Area Forecast Discussion
Issued by NWS Sterling, VA

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112 FXUS61 KLWX 211442 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 942 AM EST Tue Feb 21 2017 .SYNOPSIS... High pressure is centered over northern New England. Cooler air will seep south into the Mid Atlantic today. A weak disturbance will cross the area tonight into Wednesday. High pressure will be located off the southeast coast of the United States late in the week. A cold front will pass through the area this weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... High pressure will move off the New England coast today and an onshore flow will allow for cooler conditions compared to recent days...but still above climo. Climatologically highs should be in the upper 40s. We are still expecting highs today to be in the upper 50s...possibly lower 60s in the central Shenandoah Valley. A broken deck of high clouds will continue to move over the area as moisture sneaks in ahead of an upper-level disturbance. Partly to mostly cloudy skies are expected. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... Another "non-Feb meteorological feature" is that the jet stream will be running along the US/Canada border for the next several days. This will ensure that cold air is held at bay. Took a look at precip deficits since Dec 1: all major obs sites (DCA,IAD,BWI,MRB,CHO) are below normal. The three major airports are all 2-2.5" below normal. CHO is 3.25" below. Ten hour fuel moisture is 9-10%. None of this is terrible but we are moving into a primary fire weather season so moisture would be beneficial. Unfortunately that "mid summer moisture" over the MS River Valley appears like it will be breaking up as it progresses eastward. Through Thursday precipitation chances will be low at best. Temperatures are expected to remain well above average. Highs will be around 70 Wednesday and Thursday. Lows in the 40s. This is more reminiscent of late April. One more stat/factoid - the earliest DC cherry blossom peak bloom was in 1990 - March 15th. In the climate section below you`ll see that this has been the second warmest Feb in DC on record. 1990 was the warmest; it was actually 4.1 degrees warmer than what this Feb has been so far. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... Very mild Thu night and Fri night as area remains in the warm sector with record high minimums likely especially Fri night. Models seem to have slow down timing of fropa on Sat a bit which should allow for more warming and destabilization with showers and t-storms likely along the front some of which could be strong to possibly severe. Cdfnt clears the area by 00Z Sun with rapidly falling temperatures Sat night. High pressure then builds Sunday through Monday bringing cooler and more seasonable temperatures. && .AVIATION /15Z TUESDAY THROUGH SATURDAY/... VFR today through Wednesday. Fog development will be possible at CHO/IAD/MRB Wednesday night. Cdfnt will move through the area around 18Z Sat with showers and possible t-storms some of which could be produce strong wind gusts. && .MARINE... There are currently a few gusts on the central part of the Ches Bay in the upper teens. We`ll keep our eyes on this but at the moment am not expecting to issue an SCA. Beyond this morning am not anticipating issuing an SCA through Thursday. T-storms Sat may produce strong wind gusts and may require SMWs. && .CLIMATE... Did a check to see how warm it has been both for meteorological winter and since Feb 1 at the three major airports in terms of ranking (average temp): The statistics below are from February 1st through February 20th. Since Dec 1 Since Feb 1 DCA 5th warmest 2nd warmest BWI 14th warmest 13th warmest IAD 2nd warmest 2nd warmest Unseasonably warm temperatures are expected during the second half of the week. Below are record daily high maximum and high minimum temperature values for the 22nd through 24th (Wednesday through Friday). February 22nd DCA 77 (1874) 60 (1874) BWI 74 (1874) 51 (1874) IAD 71 (1991) 52 (1981) February 23rd DCA 78 (1874) 51 (1922) BWI 78 (1874) 52 (1874) IAD 73 (1985) 51 (1975) February 24th DCA 78 (1985) 52 (1975) BWI 79 (1985) 55 (1985) IAD 79 (1985) 53 (1985) && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ PRODUCTS...LASORSA/WOODY!/LFR

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