Special Marine Warning 99, NWS Philadelphia/Mount Holly

Area Forecast Discussion
National Weather Service Mount Holly NJ
509 AM EDT Fri Jul 21 2023

.SYNOPSIS...
A warm front lifts north through the region early this morning,
followed by a cold front late this afternoon. High pressure
builds into the region for the weekend. Several weak
disturbances will affect the area next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Line of showers and thunderstorms has moved out of southeast
Pennsylvania and is moving through New Jersey and Delmarva. Will
go ahead and allow Severe Thunderstorm Watch #530 to expire at 5
am. Severe Thunderstorm Watch #532 remains in effect for
southern and eastern New Jersey, the eastern shores of
Maryland, and Delaware until 8 am. There still remains 1000 to
1500 J/kg of surface-based CAPE for southern New Jersey and
Delmarva. In addition, there is 25 to 30 kt of 0-6 km Bulk
Shear.

As this line of storms departs, a warm front lifts north
through the region later this morning. Surface dew points rise
into the lower 70s for most of the area, proving abundant
moisture for potential afternoon showers and thunderstorms. The
question is if skies clear out enough and temperatures warm up
enough to drive instability values up. Highs should get into the
low to mid 80s, and surface-based CAPE values will rise to over
2000 J/kg. A cold front will pass through the region this
afternoon along with some shortwave energy. 0-6 km Bulk Shear
will average 25 to 30 kt. This will touch off another round of
showers and thunderstorms, mainly over New Jersey with gusty
winds and heavy rain.

Storms taper off fairly quickly after sunset. Cold front passes
through the region, and skies clear out overnight. Depending
how much rain falls today, and where it falls, there may be some
patchy fog developing prior to sunrise Saturday. Lows tonight
will largely be in the low to mid 60s.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY/...
High pressure builds into the Ohio Valley on Saturday, slides
overhead Saturday night, and then offshore on Sunday. Dry
weather, sunny skies, and low humidity levels are on tap for the
weekend, possibly making this the nicest weather weekend of the
summer!

Highs Saturday will be in the low to mid 80s, and then highs on
Sunday will top off in the mid to upper 80s as warmer air
spreads in from the west. Both days will feature surface dew
points in the upper 50s to low 60s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
High pressure continues to move offshore Sunday night and will
be well offshore on Monday. Another closed H5 low sets up shop
in Hudson Bay, Canada, and a deep trough will extend down from
that low into the Eastern U.S. Once again, mainly diurnally
driven convection will affect the area as several shortwaves
associated with this trough pass through the region.

Based on latest guidance, there are low chances Monday and
Tuesday, and then weak surface high pressure passes through the
region Wednesday. Conditions should be mostly dry on Wednesday.
Another weak shortwave approaches Thursday, bringing another
chance for convection.

Temperatures will gradually warm back up through the week, with
highs topping off in the mid and upper 80s Monday and Tuesday,
upper 80s to around 90 on Wednesday, and then in the low to mid
90s Thursday. Surface dew points will also eventually creep back
up into the upper 60s and low 70s.

&&

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

Early this morning (through 12Z)...SHRA/TSRA with sub-VFR
conditions. LGT/VRB winds, except in TSRA, the strongest of
which could have gusts 40 to 50 kt. Moderate confidence.

Today (12Z through 00Z)...Lingering SHRA/TSRA will taper off by
15Z. Conditions improve to VFR. Another round of SHRA/TSRA
possible starting around 18Z. Brief sub-VFR conditions
possible. LGT/VRB winds, becoming W-NW 5 to 10 kt. Low
confidence.

Tonight (00Z through 12Z)...Primarily VFR. Light NW winds. Low
probability for sub-VFR VSBYs in fog. Moderate confidence.

Outlook...

Saturday through Sunday night...VFR. W to NW winds 10 to 15 kt
with occasional gusts to 20 kt during the day, then LGT/VRB at
night. High confidence.

Monday through Tuesday...VFR overall. Scattered afternoon
SHRA/TSRA possible. S winds 5 to 10 kt. Moderate confidence.

Wednesday...VFR. SW winds 5 to 10 kts. Moderate confidence.

&&

.MARINE...
A line of showers and thunderstorms will work their way across
the waters early this morning with strong thunderstorm wind
gusts, lightning, and VSBY restrictions in heavy rain. Another
round of thunderstorms is possible this afternoon and early
evening before tapering off late.

Sub-Small Craft Advisory conditions on tap. South to southeast
winds will range from 10 to 15 kt with occasional gusts before
turning northwest tonight, then west on Saturday. Seas will
average 2 to 4 feet.

Outlook...

