Special Weather Statement, NWS State College, PA

Area Forecast Discussion
National Weather Service State College PA
255 PM EDT Thu Jul 29 2021

.SYNOPSIS...
Isolated wind damage and isolated tornado threats are focused
over the southern half of central Pennsylvania into this
evening. A northwest breeze will bring dry and more comfortable
air into the area on Friday, setting the stage for a refreshing
cooldown to close out July 2021.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Low CAPE high shear environment manifesting itself this
afternoon across central PA. Stratiform rainfall north of I80
with minimal to null severe threat there. South of I-80
stratification varies after a day of largely overcast conditions
and areas of rain, as shear profiles have increased dramatically
since this morning. Low LCLs and impressive 0-1km and 0-3km EHI
can promote rapid increase in cyclonic rotation as we've seen
in northern Cambria and Westmoreland/Somerset counties. All this
despite the fact that clearing and sfc heating have not
developed anywhere.

TOR Watch #401 remains in effect until 9 PM for southern half of
central PA east of the Alleghenies. 40-50kt deep-layer shear
profiles in place with 0-3km SRH values 200-300+ m2s2. Discrete
rotating cells and or bowing line segments may be possible,
producing locally damaging winds and a possible tornado or two.
This atmosphere is as sheared as I have seen in central PA, and
spinups can happen rapidly, so we'll be watching closely
throughout the afternoon and early evening.

The severe threat should end by 8PM give or take, but showers
could linger in spots for most of the night. MinT will trend a
few degrees warmer overall with the largest positive 24hr deltas
over the middle and upper Susquehanna Valley. Post-frontal NW
flow should align low clouds upslope along the western
Alleghenies into early Friday morning.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
Improving conditions are expected in the wake of the cold FROPA
Friday with much drier air poised to arrive via refreshing NW
breeze. Look for a mix of sun and clouds and low humidity. The
latest model data suggests a passing shower is possible mainly
across the NE zones under the cool pocket aloft, but this may be
more diurnal cu vs. pcpn that actually reaches the ground given
dewpoints dropping into the 40s.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
The dry/low PW airmass will set the stage for a rather cool
Friday night/AM Saturday with minTs ranging from the mid 40s
over the NW Alleghenies to the mid 50s across the southeast
valleys (good sleeping weather). MaxT Friday will be about
5-10F below daily climo. Look forward to a beautiful start to
the weekend and last day of July 2021. The next cold front is
fcst to settle down across the lower Great Lakes by Sunday
morning with NBM PPIs signaling low precip probs across the NW
mtns by 12Z Sun.

Shortwave trough pushing south across Ontario on Saturday will
lead to backing flow aloft as modest return flow sets up for
late Saturday and Sunday, spelling the return of shower chances
across the Alleghenies late Saturday. A better shot for
showers/storms will exist for all of central PA on Sunday as a
surface low moves across Lake Ontario.

Much of Monday should remain dry, outside of a few lingering
early day showers across the northern tier. Another upper low
looks to dig into the western Great Lakes/Midwest into Tuesday,
which will once again lead to increasing moisture and subsequent
shower/storm chances into midweek. Below normal temperatures
look to remain the rule, with highs generally in the low 70s
north to low 80s south and lows spanning the 50s with low 60s in
the lower Susquehanna Valley.

&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
Mainly VFR conditions will continue into this morning, except
for a period of MVFR cigs LNS, MDT, and perhaps IPT in moist SE
flow ahead of a low pressure system approaching from the Great
Lakes. That low will bring showers and storms late in the
morning and afternoon for most terminals with widespread
reductions in cigs and visbys. There is the potential for a few
TSRA with gusty winds in the afternoon as well, especially for
southern terminals.

A cold front will cross through northern terminals AOB 00z Fri
and continue through southern terminals by 06z Fri. This will
bring an end to TSRA activity but MVFR or IFR cigs will likely
persist at BFD and JST into Fri morning in moist upslope NW
flow.

Outlook...

Fri & Sat...No sig wx expected.

Sun...Chance of a shower or thunderstorm.

Mon... Mostly VFR

&&

.CLIMATE...
It's been a wet July in some parts of central PA. Through July
28th, the monthly precipitation at Harrisburg is 7.99 inches
which currently ranks 2021 as the 9th wettest July on record.

&&

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

&&

SYNOPSIS...DeVoir/Steinbugl
NEAR TERM...DeVoir/Steinbugl
SHORT TERM...DeVoir/Steinbugl
LONG TERM...Guseman/Ross/DeVoir
AVIATION...Colbert/Travis
CLIMATE...

