Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 150256 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 1056 PM EDT Sat Oct 14 2017 .SYNOPSIS... High pressure over the area will weaken rapidly through Sunday. A cold front will push into the Mid Atlantic Sunday night followed by a return to high pressure early next week. && .NEAR TERM /TONIGHT/... CAD induced low clouds which have hung over the area for the past 3 days did erode some this afternoon, but not in entirety as the eastern part of the forecast area did not erode. 11-3.9 mu imagery show these clouds are slowly working their way back westward. IAD 00Z sounding looked relatively dry, but believe low level moisture will reassert itself after midnight, question is will this be in the form of low clouds or fog. Midnight shift will have a better handle on this. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... Southerly flow will increase ahead of a cold front Sunday. Any low clouds or fog that does form will erode by mid morning. Advection and insolation will allow temps to rise back above 80 degrees. The cold front will pass through the area Sunday night. The best support will come from low-level convergence and thermal advection. Showers should result, but am not sold on a solid or prolonged period of precip, and have back POPs down accordingly. The pressure surge that follows Monday will bring gusty winds and cooler temperatures. Some upper 30s possible in outlying areas by Monday night. && .LONG TERM /TUESDAY THROUGH SATURDAY/... High pressure will promote dry conditions Tuesday through Saturday. Tuesday`s high temperatures and Tuesday night`s low temperatures will be about 5 degrees below normal. Wednesday and Thursday will warm up to near or slightly above normal with plenty of sunshine each day. Friday and Saturday are expected to be warm with sunshine. Highs each day in the middle to upper 70s. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... With plenty of moisture left in the boundary layer, anticipate either clouds redeveloping or fog forming after midnight. Currently, forecast is leaning toward the fog scenario, but could easily see low clouds instead. Either way, expect IFR (or lower) after midnight through the morning push. Mixing will be better tomorrow, so flight restrictions should dissipate quicker. VFR by mid-morning through the rest of the day. Some G20kt gusts likely. Cold front will cross through the terminals Sunday night. Associated flight restrictions should be fleeting. Best bet would be for briefly lower cigs. Monday, perhaps as early as predawn, northwest winds will increase. That would be the only potential flight restriction, due to NW flow G20-25 kt. VFR and decreasing winds Monday night. VFR conditions Tuesday through Wednesday night. Winds light and variable each period. && .MARINE... Light winds tonight, with increasing south flow on Sunday ahead of a cold front. Have a Small Craft Advisory in effect for all waters Sunday afternoon/early evening (started a little earlier for the Bay/lower Potomac). The threat likely will continue through Sunday night on the Bay and mouth of the Potomac. Confidence not as high, but Advisories have been extended accordingly. A cold front will cross the waters Sunday night. There may be a bit of a lull in the mixing during the rain/wind shift. Mixing will then improve Monday. Although not continuous, Small Craft conditions likely on Monday as a result. No marine hazards Tuesday through Wednesday night. && .CLIMATE... A surge of warm air is expected Sunday ahead of the cold front. We are not currently forecasting records, but we are expecting temps to be close. Warm Temperature Records for October 15 (Sunday)... High Warm Low DCA 87 (1975) 67 (2008) BWI 86 (1989, 1975) 66 (1941) IAD 88 (1989) 64 (1985) && .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory from 10 AM Sunday to 6 AM EDT Monday for ANZ530>534-537>543. Small Craft Advisory from noon to 8 PM EDT Sunday for ANZ535- 536.
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