335
FXUS61 KPHI 071910
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
310 PM EDT Mon Apr 7 2025

.SYNOPSIS...
A front remains south and east of our area through this afternoon as
a few weak areas of low pressure track along it through tonight. A
strong secondary cold front will then cross our area tonight as low
pressure strengthens across New England. High pressure builds in
Wednesday before shifting offshore Wednesday night. Low pressure
then arrives Thursday and Friday. This new low could linger near the
area through much of next weekend.

&&

.NEAR TERM /THROUGH TUESDAY/...
Through this evening, the area of steadier rain will continue to
shift off shore. Much of the region could still see very light
showers, but aside from the coast, not expecting anymore heavy
rain.

Attention then turns to the cold front which is expected to
sweep through the region overnight. Behind the front, expect dry
and windy conditions. Looking at the latest model soundings,
previous forecast still looks on track with maximum wind gusts
around 40 mph, with the strongest gusts between mid morning and
mid afternoon. As such, this still looks like we will be below
wind advisory thresholds.

Should have much less cloud cover tomorrow (as compared to
Monday), but locations, especially north and west of the fall
line could have mostly clouds conditions once stratocumulus
clouds develop in our region.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
High pressure centered near the Great Lakes Tuesday evening will
gradually push south and eastward towards Virginia by 12z Wednesday.
This will result in clearing skies and diminishing winds. However
since the center of the high looks to remain just to our south and
west, this should keep enough of a gradient in place to keep some
wind out of the NW of around 5-10 mph or so. Therefore, it will be a
cold night but not as cold as it otherwise would have been if winds
were to go calm. Generally expect lows ranging from the mid 20s to
around 30 except low 20s in the Poconos. We will issue a Freeze
Watch for most of our Delmarva counties (with the exception of the
Delaware Beaches and New Castle County DE) since the growing season
is considered to have officially started there. In the tier of zones
just to the north and east, the start date isn`t until the 11th.

A cool day with lighter winds (compared to Tuesday) will follow for
Wednesday as high pressure dominates bringing mainly sunny skies.
Expect highs mainly in the upper 40s to low 50s except low 40s in
the Poconos.

High pressure will eventually move off to the east of us Wednesday
night through Thursday as the next area of low pressure moves into
the eastern Great Lakes region. This will bring increasing clouds
with some rain likely by Thursday over portions of eastern PA
through Berks County northward through the Lehigh Valley and into
the southern Poconos. For these areas, POPs are 60 to 70 percent by
the afternoon. Also worth noting, there could be a little snow or a
wintry mix at the onset over the Poconos. Areas farther south and
east could also see some rain by later Thursday but POPs near and
south/east of the I-95 corridor are lower...generally around 20 to
40 percent. Expect highs Thursday mostly in the 50s except some low
60s into portions of Delmarva and 40s over the Pocono Plateau.




&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Summary...Moderating temperatures with highs returning to near
average for the end of the week into the weekend. It looks to turn
unsettled again however.

Synoptic Overview...As strong energy dives into the Ohio Valley, an
upper-level trough will amplify to our west late Thursday through
Friday. Some guidance continues to show this trough becoming closed
off as it arrives into the Mid-Atlantic region Friday night into
Saturday. If it closes off, it may linger nearby even on Sunday.
At the surface low pressure and its associated warm front approaches
Thursday night into Friday, then it may slow as it reaches the Mid-
Atlantic region later Friday through Saturday. The low should tend
to track northeastward and away from our area Sunday. The speed of
the surface low will depend on the strength and movement of the
upper-level trough that looks to close off.

In terms of the details, an initial period of rainfall is expected
by Thursday night into Friday as the upper level trough deepens and
pivots towards the coast while a low at the surface should be taking
shape near or just south of the area by later Friday. Then heading
into next weekend, an increasing number of model solutions show as
the trough aloft closes off, the surface low could become a
nor`easter centered either over the region or just offshore Saturday
morning. The system does look to continue to shift northeastward
through the day on Saturday but some precipitation may continue to
wrap around the low with the closed low overhead or near by.
Overall, the evolution of this entire system remains less certain at
this time range and therefore PoPs are held in the 40-70 percent
range Friday night through Saturday before decreasing to 30 percent
or less Saturday night into Sunday. Temperatures do look to be close
to average, although if a nor`easter does develop with strengthening
onshore flow then temperatures would end up cooler.

High pressure should eventually bring drier weather early next week.

&&

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

Today...Most sites are prevailing MVFR or IFR. Ceilings are
hovering right around 1k ft AGL, so have seen variability in the
flight category. Winds prevailing out of the NNE around 5-10
kt, but could go light and variable by late this afternoon.
Moderate confidence.

Tonight...Low clouds are expected to linger through the evening,
but should see those quickly erode as a cold front moves through
between 03 and 09Z. Then VFR through the remainder of the night.
Winds starting light and variable, but will be northwesterly
around 10 to 20 kt with and behind the cold front. Moderate
confidence.

Tuesday...VFR with only few to scattered mid level clouds. West
or Northwest winds 15 to 25 kt with gusts up to 35 kt.

Outlook...

Tuesday night through Wednesday...Winds diminish Tuesday night and
are not expected to be a significant issue Wednesday. VFR through
the period.

Thursday and Friday...Areas of sub-VFR conditions may develop with
increasing chances for showers, especially by the Thursday night
into Friday timeframe. South-southeast winds could become a little
gusty for a time Thursday.

Saturday...Rain/showers along with sub VFR conditions may linger.

&&

.MARINE...
Had some seas earlier hovering right around 5 ft, but those have
begun to diminish. Expect winds and seas to stay below Small
Craft Advisory criteria through this evening.

After midnight, a cold front will cross through the region,
bringing an abrupt shift to northwesterly winds. Winds will also
increase quickly, with gale force gusts expected to develop near
daybreak. Gale conditions are possible throughout the day on
Tuesday.

Outlook...

Tuesday night through Wednesday night...Gales diminish Tuesday
evening and the winds and seas are expected to be below Small Craft
Advisory levels by Wednesday morning. Conditions are expected to
then stay Sub SCA through Wednesday night.

Thursday...a period of Small Craft Advisory conditions will be
possible.

Friday...The conditions are anticipated to be below Small Craft
Advisory criteria.

Saturday...The potential exists for at least Small Craft Advisory
conditions but this will depend on the development and track of a
coastal low and this is currently uncertain.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...Freeze Watch from Tuesday evening through Wednesday morning
     for DEZ002-003.
MD...Freeze Watch from Tuesday evening through Wednesday morning
     for MDZ012-015-019-020.
MARINE...Gale Warning from 4 AM to 10 PM EDT Tuesday for ANZ430-431-
     450>455.

&&

$$

SYNOPSIS...Fitzsimmons/Gorse/RCM/Staarmann
NEAR TERM...Johnson
SHORT TERM...Fitzsimmons
LONG TERM...AKL/Fitzsimmons/Gorse
AVIATION...Fitzsimmons/Johnson
MARINE...Fitzsimmons/Johnson