Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 291341 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 941 AM EDT Thu Jun 29 2017 .SYNOPSIS... High pressure will settle near Bermuda today with hot and humid conditions returning and persisting through at least the first half of next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... High pressure continues to shift further offshore away from the Mid-Atlantic...with a warming/moistening southerly flow strengthening. Highs this afternoon M/U80s...near normal for late June. While we kept forecast dry for now...would not be be completely surprised to see a stray shower (or brief thunderstorm) across the higher terrain along/west of the Blue Ridge during peak afternoon heating. Any activity would be short-lived, very localized, and would dissipate by mid-evening. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... Temperatures more typical for the end of June/early July will persist into Saturday. Outside of the higher elevations temperatures will approach 90 both afternoons with lows near 70. Precipitation chances will be slim in the next 48 hours - perhaps some orographically induced showers/thunderstorms Friday afternoon/evening, but the best chance will be Saturday afternoon. Low pressure over Ontario/Quebec with a cold front dropping into NY state and a weak trough approaching the mountains will serve as the focus for storms. Bufkit profiles show a weak unidirectional wind field, so at this moment pulse severe looks to be the worse case scenario. With summer precipitation forecasting I am usually hesitant to go beyond "chance" five periods out. Given we have been advertising "likely" in the west as our surrounding offices, and GFS is forecasting 70 PoPs I`ll hold with the 60 PoP Saturday afternoon west of the Blue Ridge. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... Typical summertime conditions expected for late in the weekend and into next week with daily chances for afternoon/evening convection and very warm temperatures. A weakening frontal boundary that approaches Saturday will stall near the region Saturday night into Sunday, keeping chances for showers and thunderstorms in the forecast. This boundary will remain near or just north of the area into next week, separating a hot/humid air mass to the south from a cooler Canadian air mass to the north. Thus there will be chances for isolated/scattered showers/thunderstorms each day, but the vast majority of the time should be dry. Will show highs upper 80s to low 90s through the period for now, with lows in the 60s/70s, but will be dependent on frontal position. && .AVIATION /13Z THURSDAY THROUGH MONDAY/... VFR conditions continue today through midday Saturday. Showers/thunderstorms will be possible Saturday afternoon, especially at IAD/MRB/CHO. Mainly VFR expected through at least Monday. Isolated-scattered showers/thunderstorms possible, so some brief reductions are possible. && .MARINE... Southerly channeling ongoing on the Chesapeake Bay/Tidal Potomac - a sure sign of summer. While wind gusts have largely been below SCA criteria thus far this morning...expect winds to increase to AOA SCA threshold by afternoon as southerly flow continues to strengthen. This will likely reoccur Friday into Saturday with SCA possible. Mainly Sub-SCA conditions expected Saturday night through Monday. There is a chance for isolated-scattered showers/thunderstorms each afternoon and evening, which may contain locally gusty winds. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 7 PM EDT Friday for ANZ530>534- 537>541-543. Small Craft Advisory until 11 AM EDT Friday for ANZ535-536-542. && $$ UPDATE...MSE PRODUCTS...WOODY!/MJM is the U.S. government's official web portal to all federal, state and local government web resources and services.