Special Marine Warning 76, NWS Philadelphia/Mount Holly

Area Forecast Discussion
National Weather Service Mount Holly NJ
343 PM EDT Thu Jul 21 2022

.SYNOPSIS...
High pressure located across the western Atlantic will circulate a
southwesterly to westerly flow of hot and humid air over the region
through the weekend. Scattered showers and thunderstorms will return
Sunday and especially Monday as a cold front approaches the area
from the north. The front looks to stall near the Delmarva
peninsula, keeping things unsettled through midweek. Temperatures at
least should be a bit lower next week, bringing some relief.

&&

.NEAR TERM /THROUGH FRIDAY NIGHT/...
Broad mid-level troughing will be in place through tonight with
the primary axis positioned to our west across the
Appalachians. At the surface, modest southwesterly return flow
will prevail through the day advecting higher dewpoints into the
region through the morning hours. A cold front, really just a
dewpoint gradient, will push into the region by mid-morning then
gradually work its way through the area during the afternoon.
The boundary will move offshore by late evening and stall just
south of the area around daybreak Friday.

The latest guidance suggests our area will remain largely rain-
free today. The area will be sandwiched between the best
forcing to the north over New England and the better instability
to the south. There will also be a dry slot pushing in with the
front, possibly even outrunning the front. These factors will
be working against convective initiation other than isolated
storms in north/northeastern New Jersey and across portions of
Delmarva where chance PoPs remain. The dry mid-level dry air in
place will result in rather high DCAPE values, so any
convection that is successful in maturing will be capable of
producing downbursts.

High temperatures this afternoon will be in the mid 90s, with
80s along the coast and in the mountains. With dewpoints in the
upper 60s to lower 70s, resulting Heat Indices will range from
the mid to upper 90s across our northwestern-most zones to the
low to mid 100s near and southeast of I-95. With the cold front
arriving from the northwest into the peak afternoon heating
hours, dewpoints are expected to mix out as daily maximums are
reached. The resulting heat indices will be a very delicate
balance between increasing temperatures and dewpoints mixing
out.

Another warm night is expected tonight, but dewpoints should
generally begin to fall. Low temperatures are expected to range
from the mid to upper 60s north of I-78 to the mid 70s near and
southeast of I-95.

Those escaping the heat and humidity at the New Jersey and
Delaware oceanfronts will be quite refreshed when stepping into
the surf. Ocean water temperatures have been hovering in the
low to mid 60s from Long Beach Island south to the Delaware
Beaches because of upwelling. Upwelling conditions should
continue as long as the surface winds remain parallel to the
coastline. Once the wind direction changes, upwelling will
dissipate and warmer ocean water will return to the beaches.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Summary...Oppressive heat and humidity with this peaking again on
Sunday.

As a weak mid level shortwave tracks across our northern areas
Friday night into Saturday morning, any showers and thunderstorms
are expected to move out or dissipate across our northern areas.
However with generally weak large scale forcing for ascent and the
lack of any notable focusing mechanisms, coverage of the storms is
less certain. Given enough instability and shear, at least some
isolated showers and storms are anticipated with locally strong
winds possible through Friday evening. We will continue with area of
slight chance PoPs (for isolated convection) for a time Friday
evening across the northern areas. Dew points will be on the rise
again Friday night as the mixing maximized by the intense daytime
heating wanes.

As we go through Saturday into Sunday, it will continue to be hot
with even some uptick in the temperatures especially Sunday as
heights rise. There should be some mixing down of some drier air
aloft Saturday for at least parts of the area, but then this looks
to be less for Sunday. As a result, it will be hot both days with
high temperatures mostly in the mid to upper 90s both days (cooler
in the higher terrain of the Poconos). The low-level flow looks
light enough, therefore a sea breeze is expected to occur each
afternoon given substantial heating on land. This will provide some
temperature relief at the beaches, although dew points will likely
be higher. The combination of hot temperatures and higher dew points
will once again put heat indices back into the low to mid 100s with
these peaking on Sunday.

