Area Forecast Discussion
Issued by NWS Sterling, VA

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227 FXUS61 KLWX 281849 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 249 PM EDT Tue May 28 2024 .SYNOPSIS...
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A cold front will move over the area Wednesday night, bringing unsettled conditions tomorrow afternoon and into the early evening. In the wake of the frontal passage, high pressure will build in from the northwest and will linger through the weekend.
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&& .NEAR TERM /THROUGH TONIGHT/...
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An upper level trough and associated weak disturbance will pivot over the forecast area this afternoon and into the evening. This increase in moisture aloft can already be noticed in the fair weather cumulus clouds tracking east across the region. Isolated showers and thunderstorms are possible east of the Blue Ridge with Scattered showers and thunderstorms possible in the northwest portions of the area. The southeastern portions of the forecast area should remain dry, however, a stray shower cannot be ruled out this afternoon. Shower activity should diminish after sunset with skies clearing up overnight. Low temperatures will fall into the 50s for most with those at higher elevations dipping into the upper 40s. Metro areas will be slightly warmer tonight, with low temperatures staying in the low 60s.
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&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
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An upper level trough will pivot overhead Wednesday as a reinforcing cold front moves through the area Wednesday evening. Shortwave energy moving overhead tomorrow afternoon will bring increased coverage for showers and thunderstorms. QPF totals generally remain below 0.25" so flooding threat remains low. The airmass will be relatively stable with limited instability, so the threat for severe weather remains low. Shower and thunderstorm chances will decrease Wednesday night with the loss of daytime heating. Dry conditions are expected on Thursday as dry air moves in aloft. Winds remain out of the northwest, gusting up to 15 knots in the wake of a frontal passage. There will be a temperature gradient across the forecast area on Wednesday with high temperatures ranging from the low 60s in the Alleghenies to nearing 80 along I-95 and in the southern portions of the area. Overnight low temperatures will be in the upper 40s at higher elevations with the rest of the area staying in the 50s. In the wake of the frontal passage Wednesday night, high temperatures on Thursday will be a few degrees cooler when compared to the previous day. Highs will be in the low 60s for those at higher elevations with the rest of the area in the mid 70s. Low temperatures on Thursday night dip into the low 40s with those further east staying in the mid to low 50s.
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&& .LONG TERM /FRIDAY THROUGH MONDAY/...
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The trough axis will be to the east Friday, so there should be less cloud cover overall. Northwest flow will support another day with below normal temperatures and low humidity. The surface high will move nearly overhead by Saturday morning, so there should be favorable radiational cooling Friday night. Outlying areas should easily fall into the 40s again, while some of the deeper valleys could fall into the 30s. A narrow ridge will build aloft Saturday while the surface high continues to drift to the southeast. Temperatures will warm several degrees to around or above normal. The ridge axis will push to the east Sunday and a more zonal flow will develop across the eastern half of the country. Timing of individual waves in this regime is uncertain, rather there will just be a gradual return to more unsettled weather as we remain on the warm side of low pressure systems tracking well to the north. Ensemble precipitation probabilities and experimental convective machine learning guidance suggest potential for a more active day on Tuesday. Temperatures will continue to run above normal through early next week while humid air gradually makes a return.
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&& .AVIATION /18Z TUESDAY THROUGH SUNDAY/...
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VFR conditions are expected for the rest of today and overnight as westerly winds diminish this evening. A stray shower or thunderstorm cannot be ruled out this afternoon, but confidence on where those will initiate was too low to include in TAFs. Either way, most locations are expected to remain dry with any precipitation being isolated and shallow. Westerly winds will diminish this afternoon before shifting to northwesterly tonight. Fair weather cumulus clouds over the terminals this afternoon will clear to mostly clear skies overnight. Winds remain out of the northwest Wednesday blowing 5-10 knots. Shower and thunderstorm chances increase Wednesday afternoon, so introduced -SHRA to IAD, DCA, and BWI. Though winds remain out of the northwest Thursday, winds gust up to 15 knots in the wake of a cold front passage. VFR conditions are expected both days with the precipitation chance decreasing for Thursday. No significant weather expected Friday and Saturday with high pressure. Low chance of a thunderstorm Sunday depending on the timing of the next disturbance.
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&& .MARINE...
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Westerly winds gusting up to 20 knots are expected until 7PM this evening with a Small Craft Advisory in effect for the upper portions of the Chesapeake Bay and Upper Tidal Potomac. Winds decrease to below SCA criteria tonight and shift to northwesterly. As a cold front moves over the area, showers and thunderstorms may impact the waters on Wednesday. SMWs may be needed as any storms move over the waters. In the wake of the frontal passage, northwesterly winds pick up to SCA criteria Wednesday night. Winds are expected to remain below SCA criteria on Thursday. Lingering marginal SCA conditions are possible Friday morning, but overall winds will be lessening through Saturday as high pressure builds into the area. Winds will become southerly by Sunday but may not increase appreciably. & .TIDES/COASTAL FLOODING... Winds will remain out of the west today before shifting to northwesterly tonight through Thursday. This will lead to decreasing tidal anomalies with no coastal flooding anticipated for the next few days.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 7 PM EDT this evening for ANZ530>532-535-536-538>540. && $$ SYNOPSIS...AVS NEAR TERM...AVS SHORT TERM...AVS LONG TERM...ADS AVIATION...ADS/AVS MARINE...ADS/AVS TIDES/COASTAL FLOODING...AVS