is being set with dry air at the surface (dew points in the teens) and temperature currently at or below freezing. Precipitation is beginning to move into the region (per Doppler radar)but is falling as virga and not reaching the ground just yet with surface moisture levels so low. We'll have to wait until later this morning (8am-11am) for enough moisture to get into the region for snow to begin to fall.
Oddly enough, Reagan National Airport is reporting flurries right now, but looking out the window I don't see anything just yet and don't expect to until another couple of hours.
Here I am sitting at work on a nice December Saturday afternoon, seeing sunshine out the window and thinking how different it will be in 24 hours. Taking a look at the current surface map, high pressure to the west is helping push cool and dry air into the region, with dew points now falling into the 20s and high temperatures only in the low to mid 40s.
Tonight, winds will subside, temperatures will fall into the upper 20s to lower 30s, and clouds will begin to increase from the southwest as a disturbance moves into the region.
Futurecast for 2pm Sunday showing a mix of snow, sleet, freezing rain and rain
Precipitation is still expected to start as snow in the D.C. area. It will move in from the southwest and spread to the north and east through the morning hours. At this time light accumulations are still possible, with the highest likelihood of only 1 to 2 inches of snow by lunch time or the early afternoon.
Chances for Accumulating snow in the D.C. area (Highest totals West)
Futurecast Snowfall Predictions (Probably a little overdone)
Here is a look at snowfall accumulations from our in-house model simulation. I think it is a little on the high end, so please take this with a grain of salt. Also, once precipitation changes over to sleet and freezing rain, these accumulations won't mean much as the snow will get compacted and eventually melted by rain Sunday night into Monday morning.
Timeline from 6am to 2pm Sunday (Sorry the title is off!)
Snow is expected to change to sleet and freezing rain by the early afternoon hours. The timing is anywhere from Noon-3pm with snow hanging on a little longer in the western portions of the area.
Timeline from 4pm to Midnight Sunday
Sleet and freezing rain should then be the predominant precipitation type through the late afternoon and evening hours. Areas to the east may see a change to plain rain in the afternoon, with the highest likelihood closest to the Chesapeake Bay. Locations west of D.C. may hold on to freezing rain a bit longer into Sunday night.
Icing Chances (Highest likelihood west of D.C.)
Some locations west of the Blue Ridge in the Shenandoah Valley have the highest threat for freezing rain and icing accumulations. Some locations may stay at or below freezing into early Monday morning west of the Blue Ridge and at this time we think cancellations will be likely in those areas.
East of the Blue Ridge, enough warm air should enter the region Sunday night into Monday morning to change precipitation to plain rain, and temperatures should be above freezing Monday morning for the morning commute.
The chance is still there for cancellations and delays Monday morning east of the Blue Ridge, but minor changes in just one degree in temperatures could make the difference between more or less ice.
Our team will be starting on Newschannel 8 at 7am Sunday and will continue to be live throughout the day with updates on everything from where the precipitation is to how the roads are faring. Be sure to tune in during the day and charge your iPads and Laptops as if you lose power, you can always tune in online as well.
A strong cold front pushed through the region this morning, with temperatures in the 60s overnight pushed back into the 50s by sunrise and into the 40s through the afternoon.
Scattered showers will continue through the afternoon and end later tonight. High pressure will move over the D.C. area Saturday making for partly cloudy skies and cooler temperatures in the low to mid 40s.
3pm Friday Temperatures (WeatherBELL Models)
Saturday night will be cold and dry, with low temperatures in the 20s and 30s in the region and dewpoints back into the teens to low 20s. This is all setting the stage for a disturbance to move into the region Sunday, with warm, moist air moving over the cold, dry air at the surface beginning Sunday morning.
Winter Storm Watch from the National Weather Service
4km NAM forecast for Sunday morning (Courtesy: WeatherBELL Models)
Precipitation is expected to start Sunday morning in the form of snow before changing over to sleet and freezing rain in the afternoon hours. At some point, enough warm air will get into the region to change precipitation to rain, but the question is how late in the day or into Sunday night it will take place.
If it happens earlier, much less of an impact can be expected, but if it happens later, there could be major complications in the region due to icing. Below is a look at one forecast model depiction for Sunday evening, still showing the blue 32 degree line south and east of the D.C. Metro.
