442
FXUS61 KPHI 151928
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
328 PM EDT Tue Jul 15 2025

.SYNOPSIS...
A very warm and humid airmass will be over the region this week with
multiple rounds of showers and thunderstorms expected. A cold front
will stall within the vicinity of the area through Wednesday before
lifting back northward as a warm front on Thursday. A cold front
passes through the region on Friday with high pressure building in
on Saturday. Another cold front approaches late in the weekend,
lingering through the early part of the week.

&&

.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
A weak boundary continues to sit over Delmarva into southern NJ and
this boundary along with daytime heating and sea/bay breezes is
helping to trigger some scattered convection over portions of
southern DE into coastal NJ. The threat for severe weather with any
of these storms is low but there is a risk of localized flash
flooding as PWATS remain very high (around 2 inches) and storms are
slow moving. The limiting factors for today though are that the
forcing is very weak and there is a mid level dry air...especially
as you head farther north towards the I-95 corridor and points
northward. For this reason, storms will will continue to be isolated
to scattered and be confined primarily to our southern zones.
Farther north it will continue to be warm and humid with a mix of
sun and clouds.

Today`s convection should begin to wane and diminish around sunset
with the loss of diurnal heating. Perhaps a few showers can linger
into the overnight hours, but primary threat will come to a close.
Skies should be mostly clear early, but an increase in clouds is
expected overnight as another round of low stratus may develop after
midnight. Another warm night is expected, with lows mainly in the
low to mid 70s; upper 60s in the Poconos.

Wednesday will start dry but as we get into the afternoon there will
be some shortwave energy approaching from the west and this will
help trigger another round of convection which is expected to be
more widespread than today. Unlike today, the highest chances for
showers/storms look to be focused near and north of the urban
corridor where we have POPs of 60 to 70 percent. Unfortunately, this
includes the areas that were hard hit yesterday. Model guidance
isn`t especially robust depicting widespread heavy QPF amounts but
given the set up of continuing high PWATS (over 2 inches) with
better forcing compared to today and a setup that will favor
training and back building storms we went ahead an issued a Flood
Watch for flash flooding for our counties in central and northern
NJ...this includes from Mercer and Middlesex Counties northward.
These areas are currently very susceptible to more flooding
given yesterday`s heavy rain and flash flooding. Within this
area 1 hour FFG is below an inch in places with 3 hour FFG below
2 inches. So it won`t take much for these thresholds to be
reached. The severe weather threat for Wednesday continues to
look relatively low however the Storm Prediction Center does now
include portions of our western counties (Berks County
northward through the Lehigh Valley into Carbon County) in a
MARGINAL risk for severe weather. The main threat is damaging
winds. Highs Wednesday look to be mainly in the mid to upper 80s
with dew points in the 70s so it will be quite muggy with heat
indices topping out in the middle to high 90s.

Getting into Wednesday night, since the best forcing won`t be
arriving until later in the day Wednesday into the evening, the
convection may continue to be relatively widespread through  much of
the evening before diminishing later at night. For this reason, we
ran the Flood Watch to 3 AM Thursday. However the threat for severe
weather will have diminished by the late evening. It will be another
warm and muggy night with lows mostly in the 70s (60s over the
Pocono Plateau).

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
On Thursday, southwesterly flow will bring back warm air and
moisture advection resulting in heat index values approaching 100
degrees in many areas. This is anticipated to be the warmest day of
the week (unless the cold front on Friday is later than currently
expected). A Heat Advisory will need to be considered for Thursday
across portions of the area in a future update. There will again be
chances of diurnally driven showers and thunderstorms on Thursday,
again focused mainly northwest of I-95. Synoptic forcing is again
not very strong, and deep layer shear will be weak. A lot of
uncertainty regarding the convective environment for Thursday, and
we currently have no threats outlooks by WPC or SPC but this could
change especially on the hydrology side of things given how wet it
has been within the area of highest PoPs. PoPs are mostly 40-80%,
with the highest probabilities north and west of Philadelphia.

Thursday night will be the warmest night of the week, with low
temperatures mainly in the mid to upper 70s and should be mainly dry.

