686 FXUS61 KPHI 100117 AFDPHIArea Forecast Discussion National Weather Service Mount Holly NJ 917 PM EDT Tue Sep 9 2025
.SYNOPSIS... High pressure across New England will continue to shift eastward tonight and Wednesday. An area low pressure off the Southeast U.S. coast tracks north and northeastward through Wednesday. A front may develop across portions of our area later this weekend.
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.NEAR TERM /THROUGH WEDNESDAY/... Clouds remain across the south/east parts of the CWA but overall mostly unchanged from earlier. Some light returns on radar seem to be drying up as they approach the area. We still expect that things will become more favorable for precip near the shore later tonight. We`ll keep the current pops in place for now. Few changes were needed to the earlier fcst with timing perhaps an hour or tow later possible. Lows will range from the low/mid 50s N/W to the low/mid 60s for Delmarva and South NJ. Northeast winds 5 to 10 mph overnight, but closer to 15 mph near the shore.
For the overnight hours and into Wednesday, PoPs are 15-20% for areas west of I-95 and for the Poconos at times. For the I-95 corridor, it is 25-30% and then as you head east it increases up to 40%. The coastal areas and Sussex county Delaware will at times see PoPs up to 40-60%. This all aligns well with the coastal low bringing in moisture and setting off showers that will be isolated to scattered in coverage. There are some indications that local enhancements from areas of convergence and elevation may lead to an increase in precipitation at times across parts of our area. An isolated thunderstorm also cannot be ruled out for mainly the coastal areas.
This coastal low will stay offshore but will also lead to an increase in our winds. A high pressure system to our north/northeast along with the coastal low moving north and eventually to the northeast will lead to a tightening pressure gradient which increases our winds. Our winds will stay breezy into Wednesday with sustained winds generally up to 10 mph or 15 mph for the coast and gusts 10-20 mph for most and 20-30 mph for the coast.
In terms of temperature, we see lows tonight in the low 50s to mid 60s. Highs on Wednesday are in the upper 60s to low 70s. We trend drier by the late afternoon and into the evening on Wednesday as the coastal low moves away but it will take a bit for the winds to decrease given the tighter pressure gradient.
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.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... Any residual showers will dissipate by Wednesday evening as the low offshore stretches out and moves farther out to sea. Dry weather will persist for Thursday into Friday night as high pressure builds well to our north Thursday in eastern Canada, before shifting across New England Friday. This will keep a northerly flow across the area Thursday, before shifting to northeast and easterly Friday. Even with the northerly and easterly flow, temperatures will be close to normal at night, and a couple of degrees above normal during the day through Friday.
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.LONG TERM /SATURDAY THROUGH TUESDAY/... For Saturday, high pressure shifts offshore and gets squeezed offshore and weakens through Sunday, before a cold front moves into the area later in the weekend into early next week. This front may be mostly dry for most areas as it moves through, so we will keep with only a slight chance of rain Sunday into Tuesday. Temperatures over the weekend into Monday are forecast to be near or above normal, then near normal for Tuesday.
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.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas.
Tonight...Clouds continue to increase with sub-VFR conditions likely to develop for most terminals. (Perhaps not for KRDG/KABE). Updated times for IFR with Wednesday morning more favored now. NNE winds around 10 knots, gusts up to 20 knots remain possible at KMIV/KACY. Moderate confidence.
Wednesday...Sub-VFR ceilings for all terminals Wednesday with MVFR ceiling at KABE/KRDG. IFR Ceilings through 18Z for the I-95 terminals and KACY/KMIV. Even LIFR possible for KACY at times. Ceilings should improve late Wednesday from west to east along with any showers coming to an end as well. The best potential for gradual improvement is after 21Z Wednesday. Northeast to north winds less than or around 10 knots for most terminal with 10-15 knots and gusty for KMIV/KACY. Winds diminish late in the afternoon and through the evening.
Outlook...
Wednesday night through Sunday...VFR conditions expected with no significant weather.
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.MARINE... Small Craft Advisory remain in effect for the Ocean into early Thursday morning. Also the SCA for lower Delaware Bay was extended until 6AM Wednesday. The SCA for the upper Delaware Bay was dropped with gusts only around 20 kts expected. Scattered showers later tonight and Wednesday. Slight chance for a tstm. East to Northeast winds continue tonight and Wednesday.
Outlook...
Wednesday night...Small Craft Advisory remains for the first half of the night due to seas.
Thursday through Sunday...Conditions expected to remain below advisory levels.
Rip Currents...
A RIP CURRENT STATEMENT REMAINS IN EFFECT THROUGH WEDNESDAY.
For Wednesday, northeasterly winds around 15 to 25 mph with occasional gusts around 30 mph will gradually diminish through the afternoon. Breaking wave heights around 3-5 feet. An easterly swell around 7-8 seconds shall continue with choppy waters around 4-5 seconds. As a result, have maintained a HIGH risk for the development of dangerous rip currents for all beaches.
For Thursday, north-northeast winds subside to around 5-15 mph. Breaking wave heights lower to around 2-3 feet. An easterly swell around 7-8 seconds will persist as choppy waters abate. As a result, have opted to post a MODERATE risk for rip currents for all beaches.
For specific beach forecasts, visit weather.gov/beach/phi
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.TIDES/COASTAL FLOODING... Strong and persistent northeasterly flow continues through Wednesday, before lingering albeit weakening into Thursday. Despite being two-three days removed from the Full Moon, astronomical high tides are still high enough with water pushing into the coast for minor tidal flooding to occur at most of our tidal gauges.
The greatest potential for minor tidal flooding looks to occur with the high tide cycle tonight and on Wednesday. Therefore, have issued a Coastal Flood Advisory for all coastal zones along the ocean, backbays and as well as the Delaware Bay through Wednesday afternoon. Have also included New Castle and Salem Counties into the Advisory through Wednesday as a result of minor tidal flooding. Additional tidal flooding may occur with future high tide cycles on Thursday and possibly lingering into Friday as well.
For the tidal Delaware River, confidence is still low and less compared to areas further south. However, can anticipate at least spotty minor tidal flooding to occur with tonight`s high tide cycle. For Wednesday`s high tide cycles and beyond, minor tidal flooding appears possible, but will allow future shifts to evaluate if Advisories are needed.
No tidal flooding is expected along the northeast coast of Chesapeake Bay.
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.PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...Coastal Flood Advisory until 4 PM EDT Wednesday for NJZ016. Coastal Flood Advisory until 3 PM EDT Wednesday for NJZ012>014- 020>027. High Risk for Rip Currents through Wednesday evening for NJZ014- 024>026. DE...Coastal Flood Advisory until 4 PM EDT Wednesday for DEZ001. Coastal Flood Advisory until 3 PM EDT Wednesday for DEZ002>004. High Risk for Rip Currents through Wednesday evening for DEZ004. MD...None. MARINE...Small Craft Advisory until 6 AM EDT Wednesday for ANZ431. Small Craft Advisory until 6 AM EDT Thursday for ANZ450>455.
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SYNOPSIS...Gorse NEAR TERM...Guzzo/po SHORT TERM...Robertson LONG TERM...Robertson AVIATION...Guzzo/Robertson/po MARINE...DeSilva/Guzzo/Robertson/po TIDES/COASTAL FLOODING...PHI
NWS PHI Office Area Forecast Discussion