Severe Thunderstorm Warning 37, NWS State College, PA

Area Forecast Discussion
National Weather Service State College PA
1238 PM EDT Mon Jun 26 2023

.SYNOPSIS...
An active northern branch of the jet stream will bring a few
bouts of showers and afternoon thunderstorms to the region today
and again Tuesday.

Some of the thunderstorms today could contain localized damaging
wind gusts and heavy to potentially excessive rainfall, mainly
over portions of eastern Pennsylvania this afternoon and
evening.

Additional rounds of showers and t-storms are expected Tuesday
followed by mainly cloudy and cooler conditions for Wednesday.

Drier conditions with a rebound in temperatures back to near
normal will arrive later this week to close out the month of
June.

&&

.NEAR TERM /THROUGH TONIGHT/...
Latest regional radar loop and hires model guidance indicates a
few areas of showers/isolated TSRA mainly over northern part of
our CWA late this morning as convective parameters begin to
ramp up after earlier strong storms (that were tapping some of
the stronger storm relative inflow from a waning decoupled
boundary layer) weakened.

Latest RAP LLVL theta-e gradient is strongest just west of a
KELM to KIPT, KSEG and KTHV line where a weak lee-side
trough will strengthen and help fire an extensive/bkn line of
strong to severe convection between 18-19Z.

16Z surface dewpoints range from around 70F across the Susq
Valley and locations to the east, to the upper 50s and low 60s
across the Alleghenies of Western PA.

The line will march east into a better low-level environment
for rotating updrafts and transient supercell structure over and
to the east of the Susq Valley late this afternoon/evening.

This is where the bulk of anticipated severe weather should be
today, in conjunction with the strongest meso-b scale llvl
theta-e convergence and upper level divergence in the presence
of the left exit region of a 50 kt southerly jetlet at 300 mb.

There is also concern for several rounds of potentially training
convection and localized excessive rain over, and to the east
of the Susq Valley where a Flood Watch is in effect within WPC's
Slight Risk area for Excessive Rain.

Previous Disc...

Breaking clouds and heating of a moist/unstable air mass will
then set the stage for possible severe weather this afternoon
and evening. A relatively deep upper trough will remain over
much of the eastern CONUS, as an embedded deep-layer cyclone
approaches the upper Great Lakes region. Convection-allowing
models indicate showers and thunderstorms will fire around
midday over the western part of the forecast area, along the low
level jet and axis of higher pwats. The severe weather threat
looks low over the western counties, with fairly weak shear
profiles in the model soundings. However, increasing mid level
flow and shear is progged to develop over east-central into
southeast PA late in the day ahead of a shortwave rounding the
base of the upstream trough. Progged cape values approaching
2000 J/kg, combined with the strengthening shear supports the
chance of late day strong to severe t-storms. Dcape values over
1000 J/kg and steep theta-e lapse rates favor damaging winds as
the primary/most likely hazard.

High pwats and instability should support localized torrential
downpours over the far eastern counties this afternoon through
the evening hours. While developing cold pools are likely to
support progressive storms, the environment is expected to
generate intense rainfall rates, which may produce isolated to
scattered flash flooding. While much of the area is still
experiencing lower-end D0-D2 drought conditions, rainfall over
the past 7-14 days has been above normal in several areas which
has reduced 1hr FFG values. The 26/00Z HREF guidance continues
to show a QPF max over eastern PA with neighborhood probs and
PMM values suggesting localized 3+ inch amounts may be probable.
We issued a flood watch for the excessive rain/FF concerns along
the border with WFOs BGM and PHI. The dayshift can expand the
watch farther to the west if needed.

The severe wx threat over the southeast counties should end by
00Z Tuesday. However, falling heights ahead of the upper low
should result in lingering, scattered convection. It will be
another seasonably mild night with lows generally in the 60s.

&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
The upper low is forecast to transition to an open wave and
slow as it moves across the lower Great Lakes on Day 2. Deep
southerly flow ahead of the trough will continue to support
ample moisture, with PWs remaining around 1.5 inches over the
eastern half of the area. Destabilization and mid-level energy
lifting along the leading edge of the trough are likely to
support the redevelopment of diurnal showers and storms which
may also produce some additional isolated heavy rain/flooding
concerns. Convection will fade into Tuesday night with the loss
of heating.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Updated the grids, given the potential for more storms later
today.

Anyway, the upper leel low over the central Great Lakes
moves out after the first part of Wednesday, bringing in
some dry weather for a brief time.

Temperatures will run close to normal a shade below.

Next system moves eastward for more showers and storms by next
weekend. Pattern will support wet weather at times, as long as
an upper leve ridge remains over western Canada.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Expect multiple areas of showers and thunderstorms to develop
today. Scattered showers and thunderstorms will develop mid to
late morning, then become more organized and widespread in the
afternoon and early evening, especially over the Susq Valley and
points east.

