607 FXUS61 KPHI 101214 AFDPHIArea Forecast Discussion National Weather Service Mount Holly NJ 814 AM EDT Fri Oct 10 2025
.SYNOPSIS... High pressure will shift offshore today into Saturday. A coastal storm with significant impacts is expected to affect the region by Sunday and into early next week. Improving conditions expected by Tuesday as the storm weakens and moves out to sea. High pressure will begin building back into the region during the middle to end of next week.
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.NEAR TERM /THROUGH TONIGHT/... The chilliest morning of the season is ongoing as temperatures have fallen into the upper 20s to upper 30s outside of the immediate urban corridor, Delmarva, and coastal areas which remain in the 40s and 50s. Current Frost and Freeze headlines remain unchanged and are in effect until 9 AM today.
Virtually, today and tonight will act as the `calm` before the storm. Strong high pressure centered over interior New England will shift off the coast of Cape Cod early this afternoon before remaining situated south of Nova Scotia tonight. As it does so, return flow will become more onshore resulting in moderating temperatures with highs in the upper 50s to mid 60s. Scattered to broken low clouds will develop as the day progresses from southeast to northwest as moisture increases across the area but overall should be nothing of significance.
By tonight, an increase in clouds associated with the developing coastal storm off the Carolinas will begin to fan into the Mid- Atlantic region. This cloud cover will limit radiational cooling and keep temperatures at bay. As a result, lows will mainly range in to the mid 40s to mid 50s with upper 30s to low 40s in the higher terrain. Aside for a stray shower late, dry conditions will prevail.
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.SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/... Saturday will feature mostly cloudy to overcast skies with temperatures moderating further into the upper 60s to low 70s in most areas. While most are likely to remain dry during the daytime Saturday, some scattered showers will begin to overspread the area, moving into areas across the coastal plain SE of I-95 through the afternoon. Easterly winds will begin to increase some, especially later in the day closer to the coast.
Things really start to go downhill on Saturday night as a coastal low approaches from the south. Rain is expected to continue overspreading the area, with around a 70-90% chance of rain region-wide. Winds begin to increase, especially over the water and along the immediate coastline with gusts getting near 40-50 mph by daybreak.
***Significant impacts possible from a strong coastal storm Sunday through Monday***
Overview: We continue to closely monitor the anticipated development of a potentially significant coastal storm near the North Carolina coast along a stalled frontal boundary beginning Saturday. This storm is anticipated to strengthen and lift northward Sunday into early next week. The primary impacts will be from coastal flooding, beach erosion, dune breaching, strong to potentially damaging winds, and heavy rain. The heaviest rainfall and strongest winds are still anticipated to be near the Atlantic coast.
What has changed: There have been no significant changes to the forecast or messaging for the storm with this update. There still remains a fair amount of certainty regarding the details of the evolution of the coastal storm and its ultimate degree of impacts. There are still 2 potential solutions, which are most evident in the differences between the 00Z GFS and ECMWF model runs. A stronger storm that tracks closer to the coast will result in much more severe impacts (similar to the 00Z GFS solution). A somewhat weaker storm that tracks farther offshore will result in less severe, but still potentially significant impacts to the immediate coast. Guidance will likely continue to struggle and vary from run to run with this system until it actually forms a well defined low pressure center sometime Saturday or Saturday night. All previously issued watches remain in effect at this time due to the continued uncertainty in timing, severity, and inland extent of impacts.
Coastal Storm Forecast Details...
