Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 240136
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
936 PM EDT Mon May 23 2022

.SYNOPSIS...
High pressure will remain in place north of the region for much
of the week. Meanwhile, a weak wave of low pressure will slowly
track south of our region through midweek. A low pressure
system will arrive from the west by Friday and could linger into
at least the first part of the weekend before high pressure
eventually moves back in.

&&

.NEAR TERM /THROUGH TUESDAY/...
The main focus of the near term is what remains of the low
which is progressing northeastward from the southern
Appalachians. As this low gets closer to our region, we will
remain under high and mid level clouds.

Late tonight into Tuesday, the surface high to our north should
be strengthening and mid and upper level flow should become
more zonal. Given all that, expect the low to stay surpressed
south of our region (similar to what the GFS and ECMWF are
depicting). This would mean any significant precipitation (a
tenth to a quarter of an inch) in our region would be confined
to central and southern Delaware and adjacent areas in NE
Maryland. Further north (up to about the PA turnpike/195
corridor) some very light rain showers are possible, but
accumulations should generally be a few hundredths of an inch,
if even that.

With continued easterly or northeasterly flow, and much more
cloud cover, Tuesday should be a few degrees cooler than today,
with highs mostly in the 60s across the region.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
For Tuesday night through Wednesday, high pressure remains
centered just off to our north and northeast near New England
while a weak system continues to fizzle out to our south. This
will keep an onshore flow in place with considerable cloudiness
around though I think there should be at least some sunny breaks
during the day Wednesday. The better chance for any sun will be
northern parts of our forecast area over NE PA and northwest
NJ. It should be mostly dry during this period though I can`t
rule out a few showers lingering over Delmarva and far southern
NJ. Lows will be mostly in the low to mid 50s Tuesday night with
highs Wednesday in the 60s to near 70.

Wednesday night through Thursday, high pressure moves off the
coast east of New England while low pressure moves north and
east through the Great Lakes to our west. This will eventually
push a warm front through but given this setup there will
continue to be a component of wind off the ocean helping to keep
it mostly cloudy and cooler than it would otherwise be. This
set up will also allow for some of the remnants of the early
week system to lift back to the north through the area bringing
a chance for some showers by later Wednesday night into
Thursday. Lows Wednesday night look to be mainly in the low to
mid 50s with highs Thursday ranging from the mid to upper 60s
along the NJ coast, NE PA, and NW NJ to the low to mid 70s over
SE PA, Delmarva, and interior portions of central and southern
NJ.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Thursday night into Friday, a low pressure system and
associated upper level trough slowly lumbers east towards the
area with an increasing deep layer southerly flow well ahead of
this system`s cold front. This looks to bring widespread showers
and thunderstorms into the area by Friday. This is several days
away so it`s a bit early to be confident on any specifics but
potential for severe weather will have to be monitored over the
next couple days. Also, GFS is indicating PWATs reaching around
1.75 inches so the threat of heavy rainfall will also need to be
monitored closely.

Beyond Friday, fairly big differences in the models emerge. The
ECMWF indicates the pattern will be progressive with the system
sweeping eastward clearing us out for the weekend with high
pressure building in while the GFS and many of its ensembles
stalls a cutoff low over the east through most of the weekend.
If this solution were to verify the weekend would remain
unsettled potentially right through Memorial Day. GEM Global
solution lies roughly in the middle which would keep the chance
of showers around at least through Saturday. Given this
uncertainty, we keep the chance of showers in the forecast
through Saturday before trending the forecast drier through
Sunday and Monday. This forecast is a bit higher with POPs than
the NBM which tends to bias dry in these scenarios. Temperatures
for the long range look to be remain roughly around seasonal
but will also depend on how quickly the system moves out. More
clouds/showers than currently forecast would result in it being
cooler.

&&

.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Tonight...VFR ceilings. Scattered light rain showers around
KILG, KMIV and KACY after 06Z with little impact on the
visibility. Variable wind 6 knots or less. High confidence.

Tuesday...VFR ceilings. Scattered light rain showers around
KILG, KMIV and KACY until 15Z with little impact on the
visibility. East wind 6 to 12 knots. High confidence.

Outlook...

Tuesday night... Mainly VFR. Some MVFR CIGs along with light
rain are possible especially south of PHL. East wind 5 to 10 kt.
Moderate confidence.

Wednesday-Wednesday night... Mainly VFR, but again a chance of
some MVFR CIGs especially south of PHL. East wind becoming
southeast at 5 to 10 kt. Moderate confidence.

Thursday-Thursday night... Some restrictions at least to MVFR
are possible along with scattered showers. Southeast winds
around 10 kt, gradually turning southerly overnight. Low
confidence.

Friday-Friday night... Sub-VFR conditions possible with rain
showers as well as possible thunderstorms. Southwest winds 10 to
15 kt. Low confidence.

&&

.MARINE...
Winds and seas should generally stay below Small Craft Advisory
criteria. Wind gusts above 20 kt are possible during the day
Tuesday, but should stay below 25 kt.

Outlook...

Tuesday night-Wednesday... Sub-SCA conditions expected.
Northeast to east winds 10 to 15 kt with gusts up to 20 kt
possible. Seas 3 to 4 ft. Light rain possible especially off the
Delaware coast.

Wednesday night-Thursday... Sub-SCA conditions expected. Winds
becoming southeast at 10 to 15 kt with some gusts to 20 kt
possible. Seas 3 to 4 ft. Some light rain showers possible.

Thursday night-Friday... Mainly sub-SCA conditions expected.
Winds becoming south then southwest at 15 to 20 kt, with some
gusts close to 25 kt possible. Seas near 4 ft but locally
approaching 5 ft. Rain showers possible.

Rip currents...

A northeast to east wind 10 to 20 MPH is expected along the
coasts of Delaware and New Jersey for Tuesday and Wednesday.
Breaking waves are forecast to be 2 to 3 feet with a medium
period easterly swell. As a result on the onshore flow, we are
anticipating a MODERATE risk for the development of dangerous
rip currents on both days.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.

&&

$$

Synopsis...O`Brien
Near Term...Iovino/Johnson
Short Term...O`Brien
Long Term...Fitzsimmons
Aviation...Fitzsimmons/Iovino
Marine...Fitzsimmons/Iovino/Johnson


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