At this point, we expect areas of precipitation to begin changing to rain come Sunday evening southeast of D.C. and it will be on the edge of changing in the D.C. Metro. Travel looks poor Sunday evening.
4km NAM Sunday Evening (Courtesy: WeatherBELL Models)
Here is Chief Meteorologist Doug Hill's discussion which I thought summed up the forecast perfectly,
"At this point we can tell you what is possible on Sunday…what we expect to happen on Sunday. Because temperature profiles will be so important, we cannot yet tell you for certain, what WILL happen.
More rain with slowly falling temperatures WILL continue tonight and perhaps into the morning hours Saturday. Breezy and chilly weather WILL tomorrow with skies becoming partly sunny. Even colder air WILL settle into the region Saturday night.
On Sunday, moisture WILL rapidly increase over the area and precipitation WILL begin to fall.. It WILL begin as snow in many areas and then mix with or change to sleet for a period and then change to Freezing Rain.
Eventually, when surface temperatures rise above 32 degrees, the precipitation will become just plain rain. This IS NOT a one size fits all forecast.
Different precipitation types with different effects WILL be the story all day Sunday. Adverse to dangerous driving conditions WILL DEVELOP. The most likely areas for this to occur will be along and west of the I-95 corridor.
The longer it takes for temperatures to rise above freezing, the greater the chances for these conditions. And in general, the farther north and west you are from D.C, the greater the chances of this happening."
Take a look at what people have been posting on social media highlighting the storm over the past few days. We'll start in the middle of it in Arkansas, where ice build up as accumulated on trees making for a mess.
Moving into Indianapolis, cold air wasn't just at the surface, allowing for all snow to develop rather than the icing seen south. One person sent in a picture of their snow measurement which was up to 3.25".
Our chances for wintry precipitation will increase on Sunday. You can read about it here in our blog from last night. I'll be working on a new blog which I'll post this afternoon on the latest updates on Sunday's storm. I really don't think anyone is hoping for what is going on out west!
Winter storm warnings and ice storm warnings are posted for parts of the Deep South east into the Mississippi and Tennessee Valleys today and tomorrow and reports of icing and major traffic complications are already beginning to pile in through social media.
Above is a look at just one of the highways in Oklahoma where reports of up to a quarter of an inch of ice has built up causing multiple accidents.
Here's a look at all of the watches and warnings across the U.S. from the National Weather Service. They stretch from Texas all the way to Ohio, with the shade in pink Winter Storm Warnings and in deep purple Ice Storm Warnings.
Take a look at this tweet below showing the difference in temperature across Texas.
It gives you an idea of just how much cold air is involved with this system. The cold air is undercutting the warmer air aloft, and with precipitation falling through the warm layer above it melts precipitation to rain which will then either refreeze into sleet before hitting the ground or freezing on contact with the surface in the form of freezing rain.
Below is a nice graphic showing this type of scenario.
When there is a warm layer aloft, often times if that layer is greater than 600 ft deep or if it exceeds 3-4°C, then complete melting will occur. The next problem is figuring out how deep the cold layer is at the surface, as even if the precipitation melts aloft, it may refreeze into sleet if there is a cold layer greater than 800 ft deep at the surface.
Little nuances like that make it fun for us forecasting such a delicate process. A matter of 1 to 2 degrees are all that it takes to differentiate snow, from sleet, to freezing rain and plain rain. And you say meteorologists have it easy!
What we can give is our best guess this far out. Right now, we think hazardous conditions will be likely through the day on Sunday. Here's our current thoughts as to the timing.
Start Time Frame:7am - 11am
-Taking a look at some of the guidance, the starting time has been delayed just a bit to the mid-morning hours on Sunday. This could be bad news for people headed to the Redskins or Ravens games as it may be quiet when you wake up but treacherous by the time you exit the game. Keep that in mind for now and stay tuned to the latest updates.
850 Temperatures Sunday Evening
Changeover to Rain: 5pm (East) - Overnight (West)
-A changeover from snow and sleet early on to plain rain is still expected, but it appears like it will be a slow progression from east to west with some western areas hanging on to freezing rain through the overnight on Sunday. This will be the toughest part of the forecast and has the least confidence at this point.
