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Area Forecast Discussion
Issued by NWS Wakefield, VA
Issued by NWS Wakefield, VA
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315 FXUS61 KAKQ 152315 AFDAKQ AREA FORECAST DISCUSSION National Weather Service Wakefield VA 715 PM EDT Thu Aug 15 2024 .SYNOPSIS... Tranquil weather conditions and comfortable humidity levels are expected this evening, as surface high pressure remains in place over the region. Precipitation chances gradually return to the region from Friday night through the weekend, as a slow moving area of low pressure and series of fronts cross the region. && .NEAR TERM /THROUGH FRIDAY/... As of 305 PM EDT Thursday... Key Messages: - Seasonably warm today with highs in the mid/upper 80s under a mostly sunny sky. - Small chance of an isolated shower or storm along the immediate coast through late afternoon. Latest analysis reveals 1020+mb sfc high pressure centered over the mid-Atlantic region, with a weak surface trough in place offshore of the northeast coast, extending south over the Delmarva. To the west, low pressure continues to lift across the northern plains, with an associated surface cold front slowly crossing the plains into the middle and upper Missouri Valley. Aloft, upper troughing is sliding offshore, with upper ridging building across the region in its place, with W-NW flow aloft over the region. A seasonably warm afternoon across the local area. 19z readings are in the mid to upper 80s, slightly cooler low 80s along the immediate coast. Light downslope flow is allowing for dewpoints mixing out and falling back into the mid to upper 50s to low 60s over inland areas this afternoon. CAMs continue to suggest that we could see an isolated shower or storm pinned to the afternoon sea breeze, with the best chance along the surface trough over the MD/VA eastern shore. However, the PW values AOB 1" and a weak convective cap should keep a lid on convective chances today outside of a SCT afternoon CU field. Otherwise, and a stellar August afternoon weather wise. Skies remain mostly to partly sunny sky, aside from a bit of smoke aloft from western fires. Highs in the mid to upper 80s with comfortable humidity levels. The surface high slides toward the coast tonight, then offshore into early Friday. Incrementally milder tonight vs last night, but still expect early morning lows in the low/mid 60s, with a few upper 50s possible in typically cooler spots out in the piedmont. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... As of 305 PM EDT Thursday... Key Messages: - Seasonably warm and a bit more humid Friday with a slight chance of late evening/overnight showers west of I-95. - Increasing chances for showers/storms though the weekend as a series of weak cold fronts pass through. The flow aloft becomes more quasi-zonal Friday, as the upper ridge shifts offshore and weakens and low pres dips into the western Great Lakes region. Meanwhile, TC Ernesto will travel northward well offshore from the Carolina coast. A weak pre- frontal trough will likely trigger a few showers/storms Friday night for the far western counties, but latest guidance cont to trend drier locally, keeping the bulk of QPF to the west. Will maintain a slight chance across the western border late Fri evening and overnight. Highs will be in the mid/upr 80s, and it will be noticeably more humid as dewpoints rise into the mid 60s. Rain chances ramp up a bit over the weekend into Monday, as a series of weak cold fronts push into the area and the parent upper low slowly approaches from the west. PoPs are mostly dry for most of the day Saturday, then precip chances increase (30-50%) in the late afternoon, evening and overnight. Highs on Sat will once again be in the mid/upr 80s. Coverage of showers/storms looks to be higher on Sun with as the parent low and trough axis moves slightly closer to the area, with better forcing pushing in by afternoon and evening. PoPs will be up to around 40-50% over the entire area in the afternoon. There could easily be a few stronger storms as well, with LREF showing SBCAPE ~1000-1500 J/kg with 25-35 kt of deep layer shear. Precip will end from W to E Sun night. Highs Sun in the upper 80s. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... As of 305 PM EDT Thursday... Key Messages: - Warm and humid on Monday with another chance for afternoon thunderstorms. - Returning to cooler, drier pattern for the midweek period. Models continue to be a bit more progressive with the sfc trough early next week, with increasing confidence that a cooler, drier pattern eventually takes shape for the middle to latter portion of next week. The upper trough axis crosses the area Monday, and will serve to kick the lingering surface trough toward the coast Monday evening. Expect that this likely triggers another round of some showers/storms in the afternoon, especially east of I-95. Highs on Mon will be in the mid/upper 80s. NW flow returns Tue- Thu, as the trough moves offshore and high pressure builds in from the NW Tue- Wed, with cooler/drier conditions pushing into the region. Highs will be in the low-mid 80s with lower humidity levels (Dewpoints in the 50s to low 60s) are now well supported by model ensemble probabilities. Should be mainly dry, but cannot rule a a stray shower along the coast in the afternoons. Early morning lows in the mid to upper 60s Monday night, and in the mid to upper 50s well inland to mid 60s Wed-Thu mornings. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... As of 715 PM Thursday... Mainly FEW-SCT250 skies through the period. Could have some afternoon CU again on Friday. There is some haze due to smoke aloft. Winds will be light and variable overnight, becoming south/southwesterly at western terminals during the day and southeasterly at eastern terminals. Outlook: A slow moving cold front will approach from the west late Friday through Sunday with chances for mainly aftn/evening showers/tstms each day, especially Sunday. && .MARINE... As of 305 PM EDT Thursday... Key Messages: - Quiet conditions continue through early Friday. Elevated southerly winds are expected from Friday night through Saturday night, potentially bringing marginal SCAs to the bay. - Small Craft Advisories have been issued for the northern coastal waters starting Friday evening and are likely for the remaining Atlantic waters and mouth of the Chesapeake Bay starting on Saturday as swells from Hurricane Ernesto reach the coast (see tides/coastal flooding section below. High pressure over PA will translate slowly toward the coast tonight. Locally, winds are generally from the N and NE at 5-10 kt but will become S and SE 5-10 kt this evening and overnight. High pressure to the north moves offshore tomorrow ahead of low pressure and cold front over the Midwest. This low/front will be slow to move east tomorrow into Saturday but the pressure gradient does look to sharpen enough to result in marginal SCA conditions in the Ches Bay, especially the middle and upper portions. Meanwhile, Hurricane Ernesto, currently well E of the Bahamas, is forecast to lift NNE, tracking near Bermuda by early Sat. Impacts locally will be restricted to increasing swell and the threat for deadly rip currents. Opted to raise SCA flags for the Atlantic waters north of Cape Charles Light starting at 02z/10pm Friday. The remaining Atlantic waters and mouth of the bay will see seas/waves increase later on Saturday and additional small craft headlines will be needed in subsequent forecasts. Seas peak at 5-7 ft Sunday into Sunday evening. Waves near the mouth of the bay will increase as well, generally 2-3 ft on Saturday with 3-5 ft possible Sunday before things start to calm down Monday (though will likely have seas offshore linger at 4-5 ft possibly into early Tuesday). The models are in decent agreement that another eastern CONUS upper trough develops next week, allowing a cold front to move through the local waters Tuesday with winds shifting to the N/NW. && .TIDES/COASTAL FLOODING... As of 305 PM EDT Thursday... Key Message: - A Moderate Risk of Rip Currents is forecast for Friday, with a High Rip Risk likely for both Saturday and Sunday as long period swell from distant Hurricane Ernesto affects the region. The latest 15/12Z run of the NWPS supports high rip risk for all Atlantic coastal zones by Sat given seas of 4-6 ft with a dominant period of 13 seconds or greater. Friday is a bit more uncertain as waves may only be ~2 ft until later in the day so will continue with a Moderate rip risk for now. Some minor tidal flooding will be possible (mainly in the mid/upper Bay) by Sun/Mon as the combination of southerly winds and the potential for water becoming trapped in the Bay develops with the long period swell. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory from 10 PM Friday to 8 PM EDT Sunday for ANZ650-652-654. Small Craft Advisory from noon Saturday to 8 PM EDT Sunday for ANZ656-658. && $$ SYNOPSIS...MAM NEAR TERM...MAM SHORT TERM...MAM LONG TERM...AM/MAM AVIATION...HET/JKP MARINE...RHR TIDES/COASTAL FLOODING...RHR