761
FXUS61 KPHI 292318
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
718 PM EDT Tue Jul 29 2025

.SYNOPSIS...
Bermuda high pressure remains in control through Thursday. A
cold front slowly works its way through the region Thursday
night through Friday morning. Canadian high pressure builds in
from the north and west for the upcoming weekend, departing
early in the new work week.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
After another uncomfortablely hot day across the area, we are
set up for more muggy temperatures for tonight. Skies will be
mainly clear with just varying amounts of high clouds expected.
Lows will mostly drop into the low 70s across the N/W areas and
mid/upper 70s for Delmarva, metro Philadelphia and much of south
NJ. Winds will be light and variable.

Wednesday will be a repeat of today with more hot temps and
obnoxious humidity for the area. Overall, dry weather but there
is a chance for a tstm for the mid/late afternoon for the
southern Poconos and north NJ. The chance will be 20% to 30% for
those areas. If there is a tstm, torrential downpours and gusty
winds expected. Highs in the mid/upper 90s most spots with
upper 80s/low 90s at the shore and far N/W areas. heat headlines
will continue as before. Chose not to expand the advisories
attm with HI values short of criteria for Delmarva by 2 to 4
degrees.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
A cold front passes through the region Wednesday night, and
then a stronger cold front approaches on Thursday and passes
through the region Thursday night.

Scattered showers and thunderstorms, mainly across the northern
half of the forecast area, will taper off after midnight.
Locally heavy rain and damaging winds are possible Wednesday
evening, but storms will lose their potency by midnight or so.

Temperatures will be somewhat cooler on Thursday, mainly due to
increasing cloud cover as another cold front approaches from
the west. However, an east to southeast flow sets up that will
allow for increasing low level moisture. Surface dew points will
rise back into the Thursday and Thursday evening. With high
temperatures generally in the upper 80s to low 90s, max heat
index values will be in the upper 90s to around 100.

A frontal boundary remains draped across the northern zones on
Thursday, and scattered showers and thunderstorms may fire up on
this boundary during the day. The bulk of the activity will
hold off until late in the day and in the evening as the primary
cold front passes through the region.

While confidence is fairly high that a flash flooding event
will occur on Thursday and Thursday night, confidence in the
timing and placement of the potential flash flooding is
decreasing due to model inconsistency. 12Z/29 NAM came in much
slower, with low pressure passing from southeast Pennsylvania
through northern New Jersey late Thursday night through Friday
morning. The heaviest rain would fall across the northern half
of the forecast area. The 12Z/29 GFS came in with low pressure
passing through the Mid-Atlantic. This brings one slug of heavy
rain across the northern zones, but another slug of heavy rain
across Delmarva and southern New Jersey.

Given PWATs increasing to 2 to 2.5 inches across the area,
moderate to heavy rain will develop across the region, with 1 to
3 inches of rain possible Thursday through Thursday night.

The question now is what will happen on Friday. Cold front
comes through most of the region by Friday morning, but the
front looks to get hung up over eastern New Jersey and down into
the Mid-Atlantic. With more shortwave energy approaching from
the west, low pressure looks to develop on that front. This will
keep showers and scattered thunderstorms in the forecast for at
least the eastern portion of the forecast area, but possibly
back west as well. Much cooler, even colder on Friday, with
highs generally ranging from the mid 60s in the southern Poconos
near 80 in southern Delmarva, and highs generally in the upper
60s to low 70s for most of the region. These highs are more
typical for early May or early October!

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Front departs Friday night and showers taper off. High pressure
builds in from the north with much cooler, compared to Tuesday-
Wednesday, but warmer than Friday, and drier air. An outright
pleasant weekend is on tap with highs in the upper 70s to low
80s, though a couple of degrees warmer on Sunday, and lows in
the upper 50s to low 60s. Surface dew points will generally be
in the 50s! Payback for the heat and humidity that has been in
place most of this summer.

High pressure builds north of the area and move into eastern
Canada for the start of the new week. One thing to watch is that
a frontal boundary will be draped over the Mid-Atlantic and
several waves of low pressure will ride on that boundary. For
now, it looks like rain should stay south of the region, but
bears watching. Highs warm back into the low to mid 80s for
Monday and Tuesday and humidity levels will creep up a bit.