The period Sunday through Monday will be when our area likely experiences the brunt of the impacts from the coastal storm. If the current track holds and the coastal storm does end up just offshore or even making landfall over Delmarva, strong winds are expected, sustained near 30-40 mph (perhaps near 50 mph along the immediate coast) with gusts possibly near 60-70 mph along the coast by Sunday afternoon, Sunday night, and early Monday. There is potential for these strong winds to continue well into Monday. Gusts upward of 30-50 mph may extend inland to about the I-95 corridor and Philadelphia metro area. While there is still some uncertainty in how long strong winds last, there is at least high enough confidence that counties bordering the Atlantic Ocean will either see sustained winds or frequent wind gusts at/above criteria for a High Wind Warning. As a result, the High Wind Watch remains in effect for Atlantic coastal NJ and DE, and their respective counties as periods of 40+ mph sustained winds and/or frequent gusts near 60 mph are increasingly likely. Would not be surprised to see a Wind Advisory for more inland counties, but will wait to issue anything until confidence on inland extent of the winds is higher. Long story short, power outages and tree damage are possible, especially toward the coast.
In addition to the wind, heavy rain is forecast, and a SLIGHT (2/4) Risk Excessive Rainfall Outlook is in place for the I-95 corridor and points south and east for Sunday through Sunday night. A widespread 1-3 inches of rain is forecast across our entire area, with locally higher amounts of 3-5 inches possible, especially within the SLGT risk area near the coast. While that sounds like a lot, it is important to keep in mind that this will be falling over a 36 to 48 hour period. It has been quite dry as well. Given this, the thinking is that flooding due to heavy rain alone will be limited to poor drainage and urban areas. However, that much rainfall could exacerbate impacts near the coast with Moderate and potentially Major coastal flooding ongoing. Significant high tides are expected due to strong northeast winds resulting in water piling up along the coast.
The setup is overall very complex. The surface low will be developing over the Gulf Stream along a stalled boundary, and its northward movement will depend on how it interacts with a surface high over Nova Scotia, an upper level low over the Great Lakes, and even distant Tropical Storm Jerry. The extent and severity of impacts in our area will be directly related to the exact track and evolution of the low pressure center. Stay tuned to the latest briefing packages and forecast updates as the forecast continues to evolve and details become more apparent over the next couple days.
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.LONG TERM /TUESDAY THROUGH THURSDAY/... The early week coastal storm will be weakening significantly by Tuesday, but it`s remnant low could still linger in the vicinity of the coast yielding a chance of showers and somewhat breezy conditions. The low will eventually weaken and push out to sea Tuesday into Tuesday night. Thereafter, broad and relatively weak high pressure will build across the Great Lakes region. Its cooler airmass will arrive toward the end of the week, with below normal temperatures and fair weather anticipated for Thursday and Friday.
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.AVIATION /12Z FRIDAY THROUGH TUESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas.
Today...VFR. Clear skies early will transition to a mix of SCT/BKN clouds around 4000 feet as the day progresses. Northeast winds initially, will settle out of the east-southeast around 5-10 kt. Moderate-high confidence.
Tonight...Primarily VFR with BKN ceilings around 3500-4000 feet. Isolated instances of MVFR ceilings possible. Easterly winds around 5 kt or less, becoming variable/calm at times. Moderate-high confidence.
Outlook...
Saturday...Starting out VFR though conditions likely come down late in the day as showers and low clouds overspread the area, potentially bringing MVFR conditions to the South Jersey terminals and possibly KPHL/KILG. Northeast wind gusts near 20 kt at KACY.
Saturday Night...MVFR/VFR conditions with light to moderate rain and lower clouds overspreading the area. Highest chance for restrictions at the South Jersey terminals. Northeast wind gusts 25-30 kt at KACY, 20-25 kt at the I-95 terminals and KMIV, and 15-20 kt at the Lehigh Valley Terminals.
Sunday through Monday...MVFR to IFR conditions expected with moderate to heavy rain moving through and gusty winds. Northeast wind gusts up to 50 kt possible at KACY. Gusts out of the northeast around 25-35 kt expected at the I-95 terminals and KMIV, with 20-30 kt anticipated within the Lehigh Valley.
Monday Night...Restrictions expected with showers and low clouds. Wind gusts diminish to around 15-25 kt out of the north/northeast.
Tuesday...Conditons improve but sub-VFR conditions possible. Wind gusts could get near 20 kt at times.
