From the ABC 7 Weather team

Some Precipitation Headed Our Way - Could Impact Super Bowl Plans

January 31, 2015 - 10:32 AM
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“So here I go again with another typical D.C. winter storm. I’ve been through all the guidance I’ve ever known! Like a drifter, earlier I was lost about this storm. But I’ve made up my mind. I ain’t wasting your time. Here we go again…”

Okay, so a little Whitesnake change of lyrics to start of this post –hopefully to lighten the mood for those who really wanted snow for Superbowl Sunday (and I can’t take full credit for the witty lyrics above – the ingenious forecasters from NWS Boston gave me the idea). Either way, let’s get down to details about the next event headed our way for Sunday, shall we? Rain.
Yes, this is looking more and more like a rain event for the ABC7 viewing area. I will just go ahead and throw it out there now. However, it could start off as some winter weather.

The Surface Details

High pressure is in charge for your Saturday, eventually calming our winds and bringing us lots of sunshine and a very dry atmosphere. An area of low pressure will push out of Colorado today moving northeast. By Sunday, it will trek through the Ohio valley, eventually shooting off the east coast by Monday bringing a swath of precipitation with it.

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Caption: Low pressure will be in Missouri by 7a.m. on Sunday morning. By Sunday night it will be just north of Kentucky eventually moving through northern Virginia by Monday morning at 7 a.m.

On Thursday, the track of the low was more to the south of the region which would be a better scenario for all snow with cold air filtering in. However, this is not the case over the last two days. The track of the low continues to trend north and as the low pressure moves eastward, intensifying as it travels; warm air will be pulled into the region changing our precipitation to rain. In fact, the most of the region (if not all) will be in the warm sector Sunday overnight as the associated warm front lifts to the north. Eventually the cold front associated with the low will cross through the area on Monday morning, bringing colder air behind it. High pressure will then move quickly in from the Ohio Valley by Tuesday.

What To Expect

While we could start off with some bursts of snow on Sunday morning – mid morning, the bulk of the precip will hold off until Sunday late afternoon - evening. I am keeping the chance of snow showers on Sunday morning but I do worry about anything reaching the ground considering dry air from our high pressure moving off the coast (in other words, as precip falls through the atmosphere, it would evaporate before it hits the ground with dry air in place). However, if we can overcome that, then there could be some snow showers tomorrow morning and even some light accumulation in some spots considering how cold it has been.

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By Sunday afternoon/evening, the bulk of the precipitation will be moving in. I do expect a mixed bag of precipitation: snow to the north, a line of sleet with some spotty freezing rain and rain to the south. As we continue to pull warm air into the region through the overnight, the mixed bag of precip will eventually turn to a cold rain. The last of the area to see the changeover will be north and west of D.C., which means these are the likely areas to see some minor snow accumulations.

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Caption: Probability of snow accumulation of more or equal to 1.0” by 7 a.m. Monday morning.

We will hit our daytime high on Monday in the morning. Once the cold front passes, temperatures will begin to fall. We will have to watch for a chance for some freezing rain by early Monday morning, mainly north and west. I do believe the commute will be messy anyway with rain coming through and freezing rain will only of course add headaches.

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Caption: Best chance of some minor icing by 7 a.m. Monday morning will be along I-81 from Winchester to Hagerstown and I-70 from Frederick to Hagerstown.

The precip should be out of there by around lunch time on Monday however, if it lingers slightly longer, we could see a quick changeover to snow before it is all said and done. High pressure will quickly be moving in so most of the moisture feed should be cut off. With that being said, the incoming high pressure and the exiting low pressure will create a tight pressure gradient, kicking up winds Monday afternoon. Temperatures will drop and wind chills will be present, most likely in the 20s. After that, we will get some sunshine by Tuesday!

So sorry snow lovers, this doesn’t look like the store for us. However, we have to get through February AND March (remember St. Patrick’s Day snow storm last year?) so there are still some chances we could get snow, just not very much with this storm.

