Special Marine Warning 55, NWS Philadelphia/Mount Holly

Area Forecast Discussion
National Weather Service Mount Holly NJ
446 PM EDT Mon Jun 22 2026

.WHAT HAS CHANGED...
1. A Severe Thunderstorm Watch has been issued for the majority
of our area and is in effect until 9 PM.

2. Showers/storms now look to linger into Tuesday as the frontal
system now looks slower to depart.

3. Updated Aviation section for 18z TAFs.

&&

.KEY MESSAGES...
1. Low pressure will bring showers and thunderstorms this
afternoon into this evening bringing both the threat of severe
weather and flash flooding. Additional rounds of showers and
storms now are likely for Tuesday.

2. A HIGH risk of rip currents today for coastal Ocean,
Atlantic, and Cape May county.

3. Another cold front is expected to approach the region late
this week, bringing more chances for showers and storms.

&&

.DISCUSSION...
KEY MESSAGE 1...Low pressure will bring showers and thunderstorms this
afternoon into this evening bringing both the threat of severe
weather and flash flooding. Additional rounds of showers and
storms now are likely for Tuesday.

Low pressure will be moving across southern PA then through NJ
en-route to Long Island as we go through the rest of the day
through tonight. As of mid afternoon, we're already seeing some
showers storms developing near and north of the system's warm
front as it's situated over SE PA into NJ. ML CAPE values are in
the neighborhood of 1000-1500+ j/kg and in addition to this
there is both strong low level and deep layer shear...especially
near and north of the front. PWAT values are increasing as well
and already around 1.8+ inches. The upshot of this is that
expect showers/storms to continue to developing and become
more widespread through late this afternoon into this evening.
This will occur as the low continues to approach with a surface
trough ahead of it extending from eastern PA southward towards
the Chesapeake. Expect the main area of storms to move through
roughly in the 5-9 PM time frame. Damaging winds and flash
flooding from heavy rainfall are the biggest threats but
isolated tornadoes will also be possible. And it appears that
specifically regarding the TOR threat, it will be greatest near
the warm front meaning the I-76 / I-276 / I-195 corridor north
towards the I-78 corridor over eastern PA into NJ. South of here
damaging winds look to be the biggest threat in terms of severe
weather. As for the heavy rainfall and flash flooding threat,
the highest chances for this will be near the urban corridor.
Individual cell motion is fast but there is the potential for
some training and backbuilding to develop by early this evening
and if this sets up in urban areas, it will result in flash
flooding.

Getting towards the mid evening period, the severe weather
threat should be diminishing but the low looks to be very slow
moving across the area through the overnight meaning more
showers and possible storms will be likely. It's for this reason
that we have the Flood Watch going through the night to 6 AM
Tuesday.

For Tuesday, the big change in the forecast is that the system
now looks to get hung up over the area with the latest
indications actually being for a new low to develop near near
Delmarva. This will occur as another piece of energy moves
around the base of the upper trough over the east. This will
result in more rounds of showers and storms that could once
again be on the heavier side by the afternoon. Near the warm
sector over southern Delmarva, we can't rule out some storms
becoming severe and the SPC now has a MARGINAL risk for severe
storms just getting into Sussex County Delaware.

Low pressure with it's associated showers/storms should finally
move out through Tuesday night.

KEY MESSAGE 2...A HIGH risk of rip currents today for coastal
Ocean, Atlantic, and Cape May county.

For today, south-southeasterly winds will increase to around
15-20 mph with gusts upwards of 25-30 mph. South-southeasterly
onshore swells will increase to around 3 to 4 feet with a 6
second period. Breaking waves in the surf zone will generally be
2 to 4 feet. Due to the increase in a more onshore wind and
wave heights also increasing, a HIGH risk for the development of
dangerous rip currents is forecast for coastal Ocean, Atlantic,
and Cape May county. A Rip Current Statement remains in effect
until 8 PM today for these coastal areas. There is a MODERATE
risk for the development of dangerous rip currents at coastal
Monmouth and the Delaware Beaches. For these coastal zones, the
wind is more shore parallel.

On Tuesday, winds will be out of the south to southwest around
10 mph, turning to the north at 10 to 15 mph with gusts up to 20
mph in the afternoon. Breaking waves will be 1 to 3 feet with a
light southeasterly swell with a period around 6 seconds. As a
result, there is a LOW risk for the development of dangerous and
life threatening rip currents for the Jersey Shore and Delaware
Beaches.

On Wednesday, winds will be light and variable in the morning,
turning south around 10 mph in the afternoon. Breaking waves
will be 1 to 2 feet with a light southeast swell with a period
around 7 seconds. As a result, there is a LOW risk for the
development of dangerous and life threatening rip currents for
the Jersey Shore and Delaware Beaches.

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

KEY MESSAGE 3...Another cold front is expected to approach the
region late this week, bringing more chances for showers and
storms.

Another cold front is expected to approach our region late in
the week (likely crossing through our region Friday into
Saturday). More showers/storms are likely beginning as early as
late day Thursday and then continuing Friday.  Southwesterly
flow ahead of the front should allow for plenty of moisture
advection ahead of the rain chances. However with the best
forcing more centered north of the region, that could limit how
widespread significant rain is with this event. As for what
hazards to expect with this event, that will be highly dependent
on the timing of the showers and storms, which is still
uncertain.

