NWS Forecast Discussion
012
FXUS61 KCTP 212348
AFDCTP
Area Forecast Discussion
National Weather Service State College PA
748 PM EDT Tue Jul 21 2026
.WHAT HAS CHANGED...
* No significant changes at this time.
&&
.KEY MESSAGES...
1) Scattered to numerous severe thunderstorms are expected this
afternoon through the evening hours today.
&&
.DISCUSSION...
KEY MESSAGE 1: Scattered to numerous severe thunderstorms are
expected this afternoon through the evening hours today.
We are in standby mode for now as the copious amount of
energy/lift/strong upper level diffluent flow (associated with
the left exit region of a 100+ KT jet) has produced an
expansive area of weak convection embedded in light to moderate
rain. All of this thick/debris cloud cover will prevent deep
convection through the early afternoon, but pockets of fairly
quick destabilization via breaks of sun should spread into
western PA and remain over our far SE zones to trigger some
deeper convection by or shortly after 18Z.
We`ll be closely monitoring satellite trends and meso-B
stability and shear fields to better hone in on areas under the
gun for potential impact of fast-moving TSRA.
Previous Disc...
Thunderstorms are expected to develop ahead of an eastward-
moving cold front across the Ohio Valley and along a pre-
frontal trough crossing the CWA between roughly 2-9PM. No
changes were made to the level 3/5 enhanced risk area from SPC
for day 1 with swaths of damaging wind gusts remaining the
primary hazard. Diurnal heating within cloud breaks, combined
with upper 60s to lower 70s dewpoints, will support moderate
surface-based instability across the broad pre-frontal warm
sector. The most favorable overlap of this instability and 40-50
kt of effective shear is expected to foster a mix of organized
clusters and supercells that should evolve and spread eastward
through the day. Severe hail and a few tornadoes will also be
possible with any sustained supercells. The enhanced level 3/5
risk favors a higher confidence/coverage in severe storms with a
few significant severe storms possible reaching intensity
levels (75+ mph wind gusts and/or EF-2 tornado) we may only
experience 1x or 2x/year.
WPC has expanded the level 2/4 excessive rainfall outlook to
cover the majority of the CWA. However, despite plenty of juice
and high PWATs supportive of locally intense rain rates,
overall confidence is low/limited by the lack of a hires model
signal and relatively fast/progressive storm motions. Opted to
pass on a FF watch for this cycle and allow the dayshift to
reassess or issue a more short-fused/targeted watch.
Rain showers linger tonight into Wednesday particularly
downwind of Lake Erie and over the higher elevations, but for
the most part we anticipate a multi-day drying trend with near
to slightly below normal temps and comfortably low humidity from
midweek into the last weekend of July.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
Current SHRA/TSRA stationed just west of BFD could continue to
maintain itself over the next hour or two before running into a
layer of more stable air and generally go onto a weakening
trend. Current forecast outlines no TSRA mentions throughout the
00Z TAF package; however, VCTS could be possible at BFD through
01Z. The bulk of lightning activity is expected to be south of
the airfield; however, so no mentions. SHRA mentions retained
further east at UNV/IPT where this complex could sustain itself
and bring lower ceilings/visibilities but generally not below
IFR thresholds. Secondary complex of SHRA is expected at MDT/LNS
brining SHRA and lower ceilings/visibilities with MVFR likely
the worst-case scenario at this time.
Overnight, HREF/GLAMP guidance outlines lower ceilings and
visibilities most likely across the western terminals (BFD/JST)
so have continued to outline this potential in the updated
forecast package. Elsewhere, guidance paints a more optimistic
picture for flying conditions compared to the 18Z TAF package,
likely due precipitation not being as widespread as originally
forecast. Some pockets of MVFR/IFR will be possible at UNV/IPT
as well; however, will mainly be based on precipitation reaching
the airfield and a slight decrease in winds so this remains a
lower confidence solution at this time. Gradual improvement of
the western airfields is expected after sunrise, with widespread
VFR conditions expected to prevail in the 14-16Z Wednesday
timeframe with high (~70-80%) confidence. These conditions are
likely (~80-90%) confidence to continue after prevailing through
the end of the 00Z TAF package.
Outlook...
Thu-Fri...Some potential for valley fog across NW PA Friday
morning; otherwise, VFR conditions expected.
Sat...Generally VFR conditions with low-end (< 20%) chance of an
afternoon shower/storm across SW PA.
Sun...Increasing chances of PM showers/storms, with some
restrictions possible.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
WHAT HAS CHANGED...Lambert/Steinbugl
KEY MESSAGES...Lambert/Steinbugl
DISCUSSION...Lambert/Steinbugl
AVIATION...Beaty
NWS CTP Office Area Forecast Discussion