&&

.AVIATION /23Z TUESDAY THROUGH SUNDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Tonight...VFR conditions will be in place overnight with just
high clouds across the area. Light variable winds expected. High
confid.

Wednesday...More VFR expected. A isolated tstm possible for the
far North/Northwest areas during the afternoon. Southwest winds
5 to 10 knots but South along the shore. Medium/High confid.

Outlook...

Wednesday night...Lingering SHRA/TSRA taper off. Low CIGs/VSBYs
possible late.

Thursday through Thursday night...Sub-VFR CIGs/VSBYs in
SHRA/TSRA. Heavy rain possible late Thursday and Thursday night.

Friday through Friday night...CIG/VSBY restrictions in SHRA and
scattered TRSA during the day, then VFR at night.

Saturday through Sunday...VFR. NSW.

&&

.MARINE...
Winds and seas remain below SCA levels. Winds will be mostly
S/SW around 10 knots this afternoon and into the evening. For
Wednesday, after rather light winds early, speeds will increase
during the afternoon to 10 to 15 kts. Fair tonight and
Wednesday.

Outlook...

Wednesday night...Sub-SCA conditions. VSBY restrictions in
showers and thunderstorms early.

Thursday through Thursday night...Sub-SCA conditions. VSBY
restrictions in showers and thunderstorms.

Friday through Friday night...SCA conditions possible for
northwest winds gusting up to 30 kt. VSBY restrictions in
showers and scattered thunderstorms.

Saturday through Sunday...Any lingering SCA conditions subside
Saturday morning, then sub-SCA conditions.

Rip Currents...

For Wednesday, the surface winds will be more from the south
and southwest near 10 mph. Breaking waves in the surf zone will
continue to be 1 to 2 feet with a period around 8 seconds. A LOW
risk for the development of dangerous rip currents is expected
for all beaches.

For Thursday, winds will turn southeasterly near 10 mph.
Breakers will remain 1 to 2 feet with a period remaining around
8 seconds. A LOW risk for the development of dangerous rip
currents continues for all beaches.

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

&&

.CLIMATE...
Several days of high heat commenced Monday and will continue
through Wednesday. No records were reached Monday, but a few
sites got to within a degree or two. Here`s a rundown of record
warmest high and low temperatures.

Record Warmest High Temperatures
Site                Tuesday 7/29  Wednesday 7/30
AC Marina (55N)      96 in 2002    99 in 2002
AC Airport (ACY)     98 in 2002    96 in 2002
Allentown (ABE)      96 in 1954    97 in 1940
Georgetown (GED)     99 in 2011    99 in 1949
Mount Pocono (MPO)   90 in 1949    90 in 1954
Philadelphia (PHL)   98 in 2002    98 in 1988
Reading (RDG)        97 in 2002    97 in 1940
Trenton (TTN)       100 in 1894    98 in 1999
Wilmington (ILG)     99 in 1896    97 in 1954

Record Warmest Low Temperatures
Site                Tuesday 7/29  Wednesday 7/30
AC Marina (55N)      78 in 2020    79 in 2020
AC Airport (ACY)     78 in 2002    76 in 2015
Allentown (ABE)      75 in 2002    74 in 2024
Georgetown (GED)     78 in 2011    78 in 2009
Mount Pocono (MPO)   71 in 2002    68 in 1909
Philadelphia (PHL)   81 in 1995    80 in 2002
Reading (RDG)        78 in 1949    75 in 1933
Trenton (TTN)        80 in 1894    78 in 1894
Wilmington (ILG)     82 in 1894    75 in 2019

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Heat Advisory until 8 PM EDT Wednesday for PAZ054-055-060>062-
     070-071-101>106.
NJ...Heat Advisory until 8 PM EDT Wednesday for NJZ001-007>010-
     012>015-017>020-026-027.
DE...Heat Advisory until 8 PM EDT Wednesday for DEZ001.
MD...None.
MARINE...None.

&&

$$

SYNOPSIS...MPS
NEAR TERM...OHara
SHORT TERM...MPS/OHara
LONG TERM...MPS/OHara
AVIATION...MPS/OHara/RCM
MARINE...MPS/OHara/RCM
CLIMATE...