077
FXUS61 KPHI 261956
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
356 PM EDT Sat Apr 26 2025

.SYNOPSIS...
A cold front will track through the area this afternoon moving
offshore by this evening. High pressure begins to build back into
the area on Sunday and will be in control through Tuesday. A warm
front approaches by Tuesday night, followed by another cold front on
Wednesday. High pressure briefly returns for Thursday, before
another low pressure and its associated fronts arrive for Friday and
into the start of next weekend.

&&

.NEAR TERM /THROUGH SUNDAY/...
A cold front, attached to low pressure across southern Canada, will
cross the area over the next several hours. Limited daytime heating
has not produced much in the way widespread instability, but still
enough for a few tstms into the evening. We`ll continue with the
mainly shower wording and keep scattered tstms too. Gusty winds and
small hail are possible with any tstm. Once the front passes, the
rains decrease and gusty West winds develop. clouds will start to
decrease for the West/Northwest areas by sunset.

Tonight, the cold front moves offshore tonight and drier, cooler air
begins to overspread the region. On A gusty west wind, temperatures
will drop through the 60s/50s reaching lows in the mid/upper 40s in
mots spots by dawn. A couple upper 30s across the southern Poconos
are possible. Clouds will diminish most areas with some transient
Sc for the N/W areas.

For Sunday, high pressure drops down into the Great Lakes and begins
to build towards our region. Drier and cooler air continues on a
gusty NW winds which will gust to around 30 mph at times. Skies will
range from mostly sunny across the southern/eastern areas to partly
clouds north/west.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
The vertically stacked low over the Gulf of Maine departs the
Northeast on Sunday night as the upper level ridge shifts east
through Tuesday. At the surface, high pressure over the Great Lakes
will shift just to our south on Monday before moving off the coast
on Monday night where it will persist through Tuesday.

As a result, clear skies at night and sunny skies during the day are
expected for Sunday night and Monday with light northwest flow
around 10-15 mph. Lows on Sunday night will mainly be in the 40s
with highs on Monday in the upper 60s to mid 70s. Surface flow
begins to back to the south-southwest on Monday night as the
position of the high shifts off the coast. So while skies remain
mostly clear Monday night, low temperatures will be a few degrees
warmer than the night prior ranging from the mid 40s to low 50s. An
increase in cloud cover is expected on Tuesday as our next weather
system approaches the region from the west. Expect most the area to
remain dry on Tuesday though, although a slight chance of a shower
cannot be ruled out across northeast Pennsylvania. High temperatures
will continue to gradually step up as well with highs mainly in the
mid 70s to low 80s, with 60s along the immediate coast. Overall, a
benign weather period is in store with above normal temperatures.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
An upper level trough slides across southern Canada and the
Northeast US late Tuesday night into Wednesday. Another brief upper
ridge builds overhead on Thursday followed quickly on its heels by
another upper trough on Friday and into Saturday. At the surface, a
weak warm front lifts north of the area on Tuesday night, followed
by a cold front on Wednesday. High pressure slides by to our north
on Thursday with another low pressure system approaching the area
Friday into Saturday.

For Tuesday night and Wednesday...A warm front looks to lift across
our area later Tuesday with a cold front crossing our area during
Wednesday. This may be a quick moving system with not much time for
deeper moisture return and therefore showers may be limited with it.
Some showers and embedded thunder look possible early Tuesday night
with the warm front. On Wednesday, the cold front looks to lack any
real moisture so it may end up passing through dry, however kept a
slight chance of showers mentioned for now. In wake of the front,
should see breezy conditions to return on Wednesday as a dry west-
northwest flow kicks up in the afternoon with gusts up to 20-25 mph.
then a west to northwest breeze occurs Wednesday in the wake of the
cold front. Lows on Tuesday night will be mild as a result of the
passing warm front in the 50s/60s. Highs on Wednesday should mainly
be in the 70s/80s as a result of dry downsloping northwest flow (60s
along the coast/higher terrain).

