195
FXUS61 KCTP 261913
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
313 PM EDT Thu Jun 26 2025

.SYNOPSIS...
* Flash flood and severe t-storm risk increased this afternoon
  and evening over east central PA
* Breaking heat gives way to drenching downpours into the last
  weekend of June; unsettled pattern continues to start July

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Severe T-storm watch #464 issued for a portion of south central
PA until 10PM EDT. From MCD #1455: Thunderstorm activity has
begun to initiate across portions of the Appalachians. This
activity is expected to continue to expand in coverage through
the afternoon/evening. The environment to the east is hot and
unstable (with MLCAPE around 1000-2000 J/kg) and temperatures in
the upper 80s to 90s. Despite the weak flow aloft and weak
shear, steep low-level lapse rates (around 7.5-8 C/km) and moist
profiles will support potential for wet downbursts and damaging
outflow winds. This area will be monitored for watch potential
through the afternoon.

Several changes/updates in the near term:

1. [Flash] flood watch over east central PA: 3pm to midnight
Signals from the 00 and 12Z HREF continue to favor slow moving
storms along lee-side trough and backdoor frontal zone. Both
HREF and RRFS show pockets of elevated probabilities of >2"/hr
rainfall rates by mid-late afternoon into the evening. Despite
the lack of synoptic/kinematic support, the favorable
thermodynamic profile (1.75-2.00" PWs and max CAPEs 2000-3000
J/Kg) combined with the likelihood of slow cell motions with the
potential for repetitive convection along the aforementioned
boundaries are key drivers of the watch with point rain amounts
2-4" possible over a short duration. No change to the D1 SLGT
risk ERO from WPC.

2. SPC convective outlook upgrade from risk level 1 to 2 (SLGT)
Full sunshine this morning across south central into southeast
PA allowing temps to rise into the mid 80s to low 90s. While not
as extreme, hot/humid conditions will lead to scattered
thunderstorm development through the evening. Winds aloft are
weak, suggesting disorganized/pulse convective modes. However,
steep low-level lapse rates and moderate CAPE values will once
again result in a risk of locally damaging wind gusts.

Heat Advisory remains in effect until 7 PM EDT.

Showers will gradually fade into late tonight. There appears to
be an emerging signal for fog and low clouds overnight into
early Friday morning particularly across the eastern half of
the CWA with plenty of residual moisture and low level easterly
flow.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
Low clouds are likely to persist through the first part of
Friday thanks to an east to southeast low level flow. Any
convection would be mainly confinded to along and west of the
Allegheny Mtns. Max temps will be 10 to 20 degrees cooler vs.
Thursday with the largest 24hr delta over the middle to lower
Susq Valley. The fairly robust easterly flow signal may offer
some downside risk to max T particularly over the eastern
portion of the forecast area. Highs will generally range from
around 70F in the Endless Mtns and northeast Coal Region to the
80-85F range along the western periphery of the CWA.

Unsettled pattern continues through the last weekend/end of June
with daily opportunities for drenching downpours. After a brief
cool down on Friday, seasonably hot/humid summertime conditions
return from Saturday into Monday.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
The anomalous upper-level ridge that brought heat to much of
the eastern United States will continue to gradually be
suppressed to the south in the extended period, and long range
models suggest that it should be replaced by an upper level
trough over the northeastern United States by the middle of next
week.

As for sensible weather...the unsettled pattern will persist
into at least the first half of the upcoming weekend, with
SHRA/TSRA likely on Saturday, especially in the afternoon and
evening. Sunday looks like the better day of the weekend, with
a small area of high pressure building in, and keeping PoPs less
than 40 percent. An approaching cold front and upper trough
will bring more widespread SHRA/TSRA later Monday into Tuesday.
After that, we could be in for a welcome shot of cooler and
drier weather for the middle to later part of next week.

&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
Scattered thunderstorms may produce short term restrictions this
afternoon and evening; accounted for this risk via PROB30s.
There is an emerging signal for more prolonged MVFR to IFR cigs
later tonight into Friday particularly across the eastern 3/4 of
the airspace due to a developing east to southeast low level
flow. Confidence in sub-VFR across ZNY sector is very high >80%
into Friday morning.

Outlook...

Fri...IFR/MVFR cigs trending toward MVFR/VFR by the afternoon.
Additional showers possible.

Sat-Mon...Periods of showers and t-storms with times of fog and
low clouds overnight.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Flood Watch until midnight EDT tonight for PAZ028-037-041-042-
046-049>053-056>059-063>066.
Heat Advisory until 7 PM EDT this evening for PAZ034>036-
063>065.

&&

$$

SYNOPSIS...Steinbugl
NEAR TERM...Steinbugl
SHORT TERM...Steinbugl
LONG TERM...Colbert
AVIATION...Steinbugl