499
FXUS61 KPHI 251029
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
629 AM EDT Wed Jun 25 2025

.SYNOPSIS...
Our significant heat wave will continue through Wednesday as hot
high pressure remains centered over the Appalachians. The high will
will eventually weaken and allow a back door cold front to track
though much of the forecast area Thursday into Friday. The front
will then push back to the north as a warm front on Saturday and
Sunday with high pressure remaining in control into Monday.
Another cold front looks to cross through the area on Tuesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Significant and dangerous heat will continue through Wednesday, but
it will be our last day before the heat and humidity begin to
relent.

High pressure will begin to retreat south on Wednesday, but remain
in control. Low-level thickness values will fall slightly as high
pressure shifts south, which will translate to afternoon
temperatures falling a few degrees, but still staying very hot with
highs in the mid to upper 90s across the board. Furthermore, a more
humid airmass will return, increasing dew points and ultimately
resulting little change in the forecasted heat indicies, which are
still forecasted to be around 100-110! As a result, we have decided
to keep our heat headlines unchanged with Extreme Heat Warnings
remain in effect for almost the entire area with the exception of
the coastal beach zones and Carbon and Monroe counties where Heat
Advisories are in place.

Heat tends to have cumulative effects on the body and is exacerbated
when the body can`t recover at night. If outside, drink water, take
frequent breaks, and find some shade. Watch out for heat cramps,
exhaustion, or stroke. Don`t leave people or pets in a closed car.
If air conditioning is not available in your home, find a cooling
option with friends or family or a nearby cooling station.

As high pressure inches southward on Wednesday, a cold front will
begin to approach the region from the north. This frontal boundary
could help produce a few isolated to scattered showers and
thunderstorms during the afternoon and evening hours. With increased
humidity across the region, PWAT values will creep up to the 1.75-
2.00 inch range. The entire area is currently in a MARGINAL risk for
severe weather by SPC, but the overall threat looks low. A high
CAPE, low shear environment is in place with high moisture, so
perhaps an isolated strong wind gust brought down to the surface is
possible. Any thunderstorm that does develop would also carry the
chance for a heavy downpour given the high PWAT values.

A few showers and thunderstorms would likely continue into the
evening and gradually dissipate with the loss of daytime heating.
Overnight lows are forecasted to be a few degrees cooler, though
still quite warm, in the low to upper 70s.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Needed relief comes for the end of the weak as the strong upper
level ridge that brought record breaking heat begins to break down.
High pressure setting over New England and Quebec will result in a
backdoor front sliding in from the north, as onshore flow commences
on the south side of the high. The front starts out over the Philly
area on Thursday morning, slowly inching southward through the day
and should be south of the area by Thursday night. Areas north of
the front will see much cooler temperatures in the upper 70s/low
80s. This looks to be for northern New Jersey, Poconos, and northern
Lehigh Valley. South of the front, the heat and humidity will
continue, and where the front gets to later in the day (Eastern
Shore and Southern Delaware) could see temperatures back in the 90s
and onshore flow pumping in moisture and upping the humidity. May
need a Heat Advisory on Thursday for the Eastern Shore as heat
indices get close to 105 but will let the current headlines run
their course before a decision is made. Areas south of the front but
closer to it (northern Delaware, South Jersey, and northern
Delaware) will get into the mid to upper 80s, with heat indices
"only" in the low to mid 90s. Not anticipating need for an extension
to the heat headlines currently in place.

With the backdoor front swinging through, and continued heat in the
southern half of the area, some diurnally driven convection appears
likely. The threat for severe weather and damaging wind gusts will
be limited to Delmarva, being in the warm sector. While
thunderstorms cannot be ruled out across the region, areas along and
north of the front have very limited severe potential. A MRGL (1/5)
risk is in place for the Delmarva peninsula. Some scattered showers
and thunderstorms could hang around through the night. Outside of
that though, still looking warm and muggy, though not nearly as
oppressive as previous nights with lows in the mid to upper 60s.

Much cooler on Friday as the area should now be fully north of the
front and in an area of moist but stable air. While it won`t be a
washout to end the week, temperatures only get to the low to mid 70s
with scattered showers around. Instability will be much lower
compared to Thursday, so the severe threat is near zero. Unsettled
through the night with scattered showers and lows in the 60s.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
The backdoor front retreats northward, settling over our area for
the weekend. This will result in continued unsettled weather and
daily diurnally driven convection likely both Saturday and Sunday.
Rain chances as a result are centered around the afternoon and
evening, though only around 40-60% on Saturday and 30-40% on Sunday,
so any weekend plans and outdoor activities may still be able to
carry on.  Temperatures will be closer to normal for the weekend
though, in the mid to upper 80s.

An early look at next week, it seems like the unsettled pattern
continues until a frontal system sweeps through sometime Tuesday.
Temperatures may tick a bit upward to start next week and trend more
toward above normal levels, but nothing like what we`re in the midst
of now.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Wednesday...VFR with FEW/SCT clouds in the afternoon. Can`t rule out
a shower/thunderstorm in the afternoon along with brief period of
sub-VFR conditions, however this potential is very low and left out
of the TAFs for now. W-NW winds around 5-10 kt. High confidence.

