183
FXUS61 KPHI 111744
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
144 PM EDT Thu Jul 11 2024

.SYNOPSIS...
A cold front moves across the region this morning and will
stall over the area into this weekend. Several waves of low
pressure will track on this front before the front dissipates by
the start of the new week. Broad high pressure returns for the
start of the new week. The next front approaches the region by
the middle of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
2 PM...No major changes to the forecast at this time.

A stalled frontal boundary will remain just offshore into
tonight, then will lift northward into Friday morning.

Somewhat drier air will filter in today with W/SW winds near
10-15 mph. Much of the area can expect mostly sunny skies
(except for southern Delaware and Cape May). Some showers or
storms may linger in southern Delaware and Cape May where the
more persistent cloud cover will be found. While we will be in a
post-frontal regime, high temperatures will still be near 90
degrees in most areas. Fortunately, the lower dewpoints in the
mid to upper 60s will yield some relief to the excessively humid
conditions that have persisted the past several days, though
not particularly comfortable. Heat indices will top out in the
upper 80s to low 90s at best, and thus no heat headlines are
needed for today.

Tonight, guidance continues to support some showers and storms
riding up from the south/southeast along the stalled boundary.
PoPs and cloud cover will increase from the south/southeast
towards Friday morning. Some fog formation may occur for areas
tonight, particularly for those that see precipitation earlier
on. Winds are expected to be light and variable and/or calm.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
Frontal boundary remains along the East Coast into the weekend.
Abundant low level moisture will stream into the Northeast and
Mid-Atlantic with surface dew points well in the 70s and PWATs
in excess of 2 inches. There will be a fair amount of
instability during the daylight hours with SB CAPE values
upwards of 1500 J/kg, but 0-6 km Bulk Shear will be fairly low,
generally less than 20 kt. As a result, can expect heavy rain
and localized flash flooding as storms will be fairly slow to
move and training of storms will develop.

WPC Day 2 Excessive Rainfall Outlook for Friday and Friday
night has a Marginal Risk (1 out of 4) for northern New Jersey
and southeast Pennsylvania and a Slight Risk (2 out of 4) for
southern New Jersey and Delmarva.

The first low tracks along the coast on Friday and departs
Saturday night. A secondary low will follow behind it on
Saturday. Model guidance has it a bit warmer on Saturday
compared to Friday, with highs in the low to mid 80s on Friday
and in the mid to upper 80s on Saturday. The warmer temperatures
on Saturday may give way to a bit more convection.

Total rainfall Friday and Friday night will range from 1 to 2
inches across Delmarva and southern New Jersey, and generally
1/2 to 1 inch for for southeast Pennsylvania and northern New
Jersey. On Saturday and Saturday night, widespread rainfall
should be lower as the secondary low may pass just east of the
local area, with 1/2 to 3/4 inch of rain for Delmarva and
southeast New Jersey and 1/4 inch or so elsewhere.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Heat and humidity return for the first half of the new week as
high pressure builds east on Sunday. Once again, high
temperatures will be well in the 90s with dew points in the 70s,
resulting in heat index values around 100 and as high as 110.
Heat Advisories will likely be needed Sunday and Monday, and
then Excessive Heat Warnings may be needed on Tuesday and
Wednesday.

Isolated to scattered afternoon and evening showers and
thunderstorms are possible each day, though an approaching cold
front on Wednesday could result in better chances for showers
and thunderstorms.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Today...Mainly VFR conditions expected. West to southwest winds
near 10 kt. Moderate confidence.

Tonight...Mainly VFR, but some sub-VFR development possible
towards the later half of the period. Ceilings will lower with
time, some fog may form at some sites. KACY could see MVFR
ceilings before the end of the period. Winds light and variable
and/or calm for most sites. Moderate confidence overall, low
confidence in details.

Outlook...

Friday through Saturday night...Sub-VFR in SHRA and TSRA, with
locally heavy rain from time to time.

Sunday through Monday...Primarily VFR, though isolated to
scattered SHRA/TSRA possible during the afternoon and evening.

&&

.MARINE...
The SCA in effect for ANZ450-455 remains in effect until 6 AM
EDT Friday. SW to S winds 10-20 kt today, diminishing to 5-10 kt
tonight. Seas 3-5 feet through tonight.

Some fog development over the waters is possible tonight.

Outlook...

Friday through Saturday night...Lingering 5 ft seas possible on
Friday, and a SCA may be needed. Otherwise, sub-SCA conditions.
VSBY restrictions in rain, thunderstorms, and fog. Rain may be
heavy at times.

Sunday through Monday...Sub-SCA conditions.

Rip Currents...

Today, south to southwest winds will average 10 to 15 mph along
with breaking waves of 1 to 2 feet. Given the wind component,
this will result in a MODERATE risk for the development of
dangerous and life threatening rip currents for the Jersey
Shore. Since winds will be a bit lighter and a bit more offshore
for Delaware, there is a LOW risk for the development of
dangerous and life threatening rip currents for Delaware
Beaches.

Conditions will be fairly similar on Friday compared to today,
so will continue the MODERATE risk for dangerous and life
threatening rip currents for the Jersey Shore and a LOW risk for
Delaware Beaches.

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

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 AM EDT Friday for ANZ450>455.

&&

$$

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