289
FXUS61 KPHI 111801
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
201 PM EDT Tue Jun 11 2024

.SYNOPSIS...
High pressure will retreat offshore through the middle of the
week. Temperatures will begin to rebound through Friday ahead of
a cold front, which will bring a chance of showers and storms
across the region. With the front offshore by Saturday, high
pressure will build into the region again through the weekend
with temperatures rebounding to well above normal into early
next week.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
200 PM...An upper level low remains situated to our north over
eastern NY State with a SW to NE oriented surface trough
offshore and an area of high pressure west of us over the
midwestern states into the lower Great Lakes. The upshot of this
is that there`s considerable cloud cover across the area due to
the upper low and associated cold pool aloft combined with
diurnal heating. There`s also some low level convergence that`s
been setting up near the coast due to a generally NE flow coming
onshore (aided by sea breezes) with NW winds trying to build in
from the west with the high pressure. This will bring some
isolated to scattered showers and perhaps even a few
thunderstorms developing this afternoon over southern NJ,
Delmarva, and perhaps as far north as the I-95 corridor by later
in the day. These won`t be too widespread though as POPs are
only in the 20 to 30 percent or so range for these areas. Our
northwest zones from Berks County into the Lehigh Valley and the
southern Poconos remain precip free. It will be an otherwise
relatively cool afternoon (by June standards) with low humidity
levels.

Tonight, the upper low starts to migrate to the northeast and
heights rise rapidly. This should cause convection to die
quickly by sunset with mostly clear to partly cloudy skies
overnight. Lows will be mostly in the 50s to low 60s. Enjoy it,
as we`re about to flip the page to summer in a big way.

For Wednesday, high pressure will be centered near the area
early in the day before starting to shift offshore causing
winds to turn light westerly. Expect a partly to mostly sunny
day with highs mainly in the low to mid 80s as our warming trend
begins. Humidity levels will remain comfortable though as dew
points will still be in the 50s.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
The early week troughing will be offshore by early Wednesday,
and quasi-zonal flow will develop in its wake through the end of
the week with increasing heights and thicknesses. Another trough
axis will approach the region late Friday. At the surface, broad
high pressure will shift offshore through the end of the week
with surface flow turning toward the south/southwest.

This pattern will translate to increasing temperatures and
dewpoints with each passing day as well as a dry forecast until
Friday. Following a return to near normal temperatures with
highs in the low 80s on Wednesday, highs will increase to near
90 degrees in most inland locations on Thursday. On Friday,
widespread inland high temperatures in the low to mid 90s are
forecast ahead of the approaching cold front. While dewpoints
will be on the rise, they should top out in the low to mid 60s.
This means that heat indices will be close to the air
temperatures. Nevertheless, we will be close to early season
Heat Advisory criteria within the Philly urban/metro area on
Friday.

Some limiting factors for Friday`s heat could be the increasing
cloud cover ahead of the could front, plus the arrival of
showers and thunderstorms later in the day. Convective details
remain unclear at this time, but the medium range guidance
continues to indicate potential for at least some isolated to
scattered showers and thunderstorms along and ahead of the front
Friday afternoon and evening. With the approaching trough,
there will be at least modest shear and forcing for convection.
These could also be sufficient enough for a severe threat as
well, however the limiting factor for severe currently appears
to be the less-than-impressive instability thanks to the poor
mid-level lapse rates. In any case, we`ll need to keep a close
eye on Friday`s heat and severe weather threats. `Tis the
season!

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Friday`s trough will be pushing offshore on Saturday, then some
rather expansive ridging will begin to build across the eastern
CONUS into early next week. At the surface, high pressure will
build into the region through the weekend before moving offshore
into early next week. The high pressure will provide the area
with a return to more seasonable temperatures and humidity for
Father`s Day weekend following the late week heat, with highs in
the mid 80s both Saturday and Sunday under mostly sunny skies.

With the high pressure offshore, southwesterly surface flow and
the building ridging aloft will result in increasing
temperatures into early next week. Current indications are that
we could see a multi-day heat wave, impacting much of next week
with high temperatures in the low to mid 90s across much of the
area, along with little chances for convection. The current CPC
Week 2 outlook indicates a roughly 70% chance of above normal
temperatures for our region encompassing next week.

&&

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

This afternoon...VFR overall. Scattered showers may impact all
terminals except KRDG/KABE, with an isolated t-storm possible as
well, most likely at KMIV. A heavier storm could briefly reduce
vsby to MVFR or even IFR, but it should be very transient
should it occur. Winds this afternoon becoming mainly light NW,
at around 5 knots or less, except east to southeast at KMIV and
KACY. Moderate confidence.

Tonight...VFR. Winds becoming NW 5 kts or less. High
confidence.

Wednesday...VFR. Winds mainly west around 5 knots except
potential for seabreeze to affect KACY in the afternoon with
winds shifting to south.

Outlook...

Thursday...VFR. No significant weather expected.

Friday...Prevailing VFR conditions, however there is a 30-50%
chance of TSRA impacting the terminals, mainly between 18Z-06Z.

Saturday...VFR. No significant weather expected.

&&

.MARINE...
No marine headlines thru Wednesday. Winds generally below 10
kts. Seas 1-2 ft. An isolated thunderstorm possible, mainly this
afternoon.

Outlook...

Generally sub-SCA conditions into early Thursday with fair
weather. For the afternoon and evening periods Thursday and
Friday, gusts nearing 25 kts and near 5 ft seas are possible,
along with scattered showers/tstms Friday afternoon and evening.
Fair weather Sat/Sun.

Rip Currents...

Low risk of rip currents in place for today and Wednesday.
Winds will be onshore today, but with winds weak, and a short to
medium period swell combined with 1 to 2 foot breakers, there
is a low risk for rip currents. Similar conditions on Wednesday,
though winds go more shore parallel, still less than 10 MPH.

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

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.

&&

$$

SYNOPSIS...Staarmann
NEAR TERM...Fitzsimmons/RCM
SHORT TERM...Staarmann
LONG TERM...Staarmann
AVIATION...Fitzsimmons/RCM/Staarmann
MARINE...Fitzsimmons/RCM/Staarmann