241
FXUS61 KPHI 241844
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
244 PM EDT Mon Jun 24 2024

.SYNOPSIS...
The cold front will continue to make its way offshore this evening
as high pressure remains in control through Tuesday night. A warm
front will lift north of the area early on Wednesday before another
strong cold front passes by late Wednesday night. High pressure
returns for Thursday and continues into Saturday ahead of another
low pressure system that approaches on Sunday. High pressure returns
by early next week.

&&

.NEAR TERM /THROUGH TUESDAY/...
A much more comfortable airmass in place across the northern Middle
Atlantic region to start the week. High pressure across Michigan is
sending cooler and drier air across the area from the NW. The high
will slip south of the area Tuesday and cause the fair weather to
continue.

Skies will be mostly clear overnight and lows will be rather cool
compared to recent nights. Lows will drop into the mid/upper 50s
across the far NW areas and be in the 60 to 65 degree range for
south NJ, Delmarva and metro Philadelphia. Winds will diminish
after sunset.

On Tuesday, a sunny day expected with perhaps some late day Ci/Cs
clouds arriving. Under these sunny skies, high temperatures will
climb into the mid/upper 80s for the North and upper 80s/low 90s for
metro Philly and adjacent areas. The dew points tomorrow will remain
low (50s), so despite the temperatures, it will not feel that
uncomfortable.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
Surface high pressure moves offshore Tuesday night as a warm front
passes north of the area early Wednesday morning. As a result, these
features will allow warm air advection to commence with surface flow
becoming southwesterly ushering in a more humid airmass. Skies will
remain partly cloudy as low temps only bottom out in the mid 60s to
low 70s.

The moist and humid airmass will continue on Wednesday as surface
dew points rise into the upper 60s to low 70s around the region.
With modest SW flow continuing under mostly sunny skies through the
early afternoon, the current forecast is for highs to reach into the
low to mid 90s across inland locations. Closer to the coast and up
in the Poconos, temps should remain in the 80s. Max heat indicies at
this time look to approach 95-100 degrees mainly confined to the
urban corridor. Heat headlines likely will be warranted during the
day on Wednesday, but we`ll continue to monitor this potential.

On the other hand, we`ll also need to monitor the potential for
severe weather Wednesday afternoon and evening. An upper trough will
swing through the Great Lakes on Wednesday approaching our area by
Wednesday night with an advancing cold front. With the abundance of
moist, humid air in place, several indicators are present for
thunderstorm development. Forecast soundings show SBCAPE values
around 1500-2000 J/kg, bulk shear values around 30 kt, and lapse
rates around 7.0-7.5C/km. Shear values are also a bit modest since
forcing will be in somewhat close proximity. As a result, the
Storm Prediction Center has outlined NE PA and N NJ in a SLIGHT
Risk (Level 2/5) for severe weather with the remainder of the
area in a MARGINAL Risk (Level 1/5). The main threat should be
damaging wind gusts considering the environment. In terms of
flooding, PWATs will be up around 2 inches, so any storm will be
capable of producing heavy rainfall. Storm motion does appear
to be relatively-fast, so not expecting any significant flood
impacts at this time. In terms of timing, short-range guidance
suggests this will be a late afternoon into the evening hours
event before the cold front moves offshore on Thursday.

Some showers may linger near the coast on Thursday morning, but the
overall trend will be for decreasing clouds and lowering dew points
on Thursday as high pressure builds in from the west. It will feel
much more comfortable outside compared to Wednesday with highs
returning closer to normal.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
The long term as a whole looks fairly tranquil aside for a low
pressure system that approaches for the latter half of the weekend.

Broad high pressure over the Midwest on Thursday will shift to our
north on Friday before moving off the coast of New England on
Saturday. This will result in a dry stretch of weather with mostly
clear skies. Another low pressure system is on pace to impact the
area Saturday night into Sunday which may bring another round of
showers and thunderstorms with another frontal passage. Too far in
advance to evaluate if any severe weather is possible. In its wake,
high pressure returns to the area into early next week.

Temps through the long term period should remain quite seasonable to
possibly a few degrees above normal for the end of June.

&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

.Rest of today... VFR. SCT/BKN clouds mostly north third of the
area (KABE/KTTN). Clouds decrease late. NW winds around 15 kts
with gusts 25/30 kts possible. High confid.

.Tonight... VFR. Skies mostly clear. NW/W winds decreasing to
around 5 knots. High confid.

.Tuesday... VFR. Mostly clear skies. West winds increasing to
around 10 knots. High confid.

Outlook...

Tuesday night...VFR with increasing clouds. No significant weather
expected.

Wednesday through Wednesday night...Primarily VFR. Scattered
thunderstorms during the afternoon and evening which may cause sub-
VFR conditions. Locally gusty winds near/in any thunderstorm.

Thursday through Saturday...VFR. Other than a chance of a shower
early Thursday, no significant weather expected.

&&

.MARINE...
We`ll continue with the SCA flags for the evening (Delaware Bay) and
ocean waters (early overnight) with the W to NW winds continuing.
Gusts between 25 and 30 kts expected before decreasing overnight.
Winds and seas have been slow to increase across the DE waters and
parts of lower De Bay, but still think that there is an opportunity
of some gusts into the early evening. Seas will be choppy for
Delaware Bay and 4 to 6 ft for the ocean waters. Fair tonight and
Tuesday. Lighter W winds expected for Tuesday.

Outlook...

Tuesday night through Wednesday...SCA conditions possible. Southerly
winds around 15-20 kt with gusts up to 25 kt. Seas around 4-5 feet.

Wednesday night through Saturday...No marine headlines expected. A
chance of thunderstorms on Wednesday night, otherwise generally fair
weather anticipated.

Rip Currents...

Monday...West-northwest winds around 10-15 mph with gusts up to
20 mph and breaking waves around 2 to 3 feet. Although wind
direction will be directed offshore, wave periods are expected
to increase to around 7 to 8 seconds. For this reason, have
maintained a MODERATE Risk for the development of dangerous rip
currents for both NJ/DE beaches.

Tuesday...Northwest winds will back to southerly as the day
goes on around 10 mph. Breaking waves around 1 to 2 feet. With
winds mainly directed offshore or parallel to the coast and
much lower wave heights, have opted to go with a LOW Risk of rip
currents for all 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 8 PM EDT this evening for ANZ430-
     431.
     Small Craft Advisory until 2 AM EDT Tuesday for ANZ450>452.
     Small Craft Advisory until 11 PM EDT this evening for
     ANZ453>455.

&&

$$

SYNOPSIS...DeSilva/Hoeflich
NEAR TERM...OHara
SHORT TERM...DeSilva
LONG TERM...DeSilva
AVIATION...DeSilva/OHara
MARINE...DeSilva/OHara