043 FXUS61 KPHI 161021 AFDPHIArea Forecast Discussion National Weather Service Mount Holly NJ 621 AM EDT Tue Sep 16 2025
.SYNOPSIS... A coastal low initially located off of the Carolinas will track northward towards the area through mid-week. Wednesday into Thursday, the low is expected to weaken substantially as it makes its closest approach. A cold front moves through Friday, with high pressure building southeastward into the region through the weekend and dominating our weather into early next week.
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.NEAR TERM /THROUGH TONIGHT/... High pressure centered over Quebec will remain in place today before shifting east into the Canadian Maritimes tonight. Meanwhile, a vertically stacked low is positioned off of Cape Hatteras this morning which will retrograde into eastern North Carolina and southern Virginia later today. This low will then meander over the southern Mid-Atlantic region through tonight.
Thickening clouds associated with the low have begun to overspread the area this morning where latest radar data is now indicating that the initial rain bands are moving across the Delmarva and southeastern New Jersey. Should gradually see these bands overspreading into the rest of the area later today into tonight. With respect to the forecast, much of the day outside of the Delmarva, south Jersey and along the shore should be rather benign. Just some high clouds and perhaps a stray shower is expected through early afternoon before rain chances across the I-95 corridor increase. North and west of I-95, shower activity will likely hold off until this evening and overnight as precip will have to overcome an abundance of dry air and ridging further north. For areas, near the coast including the Delmarva and south Jersey, should continue to encounter periodic rain bands pivoting over the area for much of the day. By tonight, shower activity and rain bands are anticipate to gradually pivot further north as the low pivots closer to the area. At times, instances of thunder are possible, with greatest potential near the coast and across the Delmarva where some elevated instability is available within closer proximity to the low center. Through tonight, generally up to one of inch of rain is possible across southern New Jersey and the Delmarva. Lesser amounts up to a quarter of an inch is expected elsewhere, with locally higher amounts possible.
Also, east-northeast winds will be strengthening through the course of the day with sustained winds between 10-20 mph, highest along the immediate coast. Gusts up to 25 mph can be found around the I-95 corridor and points north and west, with gusts upwards of 25-40 mph possible near the coast. Winds are expected to remain below advisory criteria, though a brief gust to 45 mph is possible in any convection. Winds diminish by tonight as the pressure gradient laxes.
Lastly, in terms of temperatures, highs will mainly be in the 70s thanks to the cool, showery weather in place. Lows tonight will be closer to average though in the 50s and 60s.
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.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... The primary focus during this time period will be on shower chances with the coastal low Wednesday and perhaps lingering into the early part of the day Thursday. The low is expected to be located near the Virginia coast Wednesday morning, and will track slowly northeastward into Thursday. The low is expected to weaken and become an open trough with time. Even still, scattered to numerous showers and a few embedded thunderstorms are expected on Wednesday, especially southeast of the I-95 corridor, with more scattered to isolated coverage heading farther north. How soon the rain chances diminish will be dependent on how fast the low degrades, but the latest indications are that clouds and at least the chance of showers (POPs 30-40 percent) will linger into Thursday morning for areas near and south/east of the urban corridor. Clouds and shower chances look then diminish through the day.
Highs on Wednesday will generally be in the upper 60s to lower 70s. With widespread clouds Wednesday night, temperatures won`t cool much, with most locations remaining in the low-mid 60s (50s over the Poconos and NW NJ). With at least some breaks in the clouds becoming more prevalent on Thursday and with significantly less shower coverage, temperatures are expected to warm into the upper 70s to near 80. Slightly cooler lows are expected Thursday night, ranging from the mid 50s to the lower 60s.
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.LONG TERM /FRIDAY THROUGH MONDAY/... A dry cold frontal passage is expected on Friday, with high pressure centered over portions of Ontario and the Northern Great Lakes shifting southeastward into our area. This will lead to quiet weather through the weekend and into early next week.
A warm Friday is expected, with high temperatures generally in the low to mid 80s. Once the cold front clears the area, temperatures should be noticeably cooler. The Friday night through Sunday time frame should feature partly to mostly clear skies with highs mainly in the low-mid 70s and lows in the low-mid 50s. Monday will likely be slightly warmer, but most locations still remaining below 80.
The area looks to remain precipitation free through at least next Monday.
