Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 060056 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 856 PM EDT Wed Oct 5 2022 .SYNOPSIS... An upper low and associated coastal low will pull away to the east through tonight. High pressure will build back in tomorrow. A potent cold front will move through the area on Friday, with high pressure gradually building back overhead in its wake this weekend. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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Upper-level ridging will build overhead tonight behind a departing upper-level low. Weak high pressure will build overhead as well, and this will allow for clouds to continue clearing in eastern areas. Dry conditions will persist with lows in the 40s for most places to the lower 50s in downtown Washington and Baltimore. Some colder valleys in the Potomac Highlands may dip into the mid and upper 30s. Patchy fog is possible overnight, especially in the river valleys and sheltered valleys.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... A strong shortwave trough will rotate through the Great Lakes Thursday through Friday. It will kick a lead shortwave across the area on Thursday potentially increasing mid and high level clouds at times during the afternoon and evening. However, with more overall sun that preceding days and some warm advection ahead of the trough, high temperatures will rebound closer to normal in the lower to mid 70s. Dry and seasonable temperatures will continue into Friday morning. The stronger trough axis will be passing to the north during the day Friday, driving a surface low along the St. Lawrence Valley and a trailing cold front across the local area. With limited forcing and moisture, rain shower chances will be mainly limited to areas near and west of the Allgheny Front. Prior to the cold frontal passage there will actually be a fair amount of sunshine, with temperatures climbing into the 70s for most, and perhaps to near 80 in the Fredericksburg area. Strong cold advection will ensue in the wake of the cold front Friday night. Temperatures will crash into the 40s for most, with 30s along and west of I-81. With gusty winds occurring through the night, frost formation isn`t anticipated, but the absolute highest elevations along the Allegheny Front may see a freeze as 850mb temperatures drop below 0C. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... The long term period begins with general troughing over the eastern portions of the United States. An embedded shortwave trough will move in from the Great Lakes over our area Saturday afternoon. With a dry airmass overhead (PW values less than an inch) no precipitation is expected. This will bring below average temperatures and westerly flow. Northerly winds on Saturday will shift to west-southwesterly Sunday afternoon. Saturday high temperatures will be in the 50s-60s for most with higher elevations in the 40s. Overnight lows will be in the 30s to 40s depending on elevation. At least pockets of frost will be possible in rural areas west of I-95, with colder temperatures and greater chances of frost and/or freeze west of the Blue Ridge. For Sunday through Tuesday, a broad area of surface high pressure settles over the Mid-Atlantic. Throughout the remainder of the long term period, the surface high will gradually pivot northeast while generally remaining overhead. Sunday will be the coolest day with high temperatures in the low to mid 60s(40s-50s at higher elevations) and overnight lows in the 30s-40s. A gradual warming trend will take place Monday and Tuesday with high temperatures getting into the 70s on Tuesday for those near the Bay and metro areas. Dry conditions will persist throughout the long term period. && .AVIATION /01Z THURSDAY THROUGH MONDAY/...
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VFR conditions and light winds are expected tonight through the first half of Friday. Winds will pick up out of the northwest behind a (dry) cold frontal passage Friday afternoon. After the passing of the cold front, VFR conditions are expected throughout the area. Northerly/northwesterly winds on Saturday will shift to west-southwesterly Sunday afternoon.
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&& .MARINE...
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Winds will continue to diminish overnight, and remain below SCA criteria. Sub-SCA westerly winds are expected Thursday and Thursday night as high pressure crosses the area. Marginal SCA conditions may occur Friday morning, but the stronger push of northwest winds will occur during the afternoon and evening as a (dry) cold front crosses the area. Increased wind speeds behind the front may continue to result in small craft advisory criteria being met for portions of Saturday. Winds will decrease Saturday evening into Sunday with sub SCA criteria expected.
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&& .TIDES/COASTAL FLOODING...
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Anomalies are around 1 foot above normal in the southern portion of the Bay this evening. These anomalies will likely push northward later tonight through Thursday night as winds diminish. Tidal anomalies are likely to increase causing water levels to reach caution stages for sensitive areas around high tide. It is possible that minor flood thresholds are met, especially Thursday night where a little southerly flow may take place. However, confidence is too low at this time for any headlines.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...None. VA...None. WV...None. MARINE...None.
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&& $$ SYNOPSIS...ADS NEAR TERM...BJL/ADS SHORT TERM...ADS LONG TERM...AVS AVIATION...BJL/ADS/AVS MARINE...BJL/ADS/AVS TIDES/COASTAL FLOODING...BJL

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