Areal Flood Warning 86, NWS Philadelphia/Mount Holly

Area Forecast Discussion
National Weather Service Mount Holly NJ
331 AM EDT Sat Jul 13 2024

.SYNOPSIS...
Several weak waves of low pressure will ride along a stationary
front draped over our region today. High pressure returns late
tonight and persists through Tuesday night. A cold front
approaches from the northwest on Wednesday before crossing our
area during Wednesday night. High pressure then builds back in
from the west to end the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Frontal boundary lies over eastern Pennsylvania and extends
north of New Jersey and south along the I-05 corridor down into
the Southeast. Low pressure is forming over the Mid-Atlantic and
will track north over New Jersey as the morning progresses. As
low pressure departs later today, it will drag the stationary
front through the region as a cold front tonight.

Ahead of the front, widespread surface dew points will be well
in the 70s with PWATs in excess of 2 inches. SB CAPE values will
be in excess of 2 inches, while 0-6 km Bulk Shear will generally
average 20 to 30 kt. One area of showers is lifting north
through portions of southeast Pennsylvania, mainly Berks county
and moving into the Lehigh Valley. Another area of showers is
moving through Delmarva. Locally heavy rain is falling, and
locally heavy rain will continue to be the main threat through
this afternoon.

Several waves of moderate to heavy rain will continue to develop
ahead of the frontal boundary. Flood Watch remains in effect
until 2 pm this afternoon to highlight the flooding threat.

As the front passes through the region this afternoon, another
round of showers and thunderstorms are possible into this
evening. Severe threat will be minimal.

Tonight, high pressure builds in from the west. Abundant low
level moisture will remain in place, so patchy fog is likely to
develop. Fog may become locally dense, especially in areas where
heavy rain falls today.

&&

.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
Going forward, high pressure will then hold influence over the
region through the remainder of the short term period. Upper
heights begin to increase and surface flow becomes southerly.
This will usher in the return of the heat and humidity on
Sunday. Basis the latest available guidance, high temps will be
in the low to mid 90s (80s down the shore and in Poconos). Dew
points will also range from the upper 60s and low 70s. This
equates to heat indicies around 100 degrees across much of the
coastal plain into the Lehigh Valley. As a result, have opted to
issue a Heat Advisory for Sunday where conditions warrant.
Also, cannot rule out an isolated shower or thunderstorm across
eastern PA or the Delmarva which lies in proximity of the
dissipating front.

Rather benign conditions continue into Sunday night under mostly
clear skies. Lows may be a degree or two warmer compared to
Saturday night as southerly flow is a bit stronger than the
night before.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
High heat and humidity will continue to impact the area through
Tuesday, possibly lingering into Wednesday before a cold front
crosses through the area on Wednesday night.

Afternoon highs are forecast to be in the mid to upper 90s on Monday
and Tuesday, when the highest temperatures are likely to occur. Dew
points are also expected to further increase into the low to mid 70s
which will result in heat indicies upwards of 105-110 degrees across
most interior locations. Due to this potential, have opted to issue
an Excessive Heat Watch for Monday and Tuesday with this update
for the same areas where Heat Advisories are in effect for
Sunday. A chance of diurnally driven thunderstorms are possible
each afternoon as well.

On Wednesday, the heat and humidity will continue but is expected to
be a touch lower compared to the days prior as a cold front
approaches. This should result in a more widespread chance for
showers and storms late in afternoon into the evening hours.
Depending on the progression of the front, shower activity may
linger into Thursday as well. However, with the front working
its way through the region, temperatures by late week are
expected to be a few degrees below normal.

&&

.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Today...MVFR/IFR in SHRA and scattered TSRA. Low confidence on
a given TSRA passing over a given terminal, so will keep VCTS
for this threat. Heavy rain likely, and could even result in
brief sub-IFR VSBYs. Light S winds, becoming 5 to 10 kt this
afternoon. Conditions should lift to VFR by this afternoon,
generally after 18Z. Moderate confidence overall.

Tonight...VFR initially. Sub-VFR VSBYs in fog is likely.
LGT/VRB winds. Moderate confidence.

Outlook...

Sunday through Tuesday night...VFR. Otherwise, a slight chance
of a shower or thunderstorm each afternoon.

Wednesday...Primarily VFR but sub-VFR conditions possible. A chance
for showers and thunderstorms in the afternoon.

&&

.MARINE...
Will cancel the Small Craft Advisory that was in effect for the
ocean waters as seas have subsided to less than 5 feet. Sub-SCA
conditions for today and tonight for S winds 10 to 15 kt.

VSBY restrictions in showers and fog. Rain may be heavy at
times. Scattered thunderstorms possible as well.

Outlook...

Saturday night through Tuesday night...No marine headlines expected.
Wind gusts generally between 10-20 kt and seas around 2-4 feet.

Wednesday...SCA conditions possible due to winds around 20 kt and
seas build to around 4-5 feet.

Rip Currents...

For Saturday, southerly winds around 10-20 MPH with an onshore
component in Cape May, Atlantic, and Ocean County will result in
a MODERATE risk for rip currents. This is aided by breaking
waves of 2 to 4 feet. Flow will be more shore parallel in
Monmouth County and the Delaware Beaches with a LOW risk for rip
currents.

For Sunday, weak flow out of the south remains, though with
decreasing wave heights and a 5 to 7 second period, a LOW risk
for rip currents is in place at all coastal locales.

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

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Flood Watch until 2 PM EDT this afternoon for PAZ070-071-
     101>106.
     Heat Advisory from 10 AM Sunday to 6 AM EDT Monday for
     PAZ060>062-070-071-101>106.
     Excessive Heat Watch from Monday morning through Tuesday
     evening for PAZ060>062-070-071-101>106.
NJ...Flood Watch until 2 PM EDT this afternoon for NJZ001-007>010-
     012-013-015>019.
     Heat Advisory from 10 AM Sunday to 6 AM EDT Monday for NJZ009-
     010-012-013-015>022-027.
     Excessive Heat Watch from Monday morning through Tuesday
     evening for NJZ009-010-012-013-015>022-027.
DE...Flood Watch until 2 PM EDT this afternoon for DEZ001-002.
     Heat Advisory from 10 AM Sunday to 6 AM EDT Monday for DEZ001.
     Excessive Heat Watch from Monday morning through Tuesday
     evening for DEZ001.
MD...Flood Watch until 2 PM EDT this afternoon for MDZ012-015-019-
     020.
MARINE...None.

&&

SYNOPSIS...DeSilva/Wunderlin
NEAR TERM...Gorse/MPS/Staarmann
SHORT TERM...DeSilva
LONG TERM...DeSilva/Wunderlin
AVIATION...DeSilva/Gorse/MPS/Staarmann
MARINE...DeSilva/Gorse/Hoeflich/MPS/Staarmann