Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 231344 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 944 AM EDT Thu Sep 23 2021 .SYNOPSIS...
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A strong cold front associated with an area of low pressure over the Great Lakes will continue to push through the region this morning through this afternoon, resulting in periods of heavy rainfall, gusty showers, and embedded thunderstorms. Meanwhile, high pressure will continue to build into the region as dry weather returns Friday into the weekend.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Large upper level low continues to retrograde over the Great Lakes as an associated cold front continues to push through the region this morning. Latest radar imagery shows the last batch of heavy showers and embedded thunderstorms beginning to exit off into eastern MD. Latest hi-res guidance in conjunction with the latest obs shows this final band completely clearing the region within the next hour or so. Latest satellite imagery shows rapid clearing behind the front with some upslope clouds across the Alleghenies as a strong W/NW flow ensues. Numerous Flood Warnings continue across the CWA currently. However with drying conditions continuing throughout the remainder of the day, don`t anticipate any additional flooding issues. Will likely be dropping the Flash Flood Watch for the Baltimore and DC metro areas in the next few hours once the heavy rain has completely exited the area. Cooler and drier conditions are expected today through this weekend with high temperatures this afternoon in the low 70s for most with some mid 50s across the higher terrain. Lows tonight will drop down into the mid 40s for most, slightly warmer across the metros.
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&& .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
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...PREVIOUS DISCUSSION... Dry and seasonably cool on Friday with highs in the low to mid 70s as high pressure builds towards the region. This will continue into Friday night as well, with temps even a touch cooler than Thursday night. Temps start to moderate a bit on Saturday as high pressure sets of to our southwest. Temperatures won`t increase much, with highs closer to the mid 70s. With winds out of the southwest, temps overnight will trend upwards as well, increasing a few degrees compared to previous nights.
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&& .LONG TERM /SUNDAY THROUGH WEDNESDAY/... High pressure will dominate over the region early next week with near or slightly below normal temperatures and dry conditions. Temperatures will moderate Tuesday as the aforementioned high shifts offshore and winds turning a touch more southerly. Tuesday will also feature our next chance of precipitation as a weak cold front drops southward toward the region. Latest guidance depicts scant moisture with this front, so will maintain low end chance POPs in the forecast for now. Cooler conditions return toward the middle of next behind the front as Canadian high pressure builds to our north. && .AVIATION /13Z THURSDAY THROUGH MONDAY/...
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The last batch of showers and embedded thunderstorms continue to exit eastward. Latest radar imagery shows some partial clearing over BWI with the heaviest of the rain just east of MTN. Elsewhere, conditions are either or quickly becoming VFR as the winds shift to the N/NW. VFR conditions are expected to continue through early next week as high pressure remains in control.
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&& .MARINE... Gale Warnings continue through the early afternoon for the lower Tidal Potomac and the Chesapeake Bay. A Small Craft Advisory remains in effect for the upper and middle Tidal Potomac. As a strong cold front continues to track eastward, gusty showers and thunderstorms are likely where the issuance of SMWs may be required, and even the potential for an isolated waterspout. Northerly winds are expected to develop after the front moves through the region by Thursday afternoon and persist into Friday. Additional SCA was issued to cover this threat starting late tonight. SCA gusts possible in S channeling ahead of a front Sat PM before becoming NW with SCA gusts possible thru Sun. Borderline SCA conditions possible Sunday under a westerly wind regime as high pressure builds mainly south of the waters. The gradient will relax Sunday night into Monday with continued light westerly breezes. && .TIDES/COASTAL FLOODING... Tidal anomalies continue to run high thanks to strong onshore winds ahead of an approaching cold front. As a result, minor to moderate tidal flooding is occurring or forecast this morning at all tidal locations. Confidence in additional tidal flooding with subsequent high tide cycles this afternoon and evening decreases as winds will turn offshore as the front slowly crosses the area today. Additional updates to the forecast will certainly be needed later this morning as the timing of the front and wind shift becomes clearer, allowing anomalies to back off. && .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...Flash Flood Watch until 2 PM EDT this afternoon for DCZ001. Coastal Flood Warning until noon EDT today for DCZ001. MD...Flash Flood Watch until 2 PM EDT this afternoon for MDZ005-006- 008-011-503>508. Coastal Flood Advisory until 2 PM EDT this afternoon for MDZ011. Coastal Flood Warning until noon EDT today for MDZ014. Coastal Flood Advisory until 4 PM EDT this afternoon for MDZ508. VA...Flash Flood Watch until 2 PM EDT this afternoon for VAZ053-054- 506. Coastal Flood Advisory until noon EDT today for VAZ054. WV...None. MARINE...Small Craft Advisory until 9 PM EDT this evening for ANZ535- 536. Flash Flood Watch until 2 PM EDT this afternoon for ANZ535. Small Craft Advisory until 5 AM EDT Friday for ANZ530>533- 538>542. Gale Warning until noon EDT today for ANZ530>534-537>543. Small Craft Advisory until 10 AM EDT Friday for ANZ534-537-543.
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&& $$ SYNOPSIS...CJL/SOUZA NEAR TERM...SOUZA SHORT TERM...CJL LONG TERM...BKF AVIATION...SOUZA MARINE...BKF/CJL TIDES/COASTAL FLOODING...STAFF

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