The front may linger nearby next weekend and if this occurs it
would keep chances for shower/storms going, especially in the
afternoon/evening hours. There is uncertainty regarding this
though.

&&

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

Through tonight...Showers/storms expected to affect the
terminals especially during the 21-01z time frame (except
slightly later for MIV and ACY). These will bring at least
brief periods of IFR visbys with the potential for some brief
wind gusts of 35-40 knots. Thunderstorm activity should be
diminishing by late evening but showers with sub VFR conditions
expect to linger through the night and beyond. It now appears
most site should see IFR cigs by the overnight period. S/SE
winds around 10 knots gusting 20-25 knots this afternoon
shifting to SW this evening and then eventually going to NNW at
5-10 knots by daybreak. Moderate confidence overall.

Tuesday...Sub VFR with more shower and possible storms likely.
The first part of the morning should be mainly IFR due to low
cigs before some improvement will be possible by afternoon.
However any heavier shower/storms by afternoon could bring brief
IFR visbys. Winds northerly around 10 knots.

Outlook...

Wednesday...VFR. No significant weather.

Thursday through Saturday...Chances for shower/storms return
(30 to 50 percent chances) beginning late day Thursday and these
could bring brief restrictions.

&&

.MARINE...
Small Craft Advisory in effect today and tonight with southerly
wind gusts increasing to 30 knots with seas building to 4 to 6
feet. Some gusty thunderstorms will be possible this evening.

After a lull, another period of SCA conditions will be possible
late day Tuesday into Tuesday night due to gusty N/NW winds.

Outlook...

Wednesday through Saturday...Sub SCA conditions.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Flood Watch through late tonight for PAZ070-071-101>106.
NJ...Flood Watch through late tonight for NJZ008>010-012-013-
     015>019.
     High Risk for Rip Currents until 8 PM EDT this evening for
     NJZ024>026.
DE...Flood Watch through late tonight for DEZ001.
MD...None.
MARINE...Small Craft Advisory until midnight EDT tonight for ANZ430-431.
     Small Craft Advisory until 6 AM EDT Tuesday for ANZ450>455.

&&

DISCUSSION...Fitzsimmons/Guzzo/Johnson/RCM
AVIATION...Fitzsimmons/Gorse/Johnson/RCM
MARINE...Fitzsimmons/Guzzo/Johnson/MPS/RCM

Hazardous Weather Outlook
National Weather Service Mount Holly NJ
507 AM EDT Mon Jun 22 2026

MDZ012-015-019-020-230915-
Kent MD-Queen Annes-Talbot-Caroline-
507 AM EDT Mon Jun 22 2026

This Hazardous Weather Outlook is for northeast Maryland.

.DAY ONE...Today and tonight.

A slight risk of severe thunderstorms and excessive rainfall exists
today and tonight.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

Preliminary Local Storm Report
National Weather Service Mount Holly NJ
547 PM EDT Mon Jun 22 2026

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

0520 PM     Tstm Wnd Dmg     Marshallton             39.95N 75.68W
06/22/2026                   Chester            PA   Fire Dept/Rescue

            Multiple reports of wires down along Clayton
            Road. Time estimated from radar.

&&

NG

Preliminary Local Storm Report
National Weather Service Mount Holly NJ
559 PM EDT Mon Jun 22 2026

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

0518 PM     Tstm Wnd Dmg     3 SE West Marlborough T 39.89N 75.77W
06/22/2026                   Chester            PA   Trained Spotter

            Multiple large tree branches snapped near
            the intersection of Newark Road and Clonmell
            Mill Road. A tree is also down on Newark
            road. Time estimated from radar.

&&

NG

Preliminary Local Storm Report
National Weather Service Mount Holly NJ
611 PM EDT Mon Jun 22 2026

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

0605 PM     Flood            1 WSW Shawmont - Philad 40.04N 75.26W
06/22/2026                   Montgomery         PA   Dept of Highways

            Flooding on Schuylkill Expressway/I-76 west
            of Gladwyne. Seen on DOT traffic cameras.

&&

MJL

Preliminary Local Storm Report
National Weather Service Mount Holly NJ
627 PM EDT Mon Jun 22 2026

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

0616 PM     Hail             East Greenwich Twp      39.80N 75.22W
06/22/2026  E0.25 Inch       Gloucester         NJ   Emergency Mngr

            Report of pea sized hail. Time estimated
            from radar.

&&

NG

Preliminary Local Storm Report
National Weather Service Mount Holly NJ
650 PM EDT Mon Jun 22 2026

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

0623 PM     Flash Flood      1 S Wyncote             40.08N 75.15W
06/22/2026                   Montgomery         PA   Fire Dept/Rescue

            Report of a water rescue.

&&

NG

Preliminary Local Storm Report
National Weather Service Mount Holly NJ
654 PM EDT Mon Jun 22 2026

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

0645 PM     Flash Flood      2 NE Mercerville        40.25N 74.66W
06/22/2026                   Mercer             NJ   Trained Spotter

            Hughes drive flooded near Mercer County Park
            with the road impassible.

&&

NG