 

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Light precipitation expected Thursday for the evening commute

January 28, 2015 - 02:13 PM
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I’m going to start with the good news: Washington, D.C. gains two minutes of daylight on Wednesday! Finally, we have turned the page towards Spring…. Although yes, we are in the dead of winter and it feels like it today. Another piece of good news: I am going to write about some precipitation moving through the region on Thursday, but it looks LIGHT. However, it could impact the evening commute. We all know how one raindrop can affect the evening commute so I felt compelled it just mention it.

Winds will be light by Wednesday evening and clouds will begin to pile in overnight and through the day on Thursday. The first part of the day will remain dry while our next system moves out of the upper Midwest.

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Caption: Thursday morning an area of low pressure will move out of the Upper Midwest and into the Mid Atlantic.

The system will move southeastward into our region by late tomorrow afternoon and into the evening bringing some light precipitation with it. Temperatures are forecast to make it into the mid-30s to around 40 degrees on Thursday. So although observed temperatures and daytime highs will be above freezing by the time precipitation begins, road surface temperatures could remain below freezing, especially north and west of D.C. where some snow is still on the ground. Therefore, there could be some slick spots out there tomorrow evening and into the late evening.

We are expecting just some light snow and/or rain showers (some pockets of freezing rain) moving through the area during the evening commute and then zipping on out of there by the late evening hours. Again, you can see that just a little is going to fall across the region –so maybe a coating of snow possible in some areas with some light icy glaze in other parts.

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Caption: There is about a 5% chance (brown color) for more than 1.0” of snow to fall across most of our region with slightly better chances north and west of D.C.

After this, winds will pick up on Friday! We are talking wind gusts of up to 40 mph! That means with temperatures only in the 20s/30s, we are going to have wind chills in the teens for much of the day. High pressure will continue to build in on Saturday and by Sunday, we will be turning our attention to our next system that could bring us, once again, a mixed bag of precipitation Sunday night into Monday. Too early to get into details but if you are headed out for Superbowl Sunday, make sure you keep it here for the up-to-date forecast!

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Winter Weather Advisory, Winter Storm Warning Monday

January 25, 2015 - 05:11 PM
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LIVE DOPPLER  |  WARNING/ADVISORY  |  HD WEATHERBUG CAMS

Check out here for the latest Virginia School Closings/Delays, Maryland School Closings/Delays and D.C. School Closings/Delays.

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

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

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

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

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

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

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

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

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

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

 

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Winter Weather Moving In Sunday Night

January 24, 2015 - 08:54 PM
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One system moves out and yet another is on its heels.  An Alberta clipper is diving out of Canada and is currently over the northern Plains.  This clipper will continue it's trek southeastward and will bring snow to parts of our area by dinner time Sunday.

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

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

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

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

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

WeatherBell Computer Models - 18z GFS

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

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

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Read More:

A Series of Storms Headed Towards Us For the Weekend-Latest Details

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

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

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

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

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

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

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

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

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


 

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

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

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

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

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 Above Image Credit (Blacksburg NWS)

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Current Road Surface Temperatures in Maryland

Virginia Road Conditions and Cameras

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

Snowfall Forecast for Wednesday

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

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

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

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

January 13, 2015 - 11:17 AM
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Latest guidance has changed some over the past 12 to 24 hours to start depicting a better chance for light snow or a light wintry mix across parts of the D.C. area.

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

Snow and Wintry Mix Potential

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

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

Advisories and Winter Storm Watch south of D.C.

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

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

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

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

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

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

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

 

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

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

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

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

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


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

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Tuesday's Snow Forecast and Perception Versus Reality

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

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

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

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

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

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

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

Snowfall Forecast

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

Final Snowfall Reports via National Weather Service

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

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Snow overachieves in parts of D.C. area Tuesday

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

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

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

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

Live Super Doppler Radar as of 10am

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

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

Front Royal, VA: 5.3"

Middleburg, VA: 5"

Aldie, VA: 4"

Reston, VA: 3.1"

 

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Snow may snarl the Tuesday morning commute

January 5, 2015 - 02:09 AM
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It's been a bit of a snow drought so far this season with only a trace reported at Reagan National Airport. As of this blog, we have a snow deficit of 3.3" and a deficit of 3.1" at Dulles. However, we should put a dent in that tomorrow with a good chance of around an inch of snow in the Capitol City.  It's not much, but it would be the first measurable snow this year. When you sync that up with the morning commute, it often means trouble on the roads. An Alberta Clipper will dive through the Midwest today and arrive in the Mid-Atlantic before dawn Tuesday. Here is the latest ABC 7 snow futurecast model to show the timing of the snow.