There is the potential for strong to severe wind gusts and some
hail as well, mainly for the eastern half of the CWA (IPT, MDT,
LNS). Although difficult to time out at this point, vsby and
cig restrictions associated with TSRA will likely have to be
included in future TAF issuances.

Outlook...

Mon-Tue...Numerous shra/tsra, some may produce severe wind
gusts on Monday. Brief restrictions expected.

Wed-Fri...Isolated shra/tsra. Brief restrictions possible.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 11 PM EDT this evening for PAZ042-053-058-
059-066.

&&

SYNOPSIS...Lambert/Steinbugl
NEAR TERM...Lambert/Steinbugl
SHORT TERM...Fitzgerald/Steinbugl
LONG TERM...Martin
AVIATION...Lambert/Colbert/Travis

Hazardous Weather Outlook
National Weather Service State College PA
207 PM EDT Mon Jun 26 2023

PAZ017-024-033-271815-
Clearfield-Cambria-Somerset-
207 PM EDT Mon Jun 26 2023

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...This afternoon and tonight.

Isolated strong to severe thunderstorms with gusty winds are
possible this afternoon.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report significant hazardous weather.

PAZ042-053-058-059-066-271815-
Sullivan-Columbia-Schuylkill-Lebanon-Lancaster-
207 PM EDT Mon Jun 26 2023

...FLOOD WATCH IN EFFECT UNTIL 11 PM EDT THIS EVENING...
...SEVERE THUNDERSTORM WATCH 391 IN EFFECT UNTIL 9 PM EDT THIS
EVENING...

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...This afternoon and 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.
   Flood Watch.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report significant hazardous weather.

PAZ004>006-010>012-018-019-025>028-034>037-041-045-046-049>052-056-
057-063>065-271815-
Warren-McKean-Potter-Elk-Cameron-Northern Clinton-Northern Centre-
Southern Centre-Blair-Huntingdon-Mifflin-Juniata-Bedford-Fulton-
Franklin-Tioga-Northern Lycoming-Southern Clinton-Southern Lycoming-
Union-Snyder-Montour-Northumberland-Perry-Dauphin-Cumberland-Adams-
York-
207 PM EDT Mon Jun 26 2023

...SEVERE THUNDERSTORM WATCH 391 IN EFFECT UNTIL 9 PM EDT THIS
EVENING...

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...This afternoon and 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...Tuesday through Sunday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

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Special Weather Statement
National Weather Service State College PA
236 PM EDT Mon Jun 26 2023

PAZ041-042-261900-
Sullivan PA-Northern Lycoming PA-
236 PM EDT Mon Jun 26 2023

...A STRONG THUNDERSTORM WILL IMPACT NORTH CENTRAL LYCOMING AND
NORTHWESTERN SULLIVAN COUNTIES THROUGH 300 PM EDT...

At 235 PM EDT, Doppler radar was tracking a strong thunderstorm 11
miles north of Montoursville, moving northeast at 25 mph.

HAZARD...Wind gusts up to 50 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation
         possible.

Locations impacted include...
Ralston, Lincoln Falls, Barbours and Shunk.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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.

A Severe Thunderstorm Watch remains in effect until 900 PM EDT for
north central Pennsylvania.

&&

LAT...LON 4157 7652 4135 7686 4135 7698 4142 7711
      4159 7691 4159 7688 4160 7688
TIME...MOT...LOC 1835Z 226DEG 49KT 4141 7697

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH

Martin

Special Weather Statement
National Weather Service State College PA
310 PM EDT Mon Jun 26 2023

PAZ024-025-034-261945-
Bedford PA-Blair PA-Cambria PA-
310 PM EDT Mon Jun 26 2023

...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN BEDFORD...
SOUTHWESTERN BLAIR AND SOUTH CENTRAL CAMBRIA COUNTIES THROUGH 345 PM
EDT...

At 310 PM EDT, Doppler radar was tracking a strong thunderstorm near
Portage, moving northeast at 35 mph.

HAZARD...Wind gusts up to 50 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation
         possible.

Locations impacted include...
Hollidaysburg, Portage, Roaring Spring, Cresson, Claysburg,
Duncansville, Beaverdale-Lloydell, Lilly, Sankertown, Blue Knob State
Park, Queen, Ski Gap, East Freedom, Spring Hill, Newry, Cassandra,
Blue Knob Ski Resort, Allegheny Portage Railroad National Historic
Site and Mt. Aloysius College.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

A Severe Thunderstorm Watch remains in effect until 900 PM EDT for
south central and central Pennsylvania.

&&

LAT...LON 4019 7869 4022 7867 4023 7866 4024 7866
      4025 7870 4048 7868 4044 7832 4015 7856
TIME...MOT...LOC 1910Z 203DEG 31KT 4026 7858

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH

Colbert