From the ABC 7 Weather team

Archive for category Climate October 2014

Heavy rain and storms headed to the D.C. region on Wednesday

October 14, 2014 - 02:38 PM
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It seems we are throwing it back to summer today (Tuesday) with temperatures around the 80 degree mark and humidity seeping through mostly cloudy skies. Another factor that makes this feel more like a summertime forecast is the threat of some severe weather for your Wednesday.

A powerful storm continues to crawl across the southern tier of the United States lifting to the north through Tuesday. An area of low pressure is lifting towards the Ohio Valley while its attendant cold front continues to move slowly to the east-northeast. The cold front will eventually cross through the area Wednesday, making it into the Atlantic and east of the Chesapeake Bay by the early overnight hours on Thursday morning.

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This storm has a history of being severe unfortunately and while I do not foresee a completely widespread severe outbreak across the WJLA viewing area, I do believe that along with damaging winds in some cells, flooding will be the main concern across the region. 
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Ahead of the cold front, showers will begin in the afternoon and evening hours on Tuesday. Mainly the area of concern will be well south and west of the listening area but a few showers could sneak slightly to the north, along and west of the Blue Ridge Mountains and into the northern Shenandoah Valley.

This is also the area that the Storm Prediction Center outlined for a 5% chance of severe thunderstorm winds or wind gusts (58 mph or over) within 25 miles of a point on the map within the shaded area:

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However, the National Weather Service in Sterling has issued a wind advisory (areas shaded in brown) from 6p.m. on Tuesday evening until 6a.m. on Wednesday morning. With this advisory, winds could move out of the south from 20 to 30 mph with gusts up to 45 mph. This obviously will make driving slightly more difficult, especially with high profile vehicles. There is also a chance for some downed trees with the higher gusts.
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So we will keep the chance of occasional showers to the west of the D.C. metro area through the evening and overnight hours. There could even be a few isolated storms within the WJLA viewing area during the overnight hours.

Through Wednesday morning, the frontal system will continue to slide to the east bringing the rain with it. Showers and some isolated storms will increase in coverage through the early morning hours and the rain and storms will continue to spread to the east through the early afternoon.

Unfortunately, this looks like it could be a messy commute for both the morning (if you are traveling from the west) as well as the evening commute (for everybody). Some of the storms in the afternoon hours could bring some damaging winds. However, the main threat will be the rainfall that we receive.

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From Tuesday to early Thursday morning, the region could receive anywhere from 0.75” -1.50” of rainfall accumulation east of the Blue Ridge Mountains and up to possibly 3.00” of rainfall accumulation west of the Blue Ridge Mountains in the Shenandoah Valley.

Since this system is just crawling, rain will just continue to pound the region. We are expecting the rain to be heavy at times since this system is feeding of moisture from the Gulf of Mexico and the Atlantic. We will continue to monitor the issuance of a Flood Watch for the area from the National Weather Service in Sterling.

Good news is that we could use the rain now. For Washington D.C., we are about 0.53” below for the month of October and 3.14” below for rainfall since September 1st 2014. The U.S. Drought monitor has place some of the areas in Virginia and Maryland in the “abnormally dry” sector which means that there is a chance that the region outlined in yellow is headed into drought conditions: short-term dryness means slowing planting and slow growth of crops or pastures.

 

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By Thursday, the heavy rain will be off the coast as the frontal system will be east of the region. However, we are still looking at some spotty rain showers for Thursday with cloud cover as that area of low pressure will be moving through the Great Lakes region (again – its attached cold front will be east of D.C. – see first graphic in this article for surface features on 8 a.m. Thursday). Temperatures will drop back to just slightly above normal for this time of year, in the low 70s. Sunshine returns for Friday!

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