Cheltenham, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

360
FXUS61 KPHI 191047
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
647 AM EDT Sat Jul 19 2025

.SYNOPSIS...
High pressure over the area slides offshore later today.
Meanwhile, low pressure will ride along a stationary boundary
over the Mid-Atlantic through tonight. A cold front approaches
on Sunday and moves through the region Sunday night. High
pressure builds through the region for most of next week. A cold
front approaches on Friday.

&&

.NEAR TERM /THROUGH TONIGHT/...
High pressure builds north of the area and moves offshore later
today. Meanwhile, an old cold front remains over the Mid-
Atlantic. Surface areas of low pressure develop on that old
cold front as several shortwaves approach from the west and
track on that boundary.

The first wave of low pressure passes through the region this
morning. Scattered showers will move through Delmarva, the
Delaware Valley, and southern New Jersey. 00Z/19 NAM has a
bullseye over Cape May and Atlantic counties in New Jersey, but
that is an outlier. Most showers should be fairly innocuous.

Another wave approaches this afternoon and evening, and that may
result in more numerous showers with scattered thunderstorms,
mainly from Philadelphia south and with a focus on Delmarva and
southern New Jersey. Locally heavy rain is possible, mainly over
far southern Delmarva, as moisture pooling will occur near that
old front. Behind that first low, dew points will begin to creep
back up throughout the day, generally into the upper 60s and low
70s, while dew points in Delmarva will be in the mid 70s. With
increasing low level moisture, there is a Marginal Risk (1 out
of 4) for Excessive Rainfall for New Jersey and southeast
Pennsylvania and a Slight Risk (2 out of 4) for Delmarva. The
threat for severe weather is fairly low throughout, but there is
a Marginal Risk (1 out of 5) for severe weather mostly across
Delmarva. Highs today will be in the lower 80s.

Showers and thunderstorms taper off this evening, and then it
will remain cloudy and muggy for the rest of the night. Lows
tonight will be in the upper 60s to low 70s.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Conditions should be mostly quiet Sunday morning, but then as
low pressure passes well north of the area, it will drag a cold
front towards the region, and this will trigger another round of
showers and thunderstorms Sunday afternoon and evening. Ahead of
that front, southerly winds increase, and this will push surface
dew points well into the 70s along with high temperatures in the
upper 80s to near 90. This results in heat index values well in
the 90s, possibly to near 100 in parts of Delmarva and southern
New Jersey.

By Sunday afternoon, surface-based CAPE values will be up around
2000 J/kg, and low-level lapse rates will steepen to around -5C.
0-6 KM Bulk Shear values will be 30 to 35 kt. Showers and
thunderstorms will develop Sunday afternoon and evening, some of
which will be strong to severe. The Storm Prediction Center has
a Marginal Risk (1 out of 5) for severe weather for most of the
area, but a Slight Risk (2 out of 5) for northern New Jersey and
portions of the southern Poconos. In addition, PWATs will be
1.8-2.0 inches, and there is a Marginal Risk for Excessive Rain
for northern New Jersey, the southern Poconos, and Lehigh
Valley, as there is the risk for flash flooding Sunday afternoon
and evening.

Showers and thunderstorms taper off Sunday night. Cold front
passes through the region late, and then high pressure builds in
from the north for Monday and Monday night.

A much more pleasant air mass builds into the region for the
start of the new work week. Surface dew points drop into the
upper 50s and low 60s on Monday, and then even into the low to
mid 50s for most of the area Monday night! Highs on Monday will
be in the low to mid 80s and lows Monday night will be in the
upper 50s to low 60s.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Canadian high pressure passes north of the area Tuesday and then
will be centered near Cape Cod on Wednesday before moving out to
sea Thursday. Highs will mostly be in the 80s Tuesday and
Wednesday, and then return flow sets up for the end of the week.
Highs on Thursday will be back near 90, and then highs on Friday
will be back in the low to mid 90s. After several pleasant days
with dew points in the 50s to low 60s, dew points climb back up
into the 70s by Friday.

Conditions will be dry through Thursday. An approaching cold
front will trigger another round of showers and thunderstorms
Friday afternoon and evening.

&&

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

Today...VFR initially, then CIGs lower to MVFR around 2500-3000
feet by midday or so. Widely scattered SHRA, possibly a TSRA
this afternoon. Will carry VCSH due to the low confidence on
timing and placement of any given storm. Best chances will be
from KPHL south. S-SE winds around 5 kt. Low confidence.

Tonight...MVFR/IFR CIGs. Sub-VFR VSBYs, initially in scattered
SHRA/TSRA, then in BR. Light S-SE winds. Moderate confidence.

Outlook...

Sunday...Overall, VFR, but sub-VFR conditions in afternoon
SHRA/TSRA.

Sunday night through Wednesday...VFR. NSW.

&&

.MARINE...
Sub-Small Craft Advisory conditions today and tonight. S-SE
winds 10 to 15 kt with 2 to 4 ft seas.

VSBY restrictions from time to time in scattered showers and
thunderstorms throughout the day and into this evening. Patchy
fog possible tonight.

Outlook...

Sub-SCA conditions through the period. Showers and thunderstorms
will impact the waters Sunday afternoon and evening.

Rip Currents...

Today, south to southeast winds will average 5 to 10 mph with
breaking waves of 1 to 2 feet and a period of 7 to 8 seconds. As
a result, there is a LOW risk for the development of dangerous
and life threatening rip currents for the Jersey Shore and for
Delaware Beaches.

For Sunday, winds will be out of the southwest at 5 to 10 mph
along with breaking waves of 1 to 2 feet and a period of 7 to 8
seconds. As a result, there is a LOW risk for the development
of dangerous and life threatening rip currents at the Jersey
Shore 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...None.
DE...None.
MD...None.
MARINE...None.

&&

$$

SYNOPSIS...MPS
NEAR TERM...MPS
SHORT TERM...MPS
LONG TERM...MPS
AVIATION...MPS
MARINE...MPS