729
FXUS61 KPHI 220639
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
239 AM EDT Mon Jun 22 2026

.WHAT HAS CHANGED...
Flood watch issued for I-95 corridor for later today thru
tonight.

Updated the aviation section for the 06z TAFs.

&&

.KEY MESSAGES...
1. A system moves in today into tonight bringing the threat of
both heavy rainfall with an associated flash flood threat along
with the threat of severe weather.

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 one more chance for showers and storms.

&&

.DISCUSSION...
KEY MESSAGE 1...A system moves in today into tonight bringing
the threat of heavy rainfall with an associated flash flood
threat along with the threat of severe weather.

Forecast models continue to better align regarding the track of
low pressure that will impact the region for today into
tonight bringing both severe weather and flash flood threats.
Surface low pressure is expected to track eastward across
southern PA this afternoon before moving across the heart of
our CWA tonight en route to southern New England. This will
occur on the downstream side of a fairly broad upper level
trough as embedded upper disturbances in the WSW flow aloft move
through. Unfortunately this set up in the warm season is quite
favorable for both severe weather and flash flooding as it will
bring both strong low level and deep layer shear with veering
winds profiles along with PWATs maxing out in the 1.8 to 2.4
inch range, close to climatological maxes. ML CAPE values look
to max out around 750 to to 1500 j/kg which combined with deep
layer shear of 40+ knots and 0-3 km shear of 30-35+ knots along
with sufficient forcing will be enough for severe weather. And
the high PWAT values along with the potential for there to be
multiple rounds of storms with some training has us concerned
about flash flooding as well.

Getting into the details, the low will be approaching by
this afternoon as it moves from Ohio into southern PA. Ahead of
the low, its warm front looks to lift northward through the day
as it moves from near Delmarva / southern New Jersey early in
the day, ending up somewhere between I-195/east-west PA Turnpike
and the I-80 corridor by late day. There will likely be some
initial showers and possible storms around this morning into
the early afternoon, especially over NE PA into our northern NJ
zones north of the warm front but the more significant
convection in terms of severe weather and flooding looks to hold
off until mainly after 18z. Expect that getting into the mid
afternoon and beyond that we`ll see convection
developing/strengthening both near the warm front in our
aformentioned northern/central zones as well as near and ahead
of a developing lee surface trough over western MD into SE
PA/Delmarva ahead of the low. So timing wise, the window of
most concern for our forecast area is roughly 3-11 PM. There
may be some discrete cells initially but with time the
convective mode should become multi-cell clusters with the
potential for embedded supercells as storms move through the
area during the late afternoon and evening period. Damaging
winds will be the biggest threat in terms of severe weather but
with the strongly veering low level winds there will be a
tornado threat as well. The current update from the Storm
Prediction Center keeps just about all of our area in a SLIGHT
risk for severe weather, meaning scattered severe storms will be
possible.

Regarding the flash flood threat, cell motion will be fairly
fast but there will be the potential for multiple rounds of
storms during the late afternoon / evening period along with the
potential for storms to train getting into the evening period.
The PWAT values progged to be near or above 2 inches indicate
the potential for 1-2+ inch per hour rain rates in convection.
FFG values are not terribly low given how dry it`s been but are
as low as 1 hr values of 1.5 to 2.0 inches and 3 hour values of
2.0 to 3.0 inches in the urban corridor. And given the setup
just described these values could be reached or exceeded. After
collaboration with NWS NYC, we decided to hoist a Flood Watch
for flash flooding for our urban corridor zones.

As mentioned, the peak of the convection with its associated
severe weather and flash flood threats looks to be through the
evening with storms weakening and moving out through the
overnight period as the low and its associated cold front move
eastward towards the coast.

For Tuesday, a secondary cold front moving through along with
some lingering instability could result in some additional
scattered showers/storms by the afternoon. But these are not
expected to pose a severe weather or flood threat and should be
confined mainly to areas mainly near and S/E of the urban
corridor.


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 has been issued
from 8 AM to 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.

For Tuesday, winds are offshore with a north-northwest wind at
around 10 mph. South- southeasterly onshore swells will be
around 2 to 3 feet with a 5-6 second period. Breaking waves in
the surf zone will generally be 1 to 2 feet. Due to these
forecast conditions, there is a LOW risk for the development of
dangerous rip currents at all the New Jersey 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 one more chance 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. At this point, the majority of guidance keeps the main
low well north of our region (generally crossing across
southern Canada). This will mean that the area of most synoptic
scale forcing will also stay north of our region. However, even
the modest mesoscale forcing ahead of and with the front should
be enough for some scattered showers and storms as the front
approaches.

Southwesterly flow ahead of the front should allow for plenty
of moisture advection ahead of the rain chances. However with
the 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 the spread in
model guidance is as much as 18 hours at this point.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Thru 12Z this morning...VFR. Winds light and variable to
locally calm, becoming easterly late. Moderate confidence.

Today and tonight...VFR through most of the day with gradually
lowering ceilings. Showers and some thunderstorms mostly in the
afternoon from west to east. This could be mostly in the form of
a line of strong to severe thunderstorms with locally strong
winds. MVFR to IFR conditions will occur with the convection. As
of now, included a TEMPO for thunderstorms. East to
southeasterly winds increasing to 8-12 knots with some gusts to
around 20 knots. Low confidence regarding the timing details of
the showers/thunderstorms.

Outlook...

Tuesday...Showers and some thunderstorms will result in MVFR to
IFR conditions. Coverage of storms will be lower than
today/tonight, but may still be significant.

Wednesday...VFR. No significant weather.

Thursday and Friday...Chances for shower/storms return (30 to
50 percent chances) 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.

Outlook...

Tuesday through Friday...Sub SCA conditions.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Flood Watch from 2 PM EDT this afternoon through late tonight
     for PAZ070-071-101>106.
NJ...Flood Watch from 2 PM EDT this afternoon through late tonight
     for NJZ008>010-012-013-015>019.
     High Risk for Rip Currents from 8 AM EDT this morning through this
     evening for NJZ024>026.
DE...Flood Watch from 2 PM EDT this afternoon through late tonight
     for DEZ001.
MD...None.
MARINE...Small Craft Advisory from 3 PM this afternoon to midnight EDT
     tonight for ANZ430-431.
     Small Craft Advisory from noon today to 6 AM EDT Tuesday for
     ANZ450>455.

&&

$$

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