National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS61 KPHI 251010
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
610 AM EDT Thu Apr 25 2024

.SYNOPSIS...
High pressure arrives from the Great Lakes today before
shifting to our northeast and east on Friday. A warm front
should lift north of our area later Saturday, then a cold front
gradually approaches later Monday before moving across our area
later Tuesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Latest analysis shows the cold front has cleared the region,
but between wind being relatively weak behind the front plus
some lingering clouds, temps have been slow to drop. Have
trimmed back the frost advisory for a large segment and
cancelled the freeze warning for all zones.

Weak shortwave passing by this morning likely keeps some clouds
around from Philly on southward for a good chunk of the day, and
in fact there could be a stray shower, most likely over the
Delmarva but a small chance even in southern NJ. Looks like any
showers would end before noon, and we should gradually start to
dry out and clear out more late in the day. While the cold
advection has lagged, still expect today to be notably cooler
than yesterday, with highs mostly in the 50s.

High pressure builds to the north tonight with the gradient
slacking off enough. With drier air in place by then along with
clear skies, expect radiational cooling to maximize. Thus, have
leaned hard on the colder guidance and issued a freeze watch for
a large chunk of the region especially north and east of
Philadelphia. Areas further south and west look more tricky but
still likely need frost advisories for these areas. Lows overall
in the 30s, with near or below 30 in the Freeze Watch area and
Poconos but closer to mid 30s in the urban centers and Delmarva.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
An upper-level trough is forecast to shift to our east to start
Friday, allowing high pressure to build across New England and
the Mid Atlantic. After a cold start Friday morning, surface
flow shifts south- southeast by the afternoon to allow some
warming to begin. With mostly clear skies, high temps in the
afternoon should reach low 60s inland. Onshore flow, however,
will help keep the coastal communities and adjacent inland
locations in the mid to upper 50s during the afternoon. Calm
winds and clear skies to start the nighttime hours will aid in
cooling, but increasing clouds overnight will help stave off
runaway radiational cooling. We will still see temperatures
dip into the mid 30s to low 40s with patchy frost possible in
the most sheltered areas.

High pressure shifts offshore Saturday with an approaching warm
front, expected to arrive around the evening timeframe. Winds
will become more southerly with return flow of our offshore high
aiding in the warm air advection we can expect as the warm front
pushes through. That said, the increased cloud coverage will
prevent us from warming up too much, with afternoon highs
expected to reach the upper 50 to low 60s, right around or just
warmer than on Friday. While a few showers cannot be ruled out
with this warm front probabilities and coverage remain rather
minimal with the only mentionable POPs north and west of I-78.
Warmer overnight with the warm front passing through and cloud
coverage preventing much radiational cooling. Lows will be in
the mid to upper 40s.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
High pressure shifts to our south, allowing southwest flow to
really crank up the warm air advection across the region. Sunday
and Monday will look to bring some of the warmest temperatures
we have seen thus far this season with mid to upper 70s on
Sunday and low to mid 80s by Monday afternoon! Mostly dry across
the region during this timeframe as well, though a few isolated
showers or a rumble of thunder cannot be ruled out mainly across
the Poconos where the aforementioned warm front may linger
nearby.

The stacked low shifting across the upper Midwest will slowly
move into central Canada Monday into Tuesday, dragging along a
cold front across the Ohio River Valley and eventually through
the Mid Atlantic. This is where our next best chance for
precipitation will come from and will be highly dependent on the
timing of this low and its associated cold front. At the moment,
some showers will be possible Monday night as the front
gradually approaches the region, but the best chance for
showers and thunderstorms will come Tuesday as the cold front,
washing out at this point, finally arrives. Temperatures remain
warm again Tuesday with upper 70s to low 80s. Not much cooler
behind this weak cold front on Wednesday, however, with a
surface high ridging in from the southeastern US to keep things
on the mild side in the 70s.

&&

.AVIATION /10Z THURSDAY THROUGH MONDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas...

Through today...VFR. Northerly winds generally 5 to 10 knots
before diminishing late day. High confidence.

Tonight...VFR. Winds becoming more northeasterly but slacking
off to 5 kts or less overnight. High confidence.

Outlook...

Friday...VFR.

Saturday...A period of near MVFR ceilings possible, most likely
Saturday night as a warm front pushes through. Otherwise,
mainly VFR.

Sunday and Monday...VFR conditions anticipated.

&&

.MARINE...
Seas will remain elevated through today before slowly starting
to come down tonight. For this reason, the Small Craft Advisory
was extended to 22z today for our northern ocean zone off the
coast of Monmouth County with it running until 10z Friday for
the remaining ocean zones. Northeast winds will mostly be sub
SCA.

Outlook...

Friday through Monday...The conditions are anticipated to be
below Small Craft Advisory criteria.

&&

.FIRE WEATHER...
RH`s across much of the region will get quite low today, and
we`ve had little rain now for a couple of weeks, allowing fine
fuels to dry. While winds won`t likely be up to Red Flag
Criteria, there may be a need for a Special Weather Statement,
which will be firmed up after morning coordination with our
state partners.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Freeze Watch from late tonight through Friday morning for
     PAZ061-062-103-105-106.
NJ...Frost Advisory until 9 AM EDT this morning for NJZ001-007-008.
     Freeze Watch from late tonight through Friday morning for
     NJZ001-007>010-012-013-015>022-027.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ450.
     Small Craft Advisory until 6 AM EDT Friday for ANZ451>455.

&&

$$

SYNOPSIS...Fitzsimmons/RCM
NEAR TERM...RCM
SHORT TERM...MJL
LONG TERM...MJL
AVIATION...MJL/RCM
MARINE...MJL/RCM
FIRE WEATHER...RCM