Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 270744 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 344 AM EDT Wed Mar 27 2024 .SYNOPSIS...
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A slow-moving cold front will cross the Mid-Atlantic from west to east through tonight. Low pressure developing near the Carolinas will move northeastward along the front as it moves offshore Thursday. High pressure will build in from the Ohio and Tennessee River Valleys Friday, then a cold front will drop southward into the Mid-Atlantic over the weekend into early next week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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A slow-moving cold front is approaching the Appalachians as of early this morning. Warm/moist advection ahead of it via a modest LLJ was causing some showers to begin breaking out on either side of the Blue Ridge Mountains. Shower activity is expected to become more widespread east of the Blue Ridge Mountains, with waves of showers persisting through much of the day as the front slowly moves in. The onshore flow, clouds, and showers should keep temperatures in the 50s for many areas east of I-81. Rain showers will pivot east of I-95 and gradually diminish for a time this evening as the front pushes east, but a wave of low pressure developing offshore will likely bring another wave of showers along and east of I-95 late overnight/early Thursday AM.
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&& .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
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Low pressure is expected to pass offshore Thursday into Thursday night along the cold front that will have crossed the area today. The heaviest rainfall amounts are expected south and east of the local area, though around an inch of rain is possible over southern MD. As the low pulls away Thursday night into Friday, high pressure will build in its wake from the OH/TN Valleys. This will lead to fair and seasonable weather with blustery NW winds. Depending on just how strong the gradient is between the departing low and incoming high, gusts could approach or exceed Wind Advisory criteria (40 kts/46 MPH) mainly over the higher elevations Friday. Winds diminish Friday night with the loss of daytime heating/mixing and as the gradient weakens.
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&& .LONG TERM /SATURDAY THROUGH TUESDAY/...
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As high pressure moves out Friday into Saturday, we set up for a generally unsettled weekend as a warm front moves into the Ohio Valley and Mid-Atlantic and stalls in the area into early next week. With a few minor disturbances passing overhead, some clouds and shower activity are possible on Saturday and Sunday. Currently the best chance for precipitation seems to be along the Alleghenies both days with a slight chance north of I-66 Saturday and west of I-81 Sunday. Monday into Tuesday low pressure moves into the Ohio Valley bringing greater rain chances to the region. Temperatures will be well above normal over the weekend with highs in the 60s to 70s outside of the mountains, and closer to normal for the beginning of the week (50s to 60s) as the next low pressure system approaches.
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&& .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
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CIGs are FL006-FL012 are expected to persist through much of the day, with the lowest CIGs pegged by guidance through about 15Z. Brief LIFR CIGs are possible. Some guidance hints at patchy dense fog/IFR VSBY in drizzle this morning before steadier showers develop, as well. Shower activity is expected in waves and could briefly reduce VSBY to MVFR through the day. A lull in showers is expected this evening, but showers likely reappear to the metro terminals early Thu AM as low pressure tracks up the coast. Otherwise, IFR/LIFR CIGs look likely from mid to late evening into the overnight. Light SE flow is expected. Conditions improve to VFR Thu AM and persist through Fri with gusty N/NW winds to 30+ kts at times. The strongest winds are most likely Fri midday/afternoon. Restrictions are possible Saturday and Sunday with shower activity from a weak front lingering in the region. Winds could be gusty both days up to around 20-25 kt, starting out of the southwest on Saturday and becoming northwest on Sunday.
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&& .MARINE...
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Light SE winds are expected today, becoming N late tonight. Winds increase out of the N/NW Thursday-Friday, with solid SCA conditions at times, and gale conditions possible mainly Friday. Warmer air over cooler water could prevent mixing over the wider cooler waterways during the day Friday, perhaps limiting the strongest gusts to near the shore. Otherwise, periods of reduced visibility in rain and patchy fog are expected through tonight. Winds over the waters may approach SCA criteria during the day Saturday and Sunday as a weak front lingers in the area.
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&& .TIDES/COASTAL FLOODING...
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Tide anomalies have continued to increase on SE flow early this morning. Widespread minor to localized moderate flooding is expected through this morning before tide levels gradually begin to come down a bit. Minor flooding is still likely at many sites into tonight, possibly into Thursday depending on how quickly tide levels respond/decrease due to increasing N/NW flow Thursday into Friday. Given the persistent offshore flow, low water level issues may arise by Friday before rebounding.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...Coastal Flood Advisory until 7 AM EDT this morning for DCZ001. Coastal Flood Warning from 7 AM this morning to 2 PM EDT this afternoon for DCZ001. MD...Coastal Flood Advisory until 3 PM EDT this afternoon for MDZ011-016-508. Coastal Flood Warning until noon EDT today for MDZ014. Coastal Flood Advisory from noon today to midnight EDT tonight for MDZ014. Coastal Flood Warning until 6 AM EDT early this morning for MDZ017. Coastal Flood Advisory until 8 PM EDT this evening for MDZ017. Coastal Flood Advisory until 7 PM EDT this evening for MDZ018. VA...Coastal Flood Advisory until 7 AM EDT this morning for VAZ054. Coastal Flood Warning from 7 AM this morning to 2 PM EDT this afternoon for VAZ054. Coastal Flood Advisory until 3 PM EDT this afternoon for VAZ053-055-057-527. WV...None. MARINE...Small Craft Advisory from 11 AM Thursday to 11 AM EDT Friday for ANZ530>533-535-536-538>542. Gale Watch from Friday morning through Friday afternoon for ANZ530>533-535-536-538>542. Small Craft Advisory from 11 AM Thursday to 4 AM EDT Friday for ANZ534-537-543. Gale Watch from late Thursday night through Friday afternoon for ANZ534-537-543.
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&& $$ SYNOPSIS...DHOF NEAR TERM...DHOF SHORT TERM...DHOF LONG TERM...CAS AVIATION...DHOF/CAS MARINE...DHOF/CAS TIDES/COASTAL FLOODING...DHOF

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