For Thursday through Saturday...Surface high pressure is forecast to
slide by to our north on Thursday. As the flow veers from southeast
to southwest, warm air advection gets underway especially as a warm
front approaches. The increasing isentropic lift in advance of the
warm front and ahead of an approaching upper-level trough may result
in some showers later Thursday and Thursday night. Some elevated
instability cannot be ruled out, however the chance for some thunder
is low confidence as of now. The aforementioned upper-level trough
drives surface low pressure across the eastern Great Lakes and
vicinity Friday, and this pulls a cold front across our area Friday
night into Saturday. Increasing forcing for ascent tied to this
incoming upper-level trough and cold front should result in an
increase in showers for a time. Some thunder is possible, however
this looks to be more tied to how far north the main warm sector
gets and also how much instability can be achieved in advance of the
cold front. High temperatures Thursday are forecast to be in the
60s/70s on Thursday, stepping up to the 70s/80s on Friday, then back
into the 60s/70s on Saturday in wake of the cold front.

&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Thru the evening...Lower CIGS/VSBYS possible in scattered
showers/tstms which will occur prior to a cold front arriving
from the west. Kept thunder out of KRDG/KABE where it now
appears that the front will pass soon enough to preclude any TS
from affecting those areas. Kept VCTS for the Delaware Valley
terminals attm with only small chances for a thunderstorm. For
KMIV/KACY a tempo group was used for the mostly likely fropa
times.

Tonight...Winds shifting to West the Northwest late. Winds will
be around 15kts with gusts to 25 kts much of the night. VFR.

Sunday...VFR expected. Low clouds (040-050) will be BKN at
times for the northern and western terminals for the late
morning/earl afternoon. Northwest winds 15 to 20 kts with gusts
to 30 kts.

Outlook...

Sunday night through Tuesday...VFR. No significant weather expected.

Tuesday night through Thursday...Generally VFR conditions expected
through Thursday. However, a brief period of sub-VFR conditions are
possible on Tuesday night with a slight chance for showers and an
isolated thunderstorm. Otherwise, no significant weather is
expected.

&&

.MARINE...
The SCA flag will continue for the rest of today and into Sunday.
Winds and seas will trend more enhanced after the cold front moves
offshore this evening and continues east overnight. Winds will gust
25 to 30 kts and seas will be 4 to 6 ft on the ocean. A couple gale
gusts possible too, but not enough for a Gale warning. Scattered
rains/tstms into the evening than fair weather overnight and Sunday.

Outlook...

Sunday night...Lingering SCA conditions possible early Sunday
evening on the Atlantic coastal waters mainly due to wind gusts up
to 25 kt. The current SCA in effect may need to be extended for a
short period to cover this threat. Fair weather.

Monday through Monday night...No marine headlines expected. Fair
weather.

Tuesday through Tuesday night...SCA conditions probable, especially
late Tuesday afternoon and evening. Wind gusts up to 25 kt with seas
around 5 feet.

Wednesday through Thursday...No marine headlines expected.

&&

.FIRE WEATHER...
For the rest of today...Showers and isolated thunderstorms will
be around the area through the early evening. Additional, QPF up
to 0.25" possible, with locally higher totals in thunderstorms.
Given this and higher relative humidity, there are no concerns
for rapid fire spread for the remainder of today.

For Sunday, northwest winds around 15-25 mph with gusts up to 40 mph.
In addition, relative humidity values are forecast to drop to
about 30-35% near and especially south of I-78 (40-50% and
higher north of I-78). How quickly the fuels dry out from the
showers on Saturday will determine any rapid fire spread risk.
Will discuss with partners as needed.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 PM EDT Sunday for ANZ430-431-
     450>455.

&&

$$

SYNOPSIS...DeSilva
NEAR TERM...OHara
SHORT TERM...DeSilva
LONG TERM...DeSilva/Gorse
AVIATION...DeSilva/OHara
MARINE...DeSilva/OHara
FIRE WEATHER...PHI