Norristown, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

650
FXUS61 KPHI 051042
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
642 AM EDT Thu Jun 5 2025

.SYNOPSIS...
A cold front will approach the area later today and Friday,
before tracking across the Mid-Atlantic region on Saturday. High
pressure will briefly build in Sunday and Monday. A warm front
will move through the region on Tuesday. Another cold front will
then track through the forecast area on Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Uneventful weather during the near term with high pressure well
offshore and subsidence within the local region. The nearest
disturbance is a cold front back across the upper Great Lakes,
however a weak coastal system is also taking shape along the
Carolina coast. The front will creep slowly east through the day
today, and the coastal system will slowly move north along the
coast through today as well. Unlike the past couple days
though, high cloud cover from the approaching systems will
blanket the region, especially by this afternoon.

Highs today will be well above normal with mid/upper 80s across
most spots. Some stations within the area, especially from the
Philly metro and north/west, could experience their first 90
degree day of the year. The increasing high clouds will be a
limiting factor on this though, which should be thickest toward
the south across the coastal plain. Thus, places in northern NJ
and eastern PA could end up a few degrees warmer than the
typical warmer areas of the Philly metro, southern NJ, and
Delmarva. Cooler at the shore with temperatures mainly in the
70s expected. The humidity will be more noticeable today with
dewpoints rising into the mid to upper 60s, though some mixing
out may occur later in the day.

Dry conditions are expected across most of the area through
tonight. A couple of minor exceptions though, a slight chance
(15-20%) of a terrain driven shower or thunderstorm across the
Southern Poconos very late this afternoon and into tonight as
the cold front from the west approaches. The other exception
will be down in Delmarva, as the coastal low approaches, it will
potentially fire a few showers across southern Delaware late in
the overnight hours tonight.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
The cold front will inch closer on Friday. Its progress still
looks to be slow with little upper-level support and the
continued presence of the coastal surface low just south of the
region. Most forecast models have the coastal low moving out to
sea Friday night in the waking of the departing high. With the
cold front coming in from the west and being a bit closer, we`re
expecting more showers to track into the forecast area,
possibly down to the 95 on Friday afternoon and night. PWAT
values will start creeping up across the region too, topping out
between 1.25-1.75 inches. As a result, there will be potential
for a heavy shower or downpour. Our zones north and west are
highlighted in the ERO (Marginal) as a result. Across the
Delmarva and maybe even Cape May county, we can`t rule out a
stray shower as the southern coastal low makes it`s way
offshore.

By Saturday, with an upper level trough beginning to deepen to
our west and the coastal low moving further offshore, the cold
front will finally have the support to begin to move across the
area, and lead to increasing chances of precipitation. There is
some instability forecast with CAPE values of 500-1000 J/kg, and
PW values increase to 1.5-2.0 inches. So there will be the
potential for thunderstorms and brief heavy downpours. Mid-level
winds are forecast to be fairly weak, 40-50 knots or less, so
shear is not expected to be overly strong. However, there could
be a few isolated strong storms.

High temperatures on Friday will mainly top out in the mid 70s
to mid 80s. With it being unsettled on Saturday as the cold
front moves through, highs will run in the upper 60s to upper
70s. Delmarva could still see lower 80s. Lows will be in the
upper 50s to mid 60s both nights.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
The long term forecast period continues to look active. This is
in part due to a quasi-zonal pattern aloft with a series of weak
upper-level waves moving through the larger scale west-east flow
laying across region. A deepening upper level trough then does
look to approach the region by mid-week potentially signaling an
end to this pattern. Overall though, the forecast for the new
week is relatively uncertain.

At the surface, latest model guidance indicates that high
pressure may only briefly build in on Sunday before a weak wave
lifts the stalled front to our south back north towards our
region. As a result, PoPs for Sunday have increased, with a
chance (30-40%) for showers or a thunderstorm across much of the
region. As this wave departs, high pressure looks to build back
in late Sunday into early Monday, before another wave comes
along bring another chance for rain later Monday.

By Tuesday, with the deepening trough beginning to move towards
the region, the surface front will be able to push northward
through the region as a warm front, ahead of a cold front on
Wednesday as the upper-level trough swings through the region.
Showers and a few thunderstorms look likely on Tuesday and into
Wednesday before PoPs decrease later on Wednesday as the cold
front departs.

Temperatures throughout the long term period look to be within
a few degrees of normal for early June. Highs will be in the 70s
to lower 80s and lows will mainly be in the upper 50s and 60s.

&&

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

Today...VFR expected. BKN to OVC cirrus by afternoon. Light
winds becoming south to southwest around 10 knots by 18Z. High
confidence.

Tonight...VFR but BKN to OVC ceilings will be lowering as mid-
level clouds move in. South-southwest winds initially around
5-10 knots, decreasing to 5 knots or less. High confidence.

Outlook...

Friday...Mainly VFR conditions expected but sub-VFR
conditions possible with a chance (30-40%) for showers or a
thunderstorm.

Saturday...Sub-VFR conditions expected at times with showers
and thunderstorms likely (60-70%).

Sunday and Monday...Mainly VFR conditions expected but sub-VFR
conditions possible with chances (25-35%) for showers or a
thunderstorm.

&&

.MARINE...
No marine headlines expected through tonight. South-southwest
winds around 10 knots expected with a few gusts up to around 20
knots possible, particularly this afternoon. Seas of 2-3 feet.
Fair weather.

Outlook...

Friday...Sub-SCA conditions expected. However, winds will gust
to around 15-20 knots at times and seas will increase to 3-4
feet.

Friday night and Saturday...Small Craft Advisory conditions
possible. Shower and storms will be possible Saturday, which may
lead to locally higher winds and waves. Seas build to 3-5 feet.

Sunday and Monday...Sub-SCA conditions expected.

Rip Currents...

There is a LOW risk for the development of dangerous and life
threatening rip currents for the Jersey Shore and Delaware Beaches
for both today and Friday. Today, south to southwest winds will
average 10 to 15 mph with breaking waves of 1 to 2 feet with a
period of 7-8 seconds. For Friday, similar conditions can be
expected with south to southeast winds 5 to 10 mph with breaking
waves around 1-2 feet.

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

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.

&&

$$

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