The Heat Advisory continues for mainly the I-95 corridor through
early Sunday evening, and this will probably need to be expanded
especially for Sunday given the higher dew points. Some areas
especially along the urban I-95 corridor are forecast to be right
near Excessive Heat Warning criteria Sunday. It will also be very
warm at night, especially in the urban centers where temperatures at
night may not drop below 80 degrees. Sunday night looks to be the
warmest. Therefore, little to no relief will occur at night. No
convection is forecast for Saturday, while some showers and
thunderstorms might develop or arrive into the northwestern zones
Sunday afternoon with some southern expansion possible Sunday night
all ahead of an approaching cold front.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
An active and unsettled week is ahead for the area. A
closed low will slowly move through James Bay and Quebec through the
early part of the week. At the surface, a cold front will approach
from the north and west, bringing showers and thunderstorms to the
area on Monday. Out ahead of the cold front, southwest flow will
prevail to start the week, bringing another hot and humid day to the
region. Temperatures will not be as hot compared to Sunday, with low
to mid 90s expected. There is a good chance that heat indices will
approach and get over triple digits within the I-95 corridor,
Delmarva peninsula, and NJ Coastal Plain. Regarding the showers and
thunderstorms, the timing of the front will determine the severity
of impacts. Any showers and thunderstorms that do develop will have
ample moisture to work with, with PWATs getting near 2 inches.

The cold front looks to get hung up around the Delmarva peninsula
and South Jersey. With a few weak shortwaves moving through each day
from Tuesday-Thursday, shower chances will persist with the front
lingering over the southern half of the area. Each day features low
to middle end chc PoPs for areas south of Philadelphia, with slight
chc or even no mentionable PoPs for areas north of the city. The
good news is that temperatures should be lower compared to this
week. Tuesday will bring the best chance to break this string of
90+, with temperatures currently anticipated to be in the mid to
upper 80s. A gradual warming trend will follow for the middle part
of next week, with temperatures looking to get back into the
90s.&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE,
KRDG, KILG, KMIV, KACY and surrounding areas.

This afternoon...VFR. An isolated thunderstorm is possible.
Winds southwesterly 10-15 kts with gusts up to 20 kts possible.

Tonight...VFR/SKC. Winds becoming west to northwest after 00Z
and diminishing to around 5 kts. High confidence.

Friday... VFR. West/southwest winds 5-10 kts with gusts to 15
kts. High confidence.

Outlook...

Friday night...VFR. West/southwest winds 5-15 knots. High confidence.

Saturday...VFR. Westerly winds 5-10 knots becoming southwest or
south in the afternoon. High confidence.

Sunday...VFR. A shower or thunderstorm is possible later in the
afternoon and at night mainly north and west of PHL. South
to southwest winds around 10 knots. Moderate confidence.

Monday through Monday Night...sub-VFR conditions likely with
showers and thunderstorms expected. Southwest winds around 5 to
10 kt. Moderate confidence.

Tuesday through Tuesday night...slight chance of
showers/thunderstorms, otherwise VFR. West to southwest winds
around 5 to 10 kt. Low confidence.

Wednesday through Wednesday night...slight chance of
showers/thunderstorms, otherwise VFR. Southwest winds around 5
to 10 kt. Low confidence.

&&

.MARINE...
A Small Craft Advisory remains in effect through tonight for
all Atlantic coastal waters. Southerly winds 15-20 kts with
gusts around 25 kts. Seas 3-6 feet. The winds and seas will
gradually diminish overnight as a cold front moves offshore.
Winds becoming northwesterly around 10-15 kts. An isolated
shower or thunderstorm is possible. Surf temperatures from LBI
to Delaware Beaches early this afternoon are in the low to mid
60s because of upwelling.

Outlook...

Friday night and Saturday...The conditions should be below Small
Craft Advisory criteria.

Sunday...Small Craft Advisory conditions may develop later in the
afternoon due to increasing southerly winds and as seas build
some.

Sunday...Sub-Advisory conditions expected in the morning.
Southerly winds around 15 to 20 kt, with gusts up to 25 kt
possibly by the late afternoon hours. Seas 3 to 5 feet. A Small
Craft Advisory might be required late Sunday afternoon into
evening.

Monday through Monday Night...Small Craft Advisory Conditions
possible. Seas will build, with 4 to 6 foot waves anticipated.
Southwest winds around 15-20 kt with gusts up to 25 kt.