Snow Starts Before Dawn

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

ABC 7 Futurecast Snow Totals

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

Stormwatch7 Team Forecast

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

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

Model Map WeatherBell

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

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Happy Perihelion Day!

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

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

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

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

Earth's distance from the Sun

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

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

 

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Don't worry snow lovers

December 31, 2014 - 03:22 PM
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I wanted to take a look back at the number of times in D.C. when there hasn't been measurable snowfall until January. Snowfall records for D.C. began in January 1888, and the location recorded its first snow of the season in January 19 times during that span. It happened again this year and D.C. currently sits over 2.5" below average for snow this season.

Seasonal Snowfall and Departures (Credit: NOAA)

The D.C. area isn't alone. Areas from the Ohio Valley, through the Mid Atlantic and into the Northeast have been below average for snowfall. Even Buffalo, NY which experienced extreme lake-effect snowfall earlier this season is still nearly 5 inches below average, though that is likely changing as we speak with another lake-effect snow event. Maine, on the other hand, is well above average so far this year, with a 20+ inch surplus in Caribou and a 15+ inch surplus in Bangor.

Even with no recorded snowfall in D.C. so far (only a trace for the season), the region is still likely to receive snow. Of the 19 times this has occurred in the past, the least amount of snow recorded was 0.1" in 1972-73 and the most recorded was 31.1" in 1986-87.

Seasonal Snowfall in D.C. when it doesn't snow prior to January 1

Looking back through the records for D.C., it hasn't snowed until February twice. Oddly enough, for each of those occasions, the seasonal snowfall still ended up over 20 inches each time. Snow piled up to 28.6" in 1913-14 and 24.3" in 1959-60.

Don't get your hopes up for a big snow this year though, as 14 of the 19 occurrences have recorded below normal seasonal snowfall. A somewhat educated guess (yes, turns out seasonal snowfall forecasting in D.C. is difficult) would be somewhere between 3" to 10" for the season in D.C., but I guess only time will tell! My fingers are crossed for 2015.

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Travel Troubles on Christmas Eve as we Heat Up

December 22, 2014 - 03:20 PM
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Winter started officially at 6:03 p.m. EST on Sunday evening. Although it feels like winter on Monday (it doesn’t really look like it out there though with this rain), it is going to feel more like spring as we head into the Christmas holiday. So you might want to trade in the winter weather coat for a spring-like rain jacket and an umbrella for this Christmas Eve.


A deep area of low pressure will push north from the Gulf of Mexico Tuesday night through Wednesday night. This low will travel up the spine of the Appalachian, through the Ohio Valley and into the Great Lakes region. The low will aid in warmer temperatures spreading across the Mid-Atlantic and eventually traveling into the northeast as it pushes a warm front through these areas on Wednesday. This is all ahead of a strong associated cold front that will eventually sweep through early Thursday, taking the rain and the balmy temperatures with it.


A strong southerly wind associated with this low pressure will help push temperatures into the low 60s for Wednesday. Our average temperature for this time of year is in the mid-40s! Temperatures on Christmas Eve area expected to reach at least 15 degrees above normal.

ZZZZZ

Since temperatures are so warm, we are only expecting rain across the region-and possibly a lot of it on Wednesday. Precipitable water values are fairly high with this storm, given the time of year. Precipitable water is basically the amount of water contained in a vertical column, just above the surface, if it were all precipitated out—or the available moisture in the atmosphere for generating rain.

ZZZZZ

Above graphic shows where we stand as of the morning hours on Monday for precipitable water. It is currently only at 0.38” however, as this system draws moisture in form the Gulf; we are looking at some pretty high precipatable water values well over the 75th percentile.

ZZZZZ

This graphic shows large precipatable water values all up and down the east coast on Wednesday afternoon and well over 1.2” in the D.C. region. Therefore, we could get a good dose of rain in spots, especially if we get some heavy bands that set up across the region on Wednesday.


