190 FXUS61 KPHI 252035 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 435 PM EDT Fri Jul 25 2025 .SYNOPSIS... A cold front sinks south across the area late tonight into Saturday morning as weak high pressure builds over New England. This front will lift back north as a warm front on Sunday, ahead of another cold front that will pass through later Sunday into Sunday night. High pressure returns for Monday and Tuesday, before yet another front passes through on Wednesday. High pressure returns to close out next week. && .NEAR TERM /THROUGH SATURDAY/... Front sliding south across the Great Lakes and Northeast combined with passing shortwave and lots of excessive heat and humidity should make for at least a partially active evening. As of early this afternoon, storms are just starting to develop across northeastern PA and southern NY, and they`ll start making their way into our forecast area shortly. As they interact with the building heat and humidity (temps 90s, dew points well into the 70s resulting in heat indices topping 100 for most and 105 for many), shouldn`t have too much trouble getting some severe downdrafts thanks to excessive DCAPE. For these reasons, a severe thunderstorm watch is now in effect for much of the area, mainly northern Delaware northward, until 9 PM. Aside from the severe risk, anything that lingers too long could also become a flash flood risk, especially over the flashy urban corridor, but overall expect storms to move fast enough such that it still looks isolated. Extreme heat warnings and advisories expire by 9 PM, which may be too late, but either way, storms should mostly be thru the region by then as well based on latest CAMS. May not quite have cleared areas south of Philly, but with loss of insolation they`ll likely be weakening regardless. Front, however, lingers well north and won`t cross many areas until very late at night or early Saturday morning, so most of the region will remain in sticky 70s for lows. Front takes on a more back-door orientation on Saturday, finally allowing a noticeable air mass change. This should bring a more stable and overall more pleasant day, but dew points likely remain in the 70s across the Delmarva. 60s should reach Philly and some parts of northern NJ might drop into the 50s. However, the front will stall not far away, and as warmth and moisture start overriding it, a few showers or a t-storm might develop near where the boundary stalls close to our southern/western border. Highs mostly 80s with heat indices in the 90s. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... The Saturday night through Sunday night period will be the most unsettled portion of the forecast as several impulses aloft will be crossing through the area. Starting off with Saturday night, there will likely be a complex of showers and thunderstorms moving east toward the area Saturday night into early Sunday. PoPs have further increased to 40-70% across much of the region, greatest over eastern Pennsylvania. So, it does seem that this convection, albeit it will be decaying, should reach our area for the Saturday night period. Lows are expected to be in the upper 60s to mid 70s. Sunday and Sunday night remains the more active day of the weekend as another low pressure system impacts the area with a more pronounced shortwave aloft traversing across New England. This will lead to a warm front lifting north across the area early on Sunday before a cold front tracks through the area later Sunday into Sunday night. After the convection from Saturday night dies off, there should be a lull at least in the morning hours before a second round of convection develops in the afternoon ahead of the cold front. However, sunshine and instability looks rather limited as there isn`t anticipated to be much clearing in between the two impulses. As a result, there is not anticipated to be much (if any) of a severe weather threat, instead, this looks to be more of a hydro threat given that PWATs will be in excess of 2.0-2.3". Meaning, that any given shower or thunderstorm will be capable of highly efficient rainfall rates. However, storm motion should be relatively quick as the front approaches, so looking at localized instances of flash flooding possible. WPC has maintained the MARGINAL risk for excessive rainfall for our entire area as a result. Convection will begin to wane into Sunday evening as the cold front crosses through the area later Sunday night. High temperatures will be in the 80s with lows in the 60s and 70s. && .LONG TERM /MONDAY THROUGH FRIDAY/... Little changes were made to the long term period as the first half of the week will remain hot & humid whereas the latter half of the week will be seasonably cool. To start out the week, high pressure will be in control as the area remains wedged in between frontal systems, so Monday is expected to be mostly sunny and dry. Tuesday will feature increasing heat and humidity causing chances for diurnal showers and thunderstorms to develop in the afternoon, especially north and west of the urban corridor. By Wednesday, another cold front looks to be on the horizon, crossing through the area later Wednesday night. This will bring a more widespread opportunity for