Saturday through Wednesday...A prolonged period of sub-SCA
conditions expected during this time. Conditions will be dry
with no showers or thunderstorms Saturday through Sunday.
Isolated late day and evening showers and thunderstorms are
possible Monday and Tuesday. Dry weather expected Wednesday.
Winds will mostly be west to northwest 10 to 15 kts over the
weekend, becoming southeasterly 10 to 15 kts Monday and Tuesday,
and then southwesterly on Wednesday. Seas 2 to 4 ft.

Rip Currents...

Today, winds will be out of the south to southeast at 5 to 10
mph with a medium period southeast swell up to 10 seconds. As a
result, there is a LOW risk for the develop of dangerous rip
currents at New Jersey and Delaware beaches outside of
thunderstorms.

On Saturday, winds turn to the northwest at 5 to 10 mph. A
light easterly swell will be in place. Once again, there will be
a LOW risk for the development of dangerous rip currents at New
Jersey and Delaware beaches.

&&

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

&&

SYNOPSIS...MPS
NEAR TERM...MPS
SHORT TERM...MPS
LONG TERM...MPS
AVIATION...MPS
MARINE...MPS

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Preliminary Local Storm Report...Summary
National Weather Service Mount Holly NJ
636 AM EDT Fri Jul 21 2023

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

0346 AM     Tstm Wnd Dmg     2 WSW North Wales       40.20N 75.31W
07/21/2023                   Montgomery         PA   Public

            Large branch down at Morris Road and West
            Point Pike.

0302 AM     Tstm Wnd Dmg     1 WNW Upper Uwchlan Twp 40.08N 75.71W
07/21/2023                   Chester            PA   911 Call Center

            Tree down on house.

0216 AM     Tstm Wnd Dmg     2 WSW Wernersville      40.32N 76.11W
07/21/2023                   Berks              PA   911 Call Center

            Tree down on Huntzinger Road.

0249 AM     Tstm Wnd Dmg     2 W Birdsboro           40.26N 75.84W
07/21/2023                   Berks              PA   911 Call Center

            Tree down on Cedar Hill Road.

0537 AM     Tstm Wnd Dmg     2 WNW Easton            38.78N 76.12W
07/21/2023                   Talbot             MD   911 Call Center

            Tree down at Unionville Road and St.
            Michaels Road.

&&

Special Weather Statement
National Weather Service Mount Holly NJ
712 AM EDT Fri Jul 21 2023

DEZ003-004-211145-
Inland Sussex DE-Delaware Beaches DE-
712 AM EDT Fri Jul 21 2023

...A strong thunderstorm will impact portions of southeastern Sussex
County through 745 AM EDT...

At 712 AM EDT, Doppler radar was tracking a strong thunderstorm near
Georgetown, moving east at 15 mph.

HAZARD...Wind gusts up to 40 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Georgetown, Millsboro, Lewes, Milton, Selbyville, Dagsboro,
Millville, Ellendale, Sycamore, Gumboro, Long Neck and Frankford.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

A Severe Thunderstorm Watch remains in effect until 800 AM EDT for
southern Delaware.

&&

LAT...LON 3845 7556 3880 7546 3885 7514 3845 7511
TIME...MOT...LOC 1112Z 266DEG 14KT 3864 7539

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

SFJ

Preliminary Local Storm Report
National Weather Service Mount Holly NJ
742 AM EDT Fri Jul 21 2023

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

0730 AM     Tstm Wnd Gst     Dagsboro                38.54N 75.23W
07/21/2023  M40 MPH          Sussex             DE   Mesonet

            Dagsboro DEOS Station gusted to 40mph at
            7:30am.

&&

DeSilva

Special Weather Statement
National Weather Service Mount Holly NJ
743 AM EDT Fri Jul 21 2023

DEZ003-004-211215-
Inland Sussex DE-Delaware Beaches DE-
743 AM EDT Fri Jul 21 2023

...A strong thunderstorm will impact portions of southeastern Sussex
County through 815 AM EDT...

At 742 AM EDT, automated weather stations reported a strong
thunderstorm near Millville, or 13 miles north of Ocean City, moving
east at 30 mph.

HAZARD...Wind gusts up to 40 mph and pea size hail.

SOURCE...Automated weather stations.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Selbyville, Millville, Long Neck, Ocean View, South Bethany and Dewey
Beach.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

A Severe Thunderstorm Watch remains in effect until 800 AM EDT for
southern Delaware.

&&

LAT...LON 3845 7503 3846 7505 3845 7505 3845 7523
      3870 7515 3872 7497 3845 7493
TIME...MOT...LOC 1142Z 278DEG 24KT 3855 7505

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

SFJ

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