687
FXUS61 KPHI 111530
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
1130 AM EDT Tue Aug 11 2026

.WHAT HAS CHANGED...
Minor changes to Key Messages and Aviation sections.

&&

.KEY MESSAGES...
1. Daily chances for showers and thunderstorms into the middle
of the week. There is a risk for strong to severe thunderstorms,
as well as a marginal risk for localized heavy rainfall leading
to flash flooding.

2. Hot and humid conditions will persist into the middle of the
week, but humidity will not be as oppressive as recent days.

3. There is potential for minor tidal flooding during the
evening high tides this week along the Atlantic coast, Delaware
Bay, and tidal Delaware River, especially on Tuesday and
Wednesday.

&&

.DISCUSSION...
KEY MESSAGE 1...Daily chances for showers and thunderstorms
into the middle of the week. There is a risk for strong to
severe thunderstorms, as well as a marginal risk for localized
heavy rainfall leading to flash flooding.

A surface cold front will gradually sag southward across the northern
tier of the region this afternoon into evening before stalling around
the I-80 or I-78 corridors come Wednesday. During this time, a few
upper level shortwave pulses will rendezvous with the surface cold
front, bringing rounds of showers and storms through Wednesday morning.
The first round of storms this afternoon and evening will be probably
to the North/West across the southern Poconos and possibly into the
Lehigh Valley. Other more scattered activity is possible across
southern NJ. The upper vort maxs are difficult to track and the
CAMs guidance is very inconsistent, so we`ll continue with
blended guidance as well as satellite/radar trends for our
updates. That said, instability across the region does look to
be limited to the 1000-2000 J/kg range with limited deep layer
shear, which will, therefore, limit the severe weather potential
today. SPC has expanded the Marginal Risk (level 1 out of 5)
farther northeast now into the Lehigh Valley and central NJ, and
the entire area remains in the Marginal Risk (level 1 out of 4)
for excessive rainfall.

The latest guidance now suggests a second round of showers and
perhaps some convective thunderstorms to arrive early Wednesday
morning with the potential for heavy downpours during the
Wednesday morning rush hour. While there remains a fair amount
of uncertainty with this setup it appears that this round may
be a result of a decaying upstream MCS from the Ohio Valley.
This setup remains highly uncertain and fully dependent on how
the volatile setup across the Ohio Valley eventually pans out
through the overnight hours. Areas that are favored for higher
pops and heavy rains will be Delmarva and south NJ, possibly
into Philadelphia.


Additional rounds of upper level shortwaves look to ride along the
quasi-stationary boundary which will support rounds of convection
continuing at least through Wednesday night, and possibly into
Thursday. The front looks to push through by late Thursday, and
a much drier and cooler airmass will arrive by Friday and
Saturday as a result. This will bring us a more pronounced break
in convective potential and more pleasant weather conditions.

KEY MESSAGE 2...Hot and humid conditions will persist into the
middle of the week, but humidity will not be as oppressive as
recent days.

A relatively stagnant synoptic pattern will remain in place
across our region. Quasi zonal mid and upper level flow will be
in place through the middle of the week as Bermuda high pressure
persists offshore. This will keep a very warm and moist airmass
in place across the region through the period.

Hot and humid conditions will continue into the middle of the
week, although slightly lower temperatures and dewpoints will
arrive for Wednesday. Dewpoints are anticipated to mix out into
the mid to upper 60s again this afternoon. This will give some
slight reprieve from the excessive humidity we`ve experienced in
recent days, though highs will still be in the upper 80s to mid
90s. The lower dewpoints will result in maximum heat indices
mainly in the mid to upper 90s, though could get near 100
degrees in Delmarva and near the coast in New Jersey. Therefore,
hot and humid, but not to the point where any heat headlines are
needed.

By Friday and Saturday with the front finally having pushed through,
a much drier and more cooler airmass will arrive, which will bring
much more pleasant weather conditions. Dewpoints may drop into the
50s again for many areas with highs forecast to be in the low to
mid 80s. Dewpoints look to start rebounding into the 60s again
by Sunday.


KEY MESSAGE 3...There is potential for minor tidal flooding
during the evening high tides this week along the Atlantic
coast, Delaware Bay, and tidal Delaware River, especially on
Tuesday and Wednesday.

As we approach the New Moon on Wednesday, astronomical tides for
the evening high tide cycles will increase to around a half foot
below minor flood stage in many areas this week along the
Atlantic coasts of New Jersey and Delware, Delaware Bay, and
the tidal Delaware River. With tide departures running around a
half foot above average, this will raise a threat of minor flood
stage being reached for these areas.

We will continue to monitor the tide departures in the coming
total water level forecasts. Coastal Flood Advisories have been
issued for areas along the Delaware Bay for the Tuesday evening
high tide. Additional Coastal Flood Advisories may be needed
over the coming days, but at least spotty minor tidal flooding
should be anticipated around the times of the evening high tides
this week. The highest astronomical tides will occur on
Wednesday, though Tuesday`s tides are of similar height. The
threat of minor tidal flooding may linger through Thursday or
Friday as well.

Tidal flooding is not currently forecast for the Eastern Shore
of Chesapeake Bay.

&&

.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

This afternoon...VFR. A 20-40 percent chance of a shower or
thunderstorm in the afternoon with the best chance north and
west around ABE/RDG. North to Northwest winds around 15-20 kts
decreasing and backing to West late. Low confidence regarding
the shower/thunderstorm coverage/timing.

Tonight...VFR give way to MVFR restrictions with showers and
thunderstorms arriving during the overnight hours, around
06-09Z, mainly across the southern terminals. Low confidence.

Outlook...

Wednesday through Thursday...Prevailing VFR. Restrictions
possible with afternoon/evening showers and thunderstorms.

Friday and Saturday...VFR. No significant weather expected.

&&

.MARINE...
No prevailing marine hazards expected through Tuesday night.

Outlook...

Wednesday through Friday...No prevailing marine hazards
expected. Thunderstorms possible each afternoon and evening.

Saturday...No marine headlines are anticipated.

Rip Currents...

For Today...Light winds in the morning will settle out of the
west-southwest in the afternoon between 5 to 15 mph. Breaking
wave heights will remain around 2 feet or less with a southerly
2 foot swell around 5 to 7 seconds. Therefore, there is a LOW
risk for dangerous rip currents at all beaches.

For Wednesday...Light winds around 5 to 10 mph will gradually
turn from northwesterly in the morning to southeasterly in the
late afternoon. Breaking wave heights will remain around 2 feet
or less with a southerly 2 foot swell around 5 to 7 seconds.
With little changes in overall conditions, will continue with a
LOW risk for dangerous rip currents at all beaches.

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

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...Coastal Flood Advisory from 9 PM this evening to 2 AM EDT
     Wednesday for NJZ016.
     Coastal Flood Advisory from 6 PM this evening to midnight EDT
     tonight for NJZ021-023-024.
DE...Coastal Flood Advisory from 9 PM this evening to 2 AM EDT
     Wednesday for DEZ001.
     Coastal Flood Advisory from 6 PM this evening to midnight EDT
     tonight for DEZ002>004.
MD...None.
MARINE...None.

&&

$$

DISCUSSION...MJL/po
AVIATION...MJL/po
MARINE...MJL