Trevose, Pennsylvania Weather Forecast Discussion

294
FXUS61 KPHI 141757
AFDPHI
Area Forecast Discussion
National Weather Service Mount Holly NJ
157 PM EDT Sun Sep 14 2025
.SYNOPSIS...
A weakening cold front approaches the region late tonight. High
pressure briefly builds in on Monday before weakening and
shifting northeastward. Meanwhile, a coastal low which is
expected to develop off the coast of the Carolinas later tonight
will gradually drift northward, approaching our region Tuesday
into Thursday before dissipating. Late in the week, a cold front
may approach the region.
&&
.NEAR TERM /THROUGH MONDAY/...
A weak, decaying cold front will wash out as it moves into the
region tonight. Thereafter, the local area will be caught
between two systems: high pressure centered near Hudson Bay
building south, and low pressure, both at the surface and aloft,
over the Southeast that will lift towards the Mid-Atlantic by
Monday afternoon.
In terms of sensible weather, a few sprinkles, perhaps a light
shower, is possible into this evening with the approach of that
cold front this evening. There is a good deal of low levels
moisture, especially for mid-September, with dew points in the
50s to low 60s, but there is little, if any, upper level support
for more widespread showers.
While some clouds may develop with that front, especially in
northern zones, those clouds will dissipate through the
overnight. Clouds associated with the low over the Southeast
will lift towards Delmarva and southern New Jersey. These clouds
should inhibit the development of fog, but where skies are
relatively clear, some patchy fog is possible. Not expecting
dense fog. Warm and muggy tonight with lows in the 50s to low
60s.
Clouds increase from south to north throughout the day Monday as
low pressure lifts towards the Carolina coast. Onshore flow
will keep temperatures generally in the 70s to low 80s, with the
coolest temperatures near the coasts. Muggy with dew points
rising into the lower 60s.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
We should have increasing chances for rain showers especially
closer to the coast as a weak coastal low meanders closer to our
region Tuesday into Wednesday.
The biggest change in this period is the earlier potential
arrival of both rain and breezy conditions along the coast due
to the coastal low. It still appears the coast low will be weak,
and weakening as it gets this far north, so at this point, it
looks like wind gusts up to 30 mph along the coast, and
widespread rain amounts near or below 1.5 inches. Additionally,
with persistent onshore flow, boundary layer heating will be
tempered, limiting instability. Consequently, there is very
little risk for any significant impacts; Our region isn`t
outlooked in the excessive rainfall outlook, winds should stay
well below impactful levels, and while we may see some
thunderstorms, at this point the risk for severe storms appears
very low (less than 5%).
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
By Thursday, the reflection of the coastal low at the surface will
be very diffuse, if not completely dissipated. However, a mid and
upper level open wave trough may still be near our region, resulting
in continued chances for rain, primarily for the coastal plains.
Once the mid/upper level trough slides eastward by late Thursday, we
could see a brief warm up on Friday, thanks in part to a short wave
ridge. However, it still appears a cold front will approach the
region late in the week. It has some characteristics of a backdoor
cold front which are notoriously hard to model, especially with
respect to timing, this far out, so have stayed close to the blend
of guidance.
&&
.AVIATION /17Z SUNDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.
Rest of today...VFR. E-NE winds 5 to 10 kt. High confidence.
Tonight...Prevailing VFR. There is the potential for some fog,
but confidence is quite low for sub-VFR conditions to develop.
NE winds less than 5 kt, becoming nearly calm at some terminals.
Monday...VFR. E winds 8 to 12 kt. High confidence.
Outlook...
Monday night and Tuesday...Prevailing VFR for most TAF sites.
MVFR or IFR possible (30-60% chance) with low clouds, and brief
visibility restrictions in rain showers.
Tuesday night through Thursday...30 to 60 % chance of periods of
MVFR or IFR conditions with rain showers.
&&
.MARINE...
Sub-Small Craft Advisory conditions tonight through Monday. East
to northeast winds around 10 kt tonight, increasing to 10 to 15
kt with gusts up to 20 kt on Monday. Seas 2 to 3 feet tonight,
building to 3 to 4 feet on Monday.
Outlook...
Tuesday through Wednesday night...SCA conditions are likely
(60% or more) for at least a portion of this period. Areas south
of Great Egg Inlet are likely to see SCA conditions develop the
earliest, with winds at or above 25 kt possible as early as
pre-dawn Tuesday. Seas above 5 feet are likely to develop along
the coast by late Tuesday. Main period of concern for the
Delaware Bay is during the day on Tuesday and primarily due to
winds at or just above 25 kt.
Thursday...Increasing chance (80% or higher) that winds and seas
will subside below SCA criteria before Thursday morning.
Rip Currents...
For today, winds become more southerly around 10-15 mph.
Breaking waves will be around 1-2 feet with an easterly swell
around 7-8 seconds. Due to winds becoming more shore parallel
and breaking wave heights slightly lower, a LOW risk for the
formation of dangerous rip currents is forecast.
For Monday, the winds back to easterly at around 10 to 15 mph and
breaking waves increase to around 2 to 3 feet with a continuing
easterly swell around 8 seconds. Due to the winds becoming onshore
along with building wave heights the risk for dangerous rip
currents is expected to increase to a MODERATE risk for all of
the New Jersey Shore and Delaware Beaches.
For specific beach forecasts, visit weather.gov/beach/phi
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.
&&
$$
SYNOPSIS...Johnson
NEAR TERM...MPS
SHORT TERM...Johnson
LONG TERM...Johnson
AVIATION...Johnson/MPS
MARINE...Johnson/MPS

NWS PHI Office Area Forecast Discussion