509
FXUS61 KPHI 230831
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
431 AM EDT Sun Mar 23 2025

.SYNOPSIS...
High pressure builds in briefly for today as a low departs to
the northeast. The next system is forecast to move through
tonight into Monday. There is a brief break on Tuesday before
another system moves through Tuesday night into Wednesday. High
pressure then builds in for the end of the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Gusty northwest winds early this morning continue to gradually
diminish as temperatures continue to fall with a cold airmass
filtering in. Wake-up temperatures are expected to be in the upper
20s to mid 30s; the Poconos will be in the low 20s.

High pressure continues to build in through Sunday morning before
clouds increase in the afternoon ahead of the next system.
Precipitation is expected to hold off during the day, giving us a
dry forecast. Winds will become mostly calm by late morning and
early afternoon as well. Afternoon temperatures will only warm into
the upper 40s to low 50s.

High pressure will slide east Sunday evening, giving way to an
occluding low moving over the Great Lakes. Along the associated
frontal boundary with this system, a secondary low will begin to
form over the Appalachian range along the northern Blue Ridge
Mountains. As a result, a developing warm front will work its way
northward across the region overnight. Depending on how quickly this
warm front moves and how far north it gets during the overnight
period, we could get some wintry precip in some locations, mainly
for the higher elevations. Precip looks to enter the region around
midnight or so. At the moment, we do expect the warm front to
advance northward far enough so that much of the region will start
off as rain and stay that way through the duration of this system.
That said, areas along I-80 and points north and west are expected
to start off with some snow or wintry precip. As we work through the
overnight period, the warm front is likely to get hung up across the
Lehigh Valley, northwest NJ, and certainly the Poconos. A gradual
changeover to mostly rain could be rather stubborn for these
locations, particularly for the Poconos. Some hi res forecast
soundings show a warm nose developing over the Pocono Plateau as the
warm front attempts to advance northward, but surface temperatures
may cool down enough to stay right around or just below freezing. As
a result, some freezing rain could be part of a bit of wintry mix
early Monday morning for the higher elevations of Carbon and Monroe
county. Still quite a bit of uncertainty with how this warm front
will behave, but some light ice accretion is possible early Monday
morning. At this time, decided to still hold off on issuing a Winter
Weather Advisory for Carbon and Monroe counties given the high
uncertainty across a number of factors. Elsewhere, mainly rain south
and east of I-78. Overnight lows will be in the low 30s to low 40s,
but temperatures throughout the period do look to creep up warmer
towards daybreak Monday given the warm air advection from the warm
front.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
The last rains and clouds from the system from the near term will be
moving across the area Monday. The rains will slowly end from west
to east during the day but categorical pops to the east will decease
only to likely by days end while pops will go back below chance for
western/northern areas by evening. It will remain mild Monday with
highs in the mid.upper 50s across the north and low 60s for other
areas. Fair weather will return overnight with decreasing clouds.
Lows will be in the 40s S/E and 30s N/W.

Tuesday will feature dry weather with a ridge of high pressure
moving towards the region. Temperatures will be a bit cooler than
Monday, but readings will still be above normal with highs around 50
for the north and closer to 60 for Philadelphia and Delmarva.

The upper pattern continues to bring systems from the Ohio Valley
region into the Middle Altantic area. Another such system arrives
Tue night and continues into Wednesday. We`ll have chance pops for
showers with this low/front that will cross the area. Some cooler
temps N/W Tue night will be around when the precip arrives, so snow
is possible for the southern Poconos, Lehigh Valley and north NJ.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
The upper trough across the area Wednesday will be exiting the area
by late week. After some showers Wednesday, it`ll be dry for Thursday
and probably much of Friday. The latest 00Z GFS is showing some showers
for Friday which is at odds with the previous NBM which is dry. We`ll
write a dry fcst for Friday now but wouldn`t be surprised if a few
showers develop. More rains probable later Sat and into Sunday. Hopefully
we can get some totals which will help reduce the drought across
the area.

Temperatures will start the long term close to normal. As we get closer
to the weekend, readings will warm to about 10 degrees above normal
by Sat. It`ll remain cooler for the shore and the southern Poconos
though. Highs in most spots in the low/mid 60s with some upper 60s
for southern Delaware.

&&

.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
Rest of tonight (through 12Z)...VFR with clearing skies. West-
northwest winds becoming more northwesterly around 10-15 kt and
gusts up to 25 kt, diminishing after midnight. High confidence.

Sunday...VFR. West/northwest winds around 5-10 kt. High confidence.

Sunday night...Sub-VFR conditions possible with rain and fog
possible. Rain/snow mix possible for northwestern TAF sites
(ABE/RDG). Low confidence.

Outlook...

Monday...Rains and fog with sub-VFR expected. Improving late.

Monday night/Tuesday... VFR expected.

Tuesday night/Wednesday... Mostly VFR but lower conditions
possible in showers.

Wed night/Thursday... VFR expected.

&&

.MARINE...
Small Craft Advisory remains in effect for all marine zones this
morning with winds and seas expected to diminish below criteria by
mid-morning. A bit of a lull through Sunday afternoon. Come Sunday
night, as the next system approaches, SSE winds will begin to ramp
up. Another Small Craft Advisory may be needed with gusts forecasted
to climb back into the 25-30kt range.

Outlook...

Monday...SCA winds and seas Monday before winds subside during
the afternoon and seas by evening. Rains ending by evening.

Monday night...sub-SCA with Fair weather.

Tuesday thru Friday... Conditions look to remain below SCA criteria
most of the time. Winds may approach G25 kts Thu night however.
Scattered showers Wednesday, then mainly Fair into Friday.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 7 AM EDT this morning for ANZ430-
     431.
     Small Craft Advisory until 11 AM EDT this morning for
     ANZ450>455.

&&

$$

SYNOPSIS...Guzzo
NEAR TERM...MJL
SHORT TERM...OHara
LONG TERM...OHara
AVIATION...MJL/OHara
MARINE...MJL/OHara