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046
FXUS61 KPHI 071946
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
346 PM EDT Mon Jul 7 2025

.SYNOPSIS...
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Bermuda high pressure will remain in place offshore through the
week. Chantal`s remnants will pass offshore of Delmarva this evening,
then a few additional weak systems and a slow moving frontal boundary
will impact the region through the remainder of the week.
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&&

.NEAR TERM /THROUGH TUESDAY/...
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The well advertised tropical airmass has engulfed the region this
afternoon as the remnants of Chantal are moving into the region as
we speak. It feels more like Florida out there today with temps in
the 80s and low 90s with dew points in the mid to upper 70s. With
PWATs around 2.0-2.5 inches, deep warm cloud depths, light steering
flow up to 850 mb, and favorable upper jet dynamics, the potential
for significant flash flooding remains. In fact, have already issued
several flash flood warnings across portions of the area this
afternoon. Guidance has been lack-luster with total QPF so far, so
looking back upstream, it seems that up 1-2 inches of rain is on par
for most of the areas where isolated areas of up to 5 inches
possible. For this reason, the Flood Watch remains unchanged and is
still in effect until 10 PM this evening. WPC has also maintained
the SLIGHT risk for excessive rainfall through today for flash
flooding. As we progress through the early evening, the remnant
circulation of Chantal will skirt off the coast of New Jersey,
causing the rain threat to diminish by 9-10 PM this evening from
southwest to northeast. It`ll remain quite muggy outside overnight
with lows only in the low to mid 70s and upper 60s in the Poconos.

The unsettled, active, and tropical weather pattern will continue
through Tuesday due to a slow-moving cold front which will work its
way toward the area, but won`t actually cross through the area until
mid-late week. This boundary will act as the trigger for convection
in both the severe and hydro department on Tuesday. PWATs will
remain in the range of 1.8-2.3 inches; tall, skinny CAPE on the
order of 1500-2500 J/kg; and relatively low unidirectional effective
shear up to 20 kt supports the potential for training convection
where any residual boundaries are in place. There won`t be much dry
air to speak of in the DCAPE department, however steep low-level
lapse rates combined with water loaded downdrafts will yield a
localized damaging wind threat with any stronger or more organized
updrafts. As a result, the Storm Prediction Center and Weather
Prediction Center have increased the threat for severe weather and
excessive rainfall on Tuesday afternoon respectively, with both
upgrading most of our forecast area to a SLIGHT risk. Have
considered extending and expanding the current Flood Watch through
tomorrow evening to cover this potential threat, however have opted
to let the current watch run its course with the remnants of
Chantal. We`ll continue to monitor this potential threat over the
next 12-24 hours and let future shifts decide when a future Flood
Watch becomes necessary. The main takeaway here is that there is an
increase in additional flash flooding exacerbated by antecedent
conditions and additional heavy rainfall.

As for temperatures, Tuesday will feature mostly sunny skies in the
morning with increasing clouds ahead of the thunderstorm potential
mid-late afternoon. Forecast highs are expected to be in the upper
80s to mid 90s across most of the area with tropical dew points
remaining in the low to mid 70s. As a result, heat indicies are
expected to range between 100-105 degrees across much of the area.
For this reason, have kept current heat headlines in place and have
expanded the Heat Advisory south and east to include the remainder
of our southern New Jersey, Delaware, and Maryland counties
(excluding the immediate coastal strips) through 8 PM Tuesday.
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&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
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The remnants of Chantal will be long gone, but the environment will
not change much with plenty of humidity lingering across the Middle
Atlantic region. This humidity will be acted upon by daytime heating
and several shortwaves both Wed/Thu. In addition, a weak front
lingering across the area will focus showers/tstms thru the period.
We`ll have likely pops for all areas Thursday but just for Delmarva
Wednesday. Chance pops will round out the other periods. Rainfall
will be heavy at times with instances of flash flooding possible
both days. While widespread severe weather is not likely, there
could be strong gusty winds associated with downpours at times.

Temperatures will be summer-like Wed with highs above normal.
readings will top out in the upper 80s/low 90s most areas. Apparent
temps will be some 5 to 7 degrees higher with all the humidity
about. The highs for Thu will be closer to normal with upper 70s/low
80s for the N and w areas and mid 80s elsewhere.
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&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
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The period from this Friday through next Monday continues to look
rather unsettled with summer-like precipitation and rather mild
temperatures, compared to recently. The high temps through the
period are fcst to be at or a little below normal. Normal highs for
early/mid July are mostly in the mid 80s for Philadelphia, Delmarva,
the Lehigh Valley and south NJ while upper 70s/low 80s are normal
for north NJ and the southern Poconos. Normal lows are generally in
the 60s but closer to 70 for KPHL.

