FXUS61 KPHI 042326

Area Forecast Discussion
National Weather Service Mount Holly NJ
726 PM EDT Wed Oct 4 2023

High pressure will become more centered to our east and northeast
through tonight, however it will continue to extend across our
region. The high weakens and shifts more to our northeast
Thursday into Friday. A strong cold front moves through on
Saturday, which brings a colder and much drier air mass into our
region over the weekend through early next week.


Skies remain mostly clear into tonight as high pressure is in
control and winds go light, mainly out of the east. With
similar conditions to Tuesday night, will lean on persistence
and MOS guidance for overnight lows which should favor the 50s
areawide. Some fog may again develop, especially in the river
valleys but also over coastal NJ due to the light onshore flow.
There may also be some low stratus that tries to develop and
move in off the ocean late at night but forecast confidence is
low on this.

Thursday will again be another dry day and feature above average
temperatures, though a few degrees lower than Wednesday, as the
surface high migrates off to the east but extends a ridge back
across our area. 500 mb heights will slowly begin to fall as the
upper ridge axis shifts east and a digging upper trough approaches
from the west. Moisture advection aloft with southerly flow will
lead to an increase in mid-level cloud coverage ahead of the return
of precipitation chances on Friday. Low level flow will be
east/southeasterly and thus expect highs near the coast to be a few
degrees cooler. Looking at values topping out in the upper 70s
inland with low 70s along the coast.


This will be the transitional period for the weather across the
Middle Atlantic. High pressure and the mild temperatures of the
present and past few days will be moving away as the surface
high and upper ridge move away. A H5 low/trough will deepen as
it pushes our way Fri thru Sat. The low level moisture behind
the departing high will deepen thru the period as low level flow
off the ocean continues. Increasing amounts of clouds and
gradually higher pops thu the period with the greatest chances
for rains being on Sat when a surface cold front passes from
west to east. We will have mostly chance pops for Fri ramping up
to high chance/low likely pops for Sat.


An upper low to the north of the area Sat night/Sunday will continue
into the new week while weakening somewhat. By next week, the
feature will have diminished back to a trough and it will continue
to weaken after that. Cool autumn weather but mostly dry thru
the period. A couple showers Sat night as the surface low and
front from the short term continue to pull away to the NE. Some
diurnal shower activity is possible Sun with the colder
temperatures aloft remaining over the area. The showers will be
found mainly across the higher elevations of the southern
Poconos and north NJ.

Temperatures Sun and next week will be below normal with highs
Sun/Mon only in the low/mid 60s for the urban/Delmarva areas and
mid/upper 50s for the NW counties. By Tue/Wed readings will be some
5 degrees milder. Lows thru the period will be mostly 40s with some
30s N/W Mon morning. Gusty winds expected for Sat night/Sunday with
gusts 20 to 30 mph at times.


The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas...

The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.

Tonight...Areas of fog may result in MVFR/periods of IFR
visibility after 07z, especially at KMIV/KACY and KTTN/KPNE
where guidance is the most aggressive on reduced visibility. KPHL
looks to be right on the cusp of this but should stay mainly
VFR with just a tempo group for MVFR visbys indicated near dawn.
Variable wind 5 knots or less. Moderate confidence in fog
development and restrictions.

Thursday...VFR after any lingering fog dissipates through the
morning. There will be scattered low and mid level cloudiness
around. Light and variable wind in the morning becoming
southeasterly at 5-10 knots. High confidence.


Thu night... Low clouds and perhaps light rain/drizzle possible.
MVFR/IFR possible. Limited confid.

Fri thru Sat evening... MVFR/IFR at times with showers and fog
probable. Gusty winds developing later Sat. Low/medium confid.

Sat night/Sunday... VFR. Gusty winds possible. Medium confid.

Monday... VFR expected. Medium confid.


No marine headlines expected. Fair weather. Southeasterly wind 5-10
knots through tonight becoming easterly on Thursday around 10-15
knots. Seas 2-3 feet.

Thu night/Friday...sub-SCA conditions expected. Fair Thu. night
and a chance of showers later Friday.

Fri night thru Sat night... A period of SCA conditions with winds
and seas building as a low and front affect the waters. A short
period of near-Gale gusts is possible later Sat. Showers Fri
night/Sat then becoming fair overnight Sat night.

Sun thru Mon...SCA expected. Fair weather.





NEAR TERM...Brudy/Fitzsimmons

NWS PHI Office Area Forecast Discussion