423
FXUS61 KPHI 091025
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
625 AM EDT Mon Mar 9 2026

.WHAT HAS CHANGED...
Dense fog advisories cancelled for land areas as fog has already
started to scatter out.

&&

.KEY MESSAGES...
1. Dense fog has already begun scattering out, and should
dissipate entirely not long after sunrise.

2. Warm temperatures expected through Wednesday, possibly record
breaking in some spots. Dense fog possible at night.

3. A strong cold front will cross through the region late Wednesday
into Thursday, bringing the potential for widespread showers and
possibly some thunderstorms.

4. Seasonable temperatures late week into the weekend with a couple
disturbances bringing some more unsettled weather.

&&

.DISCUSSION...
KEY MESSAGE 1...Dense fog has already begun scattering out, and
should dissipate entirely not long after sunrise.

While we had areas of dense fog develop overnight, they appear
to already be starting to scatter out, possibly due to the drier
air behind the cold front finally infiltrating the region. Thus,
dense fog advisories for land areas have been cancelled, with a
Special Weather Statement issued for lingering patches until 9
AM. After the remaining fog burns off, plenty of sunshine will
push temps back well into the 60s to near 70 once again.


KEY MESSAGE 2...Warm temperatures expected through Wednesday,
possibly record breaking in some spots.

The region will be beneath a fairly benign upper pattern through mid-
week. At the surface, high pressure will be stationed out over the
western Atlantic. This high will essentially act as a heat pump,
bringing very mild temperatures to the region as much as 20 to 25
degrees above average! Daytime highs will mainly be in the low to
mid 70s for most, with 60s in the Poconos with lows in the 40s and
50s. The exception is along the coast, where highs will likely only
top out in the 50s each day with lows in the 40s due to cold
Atlantic water temps. As of now, records look to be safe on Tuesday,
but there are some low hanging records on Wednesday that could be
broken in some spots (see more in the Climate Section below). Given
the light flow, there should be a hefty sea breeze that occurs each
day as well.

In addition, there is fairly high confidence that there will be an
abundance in fog development at night given increasing dew points
and cool ocean temperatures. This will be mainly near coastal
locales, but will spread inland overnight.


KEY MESSAGE 3...A strong cold front will cross through the region
Wednesday night into Thursday, bringing the potential for widespread
showers and possibly some thunderstorms.

By later Wednesday, the upper pattern will become more much active
as a potent trough over the central US begins to work its way east.
Broad forcing for ascent is likely to begin overspreading the region
during the day on Wednesday, leading to the return of some showers
mainly north and west of the I-95 corridor. Elsewhere, should remain
mostly dry.

Continuing into Wednesday night and Thursday, height falls with the
trough are expected to maximize with the trough axis reaching the
area by Thursday afternoon. The associated surface low is expected
to pass well north of the area, cutting up through the Great Lakes
and into southern Canada. A trailing cold front is then expected to
cross through the region early Thursday morning. At this point,
categorical PoPs are expected for Wednesday night before gradually
decreasing on Thursday. Most guidance continues to depict a line of
showers moving through the region. While the timing of this is at
night, this should limit the potential for severe weather, however
guidance does indicate the potential for some elevated instability.
For this reason, have included a slight chance of thunder mentioning
for Wednesday night. Also, a strong background wind field is
expected so while gusty winds may not be in direct correlation from
precipitation, winds will still likely be gusty throughout the
period. Behind the front, shower activity is expected to wane,
however, a few rain or snow showers may linger as colder air filters
in late in the day.


KEY MESSAGE 4...Seasonable temperatures late week into the weekend
with a couple disturbances bringing some more unsettled weather.

By late week and into the weekend, a much more seasonable airmass is
expected to return to the region. During this time, a few weak
disturbances are expected to pass north of the area, which may
impact parts of the region. The first would be later Friday into
Friday night and the second would be Saturday night into Sunday. For
now, PoPs are only in the 20-40% range, but a period of rain and/or
snow showers may be possible at times across the northern half of
the area.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Today...VFR after any lingering fog breaks mid-morning. Winds
from the SSW around 5 to 10 kts. Maybe a few gusts 15-20 kts in
the afternoon, most likely at ABE. Moderate confidence.

Tonight...VFR to start, then low clouds/fog may start creeping
inland from the coast, with MIV/ACY most at risk. Winds
becoming light/variable. Low confidence.

Outlook...

Tuesday through Wednesday...VFR expected during the day, with sub-
VFR conditions possible at night due to BR/FG. A slight chance for
showers on Wednesday.

Wednesday night through Thursday...Sub-VFR conditions likely with
periods of showers and a slight chance of thunderstorms. Winds may
occasionally gust in excess of 30 kt on Thursday.

Thursday night through Friday...VFR. Winds may occasionally gust up
to 25 kt. A chance of rain/snow showers at RDG and ABE.

&&

.MARINE...
Marine Dense Fog Advisories continue for all waters thru 6 PM
this evening, and may need further extension through tonight.
Winds and seas will remain sub-SCA thru tonight.

Outlook...

Tuesday through Tuesday night...Sub-SCA conditions expected. Winds
generally less than 15 kt and seas around 2-3 feet. Dense marine fog
likely.

Wednesday through Wednesday night...SCA conditions likely to develop
late in the day. Wind gusts up to 20-30 kt. Seas around 2-4 feet
during the day building to 4-7 feet at night. Dense marine fog
possible with a chance of rain showers.

Thursday through Thursday night...SCA conditions likely, diminishing
into Thursday night. Wind gusts up to 20-30 kt. Seas around 4-7 feet
during the day, lowering to 2-4 feet at night. Rain showers likely.

Friday...SCA conditions possible. Wind gusts up to 25 kt with seas
around 2-4 feet.

&&

.CLIMATE...
Near record high temperatures are forecast for Wednesday, March
11th. Records for our climate sites are listed below:

Record High Temperatures: March 11
Site............................Record/Year
Allentown (ABE).....................73/2021
AC Airport (ACY)....................79/1967
AC Marina (55N).....................70/1879
Georgetown (GED)....................77/2021
Mount Pocono (MPO)..................66/1977
Philadelphia (PHL)..................74/2021
Reading (RDG).......................77/2021
Trenton (TTN).......................73/2021
Wilmington (ILG)....................74/2021

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Dense Fog Advisory until 6 PM EDT this evening for ANZ430-431-
     450>455.

&&

$$

DISCUSSION...Cooper/DeSilva/RCM
AVIATION...DeSilva/RCM
MARINE...DeSilva/RCM