663
FXUS61 KPHI 212051
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
451 PM EDT Fri Jun 21 2024

.SYNOPSIS...
Bermuda high pressure remains in control through much of the weekend.
A cold front will move in from the north on Friday and will stall
over the area into Saturday before returning north as a warm front.
A stronger cold front will approach the region Sunday looking to
pass through Monday. High pressure returns for Tuesday, followed
by another front for the middle of next week.

&&

.NEAR TERM /THROUGH SATURDAY/...
Cold front north of the region will remain stalled as so through
Saturday. Warm air advection will continue for the region during
much of the term, as will shortwave energy looking to propagate
through.

Showers and thunderstorms are still expected this afternoon/evening
for the northern and northwestern parts of our region. Some
thunderstorms that do develop could produce stronger downbursts
which could lead to damaging wind gusts. The SPC maintains the
MARGINAL risk for these areas. In addition, with weak flow aloft,
any showers and thunderstorms that do develop will be relatively
slow moving. A quick inch or two of rainfall in some spots leading
to poor drainage flooding cannot be ruled out. WPC maintains some of
our northern and northwestern most areas in a MARGINAL risk for
excessive rainfall.

Very warm and muggy night on tap for tonight with lows primarily in
the low to mid 70s. Some patchy fog is expected to develop across
the region tonight, especially for areas that saw showers and
thunderstorms beforehand.

For Saturday...Forecast high temperatures have come down just a bit
but overall the situation remains the same (i.e, increasing warm air
advection, etc.). With confidence growing as we get closer to the
day and temperatures having come down just a bit, opted to replace
the Excessive Heat Watch in place for the I-95 corridor with a Heat
Advisory; no other changes made besides that. The I-95 sites will
likely see the mid to upper 90s as highs, but heat indices will
likely stay in advisory criteria at best. Basically, the same shower
and thunderstorm situation seen for today will repeat for Saturday
afternoon into Saturday night.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
The heat wave will continue into the short term, then some break in
the heat Monday following a cold front which moves through. The heat
headline, excessive heat watch, for Sunday will continue with highs
in the mid 90s widespread and some chance for upper 90s for the
urban areas. Heat index values in the 100-105 range expected for
Sunday. These temps will continue with high humidity too as deep
SW/S flow continues over the region. These remains some uncertainty
with regards to how much cloud cover and how fast it arrives. The
high temperature forecast may be affected by these factors.

More certainty is seen with regards to the precipitation forecast
as a front cuts through the heat and humidity creating good chances
for tstms Sunday/Sunday night. We will carry high chance and low
likely pops for the periods and continue with gusty winds/heavy
rainfall wording for now. The front moves offshore by Monday with
some lingering clouds/showers for NJ into Monday before improvement
from W to E Monday afternoon. High temps Monday will be in the mid
80s for the N/W areas and low 90s for srn NJ and Delmarva. Humidity
levels will decrease with a drier W/NW flow becoming established
over the area.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
The upper high/ridge that has brought all the excessive heat to the
area this week and into the weekend will slowly lose its grip over
the northern Middle Atlantic region by early next week. Instead, we
will be closer to the westerlies (storm track) with the big high to
the SW and a weak mean trough across the Northeast. This means that
while we will still have the opportunity for a hot day (especially
Wed.) but we won`t be in another prolonged period of excessive
heat/humidity. Highs will largely favor the mid/upper 80s with a few
low 90s in the urban areas.

After the showers in the short term, the precipitation for the long
term will basically center on Wed./Wed night when a cold front and
upper trough cross the region. We will go with the 30-40ish (%) pops
offered by the NBM for now.

&&

.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Rest of Today...Primarily VFR. Scattered showers and thunderstorms
mainly north of I-78 may affect KABE and bring brief restrictions,
but the probability of that is low (only around 20%), so have
kept prevailing VFR for the entire TAF period. Quiet elsewhere
with winds out of the southwest around 5-10 kts. Winds more
southerly at KACY/KMIV with the sea-breeze and at KILG with the
bay-breeze. Moderate confidence.

Tonight...Primarily VFR, though some patchy fog possible at
KRDG/KABE/KACY/KMIV. SSW winds around 5 kts or less. Some sites will
see winds go light and variable. Moderate confidence.

Saturday...Generally VFR. Afternoon/evening SHRA/TSRA could result
in brief sub-VFR conditions for sites mainly north of the I-95
corridor. SW winds 5-10 kts. Moderate confidence.