Wednesday night...Mainly VFR. Brief period of sub-VFR conditions
possible with an isolated shower or thunderstorm in the evening.
Winds will remain light and variable. High confidence.

Outlook...

Thursday through Thursday Night...MVFR/IFR conditions likely at
times with 30-40% chance of showers in the morning and 60-80%
chance of showers and thunderstorms in the afternoon and
evening.

Friday through Friday Night...MVFR/IFR conditions expected with a
prevailing marine layer and scattered showers around

Saturday through Sunday...Sub-VFR conditions possible with scattered
showers and thunderstorms, primarily in the afternoon and evening
both days.

&&

.MARINE...
No marine headlines expected through Wednesday night. W-NW winds
around 5-10 kts in the morning, before settling out of the SE-S
around 10 kt in the afternoon and into the overnight. Seas of 2 feet
or less.

Outlook...

Thursday through Sunday...No marine headlines expected.

Rip Currents...

For today, winds will be light out of the south at 5 to 10 mph
or less. Waves in the surf zone will be around 1 to 2 feet with
a dominant swell around 8 seconds. This set up will result in a
LOW risk for the development of dangerous rip currents for both
the Jersey shore and the Delaware Beaches.

For tomorrow, winds turn onshore and increase to around 10-20
MPH. Seas slowly build as well, getting to around 2 to 3 feet in
the northern waters. While the period remains 8 to 9 seconds,
the onshore winds and increasing wave heights in the surf zone
will result in a MODERATE risk for the development of rip
currents for Ocean and Monmouth County, NJ.

Further south, winds will be a bit weaker with lower wave
heights in the surf zone. This will result in a LOW risk for the
development of rip currents for Thursday for Atlantic and Cape
May County in New Jersey and the Delaware Beaches.

For specific beach forecasts, visit weather.gov/beach/phi

&&

.TIDES/COASTAL FLOODING...
With the New Moon approaching on Wednesday, June 25th, astronomical
tides are increasing. Spotty minor tidal flooding was observed
for the immediate coastline and back bays as well as within
Delaware Bay last night (Tuesday evening). Given no major
changes in overall weather pattern, expecting spotty minor
flooding again with the Wednesday evening high tide.

Higher confidence in advisories potentially being needed starting
Thursday evening. While we get away from the New Moon, onshore flow
will result in water piling up and more widespread minor tidal
flooding for the coastal and Delaware Bay communities.

No tidal flooding is expected within the tidal Delaware River or
Chesapeake Bay.

&&

.CLIMATE...
Near record breaking heat is expected across the area through
today. Yesterday (June 24), all climate sites set or tied
either a record high temperature, a record warmest low
temperature, or both. Some sites also set monthly warm records.
Some sites had their first 100 degree day in over a decade.
See the Record Event Reports (RERs) sent out earlier this
morning for more details. One more day to go in this stretch of
extreme heat, where some records could fall.

Record High Temperatures
                          June 25
Site                  Record/Year
Allentown (ABE)           98/1923
AC Airport (ACY)          96/1997
AC Marina (55N)           95/1952
Georgetown (GED)          96/1952
Mount Pocono (MPO)        91/1952
Philadelphia (PHL)        98/1952
Reading (RDG)             99/1943
Trenton (TTN)             99/1997
Wilmington (ILG)          98/1894

Record Warmest Low Temperatures
                          June 25
Site                  Record/Year
Allentown (ABE)           74/1923 & 1976
AC Airport (ACY)          80/1950
AC Marina (55N)           75/1997 & 2002
Georgetown (GED)          75/2019
Mount Pocono (MPO)        69/1952
Philadelphia (PHL)        76/1909, 1976 & 2002
Reading (RDG)             75/1943 & 1949
Trenton (TTN)             75/1976
Wilmington (ILG)          75/1976

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Extreme Heat Warning until 8 PM EDT this evening for
     PAZ060>062-070-071-101>106.
     Heat Advisory until 8 PM EDT this evening for PAZ054-055.
NJ...Extreme Heat Warning until 8 PM EDT this evening for NJZ001-
     007>010-012-013-015>023-027.
     Heat Advisory until 8 PM EDT this evening for NJZ014-024>026.
DE...Extreme Heat Warning until 8 PM EDT this evening for
     DEZ001>003.
     Heat Advisory until 8 PM EDT this evening for DEZ004.
MD...Extreme Heat Warning until 8 PM EDT this evening for MDZ012-
     015-019-020.
MARINE...None.

&&

$$

SYNOPSIS...AKL/Hoeflich/Kruzdlo
NEAR TERM...MJL
SHORT TERM...Hoeflich
LONG TERM...Hoeflich
AVIATION...Hoeflich/MJL
MARINE...Hoeflich/MJL
TIDES/COASTAL FLOODING...
CLIMATE...