If you are traveling, again, it looks like rain and some gusty winds through the Ohio Valley and to the north. This area of low pressure is not as intense as it has looked in the last couple days but it does intensify well north (through Canada). Therefore, this could limit the development of the low level jet (the low level jet is the flow bringing the deep moisture from the Gulf just above the surface) which in turn may limit rainfall totals up and down the east coast but still will cause some travel headaches.

ZZZZZ

Rain will spread across the region for D.C. region Tuesday overnight into Wednesday morning and continue to move northward in New England through the first part of Wednesday. Temperatures from New York to Boston will in the mid-50s to around 60 degrees! Even Maine will be fairly warm with temperatures in the mid-40s! Rain will be heavy and winds gusty at times so I expect there will be some problems if you are traveling north (even though it will just be a plain rain in many locations).

ZZZZZ

There will be some snow however, and that will mainly be across Chicago through Indiana and up through Michigan. However, most of these areas will start of as rain with a changeover to snow by Christmas Eve night. There could even be some accumulating snow in the area shaded in blue (mainly a few inches or so and again, that won’t be until Christmas Eve night).


By early Christmas morning, the strong cold front will sweep through the region bringing dry air with it. We will gradually dry out on Thursday getting some sunshine by Thursday afternoon. Winds will be strong on Thursday though, rolling out of the west from 10-20 mph with gusts up to 30+mph. Temperatures on Christmas day will still be a little on the warm side, in the lower to mid-50s! You can see from the graphic below the cold front swinging through on Thursday morning, sliding the warm air off the coast.

ZZZZZ

More seasonable temperatures will return on Sunday though after another cold front passes through the area. This could bring some precip for the weekend so make sure to keep an eye on the weather if you are headed home from holiday travel next weekend!

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D.C. Weather Extremes in 2014

December 21, 2014 - 08:52 PM
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The weather pattern through Dec. 31 in the nation’s capital is not favoring any weather extremes that would trump the most notable ones seen so far this year. That said, it was a soggy, stormy and chilly year in Washington.

Here’s a list of the most extreme weather:

What was the hottest day? 99 degrees on July 2nd


What was the coldest high temperature? 21 degrees on Jan. 7


How many 90 degree days did we have? May 13th was the first day at 92 degrees… the last one was Sept. 11th at 91 degrees for a grand yearly total of 24.


What was the coldest low temperature? 6 degrees on Jan. 7th.


When did the highest wind gust occur? 49 mph on May 16 and July 10th.


What single day had the most rain? April 30 with 2.70 inches.


Which month had the most rain? April with 6.47 inches.


When did the biggest snowstorm hit? Feb. 13 with 5.9 inches.


Was precipitation above, at or below average?
Above average. As of Dec. 21, precipitation was 4.15 inches above average.

Were temperatures for the year above, at or below average? So far for 2014, the overall temperature has been near average. The cool months have balanced out the warmer months.

A stormy pattern will bring more rain to Washington next week and a cooler trend will likely arrive to ring in 2015! For more on the forecast, click here.

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A Trip Down Memory Lane- 5 Year Anniversary of December 2009 Snow Storm

December 18, 2014 - 02:44 PM
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The year was 2009. The month was December. Everybody in the D.C. area was gearing up for the holidays. I was at my 1st station in Winchester, VA in the northern Shenandoah Valley as their Chief Meteorologist. I was 4 years out of college and I had a little under 3 years of on-air experience. I saw this storm a-brewin’ about 10 days in advance and remember thinking “if this holds, this could be big.” Well the models kept this storm around and it was looking more and more intense as the date got closer. That date would be Friday December 18th, 2009. That date would also be the beginning of the snowiest winter in Washington D.C.’s recorded history.

 

This storm is classified as a “Miller A” type coastal storm (“Miller” named for James Miller). For this type of storm, an area of low pressure forms along a cold front in the Gulf of Mexico. That low eventually moves off the eastern seaboard and sucks up all the moisture from the Gulf of Mexico. It then continues its trek up the east coast following the jet stream, gathering up moisture and intensifying during its journey.
Everything just came together just right for this storm. It started snowing at Dulles International Airport at 7:30p.m. on Friday. The snow did not stop in our region until 11:00 p.m. Saturday. While I was out in Winchester working a 36 hour stretch while my future colleagues in D.C. were working around the clock forecasting in amazement. I remember telling my production staff snow totals that I was going to have to get on-air with that Thursday. I was forecasting 16.0” – 28.0” for the northern Shenandoah Valley and I had never been more nervous. I couldn’t believe that I was going to have to get on air in my third year of experience and say we are going to get 2 feet of snow….if this didn’t come to fruition, I was surely going to be fired.

