983 FXUS61 KPHI 152319 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 719 PM EDT Wed Jul 15 2020 .SYNOPSIS... High pressure will slide from New England to the western Atlantic through the end of the week. A warm front will lift through the region Thursday night, followed by a rather weak cold front on Friday. Bermuda high pressure becomes established for the weekend. Another cold front will cross the region on Monday, potentially stalling nearby through the middle of next week. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... As of 715 PM, the isolated showers have just about dissipated near and south/west of Philadelphia as the associated outflow combined with the well inland sea breeze is stabilizing things in their wake. Other than a rather isolated shower initiating in the lingering cumulus field in portions of eastern PA the next hour or so, the night is expected to be dry. Otherwise, some lower clouds lingering in far southeastern NJ into DE and this should either thin out for a time or eventually expand and turn into a more widespread stratus deck overnight (fog not anticipated to be an issue). Given the setup, we are anticipating a stratus deck to develop and overspread much of the area later tonight. It will be a muggy night especially across southern half of the forecast area. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/... With a fair amount of cloud cover and an east to southeast flow, Thursday will likely be the coolest day of the next seven. Highs will mainly be in the low to mid 80s, a bit cooler right at the coast. Overall, Thursday looks dry. A warm front will approach the region from the southwest Thursday night. As a result, a few showers could sneak in here before the day ends across our western zones. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... The main concern for the long term portion of the forecast is mainly the upcoming heat and humidity. Aloft, generally zonal flow with some slight ridging at time. Some troughing may start to occur early next week but no big changes are noted in the flow pattern. At the surface, high pressure will slide south of New England and settle over the western Atlantic through the rest of the period. A warm front will lift north through the region late Thursday into Friday, followed by a cold front on Friday, which looks to weaken and wash out on Saturday. The high over the Atlantic takes control through the weekend. Another trough/front will start to drop down through the region on sometime on Monday into Tuesday. The front may stall nearby and keep us unsettled through the middle of the week. Thursday night is fairly benign overall as a warm front starts to lift through the region. Showers and thunderstorms may accompany the front as it pushes northward. The flow will turn more southerly behind the front and we should have an increase of moisture through the day on Friday ahead of an approaching cold front. The cold front enters the region from the west and gradually pushes through the area. It isn't particularly fast and looks to weaken as it makes its way to the coast. Some guidance washes it our as it reaches the coast while other guidance hangs onto it briefly offshore. End result is that the feature is not that strong and dissipates near our forecast area as the surface high really strengthens over the Atlantic. Showers and thunderstorms will accompany the front and with PWATs remaining around 1.75-2.00+", heavy rain may become an issue and we will need to monitor for any flooding concerns. There is not any really cool air behind the cold front so we never really lose the influx of hot air from the south to southwest, which will set us up for warming temps through the weekend. With the high gaining strength, the southwest flow aloft will also strengthen. Temps will rise on Friday to near 90, expect lower 90s on Saturday, and then a rise to the mid to near upper 90s on Sunday and Monday, where the models show agreement on 850mb temps around 20- 21C both days. What adds insult to injury is the fact that the south to southwest surface flow keeps the moisture levels high and that means dewpoints will rise back into the lower 70s. So hot and humid will be the story for the start of the new week with heat index values rising and being between 100-110 across the forecast area. It seems likely that some form of heat headlines will be needed for the start of the week. Diurnally driven showers and thunderstorms will remain possible through the weekend. The next front arrives around Monday, which may impact the highs that day depending on the timing. The front looks to hold off until later in the day which would give more confidence to the higher side of guidance, so we continue to favor that side of the spectrum. Another item of note is that while the front may be a good forcing mechanism for storms, it lacks sufficient cool air behind it to fully break the heat and Tuesday could end up being part of the potential excessive heat wave. The front might not clear the area and ends up waffling across our region so we could potentially remain stormy and hot and humid across at least portions of the forecast area through the middle of the week. && .AVIATION /23Z WEDNESDAY THROUGH MONDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...VFR, with clouds increasing and lowering with MVFR ceilings developing in the 06-10z time frame. Southeast winds 5-10 knots diminishing to less than 5 knots or light and variable. Moderate confidence; low confidence regarding any IFR ceiling development. Thursday...MVFR ceilings improve to VFR by early afternoon. Southeast winds increasing to 8-12 knots. Moderate confidence. Outlook... Thursday night...Patchy fog/stratus or some showers with sub-VFR conditions possible near RDG and ABE, otherwise mostly VFR. Southeast winds 5 to 10 knots, becoming more southerly overnight. Low confidence on timing of the lower conditions. Friday through Friday night...Mainly VFR conditions expected. MVFR or lower conditions possible in scattered showers and thunderstorms. Areas of fog with sub-VFR conditions may develop overnight. South- southwest winds around 5 to 10 knots becoming light and variable overnight. Generally moderate confidence with low confidence on fog. Saturday through Saturday night...Mainly VFR conditions expected. MVFR or lower conditions possible in scattered showers and thunderstorms. Southwest winds around 5 to 10 knots. Low to moderate confidence. Sunday through Monday...MVFR or lower in showers and thunderstorms. Southwest winds 5 to 10 knots. Low confidence. && .MARINE... Tonight...Sub-SCA conditions expected. East to southeast winds 10 to 15 kt. Seas mainly 3 ft. Thursday...Sub-SCA conditions are expected. Southeast winds 10 to 15 kt. Seas mainly 3 ft. Outlook... Thursday night through Monday... Sub-SCA conditions are expected through Monday. Southeast winds Thursday night becoming south-southwest for the remainder of the period. Wind speeds generally 10 to 15 knots through the day with gusts around 20 knots. Seas mainly around 2 to 3 ft on the ocean. Rip Currents... Winds will remain onshore through Thursday. Wind speeds should increase a bit on Thursday over today. As a result, the risk may increase to moderate levels. But at this time, the forecast will maintain a low risk. && .EQUIPMENT... The NOAA Weather Radio All Hazards broadcast from Hibernia Park, PA (WNG704) remains off the air until further notice due to damage to the antenna during the June 3 derecho. The NOAA Weather Radio All Hazards broadcast from Philadelphia, PA (KIH28) is currently off the air. Technicians have been notified, but a return to service is unknown at this time. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...Gorse/Meola Near Term...Gorse Short Term...Kruzdlo Long Term...Meola Aviation...Gorse/Meola Marine...Kruzdlo/Meola Equipment...WFO PHI