Friday could be another hot day depending on the timing of the next
cold front. Latest guidance shows the front crossing through the
region late in the day, and into the overnight hours on Friday. If
that timing holds, most of the area (aside from Delmarva) may be a
degree or two lower on Friday as compared to Thursday. This front
may also act as a focusing mechanism for thunderstorms and
associated convective hazards, but as with Thursday, uncertainty is
high regarding any of these threats. PoPs are near 20-50% for much
of the area.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Heading into the weekend, Saturday should experience the lowest
chance of convection with a surge of slightly drier air, lower
instability, and some subsidence from the departing trough.
Temperatures returning back closer to normal, and a comparatively
nice Saturday looks to be shaping up with highs in the mid 80s and
lower humidity compared to this week. Chances for convection should
increase again some for Sunday as the boundary start lifting north
with return flow.

Unsettled conditions look to hang around through the start of next
week with the boundary lingering over the area, though too early to
say if any impactful severe weather or flood threat will come into
play. Temperatures to start next week look to be near seasonal
norms.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Rest of this afternoon...mainly VFR except some convection
occuring around ILG, MIV, and ACY could result in brief
restrictions if if moves over one of these sites. Confidence is
low on this. And farther north any convection will be even more
isolated so no mention of TS or VCTS in TAFs for today. SW winds
around 5 knots. Low to moderate confidence.

Tonight...mainly VFR this evening with the potential for a low
cloud deck to once again form for the overnight bringing cig
restrictions. Confidence is low on this but the best chances for
this occuring appear to be from the I-95 TAF sites southward.
Low confidence.

Wednesday...Mainly VFR in the morning (following any early
morning low stratus) with showers/storms developing in the
afternoon and lasting into Wednesday night. These storms are
expected to be more widespread than what`s occuring today so
will have a better chance of bringing more widespread
restrictions to TAF sites by later in the day. SW winds around
5-10 knots with some gusts to 15-20 knots possible. Moderate
confidence.


Outlook...

Thursday...Primarily VFR, though MVFR/IFR conditions possible (20-
40%) as some showers and thunderstorms develop in the afternoon,
with the highest probability for restrictions coming for KABE/KRDG.

Thursday Night...VFR. No significant weather.

Friday...Primarily VFR, though restrictions possible (15-30%) with
scattered showers and thunderstorms around in the afternoon.

Friday Night...VFR. No significant weather.

Saturday through Saturday Night...Primarily VFR. Isolated showers
around in the afternoon and early evening.

Sunday...Primarily VFR but restrictions possible (40-50%) with
showers and thunderstorms developing in the afternoon.


&&

.MARINE...
No marine headlines are in effect through tonight as SW winds
will be around 10 knots through this period. Scattered showers
and thunderstorms possible through tonight, which may cause
locally gusty winds in excess of 34 kt.

Late day Wednesday into Wednesday night southwest winds increase
to around 15 to 20 with gusts of 20 to 25 knots possible. So a
Small Craft Advisory may be needed though it will be marginal.

Outlook...

Thursday...Sub-SCA conditions expected, though cannot rule out a few
gusts near 25 kt. 15% chance an SCA is needed. Seas 2 to 4 feet.

Thursday Night through Sunday...No marine headlines expected.
Periods of showers and thunderstorms expected, mainly in the
afternoon and evening most days.

Rip Currents...

For today, southerly winds around 5-10 mph with breaking waves
around 1-2 feet, and an easterly swell at 6-7 seconds in length.
As a result, have maintained a LOW risk for the development of
dangerous rip currents at all beaches.

For Wednesday, south-southwesterly winds increase to around
10-15 mph with breaking waves around 1-3 feet, and an easterly
swell at 8-9 seconds in length. As a result, have upgraded Cape
May and Atlantic Counties to MODERATE, and maintained a LOW risk
for the development of dangerous rip currents for Monmouth,
Ocean and Delaware Beaches.

Rip currents occur often in the vicinities of jetties and piers
and the speed of the currents are generally maximized at low
tides.

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

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...Flood Watch from Wednesday afternoon through late Wednesday
     night for NJZ001-007>010-012-015.
DE...None.
MD...None.
MARINE...None.

&&

$$

SYNOPSIS...DeSilva/Hoeflich
NEAR TERM...DeSilva/Fitzsimmons
SHORT TERM...Hoeflich/Johnson/Staarmann
LONG TERM...Hoeflich/Johnson/Staarmann
AVIATION...Fitzsimmons/Hoeflich
MARINE...Fitzsimmons/Hoeflich