Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 281530 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 1130 AM EDT THU JUL 28 2016 .SYNOPSIS... Strong high pressure will remain off the Southeast coast through the end of the week with a weak frontal boundary lingering over the area today. This boundary will lift north to around the Mason Dixon line on Friday, with the front remaining in the vicinity over the weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Update...Just some minor tweaks to the going forecast. The upper ridge aloft across the area will break down later this afternoon into this evening as a weak trough over the Tennessee Valley tracks across WV and northern VA. This will allow for weak low pressure to develop along the lee trough this afternoon and will serve as a focus for showers and thunderstorms. The latest convective allowing model output continue to suggest the best development will be along and just north/west of the sfc trough which by late this afternoon will extend across the piedmont...with a secondary extension of the trough to the east of the low through the northern neck being enhanced by the sea/bay breeze. As such, have continued with likely pops across the far northern part of the forecast area but have increased pops along the western shore of the bay through the peninsula. As for the chances for severe weather this afternoon, with the best upper forcing and mid level winds across northern VA into the eastern shore, the best chance for severe weather looks to be along and just north of the boundary late this afternoon. Will need to watch for any rotation near the eastern extension of the boundary and sea breeze this afternoon...but the primary threat for severe weather would be downbursts given DCAPE values rising to above 1000 J/KG late this afternoon along the boundary. Otherwise...for southern VA and NE NC, expect widely scattered thunderstorms to develop this afternoon on locally produced convective boundaries, but given this area will be further away from the main upper energy, severe weather chances are less. In addition, locations across inland NE NC and the southern VA tidewater may experience heat index values just over 110 degrees this afternoon. Would prefer to continue with the current heat advisory given the public perception of it already being another hot day and little good it would do to upgrade to heat warning at this later hour. Will mention HI values of 105-110 degrees in current heat advisory. Previous forecast discussion below... Latest sfc analysis shows hi pressure off the Se coast with a frontal boundary draped across extreme northern VA into the Delmarva. This front remains in the vicinity today as a potent mid-level shortwave trough over the TN valley approaches from the west. Weak embedded shortwaves aloft out ahead of the aforementioned shortwave trough, in conjunction with a weak sfc trough, will lead to scattered-likely shras/tstms this aftn/eveng (pops range from 40% se to 70% nw). Best chance of rain is late aftn/early eveng just as previous days this week. SPC still has much of the area in a Slight Risk for severe weather given the better deep-layer shear (30 kt) than previous days as well as decent thermodynamics and weak shortwave energy aloft. Continued mention in HWO...with the main concerns being localized damaging wind gusts and heavy rain. Otherwise, heat advisory continues for se va/ne nc this aftn with heat indices expected to reach the 105-109 range. Temps max out in the lo/mid 90s.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... By tonight/Friday the aforementioned weak boundary washes out near the Mason-Dixon line and we`ll wait for the next cold front to approach from the north by late Friday. A potent shortwave is also expected to cross the area late tonight into midday Friday and will be the focus for additional shwrs/tstms. Will have high chc (40-50%) across northern areas Friday afternoon with lower chances S-SE (farther removed from the best support). Cannot rule out the potential for some heavy rain given PWs in excess of 2". However, there`s too much uncertainty at this time to warrant a flash flood watch. Not as hot across the north Friday given the added cloud cover and convection. Highs Friday from the upr 80s north to the low/mid 90s south. May need another heat advisory south. Lows Thursday night in the 70s. The next cold front washes out across the area Saturday and may touch off additional convection. Pops were placed at 30-40% for the afternoon. Highs from the upr 80s north to the low 90s south. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... The extended period will feature more normal temps for this time of year, but there will be decent chances for showers and tstms thru Mon. A frontal boundary will slowly drop acrs the region Sat ngt into Tue morning, with the highest POPs (40-50%) Sat ngt into Mon morning. The POPs will decrease fm N to S later Mon thru Tue, with most of the area dry later Tue thru Wed, as high pressure blds in fm the NNE. Max temps will generally range fm the mid 80s to near 90, with min temps ranging fm the upr 60s to mid 70s. && .AVIATION /16Z THURSDAY THROUGH MONDAY/... Mainly VFR conditions across area terminals this morning. Exception is with some short-lived MVFR at SBY with MIFG/Patchy ground fog, but expect this to diminish by 28/14z. Otherwise, main wx maker will be along stationary boundary situated west to east just to our north across nrn VA and ne MD early this morning. Dry conditions are expected through midday under sct high clouds, with scattered showers/tstms developing after 18z. The aforementioned boundary will remain in vicinity of the Mid-Atlantic region through Monday resulting in a 30-50% chc of afternoon/evening showers/tstms through Monday. Best chcs for convection remains across the northern tier of CWA, mainly along and N of a RIC-SBY line after 20z. Have held out of TAF for now, with timing still uncertain...but will likely have to account for areal coverage of convection with 18Z TAF. && .MARINE... A stationary front over the region today will gradually lift north tonight as low pressure tracks across the nrn Mid-Atlantic. Meanwhile, strong high pressure will remain anchored off the Southeast coast. The wind will generally be southerly at 5-10kt today and increase to 10-15kt tonight. Scattered showers/tstms are expected this afternoon and evening and any tstms have the potential to produce strong wind gusts. A cold front will push through the region Friday producing a wind shift to nw with speeds remaining 10- 15kt. The front drops south of the area Friday night resulting in an e wind of 5-10kt. The front lifts back to the north Saturday into Saturday night with the wind becoming se 10-15kt. The front settles over the region Sunday and pushes off the coast early next week. Seas average 2-3ft through the period with 1-2ft waves in the Bay. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...Heat Advisory until 8 PM EDT this evening for NCZ012>017- 030>032-102. VA...Heat Advisory until 8 PM EDT this evening for VAZ060-065>069- 078>090-092-093-095>098-513>516-518-520-523>525. MARINE...None. && $$ SYNOPSIS...MAS/MRD NEAR TERM...JDM/MAS SHORT TERM...JDM/MAS LONG TERM...TMG AVIATION...AJZ/MAM MARINE...AJZ is the U.S. government's official web portal to all federal, state and local government web resources and services.