Our thoughts are that D.C. and points east will change to rain after sunset and points north and west will hang on to freezing rain overnight. This may lead to delays or possible closings Monday morning.
-The system won't exit the region until Monday or Tuesday as the cold front moves off the east coast. Rain will fall during the day on Monday and temperatures will rebound into the mid and upper 40s. Much colder air will filter into the region Tuesday and Wednesday with highs in the mid 30s each day and lows into the teens possibly by Tuesday night!
-Areas of light snow are expected to develop in the morning hours, changing to sleet and eventually freezing rain later into the afternoon and evening. Light accumulations may be possible, though they are too difficult to pinpoint at the moment. Regardless, we think it will be enough to cause slick road surfaces and enough of a travel issue that you might want to stay home Sunday afternoon and evening.
Depending on the amounts of snow, sleet and icing, power may be lost, so be sure to just keep that in the back of your mind in the case of the worst scenario.
We will have full updates tonight on ABC 7 at 5, 6 and 11pm and will continue to update you on each live newscast. In addition, we'll be updating our website around the clock tonight and tomorrow and will continue to substantial updates through the weekend.
Numerous weather alerts are posted through the country, with heavy snow falling in the Rockies to the Midwest, and the potential for a dangerous ice storm shaping up for parts of the Central Plains and Mississippi Valley.
This will be a high impact system with numerous travel complications likely through the weekend.
Snow isn't the only issue in the forecast, as freezing rain will become a big problem from Texas and Oklahoma, east to the Ohio Valley.
Below is a look at the probability of more than 0.1" of freezing rain across the U.S. from a 48-hour period Wednesday night through Friday night.
Graphic from the WPC
This shows a 80-90 percent likelihood of greater than 0.1" of freezing rain accumulating across parts of southeast OK, much of AR and points northeast through the Mississippi and Ohio Valleys. This storm will affect those regions through Friday night into Saturday morning.
The next threat will move in behind this system and will bring an additional chance for frozen precipitation into the weekend for the D.C. area.
This has been a relatively consistent forecast since the beginning of the week and the chance for a wintry mix at the onset of precipitation and possibly a good amount of Sunday is increasing.
Above is a look at the forecast MSLP, 3-hr precipitation and 850mb temperatures for Sunday around lunch time per the GFS model. If you take a look at the northeast, you see the blue H over Canada representing a large area of high pressure.
You also see the black lines which are constant lines of pressure (called isobars) dipping on the east side of the Appalachians. This is showing cold air damming, as the cool, dry air from the high over Canada is pushing air into the D.C. area from the NE and trapping it against the mountains.
As warmer air and precipitation moves over the cold pool at the surface, the air will begin to saturate and temperatures will more than likely be below or near freezing through much of the D.C. area.
Depending on the depth of the warm air layer above the surface, precipitation may either fall as snow, melt some and refreeze in the cold pool to sleet, or possibly melt aloft and fall onto a frozen ground in the form of freezing rain.
This could cause travel complications across the D.C. area Sunday, but don't expect to have Monday off, as warmer air is expected to move into the region late Sunday into Monday morning changing everything over to rain.
Places that will hang on longest to the wintry precipitation will be in areas to the northwest such as the Shenandoah Valley. We will have further updates on this developing situation in the D.C. area over the next few days.
The sun sets at 4:46pm this evening and will continue to do so for the next week and a half. In fact, the earliest sunset of the year spans between December 1st and December 12th, all coming at 4:46pm. By December 13th, the sun begins to set later, but days continue to get shorter through the winter solstice, which lies on December 21st. The shortest days of the year are December 20th-22nd, which all have 9 hours and 26 minutes of daylight.
Above is a look at the sunrise and sunset times over the next few months. The sunrise continues to get later through the end of the month, with the latest sunrise at 7:27am from December 30th through January 10th. The first sunset at 5:00pm in 2014 will be on January 4th, and you can see how much daylight we gain by the 31st, with the sunrise at 7:15am and the sunset all the way to 5:28pm.
Back to work and all of a sudden it's December! Seems like November flew by. November ended up to be a cooler than average month by three degrees. It might be hard for you to believe that, if you recall, we hit 70 degree temperatures the first two days of that month! Winter is officially here, now. Meteorological winter is recorded as December, January and February. However, the winter solstice is on Saturday, December 21st at 12:11p.m. EST.