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.MARINE... No marine headlines are in effect through tonight. Easterly winds around 10-20 kt this morning will settle out of the east- southeast this afternoon around 10-15 kt and continue through tonight. Seas of 2-4 feet expected. Fair weather.
Outlook...
Saturday...Conditions expected to begin to deteriorate, with SCA conditions expected later in the day. Seas build to around 5 to 7 feet with winds increasing out of the east to around 20-30 kt. A Small Craft Advisory was issued for portions of the Atlantic coastal waters to highlight this.
Saturday Night through Tuesday...A Storm Watch remains in place through Monday for all marine zones except the upper Delaware Bay. Northeast winds 35-45 kt and gusts up to 50-55 kt expected within the Atlantic coastal waters and mouth of Delaware Bay. Gale Watch in effect for the upper Bay as winds should be lighter. Dangerous seas upward of 15 to 20 feet expected. Conditions will begin to improve by Monday night into Tuesday, though gale force winds may linger as the storm weakens. Periods of moderate to heavy rain and sea spray restricting visibility through Monday.
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.TIDES/COASTAL FLOODING... Minor coastal flooding is forecast with this morning`s high tide, mainly for Atlantic, Cape May, and Cumberland Counties in NJ and Sussex and Kent Counties in DE. Confidence has increased that minor tidal flooding will continue with the Saturday high tide. As a result, the Coastal Flood Advisory now continues through midday Saturday for the aforementioned areas.
There is an increasing risk of moderate to major coastal flooding impacts beginning Sunday through Monday as a strong coastal storm impacts the region. Guidance varies in potential outcomes of this storm with regard to severity of coastal flood impacts locally, however we remain very concerned about the potential for significant impacts from this storm along our coasts. At this time, the greatest threat of impacts are anticipated to occur along the Atlantic coasts of New Jersey and Delaware, and Delaware Bay. A Coastal Flood Watch remains in effect to highlight this threat for the high tides Sunday through Monday.
Significant beach erosion and dune breaching are possible along the entire New Jersey Shore and Delaware beaches due to the very high surf conditions that are expected. Interests along the Atlantic coast, Delaware Bay, back bays, and tidal waterways should remain alert for forecast updates regarding this potentially significant coastal flood event.
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.PHI WATCHES/WARNINGS/ADVISORIES... PA...Freeze Warning until 9 AM EDT this morning for PAZ054-055-061- 062. Frost Advisory until 9 AM EDT this morning for PAZ060-101>106. NJ...Coastal Flood Watch from Sunday afternoon through Monday evening for NJZ016. Coastal Flood Advisory until 4 PM EDT Saturday for NJZ021>025. Coastal Flood Watch from Sunday morning through Monday evening for NJZ012>014-020>027. High Wind Watch from Sunday morning through late Sunday night for NJZ013-014-020-022>027. Freeze Warning until 9 AM EDT this morning for NJZ001-007. Frost Advisory until 9 AM EDT this morning for NJZ008>010-015- 017>022-027. DE...Coastal Flood Watch from Sunday afternoon through Monday evening for DEZ001. Coastal Flood Advisory until 4 PM EDT Saturday for DEZ002>004. Coastal Flood Watch from Sunday morning through Monday evening for DEZ002>004. High Wind Watch from Sunday morning through late Sunday night for DEZ003-004. MD...None. MARINE...Gale Watch from Saturday evening through Monday evening for ANZ430. Storm Watch from Saturday evening through Monday evening for ANZ431-450>455. Small Craft Advisory from 10 AM to 6 PM EDT Saturday for ANZ451>455.
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SYNOPSIS...Staarmann NEAR TERM...DeSilva SHORT TERM...Hoeflich/Staarmann LONG TERM...Staarmann AVIATION...DeSilva/Hoeflich MARINE...DeSilva/Hoeflich TIDES/COASTAL FLOODING...Staarmann/AKL
NWS PHI Office Area Forecast Discussion