From the ABC 7 Weather team

Archive for category The Outside Story December 2014

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.

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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.

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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.

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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.

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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).

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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.

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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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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.

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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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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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Winter Weather Advisory for parts of the D.C. area Tuesday

December 1, 2014 - 03:27 PM
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A cold front will sweep through the region on Monday afternoon/evening. Temperatures will fall behind the front, eventually ending up in the 30s for overnight lows!

Cold front will move through Monday afternoon/evening bringing a threat of isolated showers and dropping temperatures.


Eventually that front will stall just to the south of the region. An area of low pressure will ride along the front Monday night into Tuesday bringing precip with it. At the same time, high pressure will move front the Great Lakes region to the New England area. Eventually this evening, our winds will shift to the north and east bringing moisture and cooler air off the Atlantic Ocean and right into our area. What happens is, that moisture banks up against the mountains to our west creating a “cold air damming” affect or CAD. This set up generally makes forecasting that much more difficult, especially when determining precipitation types because that colder air will slide right under the warm air aloft which would make the precip type more of that of a wintry mix (freezing rain/sleet).

Winter Weather Advisory from 1am Tuesday to 1am Wednesday

Just around daybreak and into the morning commute, we will start to experience some spotty sleet and freezing rain, mainly north and west of D.C. (Loudoun County and Central and Western Montgomery County and points northwest). Inside the beltway, along I-95 and areas to the south and east, this event mainly looks like a very cold rain event but I can’t rule out some isolated pockets around D.C. of the wintry mix.

This is NOT looking like a major event but since it comes for the morning rush, there could be some problems (as there tends to be, even if it is just plain rain). And we are really not expecting that much to accumulate at all, perhaps just a glaze in some areas. Surface road temperatures, especially around the D.C. area, are above freezing so just like last Wednesday, any frozen precip that falls will have a hard time sticking. However, north and west of town on some rural roads, elevated surfaces (bridges and overpasses) and even exits could have some slick spots.

In-house model of Tuesday morning (rain = green, wintry mix = pink)


Again, I do not think this is going to be a huge event but I don’t want it to take anybody by surprise when our temperatures do not make it out of the 30s tomorrow (considering we are around 70 in a lot of the area on Monday).

Warm air will start to erode the shallow layer of cold air and any wintry mix will turn to plain rain by the afternoon hours. Most of the precipitation should move north around the kickoff of the evening commute but I do expect there to be some drizzle and fog around the region – there could even be some freezing drizzle at the high elevations). Temperatures rebound into the lower 50s on Wednesday but another bout of precipitation could be on the horizon for Friday.

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