Upper Merion, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

268
FXUS61 KPHI 061856
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
256 PM EDT Fri Jun 6 2025

.SYNOPSIS...
A cold front slowly works its way through the region tonight.
Showers and thunderstorms again possible for Saturday. Weak high
pressure builds in from our north Saturday night through
Sunday. Low pressure pulls a warm front through the region
Sunday night through Monday. A cold front approaches the region
Tuesday, passing through into Tuesday night. High pressure
returns for Wednesday and Thursday.

&&

.NEAR TERM /THROUGH SATURDAY/...
Scattered thunderstorms have moved into Berks County PA and
also the southern Poconos. Other thunderstorms and showers have
developed across the lower Delaware Valley. More showers have
slowly edged north across Delmarva. Pop and weather grids have
been refreshed. A Flash Flood Watch has been issued too since
rainfall rates of 1 to 2 inches per hour are accompanying the
tstms to the N/W. Meso analysis indicates that these factors
will continue into the evening. The Watch continues until 10 PM.
SPC has kept a Marginal Risk for severe tstms for the far NW
parts of the forecast area for the rest of today and tonight.
Local damaging winds and large hail are possible with any severe
tstm.

Overnight, rains/tstms will end during the evening leaving
partly cloudy skies and areas of fog developing. Very mild and
humid overnight.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
Cold front looks to finish crossing through the region Saturday
night as weak surface high pressure moves eastward to our
north. A warm front from low pressure development eyes the
region from the south Sunday, possibly lifting through Sunday
night into Monday. In the upper levels, a weak ridge axis moves
eastward of the region Sunday, allowing shortwave energy pluses
to plague the region through much of the term.

With a mess of shortwave energy plus warm frontal development
and movement, expect an unsettled short term with multiple
chances for showers and thunderstorms. We could see some light
showers linger Saturday night in our southern and eastern most
areas, but the period should mostly be dry for the region. PoPs
will increase across the area from the southwest Sunday with the
likely chance for showers and thunderstorms Sunday afternoon
into the overnight time frame. SPC maintains a MARGINAL outlook
for severe weather for Delmarva, southern NJ, and southeastern
PA during this time frame.

Showers and some thunderstorm activity could linger through
much of the Sunday overnight period. Another round of showers
and thunderstorms from the northwest looks to be on the horizon
for the Monday afternoon and night time frame.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Upper level low pressure over the Great Lakes region Monday
night looks to degrade into an open trough as it lifts
northeastwards through Wednesday. Ensembles and deterministic
guidance suggest a more zonal pattern will take hold over the
region thereafter. At the surface level, a cold front approaches
Monday night/Tuesday, possibly crossing through Tuesday/Tuesday
night. Thereafter, guidance suggest weak surface high pressure
will build in from the west. This surface high pressure looks to
hold decent influence over the region Wednesday and Thursday,
possibly into Friday.

Showers and thunderstorms likely for Tuesday; dry conditions
(i.e., no PoPs) in the forecast for Wednesday, Thursday, Friday.
Temperatures expected to be around average to just slightly
above average during the duration of the term.

&&

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

Tonight...SHRA and scattered TSRA at KRDG/KABE, and also for
the Delaware Valley terminals too. Rains decrease ofter 00Z with
Fog and stratus developing after 06Z or so. MVFR/IFR and
possibly lower conditions expected. Light S winds. Low
confidence.

Saturday...More showers/tstms expected during the day with
mostly MVFR conditions expected. Local IFR possible in heavier
tstms. South to Southwest winds 10 to 15 kts. Low/medium confid.


Outlook...

Saturday night...Sub-VFR conditions in fog and stratus
possible.

Sunday through Sunday night...VFR initially Sunday, then
sub-VFR in SHRA/TSRA Sunday afternoon and Sunday night.

Monday through Tuesday...VFR Monday afternoon, then sub-VFR in
SHRA/TSRA Monday night and Tuesday.

Wednesday...VFR conditions anticipated.

&&

.MARINE...
Sub-Small Craft Advisory conditions tonight and Saturday. South
to southeast around 10 kt into tonight with 3 to 4 ft seas.
Scattered showers and tstms this evening. Fog possible
overnight. More showers/tstms Saturday.

Outlook...

Saturday night through Wednesday...Sub-SCA conditions. VSBY
restrictions in fog possible Saturday night. VSBY restrictions
in showers and thunderstorms mostly possible late Sunday and
Sunday night, Tuesday afternoon and evening. Thunderstorms may
result in locally higher winds and waves.

Rip Currents...

On Friday, winds will be south to southeast around 10 mph.
Swells will be around 1-2 feet with a period of 6-8 seconds. As
a result, breaking waves will be around 1-2 feet. Therefore,
there is a LOW risk for development of dangerous and life
threatening rip currents for all beaches on Friday.

On Saturday, the onshore swell increases to 3-5 feet with a
medium 7-9 second period. Additionally, some longer period waves
may be embedded in the swell. Breaking waves in the surf zone
of 2-3 feet are expected as a result. Winds will be around 5-10
mph out of the southwest to west-southwest. Due to the
increasing and potentially multi-period swells, there is a
MODERATE risk for the development of dangerous and life
threatening rip currents for all beaches on Saturday.

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

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Flood Watch until 10 PM EDT this evening for PAZ054-055-
     060>062-101-103-105.
NJ...None.
DE...None.
MD...None.
MARINE...None.

&&

$$

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