Area Forecast Discussion
Issued by NWS Sterling, VA
Issued by NWS Sterling, VA
663 FXUS61 KLWX 240131 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 931 PM EDT Mon Sep 23 2024 .SYNOPSIS... A front will remain stalled off to the south and west through tonight. Meanwhile, strong high pressure across eastern Canada builds southward along the Appalachians. A strong front and area of low pressure over the Great Lakes and Upper Midwest will approach through the middle of the week. High pressure will build to the north mid to late week while low pressure approaches from the south. && .NEAR TERM /UNTIL 7 AM TUESDAY MORNING/... With a stalled frontal boundary off to the southwest of the region, a persistent onshore flow will maintain a thick band of low clouds across the Mid-Atlantic. Regional radar imagery continues to show a mixture of drizzle to light showers pushing southeastward across the metros. Additionally, patchy fog may develop, particularly for areas west of I-95. Overnight low temperatures will only fall into the low to mid 60s. && .SHORT TERM /7 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/... A warm front lifts further north on Tuesday, with increasing shower chances into the afternoon. Cannot rule out a few isolated thunderstorms, especially west of the Blue Ridge where better forcing and instability will likely reside. Afternoon highs will top out in the mid to upper 60s. There may be enough forcing with the incoming shortwave Tuesday and Wednesday afternoons combined with sufficient instability and shear (mainly aloft) to result in a few stronger storms capable of a little hail, or perhaps some gusty surface winds near and west of the Allegheny Front. Additionally, there may be enough heavy rain across our far southwestern counties in VA to allow for isolated instances of flooding Tuesday afternoon and evening. Tuesday`s temperatures look cool during the day with a wedge firmly in place, but daytime temperatures may warm a bit Wednesday as the wedge weakens. && .LONG TERM /THURSDAY THROUGH MONDAY/... Narrow ridge will build over the Mid Atlantic sandwiched between an upper low over New England and a large upper low over the Mid-South. At the sfc, a cold front will drop across the area Thursday with only isolated showers and thunderstorms expected. Latest NHC forecast has Potential Tropical Cyclone Nine becoming Hurricane Helene by 12Z Wed making landfall over the Big Bend area of FL by Fri morning. Helene then gets absorbed into a large upper level low over the Mid-South. Remnant moisture from Helene makes into our area Fri night into the weekend. Sfc ridging builds again over the area Sat night into Sun suppressing moisture and bringing dry air for the second half of the weekend. && .AVIATION /01Z TUESDAY THROUGH SATURDAY/... MVFR CIGs look to persist at most TAF sites through Tuesday, with bouts of IFR possible especially at MRB/CHO and/or during the overnight/early AM hours each day. Conditions may improve slightly by Wednesday. This is all thanks to onshore flow around a wedge of high pressure over the region. Meanwhile, a frontal system slowly approaching from the west could result in a few showers or even an elevated thunderstorm (especially west of I-95) through mid week. Lastly, some patchy drizzle is possible at times in onshore flow, most likely during the AM hours. Low clouds Fri morning will likely cause flight restrictions. && .MARINE... Onshore flow will mainly remain sub-SCA the next few days, though a couple pushes of easterly flow may result in 20 kt gusts tonight, Tuesday evening/night, and Wednesday afternoon/evening. A few showers are possible at times as a frontal system approaches from the west, with most thunder chances likely remaining west of the waters until at least late Tuesday into Wednesday. Winds strengthen again Fri night through Saturday with SCA conditions likely. && .TIDES/COASTAL FLOODING... Minor to moderate coastal flooding will persist until further notice. From an astronomical standpoint, tonight`s astronomical tide will be the highest over the next several days as Moon Phase moves from Last Quarter to Waning Crescent. So, we`ll likely be seeing the last episode of moderate coastal flooding tonight with water levels gradually coming down during the second half of the week, but with minor coastal flooding persisting through the end of the week. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...Coastal Flood Warning until 4 AM EDT Wednesday for DCZ001. MD...Coastal Flood Warning until 4 AM EDT Wednesday for MDZ014. Coastal Flood Advisory until 4 AM EDT Wednesday for MDZ011-016- 018-508. Coastal Flood Warning until 10 PM EDT Tuesday for MDZ017. VA...Coastal Flood Warning until 4 AM EDT Wednesday for VAZ054. Coastal Flood Advisory until 4 AM EDT Wednesday for VAZ057. WV...None. MARINE...None. && $$ SYNOPSIS...BRO/DHOF/ADM NEAR TERM...BRO/DHOF/ADM SHORT TERM...DHOF/ADM LONG TERM...LFR AVIATION...LFR/DHOF/ADM MARINE...LFR/DHOF/ADM TIDES/COASTAL FLOODING...LFR