Special Marine Warning 59, NWS Philadelphia/Mount Holly

Area Forecast Discussion
National Weather Service Mount Holly NJ
821 AM EDT Sat Jun 27 2026

.WHAT HAS CHANGED...
The Climate section now lists the high temperature records for
Thursday and Friday of next week.

&&

.KEY MESSAGES...
1. Unsettled conditions are expected through Sunday as a front
and several weak upper systems move through, bringing periodic
showers and isolated thunder for the weekend.

2. Heat builds back into the region for the middle and end of
next week. There is increasing confidence that high temperatures
will be well in the 90s to around 100 degrees, with maximum
heat index values exceeding 100 degrees for multiple days.

&&

.DISCUSSION...
KEY MESSAGE 1... Unsettled conditions are expected through Sunday
as a front and several weak upper systems move through,
bringing periodic showers and isolated thunder for the weekend.

A slow-moving front will essentially become stalled across the
mid-Atlantic today into tonight, especially as a weak low
pressure tracks east from the OH Vly into the region by tonight.
This will cause some subtle moisture resurgence back into
Delmarva and southern parts of the local area, especially
southern NJ, during the day today. With PWs around 1.75" in
these areas by this afternoon amidst an uncapped environment,
scattered showers and isolated thunderstorms will likely
develop/blossom through peak diurnal heating. The severe
potential with these slow-moving downpours remains very low,
owing to poor low-level and midlevel lapse rates and very
marginal instability. The best chance for thunder will be in
Delmarva where instability will be greatest by late afternoon.

Coverage of activity will be largely diurnhally-driven, meaning
there should be a gradual decrease past sunset late this evening
into tonight. That being said, with very subtle forcing and a
sufficently-saturated environment in the region, some isolated
activity should continue through the overnight into Sunday
morning, especially for Delmarva and southern NJ.

Moreover, the latest guidance has trended slightly slower with
boundary clearing the region, with the potential now for
lingering showers and perhaps a few rumbles of thunder as well
into the daytime Sunday (once again favored across southern
parts of the PHI CWA). The very subtle/slow southward
progression of the front will finally make a more concerted
effort further S by Sunday night as a weak surface low finally
pulls to the E of the region. This will allow for low-level wind
fields to become more decidedly northerly, allowing for
slightly drier air to overspread the region into Monday. Drier
conditions are expected for the start of the workweek.

KEY MESSAGE 2...Heat builds back into the region for the middle
and end of next week. There is increasing confidence that high
temperatures will be well in the 90s to around 100 degrees, with
maximum heat index values exceeding 100 degrees for multiple
days.

Strong mid-level ridging will develop over the Great Lakes and Ohio
Valley early in the new week, then will build into the Northeast and
Mid-Atlantic starting on Wednesday and continuing through the end of
next week. Hot and humid conditions will return with high
temperatures well into the 90s to around 100 degrees with and max
heat index values over 100 degrees. This will likely persist for
multiple days, including into the upcoming holiday weekend.

01Z/27 NBM probabilities indicate probabilities >90% of high
temperatures exceeding 95 degrees on both Thursday and Friday,
with greater than 80% probability of high temperatures
near/exceeding 100 degrees from the Lehigh Valley north and across
the Delaware Valley, including Philadelphia, southern New
Jersey, and Delmarva both Thursday and Friday. Max heat index
values could exceed 105 degrees, which would necessitate
potential Extreme Heat Warnings for much of the local area for
several days.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

.Today...Overall a cloudy forecast with numerous showers this
morning becoming more scattered by the afternoon. There are
greater chances for showers, and perhaps some TS as well, across
south NJ and Delaware Valley sites by late afternoon into the
evening. Light and variable winds through the day will go out of
the NE/E at times during the afternoon. Confidence is low
overall regarding coverage and timing of activity, including
TSRA potential late in the day.

.Tonight... SHRA/TSRA will become more isolated by/after 06z.
With a gradual moistening of the profile, expect MVFR ceilings
to develop/overspread southern sites by the end of the period.
Cannot rule out some IFR ceilings and prevailing MVFR
visibilities toward 12z Sunday, particularly for KMIV/KACY.

Outlook...

Sunday...VFR. Lingering MVFR/IFR conds in the morning, improving to
VFR by midday. ISO to SCT SHRA or TSRA at KPHL, KILG, KMIV,
KACY, primarily during the afternoon/evening.

Sunday night...VFR. NSW.

Monday through Wednesday...VFR. NSW.

&&

.MARINE...
A nearly stationary front will remain entrenched across the
region through today, providing a focus for periods showers and
tstms. Overall, winds and seas will remain sub-SCA through
tonight. A few tstms are likely prior to 09z, with another
period of possible showers/tstms this afternoon and evening,
with chances in the high chance/low likely category.

Outlook...

Tonight through Sunday...Sub-SCA conditions. VSBY restrictions
in showers, scattered thunderstorms, and mist tonight through
Sunday morning.

Monday through Wednesday...Overall, sub-SCA conditions. Cannot rule
out a brief period of southerly 25+ kt gusts late Tuesday afternoon
north of Barnegat Light.

Rip Currents...

For today, breaking waves in the surf zone are forecast to be
around 2 feet with around a 6 second period and south-southeast
swell. Winds should be mainly southeast around 10 mph. Given
these conditions, we'll continue with a LOW risk for the
development of dangerous rip currents for both the Jersey Shore
and Delaware Beaches.

For Sunday, winds shift to mainly northeasterly around 10 mph with
continuing breaking waves in the surf zone around 2 feet with a
6 to 7 second period and southeast swell. We will continue with
a LOW risk for the development of dangerous rip currents for
both the Jersey Shore and Delaware Beaches.

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

&&

.CLIMATE...
Here is a list of the high temperature records for July 2
(Thursday) and July 3 (Friday):

Thursday July 2
Allentown...102/1968
Atlantic City Airport...100/1966
Atlantic City Marina...97/1968
Georgetown...99/1953
Mount Pocono...93/1911
Philadelphia...103/1901
Reading...102/1966
Trenton...100/1901
Wilmington...98/1966

Friday July 3
Allentown...105/1966
Atlantic City Airport...104/1966
Atlantic City Marina...99/1919
Georgetown...101/1954
Mount Pocono...103/1911
Philadelphia...104/1966
Reading...103/1966
Trenton...102/1966
Wilmington...102/1966

&&

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

&&

DISCUSSION...
AVIATION...
MARINE...

Hazardous Weather Outlook
National Weather Service Mount Holly NJ
503 AM EDT Sat Jun 27 2026

MDZ012-015-019-020-280915-
Kent MD-Queen Annes-Talbot-Caroline-
503 AM EDT Sat Jun 27 2026

This Hazardous Weather Outlook is for northeast Maryland.

.DAY ONE...Today and tonight.

There is a low probability for widespread hazardous weather.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

Hot and humid conditions are expected Wednesday through Friday. Heat
index values in excess of 100 degrees are likely each day during
this stretch.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.