-- Discussion containing changed information from previous version are highlighted. --
554
FXUS61 KPHI 251729
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
129 PM EDT Sat May 25 2024

.SYNOPSIS...
A frontal boundary remains over the area today, and then a cold
front approaches from the west tonight and washes out before it
crosses the region. Weak surface high pressure will be over the
area, but several upper level disturbances will impact the area
Sunday night through Monday. A stronger cold front will pass
through the region Monday night. Weak high pressure returns
Tuesday, but weak low pressure passes through on Wednesday. High
pressure closes out the new work week.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
Forecast on track this afternoon. Only minor tweaks were made.
Clouds continue to increase later this afternoon as a weak warm
front passes through the region. A shower or two may form in
the vicinity of this front, most likely northwest of the I-95
urban corridor, where forcing will be a bit greater.
Temperatures will be in the mid 80s across the region except at
the immediate shore where mainly low 70s are expected.

Greater chances for showers or a few thunderstorms will be
later this evening and into the overnight hours tonight.
Decaying convection initiated well west of our area will be
pushing in as a weak trough moves through. CAM guidance is still
relatively split over the extent and strength of the storms by
their arrival into the region but even the more robust solutions
indicate scattered coverage of showers and storms at best.
Maintained chance PoPs (20-40%) as a result with the higher
chances northwest of the I-95 corridor and less than 15% along
the Jersey Shore and Delaware Beaches.
-- End Changed Discussion --

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Unsettled weather on tap for the start of the new week. While
most of Sunday will be dry, an upper level trough approaches
from the west, and some shortwave energy will race out towards
the Northeast Sunday afternoon. A warm and humid airmass will be
in place over the area with highs in the low to mid 80s and
surface dew points well in the 60s. Scattered late day and
evening showers and thunderstorms are possible for the southern
Poconos, Lehigh Valley, and northern New Jersey.

Low pressure will continue to organize and develop Sunday night
and will lift into the Great Lakes and eastern Canada Monday
and Monday night. A warm front extending out from that low will
lift north through the region Sunday night, and a more organized
round of convection will develop and lift towards the western
portions of the forecast area late Sunday night through Monday
morning.

A cold front then approaches from the west as low pressure
moves into eastern Canada, and showers and thunderstorms will
develop out ahead of the front and will move into the region
late Monday and Monday night. This will trigger yet another
round of showers and thunderstorms. Given abundant low level
moisture with surface dewpoints well in the 60s and around 70,
PWATs will be up around 2 inches. Thunderstorms will be capable
of heavy rain and localized flash flooding, mainly for eastern
Pennsylvania and northern New Jersey. While severe weather is
possible, instability may be limited by thunderstorms earlier in
the day.

Cold front works its way through the region Monday night.
Showers and thunderstorms taper off after midnight from west to
east and will end by daybreak Tuesday.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
A secondary cold front passes through the region Tuesday
morning as low pressure lifts into eastern Canada, where it will
meander for most of the new week. Although the airmass will not
be appreciably cooler, it will be much less humid as surface
dew points drop from the mid and upper 60s to the mid and upper
50s. An H5 trough with strong shortwave energy will move from
the Great Lakes into the Ohio Valley and western New York and
western Pennsylvania, and a few isolated showers and
thunderstorms may move into the southern Poconos Tuesday
afternoon. Conditions will otherwise be dry and mild.

Low pressure develops over the Mid-Atlantic on Wednesday as
that upper trough builds east, touching off scattered showers
and thunderstorms during the day.

Thereafter, surface high pressure builds in from the north and
west as an upper trough remains over the Northeast. Going into
the end of the week, conditions will be mainly dry, but cannot
rule out an isolated shower or thunderstorm. It will also be
cooler with below normal temperatures.

&&

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

Today...VFR. Southerly winds 5-10 kt. High confidence.

Tonight...A period of sub-VFR conditions with some showers and
a thunderstorm possible (25-35% chance) for the Lehigh Valley
terminals. Have included VCTS for KABE/KRDG with the 18z TAF
issuance. Some patchy fog possible there late. Winds light and
variable. Moderate confidence overall.

For the I-95 terminals, currently have VFR tonight as
showers/thunderstorms should dissipate before reaching these
terminals. Winds generally light/variable but will favor a
southerly direction around 5 kt or less at times. Some patchy
fog is possible, but only put visibility restrictions at around
20% so have not included any MVFR conditions in the 18z TAF.

For KMIV/KACY, some marine stratus/fog will make its way inland.
Have rather high confidence in some sort of restrictions at
KACY, with a lower confidence that the marine layer makes it to
KMIV. Confidence in timing and extent of restrictions is also
low. Winds will also go light/variable, though favor a southerly
direction at times at 5 kt or less.

Sunday...Any fog/stratus will dissipate shortly after daybreak.
After, VFR expected. Winds out of the south/southeast around 5
kt. High confidence.

Outlook...

Sunday Night through Wednesday...Overall, SHRA and TSRA will
impact the terminals with sub-VFR conditions starting Sunday
night, but primarily Monday and Monday night. VFR Tuesday and
Wednesday, although scattered SHRA/TSRA with brief sub-VFR
conditions possibly Wednesday.
-- End Changed Discussion --

&&

.MARINE...
The conditions are expected to remain below Small Craft
Advisory criteria through tonight with seas of 1-2 feet and
winds of 5-10 knots. Fair weather.

Outlook...

Sunday through Wednesday...Sub-SCA conditions overall, but a
brief period of SCA conditions with 25 kt wind gusts and seas
around 5 feet may occur Monday night through Tuesday morning.
Thunderstorms Monday afternoon and night could result in strong
wind gusts and VSBY restrictions in heavy rain.

Rip Currents...

Both Saturday and Sunday will feature a LOW risk for the
development of rip currents. While there will be a light onshore
flow with south/southeast winds, breaking waves of only 1 to 2
feet and a short period of less than 8 seconds will mitigate the
rip current potential.

As always, rip currents can still develop, and often occur in
the vicinities of jetties and piers. Utilize any guarded beaches
this holiday weekend if venturing out into the water.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
PA...Air Quality Alert until midnight EDT tonight for PAZ070-071-
     101>106.
NJ...Air Quality Alert until midnight EDT tonight for NJZ013-014-
     016>027.
DE...None.
MD...Air Quality Alert until midnight EDT tonight for MDZ012-015.
MARINE...None.
-- End Changed Discussion --

&&

$$

SYNOPSIS...MPS
NEAR TERM...AKL/Hoeflich
SHORT TERM...MPS
LONG TERM...MPS
AVIATION...AKL/Hoeflich/MPS
MARINE...AKL/MPS