Now that we've turned the page to December, we are starting with near average temperatures. We begin the month with an average high of 52 degrees on the 1st. By the end of the month, our average high at Reagan National drops to 44 degrees.
With less daylight and colder temperatures, we typically see our first measurable snowfall at Reagan National. December gets 2.3" of snow on average for the month. The snowiest day on record was December 19th, 2009 when we had 15" of snow in 24 hours. There have also been plenty of Decembers with zero snowfall.
The coldest December day bottomed out with -13 degrees on the 31st back in 1880. And, the hottest December day featured a high of 79 on December 7th, 1998. Our forecast for the first week of the month has highs and low points. We should hit 60 degrees on Thursday, but by Sunday, it will be cold and back in the 30s with a chance for some snow.
This Thanksgiving was perfect for hot turkey, warm trimmings and even a fire in the fireplace -- it was the coldest Thanksgiving in 13 years! Yesterday reached 40 degrees.
In 2000, the Thanksgiving high temperature only reached 38 degrees. That makes yesterday's high the coldest Thanksgiving in over a decade!
We're nearing the end of the month and it will end below average in the temperature department. As of Thanksgiving, November was 2.5 degrees below average. Another cooler than average day today and tomorrow. Not only for us in the Nation's Capital, but across the U.S. Look at all that blue!
College of DuPage
Quiet weather conditions are also expected to wrap up November, which is great news for travelers returning home after the holiday. Pretty much rain free across the U.S.
At this point we think the worst of the system will move through tonight as the area of low pressure begins to move up the coast. We have already seen Tornado Warnings in the Florida Panhandle which is helping give an idea just how strong this system is gearing up to be.
HRRR Forecast Precipitation by Wednesday afternoon (Courtesy: WeatherBell Models)
As we head through the afternoon and evening, rain will continue to fall across the region yet will wait to pick up in intensity until closer to sunset.
There is the chance for 2 inches of rain or more overnight into Wednesday morning as the low moves into the region. The model shown above even brings the chance for closer to 3 inches in isolated spots across the area.
This could lead to some flooding issues but they should be limited since conditions for the month have been so dry.
Small streams and creeks may have some flooding issues but the bigger problem may be limited to ponding on the roadways.
Day 1-2 QPF from the Weather Prediction Center
Up & Down: WRF 4km has temps jumping to 50°F+ in DC for a few hours late Tues & early Wed -- then back to 30s pic.twitter.com/AN5vH0UcIg
The tweet above gives a look at the 4km NAM model, which shows the potential for temperatures to really jump during the overnight hours as the low moves over the region.
Warmest temperatures will be east of the low and parts of the Eastern Shore and even Southern Maryland could reach the 60 degree mark overnight (See image below). Areas west of the Metro are expected to hang in the 30s and 40s.
HRRR Temperature forecast for midnight (Courtesy: WeatherBell Models)
The low will pass by the region overnight and intensify over the Northeast Wednesday. Winds will change from easterly to northwesterly tomorrow and become very gusty through the afternoon and evening.
Winds appear to be the strongest tomorrow with gusts possibly to 45 mph at times. The highest winds should be in higher elevations northwest of D.C. Below is a look at the 850mb winds and temperatures. The winds may be up to 50 knots at that height which could translate down to the surface giving the higher wind gusts.
850mb Winds and Temperatures Wednesday night into Thursday morning
Snow will also be possible as the low moves north of D.C. Cold air will filter in as the winds shift and precipitation should change to snow across the area by tomorrow afternoon.
There is the possibility for some light accumulations throughout the area but they will be very limited in the D.C. Metro because of the wet and warm surface temperatures. Regardless, it will still have the potential to impact travel.
Again, if it snows tomorrow, be especially careful on bridges and overpasses if you happen to be traveling at the time. Light accumulations may be possible in the higher elevations north and west of D.C. Below is a look at total accumulated snowfall from the 12Z ECMWF model, but that doesn't take into account the wet and warm ground which would surely help melt much of the snow on impact.
Snow accumulation forecast from the ECMWF by early Thursday morning (Courtesy: WeatherBell Models)
Winds will continue to be breezy through Thanksgiving morning but high pressure will move overhead by the afternoon allowing winds to subside. Temperatures look cold Thanksgiving Day with highs in the mid to upper 30s and again on Black Friday with highs again only in the upper 30s.
