Area Forecast Discussion
Issued by NWS Mt. Holly, NJ
Issued by NWS Mt. Holly, NJ
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699 FXUS61 KPHI 111039 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 639 AM EDT Tue Jun 11 2024 .SYNOPSIS... High pressure will retreat offshore through the middle of the week. Temperatures will begin to rebound through Friday ahead of a cold front, which will bring a chance of showers and storms across the region. With the front offshore by Saturday, high pressure will build into the region again through the weekend with temperatures rebounding to well above normal into early next week. && .NEAR TERM /THROUGH TONIGHT/... Weak wave of low pressure passing by overnight that brought a band of showers and embedded thunder across the Delmarva and far southern NJ is now departing off the coast. For today, most of the area starts out quiet and dry with some sun. However, with closed low developing just to the north and plenty of vorticity rotating around, combined with the cold pool aloft and strong June insolation, and we`ll likely see a lot of cumulus to stratocumulus by midday. A lot of guidance also hits on sea- breeze front helping spawn some showers and isolated thunderstorms by this afternoon, starting out mostly over NJ and DE but possibly migrating inland toward SE PA. So, have chance POPs across much of the region for the PM, but further NW, looks like the Lehigh Valley, Berks and Poconos are more likely to stay dry. Temps will be rather cool for mid-June, with 70s common. Tonight, upper low starts migrating back to the northeast and heights rise rapidly. This should cause lingering convection to die quickly before sunset with mostly clear to partly cloudy skies overnight. Lows mostly in the 50s to low 60s. Enjoy it, as we`re about to flip the page to summer in a big way. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... The early week troughing will be offshore by early Wednesday, and quasi-zonal flow will develop in its wake through the end of the week with increasing heights and thicknesses. Another trough axis will approach the region late Friday. At the surface, broad high pressure will shift offshore through the end of the week with surface flow turning toward the south/southwest. This pattern will translate to increasing temperatures and dewpoints with each passing day as well as a dry forecast until Friday. Following a return to near normal temperatures with highs in the low 80s on Wednesday, highs will increase to near 90 degrees in most inland locations on Thursday. On Friday, widespread inland high temperatures in the low to mid 90s are forecast ahead of the approaching cold front. While dewpoints will be on the rise, they should top out in the low to mid 60s. This means that heat indices will be close to the air temperatures. Nevertheless, we will be close to early season Heat Advisory criteria within the Philly urban/metro area on Friday. Some limiting factors for Friday`s heat could be the increasing cloud cover ahead of the could front, plus the arrival of showers and thunderstorms later in the day. Convective details remain unclear at this time, but the medium range guidance continues to indicate potential for at least some isolated to scattered showers and thunderstorms along and ahead of the front Friday afternoon and evening. With the approaching trough, there will be at least modest shear and forcing for convection. These could also be sufficient enough for a severe threat as well, however the limiting factor for severe currently appears to be the less-than-impressive instability thanks to the poor mid-level lapse rates. In any case, we`ll need to keep a close eye on Friday`s heat and severe weather threats. `Tis the season! && .LONG TERM /SATURDAY THROUGH MONDAY/... Friday`s trough will be pushing offshore on Saturday, then some rather expansive ridging will begin to build across the eastern CONUS into early next week. At the surface, high pressure will build into the region through the weekend before moving offshore into early next week. The high pressure will provide the area with a return to more seasonable temperatures and humidity for Father`s Day weekend following the late week heat, with highs in the mid 80s both Saturday and Sunday under mostly sunny skies. With the high pressure offshore, southwesterly surface flow and the building ridging aloft will result in increasing temperatures into early next week. Current indications are that we could see a multi-day heat wave, impacting much of next week with high temperatures in the low to mid 90s across much of the area, along with little chances for convection. The current CPC Week 2 outlook indicates a roughly 70% chance of above normal temperatures for our region encompassing next week. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Today...VFR overall. Scattered, mainly afternoon showers may impact all terminals except KRDG/KABE, with an isolated t-storm possible as well, most likely at KMIV. A heavier storm could briefly reduce vsby to MVFR or even IFR, but it should be very transient should it occur. Winds north to northeast, becoming southeast for KMIV/KACY in the afternoon and NW for remaining terminals, generally 5 kts or less. Moderate confidence. Tonight...VFR. Winds becoming NW 5 kts or less. High confidence. Outlook... Wednesday/Thursday...VFR. No significant weather expected. Friday...Prevailing VFR conditions, however there is a 30-50% chance of TSRA impacting the terminals, mainly between 18Z-06Z. Saturday...VFR. No significant weather expected. && .MARINE... No marine headlines thru tonight. Winds generally below 10 kts. Seas 1-2 ft. An isolated thunderstorm possible, mainly this afternoon. Outlook... Generally sub-SCA conditions from Wednesday into early Thursday with fair weather. For the afternoon and evening periods Thursday and Friday, gusts nearing 25 kts and near 5 ft seas are possible, along with scattered showers/tstms Friday afternoon and evening. Fair weather Sat/Sun. Rip Currents... Low risk of rip currents in place for today and Wednesday. Winds will be onshore today, but with winds weak, and a short to medium period swell combined with 1 to 2 foot breakers, there is a low risk for rip currents. Similar conditions on Wednesday, though winds go more shore parallel, still less than 10 MPH. For specific beach forecasts, visit weather.gov/beach/phi && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ SYNOPSIS...Staarmann NEAR TERM...RCM SHORT TERM...Staarmann LONG TERM...Staarmann AVIATION...RCM/Staarmann MARINE...RCM/Staarmann