419
FXUS61 KPHI 120616
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
216 AM EDT Tue May 12 2026

.WHAT HAS CHANGED...
The rainfall totals for Wednesday into Thursday have decreased
some.

&&

.KEY MESSAGES...
1. A drier airmass spreads into the region today. A Frost
Advisory continues for the southern Poconos through 8 AM today.

2. Showers (a few thunderstorms possible) Wednesday afternoon and
Wednesday night, then some showers continuing into Thursday morning.

3. Becoming very warm to potentially hot this weekend through early
next week.

&&

.DISCUSSION...
KEY MESSAGE 1...A drier airmass spreads into the region today.
A Frost Advisory continues for the southern Poconos through
8 AM today.

Now that the cold front has moves through, high pressure will build
across the area today. A cooler and drier airmass has arrived
across the northern parts of the area and dew points and
temperatures continue to trend down. As winds will remain light,
there still remains the possibility of some patchy frost
formation across Carbon and Monroe counties. We`ll continue the
Frost Advisory until 8 AM.


KEY MESSAGE 2...Showers (a few thunderstorms possible) Wednesday
afternoon and Wednesday night, then some showers continuing into
Thursday morning.

An upper-level trough moves into the Eastern U.S. Wednesday into
Thursday before lifting out Friday into Saturday. This trough looks
to become a closed low over the Mid-Atlantic and Northeast by
Thursday. The details will depend on the timing of the closed low
and its track, however as it arrives showers will be on the increase
Wednesday afternoon and especially Wednesday night before tapering
off into Thursday as a cold front shifts offshore.

The low-level warm air advection will increase ahead of the trough
during Wednesday as will the low to mid level flow. This will result
in an increase in forcing for ascent, and some instability should
develop ahead of the main forcing. A warm front should also lift
across our area Wednesday with some ascent associated with it. As a
result, showers increase Wednesday afternoon from west to east with
forcing peaking Wednesday night as the cold front arrives. Guidance
continues to show some instability which could be enough to support
a few thunderstorms. The intensity of any thunderstorms however will
depend on the magnitude of the instability and shear. Given the
later arrival time of the showers, instability looks to be rather
weak with an isolated severe thunderstorm risk well to our west
Wednesday afternoon.

The main forcing shifts to our east and northeast Thursday with the
bulk of the showers ending. However, the presence of the closed low
especially overhead with the core of the cold air aloft could result
in additional shower development on Thursday before the system
departs our region. Rainfall totals look to be on the lighter side
(0.20-0.50 inches), although locally higher amounts are possible if
more organized showers/thunder occur.


KEY MESSAGE 3...Becoming very warm to potentially hot this weekend
through early next week.

As the closed low continues to depart going into the weekend, a ridge
starts to build across the East this weekend and into early next
week. This along with high pressure centered offshore will result in
southerly flow advecting in a much warmer air mass across our area.
As a result, high temperatures get into the 70s to low 80s Saturday
with widespread 80s on Sunday. Given a southerly wind component
though, it should be cooler along the coast. The heat looks to build
into early next week with even hot conditions possible. Highs Monday
are forecast to be in the 80s with even some areas reaching 90
degrees (again cooler along the coast). Given the presence of the
ridge aloft, no precipitation is currently anticipated. However near
the edge of the ridge/surface high, there is a slight chance (20
percent) for convection near the southern Poconos Monday afternoon
and evening.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas...

Thru 12Z... VFR. SCT-BKN mid level clouds across NJ/DE moving
offshore. Light West to Northwest winds most sites. High confidence.

Today... VFR. High clouds expected later today. North to Northwest
winds 5 to 10 knots becoming West this afternoon then South to
Southwest by early evening. High confidence.

Tonight... VFR. SCT-BKN high clouds. Light South winds expected.
High confidence.

Outlook...

Wednesday...VFR conditions during most of the day, then conditions
lower to MVFR or IFR mainly at night as showers arrive from west to
east. A few thunderstorms possible late in the afternoon and
evening. Southerly wind gusts up to 25 knots during the afternoon.

Thursday...Times of sub-VFR conditions with some showers possible,
otherwise VFR. West-northwest wind gusts to 20 knots possible.

Friday...Mostly VFR. An isolated shower possible.

&&

.MARINE...
High pressure across Pennsylvania and New Jersey this morning will
move offshore this afternoon. Fair weather is expected today and
tonight. Winds will begin the day mostly North or Northwest on the
waters and will remain light as the high moves overhead. Later
today winds will turn Southwest or South and increase to 5 to 10
knots. Tonight, winds speeds will further increase to 10 to 15
knots with gusts around 20 knots. Conditions will remain below
SCA levels but seas will increase close to 4ft by Wednesday
morning.

Outlook...

Wednesday...Small Craft Advisory conditions are probable.

Thursday through Saturday...The conditions are anticipated to be
below Small Craft Advisory criteria.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Frost Advisory until 8 AM EDT this morning for PAZ054-055.
NJ...None.
DE...None.
MD...None.
MARINE...None.

&&

$$

DISCUSSION...Gorse/OHara
AVIATION...Gorse/OHara
MARINE...Gorse/OHara