It's hard to think this November may go into the books with 4 days with high temperatures in the 30s. Ian Livingston, a colleague and writer for the Capital Weather Gang found that the two day span Sunday and Monday with high temperatures in the 30s hasn't occurred in the month of November since 2000 and the average of the two day span was the coldest in a row in November since 1970!
Guess we'll have to wait and see what the actual Winter brings!
A Winter Weather Advisory remains posted for Montgomery, Fairfax and Prince William counties and points west through the Shenandoah Valley starting at 4am. The Advisory expires at 1 p.m. closer to the metro area and 4 p.m. for locations farther north and west where cold air may hang on later in the day.
Precipitation is expected to overspread the region late tonight into Tuesday morning. Very dry air at the surface will keep heavy precipitation from occurring until the air column saturates later in the day.
At this point, it appears light snow, sleet and freezing rain will become possible by the early morning hours after 4am in the far southwestern suburbs and later closer to the D.C. Metro.
Precipitation totals appear very light through the morning commute, with less than a tenth of an inch (0.10") of liquid equivalent possible by 10am. This would mean that anything that falls will be light in nature during the early morning. This is due to extremely dry air at the lower levels.
Dew points are currently in the single digits and the air will need to saturate in the morning for precipitation to fall. With the saturation occurring, it will help cool the air, thus allowing for the onset of precipitation to be in the wintry form of snow, sleet and freezing rain. The D.C. Metro itself and places east may even experience a light wintry mix at the onset of precipitation but we're expecting a faster transition to rain by the late morning.
Frozen precipitation will change over to rain rather quickly closer to D.C. tomorrow, but may take a little while to change to rain in the western suburbs, particularly west of the Blue Ridge where cold air may pool in the valley through the afternoon.
Regardless, everything will change over to rain late in the day and into tomorrow night. Very heavy rain appears likely through Wednesday morning, with the potential of 2-3 inches of rain or even higher amounts possible.
This may cause some areas of flooding through Wednesday morning so stay tuned to the latest forecasts. A Flood Watch may be posted at some point tomorrow per the latest National Weather Service forecast discussion.
Predicted Precipitation Totals
Gusty winds would be the next threat as the low intensifies over the the Northeastern U.S. Winds may gust up to 40mph+ at times Wednesday evening into Wednesday night. The highest gusts should be in higher elevations north and west of the city.
Thursday and Friday
Thanksgiving Day and Black Friday will be chilly, with highs in the upper 30s each day but also a lot quieter. Skies should be sunny and winds will begin to diminish come Thursday morning. High pressure should make for continued quiet conditions through the weekend.
Just what the Interstate 95 corridor needs for the days leading up to Thanksgiving -- a coastal storm. Everything is lining up for wet weather that will likely impact your travel on the roads and in the air.
Let's start with the two weather systems that will combine to create this messy weather. A cold front will dive south, from Canada, into the central Plains. At the same time, an area of low pressure will develop over the Gulf of Mexico and track up the east coast.
Here's a visual of these two weather features by Tuesday morning.
Weather Prediction Center
The will be a mainly rain event for D.C. area; however, at the onset and tail end of the wet weather, there is the potential for some mixed precipitation. Precipitation will start Tuesday morning and move in from southwest to northeast.
Areas south and west of Washington may see a little freezing rain/sleet/snow Tuesday morning, as the moisture tracks into the area (no accumulation expected). This is a simulation of conditions at 7 a.m. Tuesday.
By 10 a.m., most, if not all, of the precipitation will change over to a chilly rain.
Rain will continue through the day Tuesday and will become moderate to heavy late in the day and through the first half of Wednesday. Keep in mind that this moisture will track north into New England for the day on Wednesday.
College of DuPage
This coastal storm will produce a lot of moisture. Check out these forecast precipitation totals up and down the east coast.
Weather Prediction Center
As I mentioned, most of the precipitation in the D.C. area will fall as a chilly rain. As the moisture wraps up Wednesday evening, enough cold air may spill in, for precipitation to end as a little wet snow. Little to no accumulation is expected at this time.
The good news is the coastal storm will be a fast mover, so by Thanksgiving Thursday the storm system will be north of Maine.
