582
FXUS61 KPHI 141425
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
1025 AM EDT Mon Apr 14 2025

.SYNOPSIS...
A cold front will pass through the region late tonight. A
secondary cold front crosses through late Tuesday night. High
pressure returns on Wednesday and persists into Friday. Another
disturbance and sequence of fronts approach the area late Friday
into next weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
A band of very light rain or sprinkles is moving eastward across
the northern two-thirds of New Jersey late this morning as
warm air is advected from the southwest ahead of a closed low
over the Great Lakes. The rest of the afternoon will be mild
with clouds mixing with some sunny breaks.

The closed low over the Great Lakes will shift into southern
Ontario and Quebec by this evening, dragging a cold front across
the Mid Atlantic. Anticipating widespread showers between 00Z
and 06Z across the region with this frontal passage. Embedded
thunderstorms are possible south of the I-78 corridor with the
greatest chance across the Delmarva and southern NJ. Forecast
soundings suggest that the greatest instability will be elevated
in nature mainly due to the loss of diurnal heating and a
strong surface inversion. However, there will be a decent amount
of deep layer shear in place, around 40-50 kts in the 0-6km
layer. There is a marginal risk for damaging winds and hail
across Delaware and the eastern shore of Maryland as shown on
SPC`s Day One outlook.


&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
By Tuesday, the area will be fully situated under the upper level
trough and influenced by cyclonic flow. With enough moisture still
hanging around and with a few impulses spiraling around the upper
level low, cannot rule out a few showers during the day on Tuesday
(best chance will be near the coast in the morning and in the
Poconos in the afternoon). With the afternoon round, cannot rule out
a few convective cells capable of producing some small hail/graupel
as there will be some instability combined with favorable low and
mid-level lapse rates, along with lower freezing levels. Best
dynamics for a few power showers will be for the Poconos and far
northern New Jersey. Not expecting severe weather though given low
instability and shear.

With a mix of sun and clouds around, expect highs in the upper 50s
to mid 60s and gusty winds upwards of 30 to 40 mph in the afternoon.
A stronger impulse will cross through the area on Tuesday night,
which will result in a secondary cold front to pass through at the
surface. This front will pass through dry however. Temperatures on
Tuesday Night will be in the upper 30s and low 40s, with winds
staying elevated, but much less compared to daytime Tuesday and
Wednesday.

Once the secondary front passes, a cooler/drier airmass will return
to the region with gusty winds continuing into Wednesday. Expect
wind gusts to be a touch less than the day prior, most likely in the
25-35 MPH range. Highs will be seasonably cool for mid-April, with
highs only in the 40s and 50s under a mix of sun and clouds.

Winds diminish quickly on Wednesday Night as the gradient weakens
with high pressure building in. While skies will be mostly clear,
winds will stay elevated around 10 MPH, enough to prevent
temperatures from bottoming out completely. Lows will be in the mid
to upper 30s, with some spots along and north of I-78 getting near
or below freezing. This will be the coldest night of the week.
Thinking it will dry enough to prevent frost from developing, but if
temperatures fall much further than currently forecast, we may need
some freeze headlines for areas where the Frost/Freeze program is
active (south of I-78). This will be the main thing to watch during
the middle of the week.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
The Thursday through Friday period still appears to remain quite
benign as expansive high pressure settles over much of the Eastern
US. This will allow dry conditions and sunny/clear skies to occur
for much of the period, before increasing clouds return later on
Friday. For highs on Thursday and Friday, we`ll begin to see some
moderation with highs in the upper 50s to low 60s on Thursday,
increasing to the mid to upper 60s for Friday. Lows on Thursday
Night should be in the mid to upper 30s/low 40s.

Moving forward into Friday night and next weekend, the period
overall looks to be a bit unsettled. The next low pressure system
will begin to approach as it tracks through the Great Lakes. This
will cause another sequence of fronts to cross through the area.
General consensus is that a warm front will cross though late Friday
night into Saturday with a cold frontal passage on Saturday night
into Sunday. Accompanied with these fronts will likely be some rain
showers so have included a 20-50% chance of showers for the Friday
night through Saturday night period. After the cold frontal passage,
we should begin to dry out for Sunday. In terms of temperatures,
anticipate above normal temperatures throughout the period, with
peak temperatures occuring on Saturday which look to be well into
the 70s. Temperatures for the back half of the weekend and into next
week look to go back toward more seasonal levels with the passage of
the cold front on Saturday Night.

&&

.AVIATION /14Z MONDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

This afternoon...VFR. SCT/BKN clouds around 10 kft. Wind south
to southwest 5-10 kts.

Tonight...MVFR conditions in rain showers and perhaps a few
thunderstorms. Southwest winds 10 kts or less with stronger
gusts possible in thunderstorms across the Delmarva.

Outlook...

Tuesday...Primarily VFR, though sub-VFR conditions possible with
showers (20-40% chance SHRA). Gusty west winds 15-20 kt gusting 25-
35 kt.

Tuesday Night...VFR. Westerly wind gusts around 20 kt.

Wednesday...VFR. Westerly wind gusts 20-30 kt.

Wednesday Night through Friday..VFR. No significant weather.

&&

.MARINE...
Winds and seas will stay below Small Craft Advisory criteria
through tonight. Rain showers likely with an isolated
thunderstorm possible late this evening into the early overnight.

Outlook...

Tuesday through Wednesday...A Small Craft Advisory is in effect
beginning at 10 AM on Delaware Bay and 1 PM on the ocean zones.
Westerly wind gusts of 25-30 kt expected with a few higher gusts
possible, but not getting to gale force. Seas 3 to 5 feet.

Wednesday Night...The Small Craft Advisory may need to be extended
as wind gusts diminish but could remain near 25 kt. Confidence was
not high enough to extend this far yet.

Thursday through Friday...No marine headlines expected.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory from 10 AM Tuesday to 6 PM EDT Wednesday
     for ANZ430-431.
     Small Craft Advisory from 1 PM Tuesday to 6 PM EDT Wednesday
     for ANZ450>455.

&&

$$

SYNOPSIS...DeSilva/Franklin/Hoeflich
NEAR TERM...Franklin/MJL
SHORT TERM...DeSilva/Hoeflich
LONG TERM...DeSilva/Hoeflich
AVIATION...Franklin/Hoeflich/MJL
MARINE...Franklin/Hoeflich/MJL