Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 211438 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 1038 AM EDT Sun Aug 21 2016 .SYNOPSIS...
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A cold front over the Ohio River valley will move through the Mid-Atlantic this afternoon into the evening. High pressure then builds over the area into Tuesday before persisting offshore through the rest of the week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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As of 10am, cold front has just crossed into WV/wrn PA. LWX CWA is in the warm sector ahead with dewpoints in the low to mid 70s and opaque clouds. Showers developing in this humid atmosphere and will continue to spread north across the Baltimore metro through the rest of the morning. Key feature for instability this afternoon is the clear sector over central VA spreading north. MLCAPE around 1500 j/kg with increasing shear will allow thunderstorms to develop along the Blue Ridge around noon and spread east from there. Damaging wind threat with this activity. PWATs are around 2.2 inches which will allow heavy rain, but storm motion looks high enough to limit rain totals below flood concerns. Thunderstorms look to clear the Chesapeake Bay around 6pm with activity drier NWly flow gusting 20 to 25 mph overnight. Max temps on track given sunshine spreading north - max temps upper 80s east of I-95, mid 80s east. Dewpoints drop to the low 60s overnight with min temps mid to upper 60s.
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&& .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
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High pressure builds Mon and holds through Wed with dry conditions and temperatures actually below normal for late Aug.
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&& .LONG TERM /WEDNESDAY THROUGH SATURDAY/...
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High pressure will begin to move off the Mid-Atlantic coast on Wednesday and Thursday, leading to a gradual warming trend to above normal temperatures. Most of the area should remain dry, although moisture return may allow for stray diurnal terrain convection on Thursday. A cold front is still projected to approach on Friday. Mid/upper level support is weak given a strong ridge over the SE CONUS. However, there may be enough low level convergence for at least some scattered showers and storms. ECMWF indicates highs may again exceed 90F ahead of the front. The front will begin to stall and weaken as it becomes parallel to the zonal flow around the SE ridge. However, 00Z guidance indicates Great Lakes high pressure will provide enough of a push for the front to drift south of the area on Saturday, resulting in little chance of rain. Thermal differences will be small on Saturday though, with temperatures remaining above normal.
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&& .AVIATION /15Z SUNDAY THROUGH THURSDAY/...
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Widespread showers expected with scattered thunderstorms developing around the Blue Ridge around noon and spreading east across the DC metros through the late afternoon. Brief MVFR/IFR restrictions possible with t-storms. Cdfnt moves east of terminals by 00Z Mon with showers ending quickly and winds shifting to the NW. No significant weather expected Wednesday and Thursday as high pressure moves offshore.
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&& .MARINE...
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Southerly channeling ahead of the cold front rest of the morning. Widespread showers and scattered thunderstorms expected this afternoon into early evening may pose a threat of strong gusty winds which may require SMWs. Small craft advisory conditions tonight through Mon morning with NW winds behind the cold front. High pressure then builds Mon through the middle of the week with winds gradually diminishing. Southerly flow of 5-10 kt expected Wednesday and Thursday as high pressure moves offshore. A cold front will approach Friday, and winds may increase slightly. Thunderstorms may accompany the front as well.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory from 6 PM this evening to noon EDT Monday for ANZ530>534-537>543. Small Craft Advisory from 6 PM this evening to 10 AM EDT Monday for ANZ535-536.
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&& $$ SYNOPSIS...BAJ/LFR NEAR TERM...BAJ/LFR SHORT TERM...LFR LONG TERM...ADS AVIATION...BAJ/ADS/LFR MARINE...BAJ/ADS/LFR

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