On the flip side, the bulk of the precipitation will fall on one of the busiest travel days of the year.
If you're flying, you'll want to check frequently with your air carrier for delay and cancellation updates. You can also check out this FAA website for air travel updates.
Traveling Thanksgiving day will be much quieter, as high pressure settles in. It will remain dry, but chilly for Black Friday shoppers.
Remember a few weeks ago, when winter weather was threatening the region nearly 6 days out from the forecast date?
It appears the same type of scenario is happening again, but this time around there is much better confidence for this system to impact the east coast. Let's take a look at the potential impacts next week.
The D.C. area is already expected to experience its coldest temperatures this early in the season in at least 5 years. Cold air will hang around the region this Sunday and Monday behind tonight's strong cold front. High temperatures should only reach the 30s Sunday and near the 40 degree mark Monday.
(Courtesy: WeatherBell Models)
Above is a look at the 500mb relative vorticity plot valid this morning. I've circled two areas of energy, one off the coast of Southern California and one over portions of western Alaska.
We'll be watching for the southern cut-off low meander across the U.S. over the next few days and the energy in Alaska move through Canada and eventually to the Great Lakes by early next week.
When these two finally reach the East Coast, it will result in a big trough over the eastern part of the U.S. As this trough develops, a surface reflection of low pressure is expected to develop over the Gulf of Mexico and move east, transitioning to the east coast late Tuesday into Wednesday morning.
Wednesday morning 6hr-precip and MSLP ECMWF Model (WeatherBell Models)
Wednesday morning 6hr-precip and MSLP GFS Model (Nexlab Models)
As you can see from the model guidance above (to be taken with a grain of salt; still 5 days out), an area of low pressure moves along the eastern seaboard which will have the potential to help spread precipitation along the Interstate 95 corridor just in time for everyone to travel for the Thanksgiving holiday.
7 Day QPF from the WPC
There have been hints that the precipitation could be heavy, with up to an inch or more possible from late Tuesday through Wednesday. The best timing at the moment looks like it would be from sunset Tuesday to sunset Wednesday, with the system long gone by Thanksgiving Day.
Right now, the question remains as to what type of precipitation it would be. There could be some snow, but I think the best chance would be relegated to the higher elevations in the mountains.
This is something we'll need to keep an eye on, but latest forecasts are depicting a sufficient amount of warm air in the lower levels for precipitation to fall as rain. The main problem this system will have is that there won't be a big supply of cold air into it as high pressure will have relocated well off the east coast.
The system is expected to clear out the area on Thursday with partly cloudy skies, cool temperatures in the low 40s and along with breezy winds.
Our team will continue to keep you updated on this situation through the weekend and early next week as new developments arise. Be sure to check watch ABC 7 News into the weekend and check our latest posts here online or on our Stormwatch 7 Facebook page for the latest.
Mike Halpert, whom we have interviewed in previous years for our own winter weather outlook, states why that is so important.
“It’s a challenge to produce a long-term winter forecast without the climate pattern of an El Niño or a La Niña in place out in the Pacific because those climate patterns often strongly influence winter temperature and precipitation here in the United States,” said Mike Halpert, acting director of NOAA’s Climate Prediction Center.
“Without this strong seasonal influence, winter weather is often affected by short-term climate patterns, such as the Arctic Oscillation, that are not predictable beyond a week or two. So it’s important to pay attention to your local daily weather forecast throughout the winter.”
NOAA's Precipitation Outlook for Winter
Above is the precipitation outlook, showing continued drought conditions in the Southwest and drier than normal conditions developing in the Southeast. Areas in the Northern Rockies are expected to experience above average precipitation.
NOAA's Temperature Outlook for Winter
Warmer than normal temperatures are anticipated across the South as well as the far Northeast. Cooler than normal temperatures are expected in the Northern Plains states.
What does that leave the D.C. area with? Equal chances of everything. NOAA states there isn't a "strong or reliable enough climate signal in these areas to favor one category over the others, so they have an equal chance for above, near, or below normal temperatures and/or precipitation."
NOAA even made a video for the Winter Outlook featuring Mike Halpert.
A very strong cold front will push through the region this weekend, bringing more than likely the coldest air of the season. If you remember correctly, just 7 days ago on the 13th, high temperatures only reached the 45 degree mark. This time around, highs may not escape the 30s.