Tuesday through Tuesday Night...sub-Advisory conditions expected.
South to southwest winds 10-15 kt, with gusts up to 20 kt. Seas 3
to 4 feet.

Wednesday through Wednesday Night...sub-Advisory conditions
expected. West winds in the morning will shift to the south in the
afternoon. Seas 2 to 4 feet.

Rip Currents...

A southwest wind 15 to 20 MPH is expected Thursday. Breaking waves
should be 2 to 4 feet with a medium period south swell. There is a
MODERATE risk of rip currents Thursday.

West winds around 10 MPH are expected Friday. Breaking wave heights
of 1 to 3 feet with a medium period subsiding swell.
There is a LOW to MODERATE risk of rip currents Friday.

&&

.CLIMATE...
Hot and humid conditions are expected through this weekend.
Record temperatures for Thursday can be found listed below.

Record Warmest Low Temperatures for 7/23:

Site  Record/Year
ABE       77/1978
ACY       84/2011
55N       81/2011
PHL       83/2011
ILG       80/2011
RDG       79/2011
TTN       83/2011
MPO       72/2011
GED       84/2011

Record High Temperatures for 7/23:

Site      Record/Year
ABE       99/1955
ACY       105/2011
55N       99/2011
PHL       101/2011
ILG       100/2011
RDG       100/2011
TTN       104/2011
MPO       91/1955
GED       104/2011

Record Warmest Low Temperatures for 7/24:

Site  Record/Year
ABE       76/2011
ACY       83/2010
55N       80/2010
PHL       83/2010
ILG       81/2010
RDG       78/2010
TTN       82/2010
MPO       71/2011
GED       79/2010

Record High Temperatures for 7/24:

Site      Record/Year
ABE       95/2016
ACY       100/2011
55N       96/2010
PHL       98/2011
ILG       98/2011
RDG       96/2016
TTN       98/1910
MPO       91/1914
GED       99/2011

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Heat Advisory until 8 PM EDT Sunday for PAZ070-071-104-106.
     Heat Advisory until 8 PM EDT this evening for PAZ060>062-
     101>103-105.
NJ...Heat Advisory until 8 PM EDT Sunday for NJZ008-010-012-013-015-
     017>019.
     Heat Advisory until 8 PM EDT this evening for NJZ001-007-009-
     014-016-020>023-027.
DE...Heat Advisory until 8 PM EDT Sunday for DEZ001.
     Heat Advisory until 8 PM EDT this evening for DEZ002>004.
MD...Heat Advisory until 8 PM EDT this evening for MDZ012-015-019-
     020.
MARINE...Small Craft Advisory until 6 AM EDT Friday for ANZ450>455.

&&

Synopsis...Franklin/Hoeflich/Johnson/Staarmann
Near Term...Franklin/Staarmann
Short Term...Gorse
Long Term...Hoeflich
Aviation...Franklin/Gorse/Hoeflich/Staarmann
Marine...Franklin/Gorse/Hoeflich/Staarmann
Climate...WFO PHI

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
527 PM EDT THU JUL 21 2022

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0521 PM     MARINE TSTM WIND INDIAN BEACH            38.68N 75.08W
07/21/2022  M53 MPH          ANZ455             DE   MESONET

            DEWEY BEACH MESONET MEASURED 53 MPH GUST.
            TIME GIVEN IN REPORT.

&&

EH

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
540 PM EDT THU JUL 21 2022

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0515 PM     MARINE TSTM WIND DEWEY BEACH             38.69N 75.08W
07/21/2022  M43 MPH          ANZ455             DE   MESONET

            VISTA ROAD MESONET NEAR DEWEY BEACH GUSTED
            TO 43 MPH. TIME GIVEN IN OBSERVATION.

&&

EH

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
552 PM EDT THU JUL 21 2022

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0328 PM     TSTM WND DMG     GREENTREE               39.90N 74.95W
07/21/2022                   CAMDEN             NJ   UTILITY COMPANY

            TREES DOWN ON WIRES/EQUIPMENT. TIME
            ESTIMATED VIA RADAR.

&&

EH