834
FXUS61 KPHI 132305
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
605 PM EST Mon Jan 13 2025

.SYNOPSIS...
A cold front will move across the area through this evening and
offshore tonight. High pressure builds cross the southeast for
Tuesday through Thursday, keeping west to northwest flow across
the area. A cold front will weaken as it approaches Thursday,
then a warm front lifts north of the area Friday. A cold front
is expected to move across the area later Saturday into Saturday
night. A coastal low may impact the area later Sunday into
Sunday night.

&&

.NEAR TERM /THROUGH TUESDAY/...
Just minor tweaks made to the forecast, but overall, it is on
track.

The cold front is crossing the area at this hour, and will move
off the coast around midnight. This will result in mostly clear
skies after midnight. In wake of the front, should observe an
increase in surface winds where winds may occasionally gust up
to 20 mph overnight. Overnight low temps will range from the
teens to mid 20s across the region so when factoring in the
wind, we`ll likely have wind chills in the single digits to low
teens by Tuesday morning.

For Tuesday, cold Canadian high pressure will build out of the
High Plains, slowing inching toward the Mid-Atlantic region.
This will be the start of a reinforcing cold airmass through
mid-week. Temps will struggle to reach the freezing mark with
many locations topping out in the 20s to low 30s for highs under
partly to mostly cloudy skies. A shortwave aloft will also be
passing through in the afternoon, so may see some isolated
flurries late in the day north and west of the I-95 corridor.
Confidence in this is low as the airmass behind the front is
quite dry, so have left this potential out of the forecast grids
at this time. In addition to the cold temps, a modest pressure
gradient will set-up over the region. So, Tuesday will be quite
breezy with wind gusts up to 30-35 mph possible. This should
result in wind chills remaining in the teens for Tuesday
afternoon.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
For Tuesday night through Wednesday night, high pressure will
build across the Ohio River Valley and weaken as it approaches
the southeastern states. Meanwhile, low pressure drifts offshore
of the Canadian Maritimes. In between the two, a tight pressure
gradient will keep a steady west to northwest flow across the
area. Winds will likely gust 20-30 mph or higher at times
through Wednesday. Winds will weaken some by Wednesday night.

For Thursday, high pressure dissipates to our south, as a cold
front weakens as it approaches from the west. As the front
approaches and weakens, there is a chance for snow showers to
move into the western half of the area during the afternoon.

Temperatures for Tuesday night through Thursday will be below
normal.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
On Friday, a warm front will lift north of the area, allowing
temperatures to moderate back above normal. As we move into
Saturday into Saturday night, a cold front is expected to move
across the area. Most areas will be warm enough for any
precipitation that starts our as snow to change over to rain
during the day Saturday. The front will shift offshore by
Saturday night, then there is a chance a developing coastal
storm could affect the area later Sunday into Sunday night.

&&

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

Tonight...VFR with mostly clear skies. Westerly winds around
5-10 kt, with gusts up to 20 kt increasing in frequency after
midnight. High confidence.

Tuesday...VFR. Mostly clear skies early with SCT/BKN ceilings in the
afternoon. West-northwest winds around 10-20 kt with gusts up
to 25- 30 kt. High confidence.

Tuesday Night...VFR. Gusts gradually weakening as the night goes
on, though still will be around 20-25 kt out of the
west/northwest. High confidence.

Outlook...

Wednesday through Wednesday night...Generally VFR. Gust winds
20-30 knots Tuesday through Wednesday.

Thursday-Friday night...Generally VFR.

Saturday...Sub-VFR conditions possible with a chance of showers.

&&

.MARINE...
A Small Craft Advisory is in effect for all Atlantic coastal waters
including the Delaware Bay beginning tonight through Tuesday.

West-southwest winds up to 20 kt this evening will shift to
west- northwest tonight around 15-25 kt with gusts up to 30 kt.
These wind conditions will persist through Tuesday. Seas around
4-6 feet. Fair weather skies expected.

Due to the combination of cold air/water temperatures, gusty winds
and enhanced seas, freezing spray will be likely on both the
Atlantic coastal waters and Delaware Bay on Tuesday.

Outlook...

Tuesday night...Gale Warning in effect. Light freezing spray likely.

Wednesday-Wednesday night...Light freezing spray likely in the
morning. Small Craft Advisory Conditions likely.

Thursday-Friday night...Conditions expected to be below advisory
levels.

Saturday...Small Craft Advisory conditions possible.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory from 11 PM this evening to 6 PM EST
     Tuesday for ANZ430-431-454-455.
     Gale Warning from 6 PM Tuesday to 6 AM EST Wednesday for
     ANZ430-431-450>455.
     Small Craft Advisory until 6 PM EST Tuesday for ANZ450-451.
     Small Craft Advisory until 6 PM EST Tuesday for ANZ452-453.

&&

$$

SYNOPSIS...Robertson
NEAR TERM...DeSilva/Hoeflich
SHORT TERM...Robertson
LONG TERM...Robertson
AVIATION...DeSilva/Hoeflich/Robertson
MARINE...DeSilva/Hoeflich/Robertson