showers and thunderstorms to the area. Some of the machine learning guidance is hinting at Wednesday possibly featuring some severe weather, so this will need to be monitored in the coming days. Otherwise, the Monday through Wednesday period will feature heat indicies around/in excess of 100 degrees, so will likely need to evaluate potential heat headlines for these days. As of now, the `worst` day in terms of heat looks to be Tuesday. By Thursday and Friday, should begin to see some improvement around the area as the cold front moves offshore and strong high pressure sets up over the Great Lakes. This will usher in a much cooler and refreshing airmass from Canada, where our temperatures are expected to be as much as 5-10 degrees below average. Other than a few post- frontal showers around on Thursday, this period should be dry. && .AVIATION /21Z FRIDAY THROUGH WEDNESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Rest of today...Primarily VFR. 40-70% chance of showers and thunderstorms in the late afternoon and evening which may cause temporary VSBY/CIGs restrictions. Tempo groups now at all terminals. Winds out of the southwest become more out of the northwest later today around 5-10 kt. Moderate confidence. Tonight...A broken line of showers and thunderstorms moving through may result in a brief period of sub-VFR conditions until around 03z, otherwise primarily VFR. Winds go from northwest to eventually north/northeast by Saturday morning. Moderate confidence. Outlook... Saturday night through Sunday night...Mainly VFR conditions expected with sub-VFR conditions probable at times. Several chances for showers and thunderstorms on Saturday night and Sunday. Monday through Monday night...VFR. No significant weather expected. Tuesday through Wednesday...Primarily VFR with localized times of sub-VFR conditions. A chance for showers and thunderstorms on Tuesday and especially on Wednesday. && .MARINE... No marine headlines are expected through Saturday. South- southwest winds around 10-15 kt rest of today. Winds may occasionally gust up to 20 kt this afternoon into this evening along the northern NJ coast. Seas around 2-3 feet. There is a chance (40-60%) for showers and thunderstorms this evening which decrease in coverage overnight. Winds shift northeast overnight into Saturday at 10-15 kts with seas remaining 2-3 ft. Outlook... Saturday night through Wednesday...No marine headlines expected. Winds should largely remain 15 kt or less with seas around 2-3 feet. A chance for showers and thunderstorms expected on Saturday night, Sunday and Wednesday. Otherwise, fair weather. Rip Currents... For Saturday, the surface winds become northeast to east 10 to 20 mph. Breaking waves in the surf zone will average again around 2 to 3 feet. With the onshore flow and 2 to 3 foot breakers, elected with a MODERATE risk even with a period of 5 to 8 seconds. Winds are lighter and seas are lower at the Delaware Beaches. Thus, a LOW risk for rip currents is in place for Delaware. For Sunday, flow turns more southerly but light, only around 5 to 10 MPH. Seas decrease and breakers of only 1 to 2 feet are expected. Period will remain 5 to 8 seconds. As a result, a LOW risk for rip currents is in place at all beaches. For specific beach forecasts, visit weather.gov/beach/phi && .TIDES/COASTAL FLOODING... Due to the new moon occuring on July 24, some spotty minor coastal flooding may occur again with the high tide tonight into Saturday and Saturday night into Sunday. The most likely locations for any spotty minor tidal flooding are along the Delaware Bay, as well as around Cape May. No coastal flooding is anticipated along the northeastern portion of Chesapeake Bay. && .CLIMATE... Near record breaking temperatures are forecast for Friday and Friday night into Saturday morning. Records for our climate sites are listed below: Record High Temperatures July 25 Site Record/Year Allentown (ABE) 95/1939, 1949, 1999, & 2016 AC Airport (ACY) 99/2010 AC Marina (55N) 96/1999 Georgetown (GED) 99/2010 Mount Pocono (MPO) 90/1999 Philadelphia (PHL) 97/2016 Reading (RDG) 97/2016 Trenton (TTN) 97/1999 Wilmington (ILG) 96/1987 & 2016 Record Warmest Low Temperatures July 26 Site Record/Year Allentown (ABE) 76/1995 AC Airport (ACY) 77/1949 AC Marina (55N) 78/1995 Georgetown (GED) 78/1985 Mount Pocono (MPO) 69/1937 Philadelphia (PHL) 80/1995 Reading (RDG) 77/1995 Trenton (TTN) 78/1899 Wilmington (ILG) 78/1995 && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Extreme Heat Warning until 9 PM EDT this evening for PAZ070- 071-104-106. Heat Advisory until 9 PM EDT this evening for PAZ054-055- 060>062-101>103-105. NJ...Extreme Heat Warning until 9 PM EDT this evening for NJZ010- 012-013-015>019-021. Heat Advisory until 9 PM EDT this evening for NJZ001-007>009- 014-020-022>027. DE...Extreme Heat Warning until 9 PM EDT this evening for DEZ001. Heat Advisory until 9 PM EDT this evening for DEZ002>004. MD...Heat Advisory until 9 PM EDT this evening for MDZ012-015-019- 020. MARINE...None. && $$ SYNOPSIS...DeSilva NEAR TERM...Hoeflich/RCM SHORT TERM...DeSilva/Fitzsimmons LONG TERM...DeSilva/Fitzsimmons AVIATION...DeSilva/RCM MARINE...DeSilva/Hoeflich/RCM TIDES/COASTAL FLOODING...PHI CLIMATE...Staarmaan