Severe Thunderstorm Warning 178, NWS State College, PA

Area Forecast Discussion
National Weather Service State College PA
428 PM EDT Fri Sep 8 2023

.SYNOPSIS...
A cold front will become nearly stationary over Central PA
late today into Sunday. Daily showers and thunderstorms will
form along and to the east of the front, with the bulk of the
convection occurring in the late afternoons and evening hours.
Temperatures will settle back close to normal for Sunday into
Monday.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Severe Thunderstorm Watch #674 recently issued for roughly the
SE half of the CWA and will run through 03Z Sat. Sfc cold front
drifted to near a KBGM to KUNV and KJST line as of 19Z, while a
weak lee side trough was located across our far eastern CWA
where sfc dewpoints were pooling around the 70F mark.

SLightly warmer mid level temps across our SE zones has put a
weak cap on the otherwise very unstable airmass with sfc-0.5km
ML CAPE in the 2000-3500 J/KG range near and to the SE of I-81.

Latest individual high res model members and the HREF shows
several areas of convection gradually growing
upscale/consolidating into a potent/small scale MCS as it moves
NE late today/early tonight.

This convection will be boosted by larger scale UVVEL
associated with the thermally direct cell of a 50-60 KT SSWRLY
jetlet lifting acrs Western PA. The greatest concentration of
SHRA/TSRA with some brief torrential rains and potential for
damaging microbursts will be first across the Laurel Highlands
and SCent PA through 23Z, while rapid TSRA development will
occur over the Lower Susq Valley between 21-23Z, with additional
TSRA advecting into that area from the SW.

Given the amount and location of the heaviest rain from
yesterday's convection, the main concern for Flash Flooding will
be across the Middle Susq Valley and Western Poconos where 1
hour FFG values are under 1.5 inches in spots. The greatest
areal coverage will likely be found over and just to the east of
the Susq Valley through this evening.

Latest CAMs indicate the potential of localized 2+ inch
amounts/3 hours, which could exceed FFG near the transition
from the much higher FFG numbers south of I-81 to the
aforementioned lower values further north.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/...
Saturday currently looks cloudier and a bit cooler, and drier
for much of the day with much more stable LLVLS as the cold
front sags into the southeast part of the state.

We should start the day with widespread stratus and areas of
1/2SM fog, especially in the Central Mtns and Susq Valley.

Upper level ridging and the cooler surface temps should limit
the chance of convection for much of the day. However, surging
pwats ahead of a shortwave lifting up the Appalachians should
result in a return of increasing POPS and good chance of late
day and overnight convection. The airmass should remain
relatively stable north of the stalled front, so the severe
weather threat appears low, though the DAY2 ERO is still in the
MRGL category.

Most guidance tracks a remnant upper low over the Tennessee
Valley northeast toward PA on Sunday. Increasing large scale
forcing and surging pwats ahead of this feature should support a
good chance of showers/tsra during the PM hours, as ensemble
plumes depict.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
The upper-level pattern is likely to remain in place for much
of next week, we can expect this to bring daily rounds of
scattered showers and thunderstorms. This is supported by
ensemble guidance showing agreement with the progressive
pattern. Tuesday of next week is the only day with a break from
the rain as the initial trough lifts towards the north east, and
the next trough sets up to the west.

Temperatures in the extended period are progged to be much
cooler than the hot summer like temperatures we experienced this
week. With the upper-level flow of cooler Canadian air pushing
into the region, our temps will be near seasonal to slightly
below average.

&&

.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
Generally VFR conditions will persist into the early evening
hours. However, the potential for lower cigs and vsbys will be
increasing as the areal coverage of the convection expands NE.
Following the late day early nighttime bout of convection with
potentially brief, strong wind gusts and torrential rains, light
wind and partial clearing/cooling temps in the wake of a weak
cold front will lead to areas of 1/2SM fog between 07Z-13Z Sat,
before cigs slowly lift later in the morning with sunshine
breaking through by early in the afternoon, especially across
the SE third of the CWA - near and to the SE of a KAVP to KSEG
and KMRB line.

VFR to MVFR cigs with mainly VFR vsbys should occur after 17Z
Sat through early Sat evening, when we should see increasing
convection developing NE into the state.

Sat night, Sunday and into early next week will feature some
showers and perhaps a storm now and then.

Outlook...

Sun-Mon...Scattered mainly afternoon and early evening showers
and storms. Patchy fog to start both days.

Tue...AM patchy fog. Otherwise mainly dry with VFR conditions.
Showers could return Tuesday night.

Wed...VFR with periods of IFR in SHRA/TSRA and areas of morning
fog.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

SYNOPSIS...Lambert
NEAR TERM...Lambert
SHORT TERM...Lambert/Fitzgerald
LONG TERM...Tyburski
AVIATION...Lambert

Hazardous Weather Outlook
National Weather Service State College PA
506 PM EDT Fri Sep 8 2023

PAZ004>006-010>012-017>019-024-025-033-037-041-042-045-046-092115-
Warren-McKean-Potter-Elk-Cameron-Northern Clinton-Clearfield-
Northern Centre-Southern Centre-Cambria-Blair-Somerset-Tioga-
Northern Lycoming-Sullivan-Southern Clinton-Southern Lycoming-
506 PM EDT Fri Sep 8 2023

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...Tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Showers and thunderstorms may contain heavy rain and gusty winds on
Saturday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

PAZ026>028-034>036-049>053-056>059-063>066-092115-
Huntingdon-Mifflin-Juniata-Bedford-Fulton-Franklin-Union-Snyder-
Montour-Northumberland-Columbia-Perry-Dauphin-Schuylkill-Lebanon-
Cumberland-Adams-York-Lancaster-
506 PM EDT Fri Sep 8 2023

...SEVERE THUNDERSTORM WATCH 674 IN EFFECT UNTIL 11 PM EDT THIS
EVENING...

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...Tonight.

Please listen to NOAA Weather Radio or go to
weather.gov/StateCollege on the internet for more
information about the following hazards.

   Severe Thunderstorm Watch.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Showers and thunderstorms may contain heavy rain and strong to severe
wind gusts on Saturday.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report significant hazardous weather.

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