Outlook...
Sat night thru Sun night... VFR except in sct showers/tstms
   when lower CIGS/VSBYS expected.

Monday... Morning lower clouds possible then VFR.

Tuesday... VFR expected.

Wednesday... Lower CIGS/VSBYS with scattered showers/tstms.

&&

.MARINE...
Marine headlines are not expected through tonight or early Saturday
morning. Later on Saturday, wind gusts are expected to increase to
20-25 kts with building seas across the ocean waters. ANZ450/ANZ451
may flirt with some 5 foot seas by later in the afternoon. SCA flag
may be needed for the ocean zones starting in the afternoon time
frame. Opted to not issue headlines at this time due to SCA
conditions only being marginal for most of the ocean zones starting
later Saturday. Seas generally 2-4 feet.

Outlook...

Sat night... Increasing winds/seas. Low-end SCA seas develop late.
Fair most areas but a few tstms for North NJ waters.

Sunday/Sunday night... SCA possible with enhanced winds/seas in scattered
tstms.

Mon/Tue... Mostly sub-SCA. Fair after a few morning showers Monday.

Rip Currents...

Saturday...South winds around 10-15 mph and breaking waves around
2 feet expected. Portions of the southern New Jersey coast will
maintain an onshore component of the wind, in addition to being
1 day removed from the Full Moon. As a result, have kept a
MODERATE Risk for all New Jersey beaches except Monmouth County.
For the Delaware Beaches and Monmouth County, have kept a LOW
Risk of dangerous rip currents.

Sunday...Southerly winds will increase from 10 mph in the
morning to 20 mph in the afternoon with breaking waves around 2
to 4 feet. Due to increasing winds and higher seas along the
shore, decided to go with a MODERATE Risk for dangerous rip
currents for all NJ/DE beaches. May need to evaluate the
potential for a HIGH Risk of rip currents for southern New
Jersey beaches in future updates.

Rip currents occur often in the vicinities of jetties and
piers. Utilize any guarded beaches if venturing out into the
water. For specific beach forecasts, visit weather.gov/beach/phi

&&

.CLIMATE...
Record high temperatures for today.

Location          Record High (6/21)

Philadelphia, PA      99/1923
Allentown, PA         100/1923
Reading, PA           99/1923
Mount Pocono, PA      90/1953
Trenton, NJ           97/1923
AC Airport, NJ        97/1988
AC Marina, NJ         94/2012
Wilmington, DE        98/2012
Georgetown, DE        99/2012

Record high temperatures Saturday.

Location          Record High (6/22)

Philadelphia, PA      100/1988
Allentown, PA         95/1941
Reading, PA           96/1921
Mount Pocono, PA      90/1908
Trenton, NJ           99/1988
AC Airport, NJ        100/1988
AC Marina, NJ         92/1949
Wilmington, DE        98/1988
Georgetown, DE        97/2012

Record high temperatures Sunday.

Location          Record High (6/23)

Philadelphia, PA      97/1888
Allentown, PA         95/1965
Reading, PA           96/1908
Mount Pocono, PA      90/1908
Trenton, NJ           97/1894
AC Airport, NJ        98/1988
AC Marina, NJ         91/1909
Wilmington, DE        100/1894
Georgetown, DE        100/1988

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Heat Advisory until 6 AM EDT Sunday for PAZ054-055-060>062-070-
     071-101>106.
     Excessive Heat Watch from Sunday morning through Sunday
     evening for PAZ054-055-060>062-070-071-101>106.
NJ...Heat Advisory until 6 AM EDT Sunday for NJZ001-007>010-012-013-
     015>020-027.
     Excessive Heat Watch from Sunday morning through Sunday
     evening for NJZ001-007>010-012>027.
DE...Heat Advisory until 6 AM EDT Sunday for DEZ001.
     Excessive Heat Watch from Sunday morning through Sunday
     evening for DEZ001>004.
MD...Excessive Heat Watch from Sunday morning through Sunday
     evening for MDZ012-015-019-020.
MARINE...None.

&&

$$

SYNOPSIS...MPS/OHara/Wunderlin
NEAR TERM...Wunderlin
SHORT TERM...OHara
LONG TERM...OHara
AVIATION...OHara/Wunderlin
MARINE...DeSilva/OHara/Wunderlin
CLIMATE...WFO PHI