995 FXUS61 KLWX 050058 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 858 PM EDT Mon Aug 4 2025 .SYNOPSIS... High pressure remains centered over eastern Canada and remains socked in down through the Carolinas. This remains in place over the next several days. Shower and thunderstorm chances return midweek into the weekend as onshore flow increases with broad low pressure forming along the southeast U.S coast. && .NEAR TERM /THROUGH TONIGHT/... Some high clouds will work in from the south this evening with perhaps a few low clouds and areas of river valley fog south of I-66/US-50 (mainly central VA and Shenandoah Valley) late tonight into early Tuesday morning as onshore flow increases. Lows tonight will fall into the upper 50s and low to mid 60s. These values will be a touch warmer from previous nights given the increased high level cloud cover. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... Dry conditions persist through Tuesday with rain chances set to return for some Wednesday. Strong high pressure over southeast Canada will continue to wedge it`s way south along the eastern Appalachians before shifting further east and weakening over northern New England. Meanwhile, a potent upper level trough will dig across the Great Lakes, Ohio River Valley, and through the southeastern U.S CONUS sending Gulf moisture northward into the region. The squeeze play between the wedging high and western Atlantic ridge to the north/east, incoming trough from the west, and broad area of low pressure off the southeast U.S coast will lead to an uptick in shower and isolated thunderstorm activity across the region. Instability should be fairly meager given the stable wedge conditions with east to southeast onshore/upslope flow. Highest concentration of shower/drizzle activity Tuesday will be south of I- 64 before an advancement along and south of I-66/US-50 Wednesday into Wednesday night. Some uncertainty remains amongst the models in how fast low clouds, drizzle, and rain showers push northward into central VA and the Shenandoah Valley. The EPS/ECMWF is more of the aggressor compared to some of the hi-res CAMS and GFS/GEM. Given the slow nature of the cutoff upper level trough to the west and the strong high pressure center settling over northern New England/southeast Quebec, the slower solutions are more likely to verify. With that said, maintaining 15 to 25 percent PoPs mainly west Alleghenies and over the southern Shenandoah Valley/central Blue Ridge where ample moisture will build in Tuesday morning into Tuesday afternoon due to upslope easterly/southeasterly flow. Once again, confidence is low for precip Tuesday given the residual dry air aloft from wedging high pressure. Most will see increased low and mid level cloud coverage (i.e overcast) Tuesday into Tuesday night. Highs Tuesday will range from the mid to upper 80s over central MD (where cloud cover will arrive later) to mid to upper 70s over the Shenandoah Valley/Alleghenies. Lows Tuesday night will fall into the mid to upper 60s with upper 50s west of I-81. These values will be slightly warmer, especially east of the Blue Ridge given the increased cloud cover. More scattered to numerous showers and perhaps a few isolated thunderstorms are possible Wednesday into Wednesday night as additional moisture surges into the area. Highest probabilities of precipitation are once again confined to areas along and west of US- 15 (especially across central VA and Shenandoah Valley). Highs Wednesday will range from the low 80s over northern/central MD to upper 60s and low to mid 70s over the Shenandoah Valley/Allegheny Highlands region. && .LONG TERM /THURSDAY THROUGH MONDAY/... Surface high over southern New England slowly slides offshore late this weekend into the weekend. The high doesn`t make it very far until it stalls a couple hundred miles off Cape Cod, with the surface ridge axis squarely in place over the Mid-Atlantic. This maintains a steady easterly wind over our area Thursday through the weekend, with a steady stream of clouds and some showers. The main area to watch for potential higher coverage of showers and some thunderstorms is along the southern periphery of the surface ridge axis. Current model guidance indicates this is most likely to be over Central VA to the central Appalachians, with those closer to the MD/PA border being drier. Still, there is quite a bit of uncertainty depending on how strong the ridge is and where it is located. Highs are forecast to be mainly in the lower 80s, with perhaps a slight uptick to the mid 80s by the time the weekend arrives. Overnight lows are steady in the 60s. && .AVIATION /01Z TUESDAY THROUGH SATURDAY/... Some mid-level clouds and perhaps river valley fog will move into the central VA terminals (i.e KCHO, KSHD, and KRIC) late tonight into Tuesday morning before spreading northward Tuesday afternoon and evening. Solid overcast is likely to persists through Wednesday given the strengthened wedge and increased onshore flow. Expect MVFR to perhaps some pockets of IFR (especially terminals south of I-66/US-50 and west of I-95 corridor) late Tuesday night and into Wednesday. Winds will remain out of the east and northeast through Wednesday at less than 15 kts. Sub-VFR conditions are likely at times Thursday and Friday as persistent easterly winds prevail. This brings in lower marine stratocu and passing showers. Lower CIGs and some mist/fog are most likely each night to early morning through Saturday. && .MARINE... No marine hazards are expected through Wednesday morning as high pressure continues to wedge south from southeast Canada and northern New England. Winds will remain light and variable generally out of the east and northeast at this time. Winds begin to strengthen Wednesday evening into Thursday with SCA conditions likely to return as onshore flow increases. A strong area of high pressure over Southern New England slides offshore this weekend. This maintains a steady east wind over the local waters, with a prolonged period of SCA conditions possible. This is most likely over the Chesapeake Bay and Eastern Shore bays and tributaries. Winds could start to weaken Friday night, though some elevated winds likely persist into the weekend. && .TIDES/COASTAL FLOODING... Onshore winds remain through midweek as a wedge of high pressure remains locked in from the northeast CONUS into the Carolinas. The east to northeast wind direction will result in increased tidal anomalies through Tuesday which could push the sensitive tidal sites near minor flood stage, particularly at Annapolis. As we approach Full Moon on Saturday, August 9, 2025 and onshore flow strengthens, expect the risk of minor coastal flooding to increase again during the back half of the workweek and upcoming weekend as a result. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...CJL NEAR TERM...CJL/EST SHORT TERM...EST LONG TERM...KRR AVIATION...KRR/EST/CJL MARINE...KRR/EST TIDES/COASTAL FLOODING...CJL