A lot of cold air is located over Alaska and northwestern Canada and will spill into the United States over the next few days. It's already in the single digits in parts of Montana this afternoon, but the real cold air in the -20 to -30 range has been hanging out in Canada and Alaska. As you can see in this image, Billings, MT is 47 degrees colder than it was at this time yesterday!
24-Hour Temperature Change for 5pm Wednesday
The cold air is expected to spill into the U.S. by Friday and work its way to the East Coast by Sunday as a cold front moves east and a very strong area of high pressure spills into the Midwest and Northern Plains.
Temperatures on Saturday ahead of the front will be seasonal in the low to mid 50s, but they should fall behind the cold front and continue to do so through Saturday night. Below is a look at the temperature anomaly Sunday early afternoon, showing temperatures around 20 degrees or more below where they typically are this time of year.
Temperature anomalies Sunday (Courtesy: WeatherBell Models)
Very gusty winds will accompany the cold air intrusion with the potential for wind gusts to 45 or even 50 mph during the day on Sunday. Combined with temperatures in the 30s, it will make it feel like the teens the majority of the day. The image below is a model forecast of the 850mb (around 5000ft) temperatures and winds. Over the D.C. area, winds are around 50-55 kts at that level, and some of that energy may make it to the surface which would allow for the higher wind gusts in the 45-50 mph range.
850mb Temperatures and Winds Sunday Morning
If Reagan National only reaches the upper 30s for high temperatures Sunday, it will be the earliest time to do so since 2008, when it only reached 37 degrees on the 22nd of the month.
The past two years in 2013 and 2012, high temperatures in the 30s for the first time in the season didn't occur until January 3rd.
Oddly enough, both 2010 and 2009 experienced the 30s for highs on the same date as well, but not until December 6th. I guess we'll have to wait and see how cold Sunday turns out!
NOAA's National Geodetic Survey experts measure the peak of the Washington Monument. (Photo: NOAA)
The Monument, which was built between 1848 and 1884, is a tribute to George Washington. (More on its history here) Its current official height is 555 feet, 5 1/8 inches from top to bottom.
But, it has been measured several times over the years with different results. For example, in 1998 it was measured at 555 feet, and in 2000 at 555 feet 5 1/2”. So, why the discrepancy?
Settling of the earth could be a factor over the years. After all, D.C. was built on swampy ground. Some question whether or not the earthquake in August of 2011 caused sinking. But, it could also have to do with the technique used for measuring.
Technology allows for much better accuracy and the 2013 measurement will have a margin of error of only 1-2 millimeters.
Measurements from the Ground. (Photo: NOAA)
One known recorded height change was caused by storms over the years. In 1934, it was documented that the aluminum tip had been burned by lightning and was now squared, meaning ¾”-7/8” had been burned off.
November 19, 1934 National Geodetic Survey. (Photo: NOAA)
The results of the recent measurement will be released in early 2014. Also, in the spring of 2014 the scaffolding will be down and the Washington Monument is scheduled to be open to the public to get that amazing view of our city.
However, the public won’t be allowed to the very top to get the unique view we wanted to share with you today. It is undetermined how long before anyone will be back at the "tip" or when it will be measured again. You may not want to go up there anyway, especially in winter... the top of the Washington Monument is on average 2 degrees Fahrenheit colder than at the base (if you use standard lapse rate of 6.5 degree Celsius drop per 1000 meters of height).
Winds also increase with height. For complete details on the survey, check out more photos and Q & A from NOAA on this link.
It doesn't happen very often in November, but Sunday's tornado outbreak in the Ohio Valley is a devastating reminder that tornadoes can and do happen any month of the year in the United States.
Preliminary Tornado Reports November 17th
The powerful storms spawned tornadoes in 5 states, but the hardest hit city was Washington, Ill. It was rated as a preliminary EF4 tornado with winds of 170-190 mph.
The unofficial tornado count stands at 81. This number will go down significantly though because there are often multiple reports of the same tornado. However, it looks likely that Sunday will end up in the top three of tornado days in the United States this year.
Top 3 Tornado Producing Days 2013
There was plenty of warning on the storms, but they moved very quickly at around 55 mph. The Storm Prediction Center in Norman, Okla. issued a "high risk" of severe storms, something they have only done two other times in November since 1998.
