Area Forecast Discussion
Issued by NWS Sterling, VA
Issued by NWS Sterling, VA
667 FXUS61 KLWX 221414 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 1014 AM EDT Sun Sep 22 2024 .SYNOPSIS... A frontal system will stall over the area today. A strong front and area of low pressure over the Great Lakes and Upper Midwest will approach the area during the early or middle part of the week. High pressure will follow mid to late week. && .NEAR TERM /THROUGH TONIGHT/... Ongoing low clouds and drizzle across the area. Ground fog has lifted aside from the eastern slopes of the Alleghenies where locally dense fog remains. Otherwise, previous discussion follows... A few showers are possible along the backdoor front today, but with diminishing forcing aloft expect coverage to be isolated to widely scattered. Low clouds to the east gradually eroding and lifting this afternoon. High temperatures will likely rise to around 80 F over the valleys of eastern WV and western VA west of the backdoor front, with areas further east staying in the low to mid 70s due to increased cloud cover and onshore flow. Low temperatures tonight will drop into the upper 50s to mid 60s. A few showers, drizzle, or fog are possible generally west of US-15 in the vicinity of the stalling front tonight. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... The pattern doesn`t change much heading into Monday. Thus, expect lingering cloud cover for much of the area along with muted diurnal temperature spread. Another trough and area of low pressure/frontal system begin to approach from the OH Valley/Great Lakes by later Monday resulting in increasing rain chances from west to east especially Monday night. This system will gradually push across the area Tuesday and Tuesday night with showers and a few thunderstorms likely. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... A potent upper trough over the Midwest slowly moves eastward, with an associated area of surface low pressure developing over the central Great Lakes. A wet middle of the week is likely as at least a few waves of low pressure aloft move across the Mid-Atlantic, bringing periods of scattered showers and possibly a few thunderstorms. The persistent CAD-like wedge at the surface remains in place through at least Thursday, keeping low clouds and cooler conditions in place, especially east of the Blue Ridge. Highs in the middle to possibly upper 70s are expected each day, with overnight lows in the 50s to low 60s. A weak cold front is progged to cross the area sometime late Thursday, though model solutions diverge greatly for the end of the week. This might not be enough to scour out the cloud cover and moisture over the region. There remains a lot of uncertainty with the forecast for the end of the week into next weekend. Continue to monitor for updates as we go through the week. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... Fog, dense at times, is anticipated at CHO and MRB through mid morning. The metro terminals will likely see IFR CIGs lifting to MVFR then gradually scattering out midday into this afternoon, perhaps a bit earlier at MTN as a backdoor front pushes through. Any early AM convection should wane around daybreak. Winds will be E/NE 5-10 kts through tonight. Onshore flow continues Monday into Tuesday with bouts of lower CIGs and patchy fog (especially overnight) possible at times. Showers and a few thunderstorms are possible late Monday through Tuesday night. Sub-VFR conditions are likely to continue through the end of the week, with MVFR CIGs during the day, dropping to IFR at night. Could see some fog develop, further adding to restrictions at area terminals. Expect scattered showers at times Wednesday into Thursday. Southeast winds around 10 knots Wednesday become variable Thursday, though the forecast for the end of the week becomes highly uncertain. && .MARINE... Onshore flow is expected through Tuesday night. Shower and thunderstorm activity should diminish early this morning. A few gusts of 15-20 kts are possible at times in the wake of a backdoor front, though most of the time should be sub-SCA. Southeast winds around 10-15 knots mid week become variable on Thursday. Scattered showers are expected to move across the waters each day through at least Thursday, though not expecting any strong wind gusts at this time. Marine fog could develop each night into morning over the waters. && .TIDES/COASTAL FLOODING... A very prolonged period of onshore flow (east to southeast) will continue through much of the week. Minor coastal flooding is likely at high tide at all sensitive locations for the next few days. Coastal Flood Advisories are in effect for nearly the entire western shoreline of the Chesapeake Bay and tidal Potomac River, including Washington DC. A steady rise in anomalies is expected to produce Moderate flooding at Annapolis through tonight. As a result, a Coastal Flood Warning remains in effect. Also, Washington DC SW Waterfront/Alexandria could approach Moderate flooding. Expect headlines to be extended for much of the upcoming week. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...Coastal Flood Warning until 5 AM EDT Tuesday for DCZ001. MD...Coastal Flood Warning until 5 AM EDT Tuesday for MDZ014. Coastal Flood Advisory until 5 AM EDT Tuesday for MDZ011- 016>018-508. VA...Coastal Flood Warning until 5 AM EDT Tuesday for VAZ054. Coastal Flood Advisory until 5 AM EDT Tuesday for VAZ057. WV...None. MARINE...None. && $$ SYNOPSIS...DHOF NEAR TERM...DHOF/CPB SHORT TERM...DHOF LONG TERM...KRR AVIATION...DHOF/CPB/KRR MARINE...DHOF/CPB/KRR TIDES/COASTAL FLOODING...LWX