Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 251957 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 357 PM EDT Tue Jul 25 2017 .SYNOPSIS... A weak frontal boundary will remain south of the area tonight into Wednesday as high pressure slides off the Northeast coast. The next low pressure system affects the region late Thursday through at least Friday night. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Latest sfc analysis shows a stalled frontal bndry stretching across NC with ~1024 mb high pres centered over the Great Lakes region. The front remains off to the south tonight as the high slides east into the NE states. Kept the forecast dry, but can`t rule out a light shra over the Lwr MD Eastern Shore associated with weak low-level convergence. Otws...expect light onshore flow under a partly/mostly clear sky, with low temps mainly in the mid/upr 60s. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/... Dry wx continues for the beginning of the short term period with the aforementioned sfc high sliding off the NE coast and onshore flow continuing with the front weakening south of the area. There is a very small chance of a shra over eastern areas, but the chance is not high enough to include mention in the forecast attm so will re-evaluate with future updates. Another day of below normal temps with highs only in the low/mid 80s. Attention then turns Thu to an approaching potent mid-level shortwave trough and associated sfc low. Expect dry wx Thu morning, with PoPs increasing later in the day to 30-40% along/west of I95 late aftn/early eveng in association with a lead shortwave aloft and sfc prefrontal trough. Chances of rain then further increase into Thu night to chance-likely PoPs everywhere as the main sfc low/cold front approach the Mid Atlc. SPC has included the entire fa in a slight risk for severe storms, with the main threat being damaging wind gusts. This threat may continue into Thu night, and potentially Fri with the area still in the warm sector, and strong deep layer shear and shortwave energy aloft for late July. Heavy rain is also psbl with the strong forcing and high PWAT. Will include mention in the HWO. Bumped up PoPs to 60% everywhere Fri. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... Potent shortwave progged to dig into the Mid-Atlantic region Friday night into Saturday, before de-amplifying and pushing offshore Saturday. An associated cold front pushes offshore Saturday morning. Have kept high end chance POPs central Virginia eastward Friday night as the front pushes across the region. Low pressure forecast to develop along the frontal boundary as the strongest height falls spread across the region. The low lifts along the Northeast coast Saturday as the front stalls along the Southeast coast. Lingering mid-level moisture and the shortwave pushing across the region will keep slight chance to chance POPs Saturday afternoon. Cooler behind the front, with highs generally in the mid 80`s. An upper level trough remains over the eastern US through early next week, as a ridge of high pressure remains entrenched over the western Atlantic. High pressure slowly builds in from the Midwest Sunday and Monday as the front stalls along the Southeast coast. The GFS keeps the moisture farther offshore, but the ECMWF hugs the coast, developing a wave of low pressure off the Carolina coast. Have kept slight chance to low end chance POPs across the far southeast forecast area Sunday and Monday. Highs Sunday and Monday generally in the mid 80`s. Medium range guidance indicates the subtropical high over the western Atlantic may retrograde slightly Tuesday, which could push the coastal front inland. Have introduced low end POPs Tuesday as a result. Warmer, with highs in the mid to upper 80`s, but still relatively comfortable this time of year with dewpoints in the low to mid 60`s. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... Expecting primarily VFR conditions through the 18Z TAF period. A broken deck of cumulus, generally 3500-5000 feet, will impact northern portions of the area including SBY. A very isolated shower cannot be ruled out at SBY this afternoon and evening. Winds turn to the NE/E overnight tonight which may allow for the potential for low ceilings and fog at SBY. Left any sub-VFR conditions out of the forecast at this time due to low confidence. Winds this afternoon will generally be out of the north at 5-15 knots, winds shift to the NE/E overnight and into Wednesday. Outlook: Primarily VFR conditions are expected through the period. A cold front approaches the area late Thursday into Friday bringing the threat for showers and thunderstorms. Showers and thunderstorms may linger into Saturday, but drier conditions arrive for the second half of the weekend. && .MARINE... Latest surface analysis places a cold front south of the local waters with high pressure over the Great Lakes. A weak area of low pressure is centered just offshore the Mid-Atlantic coast. Obs indicate a north to northeast wind of 10 to 15 knots. Seas generally 2-3 feet and waves 1-2 feet. Gradient winds diminish tonight as low pressure pushes away from the coast and high pressure builds across the Northeast, but some modest cold advection will keep speeds around 10-15 knots. An onshore flow of 10-15 knots Wednesday will push seas to 3-4 feet. Waves generally 2 feet. High pressure slides offshore Wednesday night ahead of an approaching cold front. Flow becomes southerly, and increases to 10-20 knots Thursday afternoon as the gradient strengthens. Marginal SCA conditions are possible. The front stalls near the coast Thursday night into Friday, before an upper level disturbance pushes the front offshore Friday night. Expect a west to southwest wind Friday at 10-15 knots, with marginal SCA conditions possible ahead of the front Friday evening. Flow becomes north to northwest 10-20 knots behind the front Friday night. Strong cold advection and strong pressure rises expected late Saturday and Saturday night as low pressure deepens along the Mid- Atlantic and Northeast coast. The result will be solid SCA conditions over the waters, with the potential for low end Gale conditions over the upper Bay and northern coastal waters. The front stalls along the Southeast coast through early next week as high pressure slowly builds in from the west. A north to northeast wind at or below 15 knots is expected through early next week. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...MAS NEAR TERM...MAS SHORT TERM...MAS LONG TERM...SAM AVIATION...AJB MARINE...SAM

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