Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 200459 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 1259 AM EDT WED JUL 20 2016 .SYNOPSIS... High pressure will remain over the region through Friday. A cold front may move into the area and dissipate Friday night into Saturday. Strong high pressure then re-establishes itself into next week, but another cold front will slowly approach from the northwest late in the weekend. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Grid update to take into account the recent uptick in convection over Chesapeake Bay/Delmarva region was sent shortly after midnight. An upper shortwave trough can be seen moving southeastward thru the DC area with another strong one digging in behind it near the the OH-PA border. These impulses will provide the lift for convection across our southern zones. The last few runs of the HRRR/RAP and now the 00Z NCEP WRF ARW/NMM have a decent handle on the ongoing convection. Expect these showers and storms that are currently over the Delmarva to be move/redevelop eastward into far southern NJ overnight and then across our offshore waters by early morning. Added enhanced wording for gusty winds and hail overnight from about Kent Co MD to Kent Co DE southward where SPC mesoanalysis shows a moderate amount of instability (MUCAPE 1500-2000 J/KG). With surface temperatures in the low/mid 70s, convection is likely non-surface-based. We`ve already seen a downward trend in storm intensity after midnight but the potential for a storm to pulse back up and produce large hail. Locally damaging winds now appears to be a waning threat with convection expected to become increasingly elevated as the nocturnal boundary layer establishes itself farther downstream. 945 PM Discussion... Dry air will continue to filter into our region from the northwest and north overnight. We are anticipating a partly cloudy sky. There will be some lingering low level moisture in our southern counties. A mid level short wave trough dropping over our region during the night will continue to trigger scattered showers and isolated thunderstorms in our Delmarva counties and on the adjacent coastal waters. The wind should remain relatively light. Minimum temperatures should be in the 50s up north and in the 60s elsewhere. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/... The mid-level trof axis moves off the eastern seaboard allowing surface high pressure to build across much of the forecast area. Temperatures tomorrow look to be the coolest of the week with mid 70s to mid 80s expected. The heat is on thereafter. Winds won`t be as gusty tomorrow and will go southwest during the afternoon. We will keep very small POPs in the forecast across southern Delaware during the morning hours. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... Sfc high pres will be over the area thru Fri and there will likely be few clouds. However, conds will be genly pleasant but withe increasing humidity by Fri. Aloft, a large and strong h5 ridge will be parked over the mid-section of the country and will gradually shift a bit ewd. A cdfnt will move acrs the region later Fri aftn into Fri eve and bring probably the best chc of any precip in the next 7 days. There is still some uncertainty as to how much of the heat associated with this ridge we get and when. Latest guid now indicates the peak of the heat will be Sun and Mon, and the GFS continues to be the hottest of the mdls and got even hotter with its 12Z run. The ECMWF, which trended cooler last night has gotten hotter again. Some for of heat headlines may be needed over the weekend or into next week. The CMC a bit cooler. Temps look to be well into the 90s Fri-Mon, with dewpoints becoming worse by Sun and Mon. There is always the chc of some diurnal convection in a humid ams, but the guid differs on its extent especially around Mon. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. VFR conditions are expected through the TAF period under a partly cloudy sky. One exception may be some MVFR visibility restrictions around KMIV near daybreak on Wednesday. Wind speeds are forecast to be less than 10 knots. The direction should favor the northwest to northeast overnight, veering toward the southeast to southwest on Wednesday. OUTLOOK... Wed night through Thu...VFR. High pressure. High confidence. Fri...Mainly VFR. However, shra/tsra psbl with lcl mvfr and psbl ifr late Fri aftn into Fri night. Moderate to high confidence. Sat through Sun. Mainly VFR. High pressure. High confidence. A slight chc of diurnal tsra n and w on sun aftn. && .MARINE... Tonight...We are watching strong storms developing over eastern MD late this evening. These storms may pose a threat to mariners (locally strong winds and higher seas as well as lightning) in the DE Bay overnight and our southern coastal waters toward early morning as they move eastward. Otherwise, winds and seas will remain below Small Craft Advisory criteria. N winds will become NE overnight. As they veer NE, they could gust into the 15 to 20 kt range. Wednesday...Winds and seas are not expected to reach SCA criteria. The NE winds could continue in the 15 to 20 kt range in the morning hours. They are expected and become more easterly in the afternoon. OUTLOOK... Thu and Fri....Predominately sub-SCA conditions in S-SW flow. However, there is a chance some wind gusts near 25 knots on Fri, as well as increasing seas in advance of a cdfnt. Sat and Sun...Brief elevated wind/seas are psbl early Sat before subsiding to below SCA for the remainder of the pd. RIP CURRENTS... The risk for the formation of dangerous rip currents on Wednesday will be low at the DE and NJ beaches, but very localized moderate rips are possible along the NJ coast. We have had some reports of upwelling along the coast, where temperatures have dropped into the low 60s. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...Nierenberg Near Term...Iovino/Klein Short Term...Kruzdlo Long Term...Nierenberg Aviation...Iovino/Nierenberg Marine...Klein/Kruzdlo/Nierenberg is the U.S. government's official web portal to all federal, state and local government web resources and services.