Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 190110 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 910 PM EDT Tue Jul 18 2017 .SYNOPSIS...
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A trough of low pressure will keep isolated showers and thunderstorms around the area Wednesday. High pressure builds toward the Mid Atlantic for the rest of the week, bringing a return to hot and humid conditions.
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Mid evening MSAS has a sfc trof across the mts with high pres over the area. Most convection from the afternoon has dissipated with loss of heating except for nern NC just south of ECG attm. High res data shows another weak impulse riding NE along the Outer Banks/ VACAPES late tonight/early Wed morning. Thus, dropped pops for the rest of the night except for low chc across nern NC. Otw, some patchy fog possible after midnight given light se winds. Lows 70-75.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/... Other than the building heat through Friday, there will really not be much of any other weather concerns. As the upper trough over the area today continues to slowly move east, expect heights to gradually rise across the area through Friday with broad westerly flow developing. This will allow for increasing heat and humidity through the period. Wednesday will see temps top out in the mid 90s across most areas, then rising to near the triple digits by Friday. With the 850mb temps forecast by the GFS and the ECMWF to be around +24c Friday afternoon and 700mb heights of around dam (as well as relatively dry ground), a few locations with high temps in the triple digits does not seem terribly unreasonable. In fact, will go with temps of 100F in the RIC metro for Friday. A heat advisory seems likely on Friday, and possible on Thursday. For now, will continue to highlight the heat/humidity in the Hazardous weather outlook and various social media outlets. Certainly not unprecedented heat for this part of the country during this time of year, but it will be very hot nonetheless and potentially dangerous for those not prepared for it. Otherwise, one cannot rule out a stray thunderstorm Wednesday afternoon especially along any boundary as the upper trough. See no reason why we would not need a head advisory on Friday, and it is very close on Thursday.will still be close enough to perhaps help trigger storms. Beyond Wednesday, it looks just dry and hot. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... Bermuda High retrogrades to a position well off the Southeast Coast Fri night into early next week. This allows the overall upper level flow to flatten...becoming more swly early next week as another upper trough drops out of Canada and over the Upper Midwest. Hot and muggy conditions will persist through the weekend. Expect high temperatures in the upper 90s to around 100F inland and low-mid 90s beaches. Lows in the mid-upper 70s Fri-Sun nights. Dewpoints in the low-mid 70s will result in widespread heat indices of 105-109F (heat advisory criteria). If forecast highs increase a degree or two (which has been the trend in 12z model runs over the past several days), this would be enough to push heat indices into excessive heat warning values; will monitor closely. Although Monday highs are a few degrees cooler than the weekend, they could end up being just as hot as the upper trough starts to dig into the Upper Midwest and reinforces sw flow over the region and thus the continued influx of hot 850mb temps. Periods of isolated to scattered thunderstorms should be anticipated each aftn/evening... especially invof lee trough axis which remains steadfast in this hot/humid airmass regime. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... Convection dissipating with loss of heating this evening with only sct CU and bkn CI around the area. Thus, VFR conditions to start off the forecast period. Given a light onshore flow, expect some MVFR fog to develop after 06Z. Kept fog out of ORF for now, but would not be surprised to see some there given the seabreeze tstm that develop there this afternoon. Another persistant forecast Wed as the main trigger for sct convection will be across the piedmont. However, sct convection possible on local seabreezes once again. OUTLOOK...VFR conditions expected Thu into the weekend, as high pressure builds toward the Mid Atlc region. && .MARINE... Isolated thunderstorms have developed along the leading edge of an upper level trough as well as along seabreeze boundaries near the coast this aftn. As the trough shifts ewd through this evening, thunderstorms may migrate over srn waters from the mouth of Ches Bay to Duck. Once again, storm movement is slow and therefore heavy rainfall and frequent lightning will be the main impacts from any storm that develops. Otherwise, the Bermuda High settles over the cntrl Atlantic through Friday as upper level troughing persists over the Eastern Seaboard. Expect periods of unsettled weather and generally south winds aob 15kt during this timeframe. The Bermuda High retrogrades to a position well off the Southeast Coast Fri night into early next week. This allows the overall upper level flow to flatten... becoming more swly early next week as another upper trough drops out of Canada and over the Upper Midwest. Winds generally SW aob 15kt during the later forecast periods. Seas average 2-3ft; waves 1-2ft. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...MPR NEAR TERM...MPR SHORT TERM...MRD LONG TERM...BMD AVIATION...MPR MARINE...BMD is the U.S. government's official web portal to all federal, state and local government web resources and services.