Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 161514 AAA AFDLWX Area Forecast Discussion...UPDATED National Weather Service Baltimore MD/Washington DC 1014 AM EST Thu Feb 16 2017 .SYNOPSIS... High pressure builds overhead through Friday. A weak cold front will move through early Sunday. High pressure returns Sunday into early next week. && .NEAR TERM /THROUGH TONIGHT/...
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Update to expire Winter Weather Advisory across the upslope areas. Some snow showers will continue into this afternoon, but the majority of the accumulating snow has ended. Previous Discussion from 930 AM: Gusty northwest flow across the area this morning will persist into the afternoon. Scattered flurries and snow showers have developed and continue to move across the region from about the DC metro on northward. Brief reductions in visibility and a quick dusting to locally up to a half inch of snowfall accumulation are possible, especially the closer you go to the Mason-Dixon line. Latest hi-res model runs and NAM12 snow- squall parameter depict snow shower coverage decreasing across much of the region later today, except northeast Maryland as lobe of vorticity rotates through, where scattered flurries likely to continue. Otherwise, partly- mostly cloudy skies with gusts up to about 30 mph. Highs in the 30s to low 40s. Strong radiational cooling tonight under clear skies and weakening wind speeds will allow low temperatures to fall into the 20s across the entire area.
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&& .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... High pressure slides to the south Friday...keeping westerly wind component through much of the day. This will help temper warming somewhat. Though, gradual airmass modification will bring temperatures back near climatological norms. It will certainly feel warmer...as we won`t be battling the gusty winds of previous days. Southerly return flow develops late Friday as high pressure slides to our southeast. Rapid warm-up with highs Saturday 15-20 F above normal. Despite the anamolous warmth, highs Saturday still 10 F or so below records. Weak upper-level disturbance approaches late Saturday into Sunday morning. Some very light precipitation is possible across Central VA and perhaps into N VA during this period. All liquid as low temperatures well above freezing. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... In the wake of the departing southern stream low, a deep amplified ridge of high pressure will build. This will be the primary weather feature for Sunday and Monday, providing sunny skies and anomalously warm temperatures. Northern stream shortwave energy will flatten the 500 mb ridge axis somewhat by Tuesday as a frontal system approaches. Cold advection looks limited, as much of the moisture and forcing remains confined to the Great Lakes/southern Ontario to New England/southern Quebec, but temperatures may ease down a few degrees Tuesday and Wednesday as clouds increase and small PoP chances surface. && .AVIATION /15Z THURSDAY THROUGH MONDAY/... While predominantly VFR conditions prevail through Saturday night...gusty NW winds will continue through this evening. A few scattered flurries or snow showers are possible into this afternoon as well, with the potential for localized and brief sub-VFR conditions. Gusts of ~25-30 knots likely through late this afternoon...before wind gusts subside by this evening. Relatively light winds Friday and Saturday. VFR flight conditions should persist Sunday and Monday under building high pressure. && .MARINE... SCA criteria gusts ongoing across much of the waters. Despite increased mixing depth through the morning...wind field weakens enough to keep gusts mostly high-end SCA. Winds lessen tonight. Light winds expected Friday and Saturday with high pressure nearby. There may be a little burst of wind Sunday in the wake of passing low pressure. However air temperatures will be substantially warmer than the 40 degree water, which will prevent mixing. Otherwise winds will be 10 kt or less under building high pressure. && .FIRE WEATHER... Conditions may become marginally favorable for an enhanced threat for the spread of wildfires across central VA for a few hours during the afternoon...as RH values bottom out between 25-30% with reduced fuel moisture. Limiting factors are winds and temperatures...as sustained winds across this area expected to remain near 10 kts (gusts 15-20 kts) with high temperatures in the lower 40s. && .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 1 AM EST Friday for ANZ530>533- 538>542. Small Craft Advisory until 4 AM EST Friday for ANZ534-537-543. Small Craft Advisory until 7 PM EST this evening for ANZ535- 536.
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&& $$ SYNOPSIS...MSE NEAR TERM...MM/MSE SHORT TERM...MSE LONG TERM...HTS AVIATION...MM/MSE/HTS MARINE...MM/MSE/HTS FIRE WEATHER...MSE

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