


Area Forecast Discussion
Issued by NWS Mt. Holly, NJ
Issued by NWS Mt. Holly, NJ
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-- Discussion containing changed information from previous version are highlighted. --560 FXUS61 KPHI 010003 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 803 PM EDT Mon Jun 30 2025 .SYNOPSIS... The stalled front across the southern half of the region will slowly return northward as a warm front through tonight followed by a cold front later Tuesday. High pressure builds closer later Wednesday into Thursday before settling over our area on Friday and into the weekend. && .NEAR TERM /THROUGH TUESDAY/...-- Changed Discussion --The first round of showers and thunderstorms associated with the lifting warm front and daytime heating has exited the area. We are now on to round 2. Showers and thunderstorms associated with an approaching short wave/vorticity impulse continue to develop to our southwest and will move across our area over the next few hours. There remains enough instability and shear for an occasional strong to severe storm to develop. However, heavy rainfall and the possibility of localized flooding, especially areas that received heavy rainfall earlier may be the greater concern. The third round of showers and thunderstorms is also possible overnight/after midnight. However, these storms likely will not be as severe and should be more progressive. The silver-lining is that the rain-cooled air from the afternoon storms have allowed us to cancel the Heat Advisory that was previously in effect across the urban corridor. Lows tonight will be in the upper 60s to upper 70s. For Tuesday, with the warm front well north of the region and the entire forecast area in the warm sector, another round of severe thunderstorms and flash flooding is expected. In the upper levels, an upper-level trough is forecast to shift eastward and amplify some as it overspreads the Northeast and Mid-Atlantic. This will drive a cold front across our region later Tuesday. In terms of the set-up for the second half of Tuesday, shear will be more notable, around 30 kts of deep layer shear (0-6km). Also, highs in the upper 80s to low 90s with dew points in the low to mid 70s will provide an environment for growing instability ahead of the cold front, with MUCAPE values likely reaching 3000J/kg. At this time, there is still some uncertainty on how well the shear and areas of higher CAPE overlap along with the timing of the cold front. Another uncertainty is the possibility of morning convection. If lingering early morning convection remains more widespread and takes longer to dissipate and clouds linger longer, this will have impacts on how well we destabilize before the cold front. Right now, the morning activity looks to be done by the mid-morning hours of Tuesday with enough time to get moderate instability. The latest severe weather outlook continues with a Slight (2/5) risk for most of our area with the remainder of the area (Poconos and coastal strip) in a Marginal (1/5) risk. The primary threat will be damaging wind gusts. One other key impact point for Tuesday is a flash flooding threat. Most of the area is in a Slight (2/4) Risk for excessive rainfall with the Poconos and high elevations of northwest NJ in a Marginal (1/4) Risk. PWAT values will rise to 2-2.5 inches with warm cloud depth of 10-12 kft, so the signal is there for the convection to be sufficient rainfall producers. The good news is that the convection will be moving but any training of showers or thunderstorms could lead to increased concern for localized flash flooding. There is also a signal for some frontogenetic forcing with the cold front which could also enhance the precipitation rates with the convection. While heat index values will be in the upper 90s Tuesday across the Philly Metro, the criteria for a Heat Advisory changes on July 1st to a heat index of 100 to 104 degrees for two consecutive hours. A few locations near Philly may touch a 100 heat index, but it is not forecast to be widespread enough at this time to warrant a heat advisory.-- End Changed Discussion --&& .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... The severe threat looks to come to an end around 00Z-03Z Wednesday, but given the front slowing down Tuesday night, it is still near the coastal areas by Wednesday morning. This will continue to lead to the potential for lingering coverage of some showers or an isolated rumble of thunder through Tuesday night into Wednesday morning. Lows Tuesday night are in the mid 60s to low 70s. Heading into Wednesday, our Tuesday cold front should be south and east of our area by midday, and while temperatures do not look to drop much, the dew points are forecast to lower some in the wake of the cold front. Despite the presence of the upper-level trough, less in the way of deeper moisture should keep the instability lower as well. Given surface high pressure building closer to our area with time, the chance for any showers and thunderstorms at this time is little to none for the remainder of Wednesday into Wednesday night. && .LONG TERM /THURSDAY THROUGH MONDAY/... The upper level trough looks to become reinforced as it remains across much of the Northeast through the end of the work week before moving offshore over the weekend. At the surface, a high pressure system continues to build in Thursday before settling over our area on Friday and Saturday and moving offshore on Sunday. While high pressure will be increasingly in control, a weak cold front looks to sink southward during the afternoon and evening on Thursday. This cold front looks to set off some showers and maybe an isolated thunderstorm for areas near and NW of I-78. The remainder of the forecast looks dry until Sunday when the high moves offshore. Daytime temperatures in the 80s for most through Saturday, with temperatures look to warm closer to 90 on Sunday. Dew points are forecast to be in the low to mid 60s before increasing to around 70 on Sunday. Overall, the most pleasant day does look to be Friday which should make for a nice forecast for the 4th of July. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/...-- Changed Discussion --The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...Primarily VFR outside of any thunderstorms. Restrictions are possible with scattered showers and thunderstorms. There are two possible windows of thunderstorms. 00z-04z is the more likely time period to affect everyone, then 04z-08z is less likely to affect all areas. Due to outflow boundaries, winds are all over the compass, but should favor more of a south to southeast direction early this evening. Winds may become variable for many areas overnight, then shift to a more southwest direction overnight. Moderate confidence. Tuesday...VFR to start. Restrictions likely with thunderstorms in the afternoon (60-80%). Winds from the southwest around 10 kts gusting to 15 kts. Higher gusts possible in thunderstorms. Moderate confidence. Outlook... Tuesday Night...Restrictions likely (40-60%) with showers and thunderstorms moving through. Wednesday through Saturday...VFR. No significant weather.-- End Changed Discussion --&& .MARINE... SCA conditions build overnight and into Tuesday. Seas 3-4 feet tonight build to 3-5 feet early Tuesday morning across the southern waters and spread north. Seas expected to be 4-6 feet by Tuesday afternoon. South-southwest winds 15-20 kts tonight build to 20-25 kts in the afternoon. Outlook... Tuesday night...SCA conditions continue through 06Z. Wednesday into Saturday...Sub-SCA conditions expected. Rip Currents... On Tuesday, winds turn more south-southwest and the period will be around 7 seconds with breaking waves around 3 to 4 feet. Thus, we will continue with the MODERATE risk for the development of dangerous rip currents for the NJ Shore and LOW risk for Delaware Beaches as flow will be more offshore there For Wednesday, winds go more west/southwesterly and lighten to around 10 MPH or less. Seas decrease as well within the surf zone to around 2 feet. As a result, a LOW risk for the development of rip currents will be in place for the Jersey Shore and Delaware Beaches. For specific beach forecasts, visit weather.gov/beach/phi && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory from 11 AM Tuesday to 2 AM EDT Wednesday for ANZ450. Small Craft Advisory from 5 AM Tuesday to 2 AM EDT Wednesday for ANZ451>455. && $$ SYNOPSIS...AKL/Guzzo/Hoeflich NEAR TERM...AKL/MJL/Robertson SHORT TERM...AKL/Guzzo LONG TERM...AKL/Guzzo AVIATION...Guzzo/MJL/Robertson MARINE...Guzzo/Hoeflich/MJL