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710
FXUS61 KPHI 220844
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
444 AM EDT Sat Jun 22 2024

.SYNOPSIS...
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Bermuda high pressure remains in place through Sunday
bringing the heat. A strong cold front comes through on Sunday,
moving offshore by Monday morning. High pressure settles in for the
early part of the week before another cold front moves in for the
middle of the week. High pressure returns for the end of next week.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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Patchy fog is possible early this morning mainly where some rain
occurred last night.

For Saturday, the overall pattern/situation remains the same as the
hot conditions continue. Did increase temperatures by a degree in
some places, but overall the forecasted heat indicies remain
relatively unchanged. Forecast soundings still show a well-mixed
boundary layer for much of the day, allowing for some lower dew
points to mix down and limiting the extent of how high our heat
indicies will rise. Another limiting factor could be scattered
clouds across northeast PA and northern NJ this afternoon resulting
from a sagging stationary boundary to the north of the region. While
the front won`t be pushing through the region, this mild disturbance
along with a sea breeze could be enough to trigger some showers and
thunderstorms across the northern half of the forecast area in the
afternoon. Cloud coverage along with rain-cooled air could provide a
brief reprieve to the heat for some locations, though high res
guidance is in disagreement with how extensive the storm coverage
will be. Regardless, the takeaway here is there is a chance for
showers and thunderstorms mainly along and north of the I-195
corridor this afternoon and the Heat Advisory remains in place.

After another hot afternoon, we can expect another uncomfortable
night to follow. Temperatures will only cool off into the low to mid
70s with upper 70s across the urban corridor and Delmarva.
Meanwhile, dew points will remain in the 70s as well, keeping it
mild and muggy tonight. Lingering showers and storms into tonight
may bring some brief relief temperature-wise, but won`t do anything
to reduce the humidity.
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.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
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Oppressively hot and humid conditions are expected for Sunday, the
hottest day of this stretch of heat. Excessive Heat Warnings were
posted for the urban corridor and parts of the NJ Coastal Plain as
heat indices of 105-110 are expected. This, combined with the nearly
week long stretch of heat, are going to result in dangerous
conditions outside for Sunday as the effects of heat stress on the
body can be cumulative. Time outside should be limited and if
you are out and about, drink plenty of water! For the rest of
the area, the Excessive Heat Watch was replaced by a Heat
Advisory, where triple digit heat indices are expected.

With such a hot and humid airmass in place, and an approaching cold
front, there will be the chance for some severe weather. Lift will
be aided with a shortwave and pre-frontal trough coming into a moist
and unstable airmass. Deep layer shear of around 30-40 kt and
moderate instability (around 1000-2000 J/kg of SBCAPE) will support
the development of thunderstorms capable of producing damaging wind
gusts. The limiting factor is the better shear will be located
further north but still think there is sufficient shear to support
some strong to severe thunderstorms. A SLIGHT (2/5) risk exists from
the I-78 corridor on north with a MARGINAL (1/5) risk elsewhere. Not
overly concerned with the flooding potential at the moment as storm
motion should be steady , though with PWATs pushing 2 inches, any
thunderstorms will produce heavy rain capable of dropping an inch or
two of rain quickly.

The front comes through on Sunday Night/Monday morning, knocking
down dew points good 15 degrees or so. It will feel much more
comfortable on Monday with dew points back into the 50s and
temperatures getting into the mid to upper 80s. Monday looks
unsettled though as a series of shortwaves rotate around the base of
the trough passing by to the north. This will result in a some
scattered showers and thunderstorms, though the severe potential
looks much lower compared to Sunday. Any showers/thunderstorms
dissipate after sunset, and it should be a quiet night overall as
high pressure moves in. Temperatures on Monday Night will get down
into the 60s.
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.LONG TERM /TUESDAY THROUGH FRIDAY/...
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Above normal temperatures will continue for the long-term, however
most of next week with the exception of Wednesday will not be as
oppressive as the heat this weekend. High temperatures through most
of the extended look to be in the upper 80s/low 90s. The exception
being Wednesday, as high pressure moves offshore resulting in a
southerly flow and warm air advection. This will bring temperatures
towards the low to mid 90s and heat index values near 100. Will
likely need a Heat Advisory for some areas, but want to get through
this weekend`s heat before moving on to next week.

