Area Forecast Discussion
Issued by NWS Sterling, VA
Issued by NWS Sterling, VA
786 FXUS61 KLWX 291422 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 1022 AM EDT Sat Aug 29 2026 .WHAT HAS CHANGED... No changes to the forecast at this time. && .KEY MESSAGES... - 1) Cooler and less humid this afternoon; warmer and more humid Sunday with isolated afternoon thunderstorms. - 2) Late summer heat returns next week. - 3) Thunderstorm chances increase next week. && .DISCUSSION... KEY MESSAGE 1...Cooler and less humid this afternoon; warmer and more humid Sunday with isolated afternoon thunderstorms. High pressure will pass north of the area this afternoon and then off the Mid Atlantic coast Sunday. It will be slightly cooler and less humid this afternoon on NNW winds. As a result, most areas should remain dry and seasonable this afternoon, although an inverted surface trough may result in isolated showers along the Allegheny Mountains. Southerly flow returns Sunday, bringing increasing heat and humidity. A passing shortwave trough may support a few afternoon showers and thunderstorms about anywhere. KEY MESSAGE 2...Late summer heat returns next week. Guidance remains steadfast on late summer heat returning to end meteorological summer (June 1-August 31) and begin meteorological autumn (September 1-November 30). A strong mid-level ridge will build across the southern CONUS and into the Mid-Atlantic beginning on Sunday, and persist through at least the middle of the week. Some guidance has been trending towards having the ridge axis a bit further south and west, which would lower heights a bit and introduce more chances for showers and thunderstorms at times in large scale NW flow aloft. This lends to a bit of spread in the temperature forecast, especially if any back- door surface cold fronts slide into the region by mid/late week. Despite the uncertainties, it remains likely that high temperatures will reach the lower to middle 90s for much of the region for much of the upcoming week. Depending on smaller scale details, dew points could end up a little higher or lower than currently progged which will ultimately affect how high heat index values get. Values approaching Heat Advisory criteria (100-104 west of the Blue Ridge, 105-109 east of the Blue Ridge) can`t be ruled out, but the more likely scenario is for heat indices a bit below those values. KEY MESSAGE 3...Thunderstorm chances increase next week. Disturbances rounding a ridge to the south and west in NW flow aloft will introduce shower and thunderstorm chances at times next week. The timing and amplitude of these waves have very low predictability beyond a couple days in advance (at best). But the general theme will be enhanced lift and shear clashing with an increasingly hot and unstable airmass over or near the Mid-Atlantic. AI/ML guidance has broad elevated probabilities of severe weather much of next week, the details (including timing and magnitude/potential impact) of which will be ironed out in the coming days. It should be noted that there is a conditional potential for one or more organized clusters of strong to severe storms at some point next week. The most likely time currently appears to be around mid week, but changes are to be expected at this time range. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... VFR conditions this afternoon through Monday. Isolated t-storms possible Sunday afternoon. Prevailing VFR expected through early next week, with PM TS and early AM valley fog possibly introducing restrictions at times. Winds will generally be S/SW (except briefly NW Mon) 5-10 kts. && .MARINE... SCA conditions possible again Sunday night into Monday morning in southerly channeling. Some southerly channeling could result in at or near SCA criteria gusts Sunday evening into early Monday morning. Additional bouts of channeling may be possible by mid next week. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ DISCUSSION...LFR/KLW/DHOF AVIATION...LFR/KLW/DHOF MARINE...LFR/KLW/DHOF