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Special Weather Statement
National Weather Service State College PA
1005 AM EDT Thu Jul 29 2021

PAZ010-291430-
Elk PA-
1005 AM EDT Thu Jul 29 2021

...STRONG THUNDERSTORMS WILL AFFECT PARTS OF ELK COUNTY UNTIL 1030 AM
EDT...

At 1004 AM EDT, Doppler radar indicated strong thunderstorms along a
line extending from 9 miles east of Marienville to near Portland
Mills. Movement was east at 40 mph.

Wind gusts up to 50 mph are possible.

Locations impacted include...
St. Marys, Ridgway and Johnsonburg.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4149 7842 4141 7842 4139 7887 4145 7896
      4154 7896 4156 7851
TIME...MOT...LOC 1404Z 269DEG 34KT 4150 7895 4144 7882

Banghoff

Special Weather Statement
National Weather Service State College PA
1047 AM EDT Thu Jul 29 2021

PAZ004-291530-
Warren PA-
1047 AM EDT Thu Jul 29 2021

...STRONG THUNDERSTORMS WILL AFFECT PARTS OF WARREN COUNTY UNTIL 1130
AM EDT...

At 1046 AM EDT, Doppler radar indicated strong thunderstorms along a
line extending from near Wattsburg to near Sugarcreek. Movement was
east at 45 mph.

Wind gusts up to 50 mph are possible.

Locations impacted include...
Warren, Sheffield, Columbus, Youngsville, Russell, Spring Creek,
Scandia, Lottsville, Grand Valley, Warren South, Garland, Kinzua Dam,
Chapman State Park, Tidioute, Sugar Grove, Starbrick, Clarendon and
Bear Lake.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4200 7892 4183 7892 4183 7895 4162 7896
      4163 7961 4200 7960
TIME...MOT...LOC 1446Z 273DEG 39KT 4195 7976 4151 7981

Banghoff

Special Weather Statement
National Weather Service State College PA
112 PM EDT Thu Jul 29 2021

PAZ017-018-291745-
Northern Centre PA-Clearfield PA-
112 PM EDT Thu Jul 29 2021

...A STRONG THUNDERSTORM WILL AFFECT PARTS OF NORTHERN CENTRE AND
CLEARFIELD COUNTIES UNTIL 145 PM EDT...

At 112 PM EDT, Doppler radar indicated a strong thunderstorm near
Hyde, moving east at 40 mph.

Wind gusts up to 50 mph are possible.

Locations impacted include...
Clearfield, Woodland, Curwensville, Hyde, Plymptonville, Karthaus,
Snow Shoe, North Philipsburg, Clarence, Moshannon, Pine Glen, Black
Moshannon State Park, Lecontes Mills, Morrisdale, West Decatur,
Grassflat, Grampian, Kylertown, Wallaceton and Clearfield-Lawrence
Airport.

LAT...LON 4110 7861 4117 7805 4114 7801 4116 7800
      4117 7798 4118 7792 4093 7792 4088 7801
      4096 7863
TIME...MOT...LOC 1712Z 268DEG 36KT 4103 7853

JCG

Special Weather Statement
National Weather Service State College PA
222 PM EDT Thu Jul 29 2021

PAZ018-019-291845-
Northern Centre PA-Southern Centre PA-
222 PM EDT Thu Jul 29 2021

...A STRONG THUNDERSTORM WILL AFFECT PARTS OF NORTHERN CENTRE AND
SOUTHERN CENTRE COUNTIES UNTIL 245 PM EDT...

At 221 PM EDT, Doppler radar indicated a strong thunderstorm near
Julian, moving east at 20 mph.

Wind gusts of 50 to 55 mph are possible.

Locations impacted include...
Bellefonte, Pleasant Gap, Zion, Milesburg and Unionville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4090 7800 4095 7799 4097 7768 4083 7771
TIME...MOT...LOC 1821Z 274DEG 19KT 4092 7793

Banghoff

Special Weather Statement
National Weather Service State College PA
258 PM EDT Thu Jul 29 2021

PAZ026-027-291930-
Huntingdon PA-Mifflin PA-
258 PM EDT Thu Jul 29 2021

...A STRONG THUNDERSTORM WILL AFFECT PARTS OF HUNTINGDON AND MIFFLIN
COUNTIES UNTIL 330 PM EDT...

At 257 PM EDT, Doppler radar indicated a strong thunderstorm over
Mcalevys Fort, moving east at 35 mph.

Wind gusts of 50 to 55 mph are possible.

Locations impacted include...
Lewistown, Burnham, Belleville, Highland Park, Strodes Mills, Juniata
Terrace, Mcalevys Fort and Maitland.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4061 7791 4066 7788 4062 7749 4058 7750
      4051 7762
TIME...MOT...LOC 1857Z 283DEG 29KT 4062 7784

Banghoff