Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 191813 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 213 PM EDT Thu Oct 19 2017 .SYNOPSIS... High pressure will remain across the Mid Atlantic through this weekend. A low pressure system will affect the region early next week. && .NEAR TERM /THROUGH TONIGHT/...
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An elongated area of high pressure stretches from the Deep South northeastward across the southern Appalachians and off the Mid-Atlantic coastline. At the same time, a weak cold front is tracking through the Great Lakes region. For the rest of today, expecting mostly sunny skies, light winds, and mild temperatures. Highs will range from 70-75F. The weak front will push east-southeastward this evening, with its tail end crossing the region tonight. Aside from a shift to light northwest winds and a few added cirrus, no real sensible weather impacts are expected with this decaying front. Although as winds do turn to the northwest, there may be some terrain- induced strato-cumulus along the Allegheny Front by morning. Should still have decent radiational cooling tonight, but with some added light winds, won`t be as ideal as previous nights. Lows in the 40s to near 50F for most, except low/mid 50s in the urban centers and along the shorelines of the Chesapeake and Tidal Potomac.
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&& .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
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High pressure will gradually build back overhead for Friday and Saturday, providing for mostly sunny skies, relatively light winds, and mild temperatures. There may be some patchy fog each late night/morning, but nothing widespread expected. Highs will reach the low to mid 70s, with lows in the 40s/50s.
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&& .LONG TERM /SUNDAY THROUGH WEDNESDAY/...
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High pressure system will move away from the east coast on Sunday. A cold front approaches from the west with a wave of low pressure tracking northeast from the Gulf states towards the Mid-Atlantic region Monday into Tuesday. This system will put an end to the dry spell we`ve been experiencing, with precipitation associated with it starting sometime on Monday and remaining into Tuesday. The pattern will evolve from warm and dry to cold and unsettled as this system moves through, with some uncertainty on the timing. In the upper levels, a large and deep trough will move over the eastern CONUS Wednesday into Thursday. Guidance suggests that this could bring some upslope showers on Wednesday, and then dry into Thursday. High temperatures on Monday will be between the low to mid 70s decreasing into the 60s into Thursday.
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&& .AVIATION /18Z THURSDAY THROUGH TUESDAY/...
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Patchy fog possible at MRB/CHO/IAD over the next few mornings, but chances are low and any fog would be brief. Otherwise, VFR through Sunday night with relatively light winds under high pressure. Precipitation associated with a cold frontal system is then expected later Monday into Tuesday, which could bring sub-VFR conditions at times.
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&& .MARINE...
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A weak cold front will approach and cross the waters tonight. Expecting an increase in southwest winds out ahead of the front, followed by a surge of northwest winds behind the front. While a surface inversion will limit mixing and wind gust potential along the shores, over the open warmer waters, gusts in excess of 20 knots are possible, especially late tonight into Friday morning. Therefore will leave Small Craft Advisory in effect from 9 PM tonight through Noon Friday. Winds will drop below SCA criteria by Friday afternoon and remain below through Sunday. Southerly winds will increase out ahead of the next frontal system Monday and Tuesday, and a Small Craft Advisory may be needed.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory from 9 PM this evening to noon EDT Friday for ANZ531>534-537-539>541-543. && $$ SYNOPSIS...MM NEAR TERM...MM SHORT TERM...MM LONG TERM...IMR AVIATION...MM/IMR MARINE...MM/IMR

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