As we all know, it did come to fruition (thank goodness) and we received A LOT of snow across the region.

ZZZZZ
Wet, heavy snow began to pile up very quickly and cut off many city services. Metro trains stopped running above ground because of the sheer depth of the drifts. I was living in Tyson's Corner at the time commuting to Winchester and driving on 66 on that Saturday was sheer madness. It took me 4.5 hours instead of the usual hour long drive to get from Winchester, VA to Tyson's Corner. A 2 foot wall of snow cut off 66 between Frederick County, VA and Warren County because plows had yet to reach the interstate. Schools shut down leading up to Christmas due to the massive amounts of snow. And as we all know, it only got worse as that winter continued.

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Odds of a White Christmas for Washington D.C.

December 11, 2014 - 02:42 PM
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Are you dreaming of a white Christmas? Okay, let me be honest. After a few days of just a cold rain, I am ready for some snow—and right in time for Christmas. So, what are the chances we can see a white Christmas around the WJLA viewing area?

 

ZZZZZ

 

According to this map put together by the National Climatic Data Center, there is about a 11% -25% chance that there will be at least 1.00” of snow on the ground on December 25th. To break it down, there about a 15% chance of that scenario unfortunately for most of the WJLA viewing area (the data in this map is based on the historic probabilities measured over the last 3 decades from 1981/2010). “This dataset contains daily and monthly normal of temperatures, precipitation, snowfall, heating and cooling degree days, frost/freeze dates and growing degree days calculated from observations at approximately 9,800 station operated by NOAA’s National Weather Service.” (NCDC)

Our local National Weather Service Office has done some incredible research in this category. They found that since 1888, there were only 19 occurrences with measurable snow on the ground already from a previous snow storm OR measurable snow fell on Christmas Day. That on average is about once every 6 or 7 years or 15%.

So you’re telling me we have a chance?! (Inset Dumb and Dumber quote here). Well yes, albeit a small one. The last time we had snow ON Christmas Day was in 2002 when we received a whopping 0.2” at Reagan National Airport. Think about it this way, measurable snow (at least 0.1” of snow) has only fallen on the City of D.C. ON Christmas Day 10 times in the past 130 years. Therefore, on average, snow falls on Christmas Day every 13 years or around 8%.


Check out these stats from the National Weather Service in Sterling (full report here):


“In the past 20 years there have only been two Christmases that had snowfall: 1993 and 2002. Both years featured just a fraction of 1.00”. Furthermore, there were only two years in the past 40 that had 1.00” or more of snow on the ground on Christmas. They were during the very cold December of 1989 when nearly 2.00” f snow was on the ground from previous snowfall that month. More recently in 2009 we had 7.00” still on the ground from the first of our major snowstorms that record setting winter. All 7.00” of that snowpack on Christmas 2009 melted by the next morning (as temperatures rose into the mid-40s).


Of note, 18 years ago in 1993, in a span lasting less than 30 minutes in the evening, 0.2” of snow fell with upwards of 1.00” falling in the western suburbs. That quick bust of snow on Christmas night in 1993 caused severe travel problems. Much of the snow melted on contact with paved surfaces as temperatures were just above freezing at the time the snow feel. However, an arctic cold front swept in just after the snow ended. Any water remaining on roads and sidewalks from melted snow quickly flash froze into a thin layer of ice which caused gridlock and treacherous travel that night.

Precipitation of any sort (rain included) is much easier to come by of course. Fifty-one Christmases have had measurable precipitation. That translates to about a 36% probability of measurable precipitation or roughly on in every three years. “


So with snow falling ON Christmas Day averaging every 13 years and last time we saw snow on Christmas Day was 2002, we may have to wait until 2015 to see some snow fall ON Christmas Day. Usually the typical Christmas Day consists of a morning low of 30 degrees with daytime highs rising into the mid-40s. History also tells us that is it partly cloudy on Christmas Day.

