Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 222000 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 400 PM EDT Sat Jul 22 2017 .SYNOPSIS... Very hot and humid conditions will continue over the region through Sunday. A weakening cold front will gradually push across the area late Sunday night through Monday and stall across the Carolinas through the middle of the upcoming week. Temperatures will cool down to near normal levels Monday through Thursday. && .NEAR TERM /THROUGH SUNDAY/... Latest analysis indicates a weak sfc/lee trough lingering over the Mid- Atlantic region from NJ down SSW into the piedmont of the Carolinas. WNW flow prevails aloft and in combination with the hot/unstable airmass, convection has overspread the local area. Some fairly weak/isolated storms have developed near the VA/NC border along the low level theta-E ridge where sfc dew pts along/SE of this are near 80 F. More significant, an area of storms is moving into the eastern shore and will pass through over the next few hrs. Upstream, more scattered tstms are developing across the VA Piedmont. With shortwave energy moving through the WNW flow aloft this evening/overnight, expect a good chc for redeveloping storms and with decent shear/especially over the N/NE zones, there will be at least some threat for strong to severe storms well into the evening/overnight. Damaging wind gusts will be the primary threat, though steepening mid- level lapse rates could portend to some strong updrafts and the potential for some large hail (best chance over the northern neck/eastern shore). Have maintained a general likely PoP/60% NE with 30-50% scattered coverage most other areas through after midnight. Otherwise, heat adsy remains in effect through 8pm for most of the CWA, heat indices on avg are 100-105 F central VA where dew pts are not as high (though actual temperatures are in the upper 90s to near 100 F). Across the SE/especially NE NC, a few spots have seen heat indices to 110 F+. Lows most areas 75 to 80 F, slightly "cooler" across the north, especially in areas the do receive rain. Continued hot and humid with additional heat headlines now issued for about the southern 2/3 of the CWA (along/S of WAL to RIC to Lunenburg Co. line) where heat indices of 105 to 109 F expected. Could potentially reach to 110+ along for NE NC but do anticipate highs a little cooler than today so have held off on this for now. Sunday remains a bit of a conditional convective threat. Numerous convective boundaries are likely to be in place, which would serve as a focusing mechanism for afternoon and evening convection. However, uncertainty exists regarding the extent and degree of cloudiness from convective debris which hangs around into Sunday, thereby serving to dampen destabilization. Models are still split on extent of cloudiness through the early afternoon and have therefore elected to keep POP in chance range (40-50%) for now, highest over the NE CWA. Should convective debris clear out in a timely way on Sunday, it`s easy to visualize a scenario in which more widespread convection occurs, given better lift/lapse rates courtesy of the approaching upper trough and the strong heating/destabilization that would result from quicker clearing. Once again, damaging winds again the primary threat with storms on Sunday. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... Cold front slated to pass through while weakening late Sun night through Mon. Will maintain high chc PoPs all zones Sun night, and favor highest PoPs Mon shifting south across SE VA & NE NC with 20% PoPs for the N. Slightly less humid Monday over the NW CWA. Not quite as hot, with highs Mon 90 to 95 F. Front stalls in NC Tue, with mainly diurnal tstms possible again over the S, 15-20% N. Seasonable highs upper 80s to lower 90s. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... High pressure moves off the coast Wed with any support for pcpn across southern half of fa closer to a stalled frontal boundary. Highs in the mid-upr 80s. Lows in the upr 60s-lwr 70s. This boundary begins to drift north Thurs resulting in slght chc pops across the region. Highs in the upr 80s-lwr 90s. Lows 70-75. Next boundary approaches from the north, then stalls across the region Fri and Sat. Chc pops each day though pcpn may tend to concentrate across the southern half of fa Sat depending on how far south the boundary actually gets. Highs Fri in the upr 80s- lwr 90s. Lows in the upr 60s-mid 70s. Highs Sat in the mid-upr 80s. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/... VFR conditions expected through most of the forecast period as high pressure remains off the coast. Sct convection possible across northern TAF sites after 22Z as a series of convective complexes ride se along a stalled front well north of the fa. First complex tracking across northern VA/MD attm is progged to continue SE across the lwr MD eastern shore towards 00Z. Given decent agreement in high res data, added VCTS to SBY`s forecast for a few hours beginning at 22Z. Otw, kept thunder out of the other TAFs as any storms that do develop are not expected until after 00Z. Convection may not make it to the SERN TAF sites until late tonight if at all. Expect lcl MVFR CIGS/VSBYS in any storm with the potential for IFR VSBYS in any one downpour. Expect a repeat performance Sunday as the persistant pattern continues early in the week. Outlook: Convection slowly shifts south into south central VA and NC for Monday. VFR should dominate through this period, with periods of periods of sub-VFR possible in heavier showers/TSRA. A weak cold front pushes into the area for the mid week period. && .MARINE... No headlines expected as a SW wind aob 15 kt prevails into the early week. There could be a few gusts to 20 kts Sun aftrn, but duration is not expected to be long enough to justify a SCA headline. Seas 2 feet nearshore to 4 ft out near 20 nm. Sct tstms possible in the afternoon/eve hours. The next frontal boundary crosses the area Tues with a wind shift into the E-NE. At this point, winds are expected to remain below SCA levels (aob 15 KTS). Seas 2 to 4 ft. Weak onshore flow continues for the rest of the week as a frontal boundary stalls across the area. This will also act as a trigger for sct late day convection as well. && .CLIMATE... Heat wave is expected to continue through Sunday. The 2nd half of July is climatologically the hottest few weeks of the year, so we still may not set any daily records at our main climate sites. For reference, record highs for today and Sunday are listed below: * Date: Sat(7/22) Sun(7/23) * RIC: 103/1952 103/1952 * ORF: 102/2011 103/2011 * SBY: 104/1930 103/2011 * ECG: 104/1952 104/1952 && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...Heat Advisory until 8 PM EDT this evening for MDZ021>024. NC...Heat Advisory until 8 PM EDT this evening for NCZ012>017- 030>032. Heat Advisory from 10 AM to 8 PM EDT Sunday for NCZ012>017- 030>032-102. VA...Heat Advisory until 8 PM EDT this evening for VAZ060>062- 064>069-075>090-092-093-095>100-511>525. Heat Advisory from 10 AM to 8 PM EDT Sunday for VAZ065>068- 078>090-092-093-095>100-512>516-518-520-523>525. MARINE...None. && $$ SYNOPSIS...LKB NEAR TERM...LKB SHORT TERM...LKB/MAM LONG TERM...MPR AVIATION...MPR MARINE...AJB/MPR CLIMATE... is the U.S. government's official web portal to all federal, state and local government web resources and services.