Precipitation will be showery, each day, with tstms too mostly
afternoon and early evening hours. Models are not showing strongly
synoptic cues to organize precip, mostly just subtle disturbances in
the flow which are notorious for difficult timing/placement. The
precip fcsts offered by the models will change several times before
the day arrives. The broad-brushed chance pops offered by the NBM
are accepted without change.
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&&

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

Rest of Today...VFR conditions expected for the remainder of the
afternoon. Showers and isolated thunderstorms expected mainly
between 19Z-00Z for all terminals, included in TEMPO groups.
VSBY/CIGS restrictions down to MVFR possible. Southerly winds around
10 kt, with gusts up to 20 kt at KMIV/KACY. Moderate confidence.

Tonight...Primarily VFR. Scattered mid-high clouds with a few low
clouds possible. Southwest winds around 3-5 kt, becoming VRB/calm at
times. High confidence.

Tuesday...VFR expected for much of the day with sub-VFR conditions
possible late in the afternoon as scattered thunderstorms move into
the region after 19Z. Southwest winds around 5-10 kt with gusts up
to 15 kt possible. Moderate confidence.

Outlook...

Tuesday night through Saturday...VFR should generally prevail
during the daytime periods with daily chances for thunderstorms,
especially in the afternoon and evening hours. Areas of fog and
low clouds with restrictions more probable at night.
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&&

.MARINE...
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Small Craft Advisories have been issued for the Atlantic coastal
waters from Fenwick Island to Cape May until 12 AM Tuesday and from
Cape May to Manasquan Inlet until 5 AM Tuesday due to seas around 5
feet.

South-southwest winds around 10-15 kt expected through Tuesday, with
occasional gusts up to 20 kt possible. Seas up to 5 feet expected
tonight with seas around 2-4 feet expected on Tuesday. Several
rounds of showers and thunderstorms expected.

Outlook...

Tuesday night through Friday...Winds and seas are forecast to remain
below advisory criteria. Daily chances of showers and thunderstorms.
Some areas of fog possible at times.

Rip Currents...

For today, southerly winds will increase to 10-15 mph. Breaking
wave heights increase to 3-4 feet with a primary SE swell
around 1-3 feet and an 8 second period increasing to around
12-14 seconds during the afternoon. With the winds looking more
onshore, have opted to increase the rip current risk to HIGH for
dangerous rip currents from Cape May to LBI. Will maintain
MODERATE for the easterly facing beaches across Delaware and
Monmouth in NJ.

For Tuesday, winds shift southwesterly becoming more alongshore
flow around 5-10 mph in the morning increasing to 10-15mph in
the afternoon. Breaking wave heights should be in the 2-4 foot
range depending on beach orientation with a primary SE swell
increasing to 4 feet at a 6-8 second period. Given the tides
will be around low tide in the morning with the increase in
swell, will maintain a HIGH risk for rip currents for the
easterly facing beaches and MODERATE elsewhere.

Rip currents occur often in the vicinities of jetties and piers
and the speed of the currents are generally maximized at low
tides.

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

.HYDROLOGY...
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The Flood Watch remains in effect through 10 PM this evening. A
tropical airmass with precipitable waters in excess of 2 inches will
persist over the region today. Weak steering flow and the abundance
of tropical moisture will lead to highly efficient rainfall rates
across the region. Basin wide rainfall totals are anticipated to be
in the 1 to 2 inch range with the potential for up to 5 inches in
heavier thunderstorms. Main stem river flooding is not anticipated
but flash flooding of smaller streams/creeks and areas of poor
drainage will be possible. Please heed any road closures and law
enforcement instructions in case of flooding.
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&&

.PHI WATCHES/WARNINGS/ADVISORIES...
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PA...Flood Watch until 10 PM EDT this evening for PAZ070-071-
     101>106.
     Heat Advisory from 10 AM to 8 PM EDT Tuesday for PAZ070-071-
     101>106.
NJ...Flood Watch until 10 PM EDT this evening for NJZ009-010-012-
     013-015>019-021.
     Heat Advisory from 10 AM to 8 PM EDT Tuesday for NJZ009-010-
     012>023-027.
     High Risk for Rip Currents until 8 PM EDT this evening for
     NJZ024>026.
DE...Flood Watch until 10 PM EDT this evening for DEZ001>003.
     Heat Advisory from 10 AM to 8 PM EDT Tuesday for DEZ001>003.
MD...Flood Watch until 10 PM EDT this evening for MDZ012-015-019-
     020.
     Heat Advisory from 10 AM to 8 PM EDT Tuesday for MDZ012-015-
     019-020.
MARINE...Small Craft Advisory until 6 AM EDT Tuesday for ANZ451>453.
     Small Craft Advisory until midnight EDT tonight for ANZ454-455.
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&&

$$

SYNOPSIS...Staarmann
NEAR TERM...Deal/DeSilva/Staarmann
SHORT TERM...OHara
LONG TERM...OHara
AVIATION...DeSilva/Staarmann
MARINE...DeSilva/Staarmann
HYDROLOGY...PHI