When the cold front knocked on our door, it was the middle of the night, losing some of the prime daytime heating and the storm energy had lifted north. We ended up with some gusty showers between 2 a.m. and 3 a.m. Here are a few peak wind gusts from our WeatherBug network.
Weather Bug Peak Wind Gusts Overnight
No damage has been reported in our area as of this writing. Rainfall totals weren't terribly impressive either. We had .15" at Reagan National Airport. The cold air that typically ushers in behind a front like this is still back in the Midwest.
Forecast Highs Today
While it will be breezy today, temperatures will remain mild in the 60s for highs. The cooler air settles in tomorrow with high temperatures near 50 degrees.
Speaking of extreme weather, I might also want to add that Hurricane Season is still ongoing.
Possible Tropical Development Atlantic-NHC
It officially ends on Nov. 30. After a very quiet month so far, a subtropical storm Melissa has developed Southeast of Bermuda. It is no threat to the U.S. To get the latest on Melissa, go to www.nhc.noaa.gov
Over 75 tornado reports, 270 wind reports and 40 reports of hail have been made so far Sunday and more are anticipated as this system pushes towards the east coast. Extensive damage has been reported in parts of Illinois including Washington, IL, where reports are coming in of homes being destroyed and potential fatalities.
A number of storm surveys will be conducted tomorrow and some were started this afternoon after the storms moved out of the area. From the looks at the tweet above, it appears the tornado that struck Washington, IL was rated at EF4, though I couldn't find anything about it online just yet.
The weather pattern across the U.S. has been very progressive this month; multiple cold fronts have crossed the country, with warm air in advance in colder winds in their wake.
The next front is organizing in the Northwest and poised to roll through just in time for the morning commute Monday. The upper-level energy from this weather system will push into the Plains Sunday and then lift into the eastern Great Lakes Monday. Ahead of it, there is significant potential for severe storms in the Midwest and Ohio Valley. The Government’s Storm Prediction highlights a moderate potential for damaging thunderstorm wind gusts in the bull's eye seen on the map below.
The jet stream, or zone of upper-level winds, this time of the year favors strong winds because temperature contrasts in northern and southern latitudes increases, allowing for a faster flow of air and more atmospheric mixing (cold air sinking and warm air rising).
This front will draw upon the fast jet stream winds to produce rain and wind. Looking closer at the data from Reagan National Airport, notice on the image below how winds not far from the surface (5,000 feet) are 57 knots, which translates to about 65 mph. This image shows the atmosphere profile (vertical cross section) of the winds, temperature and dew point in Washington early Monday morning just before the front is slated to move through.
The cold front will likely cross just as the morning commute is in full swing. Notice the light blue or pink line highlighted in the image below. This shows a sharp pressure rise immediately in the front’s wake. A combination of high winds aloft and a sharp pressure rise will contribute to gusty winds along the leading edge of the front in the showers that move through.
While all of the high winds aloft will not translate to the surface, at least half of this momentum will transfer to the ground in the heavier showers. Gusts will likely reach 35 mph in Washington. Closer to the best upper-level support with the front in the western suburbs and where there are elevations closer to that critical 5,000 foot level, gusts of 40-50 mph are likely. Due to these factors, Wind Advisories will likely be issued along and west of the Blue Ridge ahead of the front on Sunday.
If you recall, on November 1, a line of thunderstorms trucked through the Ohio Valley and became a north to south line of showers by the time it reached I-81 and then drove east through the morning. Wind gusts were 35-45 mph and sporadic damage was noted, mainly tree branches down, in Frederick and Carroll County.
Be prepared for a potentially longer than normal commute Monday due to the brief intense rain and gusty winds and it may be wise to set an alternative alarm in case the power briefly goes out in your location overnight Sunday. Stay with ABC7 for the latest forecast and the latest wind-related advisories that could be issued for parts of the region.
The air behind the front initially won’t be very chilly. As a matter of fact, the breezy northwest winds in the front’s wake will downslope, warm off the Blue Ridge (when air compresses it warms up) and overcome the bit of cooling to the post-frontal air, allowing temperatures to actually recover close to 70 degrees in downtown Washington Monday afternoon.