It will be a mostly dry week as high pressure and ridging aloft will
be in control for Tuesday into Wednesday morning. A cold front will
approach for Wednesday, bringing some scattered showers and
thunderstorms to the region for the Wednesday PM to Thursday
timeframe. Am a bit concerned on the hydro side of things as the
front looks to be a little on the slower side, and we will have a
very warm and moist airmass in place. With such a warm and moist
airmass in place, cannot rule out some stronger thunderstorms as
well. However, the area could use some rain. Will continue to
monitor over the next few days, but this system is really the only
impactful thing in the extended other than the Wednesday heat.
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&&

.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Rest of tonight (through 12Z)...VFR. South to southwest winds 5-10
knots, becoming locally light and variable at some terminals.
Moderate confidence.

Saturday...VFR, however some afternoon showers and thunderstorms
will be possible especially from near KTTN, KABE and KRDG.
Southwest winds increasing to near 10 knots, becoming south in the
afternoon mainly at KILG and KACY due to bay/sea breezes. Moderate
confidence.

Saturday night...VFR except in sct showers/tstms when lower
CIGS/VSBYS expected.

Outlook...

Sunday through Sunday Night..VFR through the first half of the
day though restrictions likely (60-80%) with showers and
thunderstorms for the afternoon and into the overnight hours.

Monday...Primarily VFR though restrictions possible (30-40%) with a
chance of showers/thunderstorms in the afternoon.

Monday Night...VFR. No significant weather.

Tuesday through Tuesday Night...VFR. No significant weather.

Wednesday...Sub-VFR conditions possible (40-50%) in the afternoon
and evening with showers and thunderstorms.
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&&

.MARINE...
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No headlines expected through Saturday night. S-SSW winds will get a
bit gusty Saturday afternoon, increasing to 20 kts and remaining
elevated into Saturday night, but still expected to remain below
advisory criteria. Seas remain 3-4 feet, but begin to build
overnight Saturday into early Sunday morning.

Outlook...

Sunday through Sunday Night...A Small Craft Advisory was issued for
all Atlantic coastal zones as seas will be around 4 to 7 feet with
gusts in the 25-30 kt range out of the south/southwest. Showers and
thunderstorms likely on the waters on Sunday Night.

Monday...Lingering 5 foot seas may result in the extension of the
SCA into Monday. By late Monday, conditions go down to sub-SCA
levels.

Monday Night through Wednesday...No marine headlines expected.

Rip Currents...

Today...Winds around 10 to 15 MPH will be shore-parallel for
the most part, though an onshore component exists for the
southern New Jersey coast. With an 8 second period, a day
removed from a full moon, the tide going out for most of the
day, and 2 to 3 foot breaking waves, have gone with a MODERATE
risk for the development of rip currents for today.

Sunday...Similar setup to today, though with stronger winds and
higher waves. As a result, have upgraded to a HIGH risk for the
development of rip currents for Cape May/Atlantic/Ocean County
and a MODERATE risk for Monmouth and Sussex, DE beaches.

For specific beach forecasts, visit weather.gov/beach/phi
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&&

.CLIMATE...
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Record high temperatures Saturday. Sites within the I-95
corridor and Lehigh Valley have a chance to break their record
high temperature.

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
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&&

.PHI WATCHES/WARNINGS/ADVISORIES...
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PA...Heat Advisory until 6 AM EDT Sunday for PAZ070-071-102-104-106.
     Excessive Heat Warning from 6 AM to 8 PM EDT Sunday for PAZ070-
     071-102-104-106.
     Heat Advisory until 8 PM EDT Sunday for PAZ054-055-060>062-101-
     103-105.
NJ...Heat Advisory until 6 AM EDT Sunday for NJZ010-012-013-015>020-
     027.
     Excessive Heat Warning from 6 AM to 8 PM EDT Sunday for NJZ010-
     012-013-015>020-027.
     Heat Advisory from 6 AM to 8 PM EDT Sunday for NJZ014-021>026.
     Heat Advisory until 8 PM EDT Sunday for NJZ001-007>009.
DE...Heat Advisory until 6 AM EDT Sunday for DEZ001.
     Excessive Heat Warning from 6 AM to 8 PM EDT Sunday for DEZ001.
     Heat Advisory from 6 AM to 8 PM EDT Sunday for DEZ002>004.
MD...Heat Advisory from 6 AM to 8 PM EDT Sunday for MDZ012-015-019-
     020.
MARINE...Small Craft Advisory from 8 AM Sunday to 6 AM EDT Monday for
     ANZ450>455.
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&&

$$

SYNOPSIS...Hoeflich
NEAR TERM...MJL
SHORT TERM...Hoeflich
LONG TERM...Hoeflich
AVIATION...Hoeflich/MJL
MARINE...Hoeflich/MJL
CLIMATE...NWS PHI