Area Forecast Discussion
Issued by NWS Sterling, VA

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833 FXUS61 KLWX 221912 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 312 PM EDT Wed May 22 2024 .SYNOPSIS...
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Surface high pressure will continue to shift offshore as a cold front approaches the area from the west through tonight. The cold front will move over the Mid-Atlantic throughout the day on Thursday before lifting northward as a warm front Friday afternoon.
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&& .NEAR TERM /THROUGH TONIGHT/...
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As of 2:15PM, storms are beginning to initiate along and west of the Blue Ridge and move eastward across the forecast area. While more favorable conditions for strong to severe thunderstorm development lie to the west of the I-95 corridor, SBCAPE values of 2000-3000 J/kg and steep lapse rates are expected areawide. Bulk shear will be lacking along the I-95 corridor with higher values of 30-40 knots expected in the western half of the area. Showers and thunderstorms will continue moving eastward this evening with damaging wind gusts and large hail as the main hazards expected. With convection initiating earlier, storms will move out of the area earlier with light rain showers persisting through the overnight. PWATs 1.25-1.75 inch are expected providing ample moisture for heavy rain. There is enough flow to keep the flooding risk low, but locally heavy rain could result in an excessive rainfall risk. Temperatures will rise into the mid to upper 80s this afternoon with higher elevations staying in the upper 70s. Overnight lows dip into the 60s with metro areas staying in the low 70s.
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&& .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
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An approaching cold front from the west will move over the Mid- Atlantic Thursday afternoon before lifting northward as a warm front Friday afternoon. This nearby boundary will provide stronger forcing for daily shower and thunderstorm chances. The threat for convection is higher on Thursday compared to Friday with the cold front moving overhead. Cloud cover could inhibit convection development but SBCAPE values 1500-2500 J/kg, bulk shear around 35 knots, and lapse rates 6-7C/km will allow for at least a conditional risk for strong to severe thunderstorms. Showers and perhaps a thunderstorm continue overnight as the front remains nearby. As the front lifts north of the area on Friday, precipitation chances decrease Friday morning. Slight chance to chance PoPs continue throughout the day with plenty of moisture aloft. Shortwave energy moving aloft will continue a slight chance for showers and thunderstorms. The threat will be mostly confined to the southern portions of the forecast area. Temperatures will be in the 80s for most with higher elevations staying in the mid to upper 70s. Overnight low temperatures will be upper 50s to mid 60s.
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&& .LONG TERM /SATURDAY THROUGH TUESDAY/...
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Unsettled conditions will continue through the holiday weekend and into early next week. Strong to severe thunderstorms will be possible Saturday through Monday, with the best chances on the bookends of the period. A shortwave trough on Saturday will move through the area with increasing instability during the afternoon and evening hours. Highs will top out in the low 80s on Saturday. By Sunday, thunderstorm chances remain but forcing may be a bit weaker compared to Saturday, so overall coverage and intensity of the storms may be a bit lower comparatively. By Monday, a strong cold front will approach the area as a result of a deep low pressure system situated near the Great Lakes region. Strong to severe thunderstorms will certainly be possible Monday afternoon and evening. Main hazards for this system will be damaging winds and large hail. Afternoon highs will climb into the upper 70s to low 80s across much of the area. Cooler and less convective conditions arrive behind the front on Tuesday with highs in the 70s and overnight lows dropping down into the mid to upper 50s.
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&& .AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
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VFR conditions are expected at all terminals with the exception of reduced flight conditions during showers and thunderstorms this afternoon. Greatest chances for thunderstorms still remains in the western terminals (MRB, CHO, and IAD) where more favorable conditions are. Thunderstorms move out of the area this evening around 00Z-02Z. For the 18Z TAFS, kept a wider range for timing of thunderstorms due to model uncertainty. Storms are firing up along and west of the Blue Ridge, so am expected storms to impact the metro terminals in the next few hours. Overall, winds remain light and blowing out of the southwest this afternoon at around 5 knots. Winds shift to westerly by Thursday morning and will remain out of the west through Friday afternoon. Diurnally driven showers and thunderstorms are possible Thursday and Friday, bringing chances for flight restrictions at all terminals. Sub-VFR conditions will be possible Saturday and Sunday with any showers and thunderstorms that cross the terminals, especially in the afternoon and evening. Winds will be fairly light out of mainly the south.
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&& .MARINE...
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Southerly winds over the waters gust 15-20 knots this afternoon and through overnight before diminishing before sunrise Thursday morning. A Small Craft Advisory is currently in effect until 2AM Thursday morning for winds blowing 10-15 knots and gusts up to 20 knots expected. Winds shift to southwesterly Thursday morning before shifting to westerly in the afternoon. Winds remain below SCA criteria through Friday. Daily shower and thunderstorm chances may bring hazardous conditions to the waters with some possibly requiring SMWs. Sub-SCA winds are expected for the weekend aside from any showers and thunderstorms that cross the waters. Special Marine Warnings may be needed both afternoons and evenings.
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&& .TIDES/COASTAL FLOODING...
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Minor coastal flooding is possible at DC Waterfront, Annapolis, and Havre De Grace with the high tide cycle Thursday morning. After high tide Thursday morning, winds shift from southerly to westerly allowing tidal anomalies to begin decreasing.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 2 AM EDT Thursday for ANZ530>534- 537>541-543.
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&& $$ SYNOPSIS...AVS NEAR TERM...AVS SHORT TERM...AVS LONG TERM...ADM AVIATION...AVS/ADM MARINE...AVS/ADM TIDES/COASTAL FLOODING...AVS