Last year, temperatures were fairly cold in Washington D.C. with some snow flurries on Christmas Eve and as well as the 26th of December. We topped out around the freezing mark (official temperature recorded AT DCA on December 25th was 32 degrees in 2013). Last year was the coldest Christmas since 2004 (high temperature of 31 degrees).

Nothing in the works yet as far as precip or temperatures as we are waaaaaay too far out but as always, we will continue to keep an eye on it as we get closer to the 25th.

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Coastal Storm Brings Wet Weather Beginning Monday Night

December 7, 2014 - 05:58 PM
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It's been a grey start to December, but we finally saw a nice, clear day today.  This was the first fully sunny day since November 21st!  Soak up the sun early tomorrow morning because clouds will quickly thicken, as our next weather system approaches the area.

A developing area of low pressure, off the coast of the Carolinas, will increase cloud cover through the day Monday.  With the clouds, temperatures will only reach the mid 30s by the afternoon.  Here is a look at forecast highs on Monday.

Forecast Highs Monday

Both the morning and evening commutes will be dry, with wet weather from the coastal storm arriving after 8 PM.  Temperatures won't fall much overnight Monday into Tuesday, in fact, temperatures may actually climb a few degrees with an easterly wind component.  Check out our local simulation of radar at 10 PM Monday (1st image below) and 6 AM Tuesday (2nd image).

Local RPM Model Monday 10 PM
Local RPM Model Tuesday 6 AM

This model depicts all rain, which seems to be the trend among most guidance.  As the coastal low tracks farther north Tuesday, there may be a brief transition to snow late Tuesday night well NW of D.C.  Little to no accumulation is expected.  In fact, by Tuesday at 8 PM the coastal storm will be greatly impacting New England.  Here is a simulation of the coastal storm at 8 PM Tuesday.

Surface Features Tuesday at 8 PM

This will be a predominately rain event for us with the greatest snow potential over interior New England.  Check out forecast snowfall accumulations by Thursday afternoon.  Areas shaded in pink could receive over 10" of snow.

WxBell GFS Forecast Snow Total By Midday Thursday

The area of low pressure will get cut-off from the jet stream midweek and will spin freely over New England through at least Thursday.  That means added clouds for us Wednesday and Thursday with possible light rain and snow showers. 

There are still uncertainties to the forecast, since the coastal storm has yet to develop.  The Stormwatch weather team will continue to update the forecast, as new information becomes available. 

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More unsettled weather for the weekend ahead

December 3, 2014 - 05:34 PM
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The pattern doesn't appear like it will change anytime soon after bringing nearly an inch of rain to parts of the region Monday night into Tuesday and clouds on Wednesday. Thursday should experience a lull in the action, just in time for the National Christmas Tree Lighting, which Chief Meteorologist Doug Hill will be out live broadcasting tomorrow evening.

At this point we are expecting some sunshine in the morning hours followed by afternoon clouds as the next system pushes in from the west. A few models have depicted the chance for a few showers late tomorrow night into Friday morning, but this should be a low probability at this point with the best chance south and west of D.C.

Water Vapor image with tomorrow's disturbance and Saturday's disturbance

Looking west, an area of low pressure has been bringing inches of rain to parts of California over the past few days. A bit of energy and associated moisture has spun off this system and will help bring clouds to our region Thursday afternoon through Friday night.

Thursday rainfall totals as of 5pm for parts of California

Another area of energy will push into Southern California tonight into Thursday morning. This disturbance will move across the U.S. and into the Mid Atlantic this weekend, increasing chances for rain Friday night into the day Saturday.

Precipitation forecast for Friday through Saturday evening

Beyond Saturday, there are stark differences in model depictions, with a few models spinning up additional areas of low pressure off the east coast and socking the region in clouds and precipitation Sunday and Monday, and another completely clearing the region out Sunday with sunshine and mild temperatures. We will get a much better handle on this forecast in the next 12-24 hours but at this point are content on keeping the rain chances in for Sunday and again Monday.

Forecast precipitation Saturday through Monday Evening

 

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