462 FXUS61 KPHI 272054 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 454 PM EDT Fri May 27 2022 .SYNOPSIS... A cold front will progress through the region through Saturday afternoon. High pressure builds in for the first half of next week. Another cold front may approach the region Thursday into Friday. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... We cleared more of the watch behind the initial line of thunderstorms. Behind the initial line, the boundary layer is relatively stable, so despite still sufficient effective shear, precipitation mode is almost entirely showers. Severe Thunderstorm Watch 278 remains in effect through 7 PM for portions of northern and central NJ with the main line. A fractured wave pattern is still evident on water vapor late this afternoon with a vertically stacked area of low pressure over the IN/ OH border and another wave over eastern Quebec. The vertically stacked low over IN/ OH this afternoon is forecast to slowly move northeast with a broad area of 40 m height falls across the region. Timing wise, the broken line of showers and thunderstorms should clear the area by 7 PM. With PWats rising into the 1.5"-1.9" range (potentially record breaking values for May 27th), heavy rain and thus flash flooding continues to be a threat with this system somewhere across the Mid-Atlantic region. The confidence in the greatest threat area for flash flooding remains eastern PA. The Flood Watch for Flash Flooding remains in effect until midnight tonight. We are currently forecasting widespread QPF around one inch across the Lehigh Valley with values decreasing east towards the NJ coast. Locally, totals up two to three inches are possible if convection trains over the same area. SPC and WPC have maintained the Slight Risks for severe weather and excessive rainfall respectively for our area. Aside from the showers and thunderstorms today, it will be a warm and rather muggy day with dewpoints rising well into the mid to upper 60s. Expect high temperatures in the mid 70s to upper 70s in most areas along with mostly cloudy to overcast skies. Southerly winds will increase into the afternoon to around 10-20 mph with gusts of 25-30 mph possible. The southerly winds will lessen overnight and shift more to the southwest. Given the continued stacked southerly flow regime, expect continued mostly cloudy and muggy conditions with minimum temperatures in the low to mid 60s. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... Saturday morning, the upper level low will be located over central PA, with the core of the DCVA moving overhead. The weak surface reflection from the decaying mid-level low will also be located near central PA with a very weak cold front extending southwest. Underneath the upper level low, mid-level temperatures are forecast to fall off rapidly (to around negative 16/17 degrees C) with lapse rates responding accordingly. 850/500 MB and 700/500 MB lapse rates both steepen to around 6.5 to 7 degrees C. As this occurs shower and thunderstorm development will become rather widespread (especially along a Chester to Philadelphia to Atlantic City line and north). Given the cooler 500 MB temperatures, some small hail and gusty winds is possible in any of the strong thunderstorms. High temperatures Saturday will also likely be held down a bit given the clouds and precipitation. For the most part am expecting mid to upper 70s across the region Saturday, with upper 60s forecast over the Poconos. The upper level low will exit the region Saturday afternoon into evening with precipitation coming to an end late Saturday afternoon. As the mid-level low exits the region, the slightly stronger cold front will then cross the area Saturday night ushering in drier air. Low temperatures Saturday night will be in the mid to upper 50s. No precipitation is expected Saturday night. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Overview: Hot and dry conditions will be the primary story for the first half of the week, with the last half of the week starts to become a bit more active with multiple chances for showers and thunderstorms, most notably on Thursday or Friday when a cold front approaches from the west. Details: Sunday through Tuesday...A ridge will begin to build over the eastern half of the country. Consequently, expect drying conditions along with a pronounced warming trend. By Tuesday, highs should range from the upper 80s to mid 90s. Wednesday...The ridge may begin to weaken as it slowly progresses east. While there is some disagreement between the models on when this will happen and how quickly the ridge will break down. If it happens faster, then we could start to see shower and thunderstorm chances increase as early as Wednesday with embedded short wave troughs following along the periphery of the ridge. If it is slower to break down than Wednesday may be drier and warmer than the current forecast. Thursday and Friday...The ridge will further weaken as a mid and upper level short wave trough and a surface cold front approach from the northwest. This looks to be our next significant chance for widespread shower and thunderstorm chances across the region. Considerable timing differences between guidance, which means there are considerable differences in threat details as well. && .AVIATION /21Z FRIDAY THROUGH WEDNESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Rest of today... CIGS have been slow to improve this afternoon, most areas MVFR as of the early afternoon. Continued improvement expected before a line of showers/sct tstms arrives from the SW for the mid/late afternoon. IFR possible as the activity moves through. S winds 10 to 15 kts with G30-40 kts possible in tstms. Medium confid overall. Tonight... Behind the showers and tstms this evening, lower CIGS and VSBYS (in fog) are expected. IFR will likely be at most terminals overnight with LIFR possible. Winds will be rather light favoring the SW or W. Low/medium confid. Saturday... Unsettled conditions with improving CIGS/VSBYS early then more scattered showers and a few tstms for the morning/early afternoon. MVFR CIGS/VSBYS are possible for this activity. West winds 8 to 12 kts mostly. Low/medium confid. Outlook... Sunday...VFR. Winds from the southwest 5 to 10 knots. Moderate confidence. Sunday night...VFR. Winds from the south-southwest 5 knots or less. High confidence. Monday and Tuesday..VFR. Southwesterly and westerly winds 5-10 kts. Moderate confidence. Wednesday...VFR. Winds becoming light and variable. Moderate confidence. && .MARINE... Elevated seas and winds gusting near or above 25 kt are expected to continue on the Atlantic Coastal Waters through at least mid day Saturday. Additionally, elevated winds and seas are possible in the vicinity of any strong or severe thunderstorms through this evening. Outlook... Sunday through Tuesday...winds and seas should stay below SCA criteria. Rip Currents... Southerly winds will average 15-20 mph today. Breaking waves should remain in the 2 to 3 foot range with a medium period east to southeast swell. Will maintain a HIGH risk for the development of dangerous and life threatening rip currents for all New Jersey and Delaware beaches. For Saturday, winds will shift to the southwest and remain around 10- 15 mph. However, the dominant swell will remain onshore resulting in a HIGH rip current risk for the New Jersey beaches and MODERATE for Delaware Beaches. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Flood Watch until midnight EDT tonight for PAZ054-055-060>062- 070-071-101>106. NJ...Flood Watch until midnight EDT tonight for NJZ007-009-015. High Rip Current Risk until 10 PM EDT this evening for NJZ014- 024>026. DE...Flood Watch until midnight EDT tonight for DEZ001. High Rip Current Risk until 10 PM EDT this evening for DEZ004. MD...None. MARINE...Small Craft Advisory until 2 PM EDT Saturday for ANZ450>454. Small Craft Advisory until 6 AM EDT Saturday for ANZ455. && $$ Synopsis...Hoeflich/Johnson/RCM Near Term...Haines/Johnson Short Term...Haines Long Term...Johnson Aviation...Davis/Hoeflich/Johnson/O'Hara Marine...Johnson