Area Forecast Discussion
Issued by NWS Sterling, VA
Issued by NWS Sterling, VA
853 FXUS61 KLWX 070111 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 911 PM EDT Sun Sep 6 2026 .WHAT HAS CHANGED... Closely monitoring the threat of tidal flooding at Annapolis due to prolonged onshore flow. Coastal Flood Advisories may be needed shortly. && .KEY MESSAGES... - 1) Dry and seasonable conditions, with lower humidity through early portions of the week. - 2) Shower and thunderstorm chances return by mid week. && .DISCUSSION... KEY MESSAGE 1...Dry and seasonable conditions, with lower humidity through early portions of the week. A broad area of surface high pressure currently stretches across the Great Lakes. Net northerly winds on the eastern side of this anticyclone is supporting dry conditions over the area. The 00Z IAD sounding depicted a bit of saturation around 800-750 mb which was likely associated with the lingering mid-level clouds. Otherwise, the profile is rather dry, and will remain that way through Monday. This will maintain a lower dew point air mass into the Labor Day holiday. Daily high temperatures through Monday will be in the low 80s, accompanied by overnight lows in the 50s and low 60s. Surface high pressure begins to transition south of the Mid- Atlantic on Tuesday as upper level ridging builds over the southeast CONUS. Temperatures likely begin to creep up again during this time, accompanied by increasing humidity as mid- level dry air tracks south of the region with more humid air coming in from the north. KEY MESSAGE 2...Shower and thunderstorm chances return by mid week. Upper-level ridging over the Appalachians starts to flatten into zonal flow beginning Wednesday. As this occurs, a trough forming over Quebec will begin to track east across the northeast CONUS, with a stemming cold front moving across the East Coast by Thursday. Temperatures gradually increase during this time, along with increasing humidity ahead of the front. By Thursday, temps potentially reach the upper 80s to low 90s. As this frontal boundary tracks through the Mid-Atlantic, showers & thunderstorms are possible across the region, beginning Wednesday evening and into Thursday. The 12z guidance remains unclear in terms of timing and the exact evolution of this system, so a lot of uncertainties remain. There is general agreement in trough digging south into the region, but the exact strength and timing of that trough is still being ironed out. Temperatures Thursday are expected to be in the 80s to near 90, with dew point in the 60s to perhaps low 70s. This should yield plenty of CAPE south of the front itself and allow for at least some thunderstorm development if the forcing arrives near peak heating. The severe threat is still in question, but remains non-zero. If the trough tracks far enough south, there could be a fair amount of wind shear to work with as well, which would increase that severe threat. Some of the AI guidance (particularly the WxNext) do highlight our region, so it is certainly something to keep a close eye on. Will continue to monitor latest guidance in hopes of honing in on a more confident solution. As this cold front transitions offshore towards the end of next week, temps drop again & conditions become much drier heading into the weekend as high pressure moves in overhead. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... VFR conditions should persist through Wednesday evening given the general influence of high pressure over, or near the region. This dome of high pressure does depart by Tuesday which yields a return of south to southwesterly flow. Showers & thunderstorms associated with an incoming cold front could temporarily bring sub-VFR conditions to terminals by Thursday afternoon. Ahead of the front on Thursday, winds could gust between 20-25 knots before diminishing overnight. && .MARINE... No marine hazards are expected through the holiday weekend. Generally light flow is expected, although gusts could creep up to 10 to 15 knots at times. Northeasterly winds Monday shift southerly on Tuesday, remaining below SCA levels. SCAs are possible across the Bay by Wednesday evening ahead of an incoming cold front. Winds could remain elevated throughout Thursday as this frontal boundary tracks east across the coast. && .TIDES/COASTAL FLOODING... Tidal anomalies remain elevated over the next several days due to an onshore flow. The current forecast would carry Annapolis into minor tidal flooding during the next couple late night high tides. Depending on how the tidal anomalies change in the next hour, Coastal Flood Advisories may be needed. At other sensitive locations, some places could push into Action. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ DISCUSSION...BRO/CJL/CPB AVIATION...CJL/CPB MARINE...CJL/CPB