352
FXUS61 KPHI 131901
AFDPHI

Area Forecast Discussion
National Weather Service Mount Holly NJ
301 PM EDT Wed May 13 2026

.WHAT HAS CHANGED...
Slight downward adjustment in temperatures for this weekend and next
week. Still very warm though.

&&

.KEY MESSAGES...
1. Low pressure passing through the region will bring showers and
isolated thunderstorms later today through Thursday.

2. Above normal temperatures take over beginning this weekend,
with temperatures potentially climbing towards the 90s next
week.

&&

.DISCUSSION...
KEY MESSAGE 1...Low pressure passing through the region will bring
showers and isolated thunderstorms later today through Thursday.

An upper trough extending from a closed H5 low over Ontario will
move through the eastern Great Lakes and into the Ohio Valley
tonight. The primary surface low pressure associated with this low
will stay well north of the area, but the closed low will sag down
into the Northeast by Thursday. Behind the departure of the surface
low, a cold front slides through the region. Unsettled weather on
tap during this period.

Getting into the details, the cold front associated with the
aformentioned low was located over western PA as of early this
afternoon and there are showers and storms that have developed just
ahead of it. Farther east, there`s another area of some showers
getting into eastern PA but this is weaker with much less in the way
of any lightning. As we go through the rest of the afternoon into
this evening, this first area of showers could bring some showers or
sprinkles into our eastern PA zones through mid to late this
afternoon but really not expecting much if any lightning to occur.
The stronger line farther west will continue to move eastward as
well and likely get into our CWA around the early to mid evening
timeframe. There`s actually a fair amount of shear and strong
dynamics with this system but the limiting factor will be
instability as CAPE values will be diminishing as we get into the
evening. Thus while the chance of severe weather is not zero, it is
low with the Storm Prediction Center continuing to keep the MARGINAL
risk of severe storms just to our west. In other words, the line of
showers/storms should be weakening as it enters our forecast area.
Main period of concern looks to be the evening into the first part
of the overnight with precip generally diminishing west to east after
this time.

For Thursday, there may be some lingering showers early in the day
near the coast with some additional scattered showers developing in
the afternoon over portions of NE PA and northern NJ due to the
upper level low. Otherwise, it will be cooler with considerable
clouds around and highs generally in the 60s.

Total precipitation amounts through the course of the next 24 hours
continue to not look very impressive, generally speaking. Amounts
should mostly be a tenth to a quarter inch with some locally higher
amounts possible in storms.


KEY MESSAGE 2...Above normal temperatures take over beginning this
weekend, with temperatures potentially climbing towards the 90s next
week.

An upper level ridge builds into the Eastern US this weekend and
into next week, bringing a period of above normal and summer-like
temperatures. At the surface, high pressure over the western
Atlantic anchors off the coast of the Mid Atlantic. This will result
in a warm southerly flow for several days and gradually warming
temperatures from Saturday through Tuesday or Wednesday. Given the
NBM has been running a bit warm lately, temperatures were lowered
slightly Sunday through Tuesday as most of the deterministic
guidance has highs a few degrees lower than what the newest NBM had.

Regardless, it will be quite warm in the extended to borderline hot.
Saturday will feature upper 70s to low 80s, with Sunday getting into
the low to mid 80s. Temperatures continue to climb for Monday with
mid to upper 80s and an outside shot at 90. Tuesday looks to be the
warmest day of the stretch with upper 80s and low 90s currently
anticipated. Tuesday could flirt with Heat Advisory criteria for
the I-95 corridor and adjacent counties, where the current
threshold through June is a heat index of 96 degrees F or
higher. The heat looks to break down after Tuesday though
another warm day could come on Wednesday. It will depend on when
a cold front comes in sometime midweek.

Overall this stretch looks mostly dry. Guidance is now trying to
hint at some diurnally driven showers/thunderstorms though, mainly
on Sunday as a shortwave passes by to the north. Don`t have more
than 15-20% PoPs in though as forcing looks weak but we will have a
better idea once we get into range of the CAMs.

As mentioned earlier, sometime mid-week next week a cold front will
approach and likely bring an end to the stretch of above normal
temperatures. Precipitation will likely accompany that front
but too early to speculate on specific impacts or hazards.


&&

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

Rest of this afternoon...VFR with increasing clouds. Southwest winds
generally 15 to 20 gusting 25 to 30 knots except winds more S/SE at
MIV and ACY. Moderate confidence.

Tonight...Lowering ceilings then visibilities as showers and storms
overspread TAF sites west to east this evening. MVFR expected, but
IFR possible by late evening. Good chance for storms affecting RDG
and ABE with lower confidence farther S/E. S/SW winds 10-15 knots,
becoming shifting to NW late with the passage of a cold front. Low
confidence.

Thursday...Lingering MVFR cigs likely early in the day at MIV and ACY
but otherwise generally VFR. Northwest winds 10 to 15 with some
gusts up to 20 knots possible. Moderate confidence.


Outlook...

Thursday Night through Monday...VFR conditions with no
significant weather expected.

&&

.MARINE...
Southerly winds 20 to 25 gusting up to 30 knots continue into this
evening along with seas around 5 feet. These conditions abate by
later in the evening but there will also be some showers with the
chance of isolated thunderstorms reaching the waters late this
evening into the overnight. Any storms could produce locally gusty
winds.

Sub Small Craft Advisory conditions for Thursday with west winds 10
to 15 knots and seas around 3 to 4 feet.

Outlook...

Thursday Night...Sub-SCA conditions expected.

Friday...Chance (20-30%) of SCA conditions on the ocean waters
as seas could near 5 feet.

Friday Night through Monday...Sub-SCA conditions expected.


&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 10 PM EDT this evening for ANZ430-
     431-450>455.

&&

$$

DISCUSSION...Fitzsimmons/Hoeflich
AVIATION...Fitzsimmons/Hoeflich
MARINE...Fitzsimmons/Hoeflich