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.AVIATION /10Z TUESDAY THROUGH SATURDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas.
Today...Primarily VFR. Cloud bases lower as the day progresses but should ultimately remain VFR. A chance of MVFR conditions possible at KMIV and KACY late in the afternoon, but thinking should hold off until early this evening. East-northeast winds will be increasing throughout the course of the day around 10-16 kt sustained. Gusts upwards of 20 kt are possible for most terminals with the exception of KMIV and KACY which may gust upwards of 25-30 kt. Moderate confidence overall.
Tonight...VFR early outside of KMIV and KACY, otherwise a gradual lowering to MVFR/IFR conditions expected as stratus moves in and more moderate to heavy rain especially after midnight. Primarily VFR at KRDG/KABE until late as steady rain stays to the south and east. Northeast winds 5-10 kt with locally higher gusts possible near KMIV and KACY. Low confidence.
Outlook...
Wednesday through Wednesday night...Periods of sub-VFR conditions likely in scattered showers and perhaps a few embedded storms.
Thursday...Primarily VFR. A few isolated showers could linger across the area, with periods of sub-VFR conditions still not out of the question in the morning.
Thursday night through Saturday...VFR. No significant weather.
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.MARINE... A Gale Warning is in effect for the coastal waters from Great Egg Inlet to Fenwick Island until 10 PM tonight. A Gale Warning is also in place for the lower Delaware Bay until 6 PM today. Elsewhere, Small Craft Advisories are in effect for all waters through tonight. Once the Gale Warnings end, a SCA will be needed for those waters.
East-northeast winds around 15-25 kt this morning will increase to 20-30 kt this afternoon. Wind gusts up to 35-40 kt are possible in Gale Warning areas with gusts up to 25-32 kt elsewhere. Seas of 4-8 feet this morning will build to 6-10 feet this afternoon, before gradually diminishing to 5-8 feet tonight.
Rain showers likely through tonight with isolated thunderstorms possible. Visibility restrictions in rain and fog will continue through tonight.
Outlook...
The winds should be below Small Craft Advisory levels by around sunrise Wednesday however seas look to remain elevated at around 5 to 7 feet through the day into early evening.
Wednesday overnight and beyond, no marine headlines are anticipated with winds remaining below 25 kt and seas below 5 feet.
Rip Currents...
For today, northeast winds further increase to around 15 to 25 mph with breaking waves increasing to 4 to 6 feet with a few 7 foot seas possible along the Delaware coast. Furthermore, a strong 9 foot 9 second east to east-northeast swell will contribute significantly. This will result in a HIGH risk for the development of dangerous rip currents.
For Wednesday, northeast winds diminish to around 10 to 15 mph with breaking waves of 3 to 5 feet. The east to east-northeast swell does subside to around 5 to 7 feet at 8 seconds, but will remain quite strong. As a result, a HIGH risk for the development of dangerous rip currents is expected to continue.
For specific beach forecasts, visit weather.gov/beach/phi
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.TIDES/COASTAL FLOODING... A coastal low off the Carolina coastline will bring a persistent fetch of northeast winds across the region. This is expected to cause water along the Delaware Bay to build up along the southern side along the tidal waterways along the Delaware coast. As a result, Minor coastal flooding is expected for the shorelines and tidal waterways of Kent and Sussex County Delaware during the Tuesday late afternoon/evening high tide cycle.
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.PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...High Risk for Rip Currents through this evening for NJZ014-024>026. DE...Coastal Flood Advisory from 3 PM this afternoon to 9 PM EDT this evening for DEZ002>004. High Risk for Rip Currents through this evening for DEZ004. MD...None. MARINE...Small Craft Advisory until 6 AM EDT Wednesday for ANZ430. Gale Warning until 6 PM EDT this evening for ANZ431. Small Craft Advisory until 8 PM EDT Wednesday for ANZ450>452. Gale Warning until 10 PM EDT this evening for ANZ453>455.
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SYNOPSIS...Cooper/Fitzsimmons NEAR TERM...DeSilva/MPS SHORT TERM...Cooper/Fitzsimmons LONG TERM...Cooper/Fitzsimmons AVIATION...DeSilva/Fitzsimmons MARINE...DeSilva/Fitzsimmons TIDES/COASTAL FLOODING...PHI
NWS PHI Office Area Forecast Discussion