449
FXUS61 KPHI 052317
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
617 PM EST Wed Feb 5 2025

.SYNOPSIS...
A low pressure system and its associated fronts cross the
region late tonight through Thursday night, bringing a slew of
wintry precipitation. After that, high pressure looks to briefly
return for the end of the week before our active pattern
returns and the next disturbance approaches for the weekend.
Another storm system may then affect our region toward the
middle of next week.

&&

.NEAR TERM /THROUGH THURSDAY/...
615 PM...Latest analysis depicts a broad area of high pressure
extending from the Great Lakes region east and southeast through
the mid Atlantic. Stalled front aloft has helped focus mid and
high clouds, and virga, across our southern zones but not really
expecting much in the way of precip until very late this evening
into the overnight. In fact, with the early evening update we
delayed the onset slightly based on latest trends in short term
model guidance as well as observations. Previous discussion
follows below.

Tonight, a low pressure wave starting to form over the mid-
section of the country presently will head east northeastward
toward us, with warm advection precip overspreading the area
ahead of it. Temps fall below freezing most areas before or
during onset of precip. Thus, expect snow likely beginning in
southern areas before midnight, spreading northward after
midnight. As the warm advection increases aloft, warming temps
will result in a change to sleet and then freezing rain from
south to north, with a change from freezing rain to rain from
southeast to northwest. That`ll bring up to an inch of snow and
sleet across the region late tonight into early Thursday, with
highest amounts north, and up to 2 tenths of an inch of ice from
freezing rain, with highest amounts well inland. Precip
probably doesn`t actually change to plain rain in the Poconos
before ending, in fact, but elsewhere, most areas should get
above freezing. Most precip ends around midday, but expect
lingering drizzle and mist thru the afternoon thanks to moist
low levels over cold ground and little wind to clear it out.
Highs 30s northwest of I-95, 40s southeast of I-95.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
A cold front sweeps through on Thursday Night, and although it will
mainly be moisture starved, a few showers cannot be ruled out
for South Jersey and Delmarva. Slightly drier airmass begins to
work in for Friday, with skies trying to clear out late Thursday
Night. Temperatures will generally be in the 30s for lows.

Friday is shaping up to be a rather nice day as the region will be
in between two systems. A secondary, reinforcing dry cold front will
move in early in the day, with winds picking up in the wake of the
front. Gusts will be around 20-30 MPH through the mid afternoon.
Temperatures get into the upper 30s/low 40s north of Philadelphia,
with mid to upper 40s from the city on south. Could potentially see
low 50s in southern Delmarva.

A brief period of high pressure moves in for the evening as winds
drop off quickly with the gradient weakening. Should be quiet
through Friday Night, with lows dropping into the 20s region-
wide.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
An active pattern is expected through the middle of next week with a
series of systems moving in, bringing the potential for more rain,
snow, and ice.

First system comes through late Saturday into Sunday. The weekend
will start out quiet though as high pressure moves offshore. An
area of low pressure looks to develop over the Ohio River
Valley on Saturday morning, pushing towards our region on
Saturday Night. Warm-air advection ramps up ahead of the low,
with precipitation overspreading the region on Saturday
afternoon. The majority of precipitation looks to come through
Saturday night, which could be favorable for more snow or
freezing rain/ice, especially north and west of the I-95
corridor. Areas south and east of the I-95 corridor could start
as snow but should see a quick change to rain. Highest
uncertainty in terms of precipitation type will be right along
the I- 95 corridor. Still a lot to iron out with timing and
track of the surface low.

Sunday/Monday look rather quiet with high pressure filtering in.
Sunday will feature temperatures near/above normal with a period of
below normal temperatures on Monday with highs only getting into the
mid to upper 30s.

Both global and deterministic guidance hint at a winter storm for
the middle of next week. Still 6-7 days out though but the signal is
there for at least some snow. The 13z NBM Probability of 4+ inches
of snow ending 00z Thursday is around 40-60% region-wide. The global
ensembles are a bit less enthusiastic but still show potential for
impactful snowfall. Temperatures through the middle of next week
look to be below normal.

&&

.AVIATION /23Z WEDNESDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Tonight...VFR conditions to start but IFR conditions developing
from south to north as a mix of precipitation moves in...mainly
after midnight. Dominate precipitation type is expected to
begin as snow, before gradually changing to sleet and then
freezing rain. However, multiple precipitation types occuring
simultaneously is likely. Winds becoming southeasterly around
5-10 kts. Moderate confidence in overall pattern, low confidence
in timing of precipitation type and category changes.

Thursday...IFR or quickly becoming IFR with steady mixed precip
changing to rain before tapering off to mist and drizzle for
the afternoon. Cigs and vsby both impacted and likely down at
IFR levels especially in the afternoon after steady precip
tapers off.

Outlook...

Thursday Night...IFR/MVFR CIGs possible for the first half of the
night, lifting to VFR late.

Friday...VFR. Gusty west/northwest winds expected with a brief
period of 20-30 kt gusts.

Friday Night...VFR. No significant weather.

Saturday...Primarily VFR, though rain/snow showers move through
later in the day.

Saturday Night...Sub-VFR conditions expected with all precipitation
types possible.

Sunday through Monday...VFR. No significant weather.

&&

.MARINE...
Conditions are anticipated to remain below Small Craft Advisory
criteria through tonight. Northwesterly winds continue to
diminish from south to north early this morning, and seas are
below 5 feet. The winds today will be light from the northwest
and north, before becoming more from the northeast or east later
in the day. Tonight, winds become east to southeasterly and
begin to increase once again to around 10-15 knots with gusts up
to 20 knots. Rain/snow/sleet precipitation mix progresses
northward through the night. Seas remain around 2-4 feet.

For Thursday, marginal SCA conditions are possible, with gusts
possibly up around 25 kts and seas possibly reaching 5 feet, but
confidence at this time is low.

Outlook...

Thursday Night...A Small Craft Advisory is in effect for all ocean
zones as seas around 5 feet are expected. Sub-SCA conditions
expected on Delaware Bay.

Friday...SCA conditions possible (50-60% chance) as wind gusts of 25-
30 kt are possible during the daytime.

Friday Night through Saturday Night...No marine headlines expected.

Sunday through Sunday Night...SCA conditions possible (40-50%
chance) with wind gusts nearing 25 kt.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Winter Weather Advisory from 11 PM this evening to 1 PM EST
     Thursday for PAZ060>062-101>103-105.
     Winter Weather Advisory from 11 PM this evening to 10 AM EST
     Thursday for PAZ070-071-104-106.
     Winter Weather Advisory from 11 PM this evening to 3 PM EST
     Thursday for PAZ054-055.
NJ...Winter Weather Advisory until 8 AM EST Thursday for NJZ016-
     021>023.
     Winter Weather Advisory from 11 PM this evening to 1 PM EST
     Thursday for NJZ001-007>009.
     Winter Weather Advisory from 11 PM this evening to 10 AM EST
     Thursday for NJZ010-012-013-015-017>020-027.
DE...Winter Weather Advisory until 8 AM EST Thursday for DEZ001>003.
MD...Winter Weather Advisory until 8 AM EST Thursday for MDZ012-015-
     019-020.
MARINE...Small Craft Advisory from 6 PM Thursday to 6 AM EST Friday for
     ANZ450>455.

&&

$$

SYNOPSIS...MJL/RCM
NEAR TERM...Fitzsimmons/RCM
SHORT TERM...Hoeflich
LONG TERM...Hoeflich
AVIATION...Fitzsimmons/Hoeflich/RCM
MARINE...Hoeflich/RCM