Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 134, NWS State College, PA

August 27, 2020McKean County, Potter County, Pennsylvania

NWS State College, PA issued this severe thunderstorm warning at Aug 27, 2020, 5:35 PM EDT for McKean County, Potter County, Pennsylvania. It was in force for 55 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Aug 27, 2020, 5:35 PM EDT (21:35 UTC)
Expired
Aug 27, 2020, 6:30 PM EDT
In force
55 min
Issued by
NWS State College, PA
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties McKean County, PA, Potter County, PA

The radar

The State College radar (KCCX), 97 km from the middle of the area, began a volume at 21:35 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Aug 27, 2:49 PM EDTSevere Thunderstorm WatchSPC5 hr

The nearest sounding before it

Buffalo Intl Airport, NY (KBUF), launched 12:00Z, 9.6 hours before the alert went out and 134 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Buffalo Intl Airport, NY at 12:00Z on 2020-08-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1176 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Buffalo Intl Airport, NY at 12:00Z on 2020-08-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 246 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
1176 J/kg
Mixed-layer CIN
-43 J/kg
Mixed-layer LCL
832 m above ground
0-6 km bulk shear
54 kt
0-1 km storm-relative helicity
246 m²/s²
0-3 km storm-relative helicity
245 m²/s²
Significant tornado parameter
1.5
Supercell composite
8.5

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS State College, PA wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 27, 2:17 PM EDT, 3 hours 18 minutes earlier.

Area forecast discussion, Aug 27, 2:17 PM EDT, 3 hours 18 minutes before
Area Forecast Discussion
National Weather Service State College PA
217 PM EDT Thu Aug 27 2020

.SYNOPSIS...
There is an enhanced risk of severe storms across north central
and northeast Pennsylvania this afternoon and evening. Damaging
winds being the main threat.

Wet weather will be possible again on Friday, and more likely
on Saturday, as the remnants of Laura track just south of
Pennsylvania. Some of the rainfall could be on the heavy side.

A cooler and drier/less humid airmass prevail Sunday into early
next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
No change to day one SPC outlook, warm temperatures aloft
should hold back storms till at least late afternoon and
evening. The other factor is the strong westerly flow has
mixed out some of the low level moisture. However, have to
watch how things could change near sunset. Storms could linger
until midnight, given the intense heating we have seen today.

Main threat is strong to severe winds, given wind fields aloft
and deep mixing. A bit too far west to have much potential for
rotating storms.

Prior to this a few showers and isolated storms over the
southwest counties. The HRRR has little early on this aft.

Lows will be within a few degrees of 70 degrees.

Showers will likely linger in spots into late tonight but the
severe threat should fade.

&&

.SHORT TERM /FRIDAY/...
Additional strong storms with gusty wind threat (MRGL risk or
level 1 out of 5) are possible later Friday afternoon. SPC did
edge the far western areas into slight. Wind fields not as
strong today, thus expect more of a typical day of lighter winds
and more of a pulse type day. Main concern is over today at this
time, later shifts can adjust wording in DDS type products, as
the event unfolds.

The main change for Friday, was to edge dewpoints down in the
southeast, and up a little across the north and central areas,
given overall weather pattern.

More informatin below for later Friday.

There is a broad model signal for moderate to perhaps locally
heavy QPF amounts across the northwest part of the area heading
into Friday night/Saturday morning. This would be the point
where moisture from Laura would be transported northward along
cold front pushing east from the Great Lakes/Ohio Valley.

Some chat with LWX and WPC today, and the MARFC. Main concern
mainly out of our area, given current track and how dry it has
been.

A cold front accompanying a progressive northern-stream trough
will advance southeast through the OH Valley and Northeast
States, reaching the Middle Atlantic during the evening on
Saturday. Showers and thunderstorms will be ongoing along and
ahead of the front. Additional storms will likely develop as the
warm sector destabilizes during the afternoon, posing a threat
for mainly damaging wind. SPC has placed a SLGT risk area over
far southeast zones which just clips a part of the lower Susq.
Valley.

The remnants of Laura are forecast to track to the south of PA
Saturday and Saturday night. Some moisture entrainment is
possible along/ahead of aforementioned cold front. While some
heavy downpours are likely, the forecast wild card here is
whether or how much moisture from Laura can interact with the
frontal boundary. If this occurs, storms could pose more of a
flood threat. But at this time, rainfall impacts appear to be
limited. WPC has introduced a marginal risk ERO and will continue
to monitor for an increase in heavy rainfall potential Saturday.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Behind the front and Laura, much cooler air will move into the
region late this weekend and into next week. Expect high temps
to be more in the 70s and lower 80s with low humidity.

High pressure will lead to generally dry weather Sunday and
Monday, although it may be cool enough aloft on Sunday for some
lake effect rain showers to form off of Lake Erie which could
move into the northern tier of PA. High pressure will drift
eastward Monday with southerly flow developing across the
region. This flow will bring an uptick in moisture for Tuesday
and Wednesday leading to the chance for showers or thunderstorms
each afternoon.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
Several small areas of showers and isolated storms on radar as
of 2 PM.

Tried to cover these in the 18Z TAF package, as well as the
potential for more activity later this afternoon and evening.

Gusty west winds to prevail this afternoon.

Some fog and low clouds late tonight.

More showers possible across the west on Friday morning, working
eastward later in the day.

A wet day expected on Saturday, as a strong cold front nears.

Outlook...

Fri...AM low cigs possible wrn highlands. Sct PM tsra impacts
possible.

Sat...Widespread showers and reductions are expected.

Sun-Mon...Generally VFR w/ no sig wx expected.

&&

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

&&

SYNOPSIS...Steinbugl/Martin
NEAR TERM...Steinbugl/Martin
SHORT TERM...Steinbugl
LONG TERM...DeVoir/Travis
AVIATION...Martin
Hazardous weather outlook, Aug 27, 3:09 PM EDT, 2 hours 26 minutes before
Hazardous Weather Outlook
National Weather Service State College PA
309 PM EDT Thu Aug 27 2020

PAZ004-005-010-011-281000-
Warren-McKean-Elk-Cameron-
309 PM EDT Thu Aug 27 2020

...SEVERE THUNDERSTORM WATCH 456 IN EFFECT UNTIL 8 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...Friday through Wednesday.

Isolated severe thunderstorms are possible on Friday.

Locally heavy rainfall is possible on Saturday.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report significant hazardous weather.

PAZ006-012-037-041-042-045-046-281000-
Potter-Northern Clinton-Tioga-Northern Lycoming-Sullivan-
Southern Clinton-Southern Lycoming-
309 PM EDT Thu Aug 27 2020

...SEVERE THUNDERSTORM WATCH 456 IN EFFECT UNTIL 8 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...Friday through Wednesday.

Locally heavy rainfall is possible on Saturday.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report significant hazardous weather.

PAZ018-019-025>028-034>036-050-056-063-281000-
Northern Centre-Southern Centre-Blair-Huntingdon-Mifflin-Juniata-
Bedford-Fulton-Franklin-Snyder-Perry-Cumberland-
309 PM EDT Thu Aug 27 2020

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...This afternoon and tonight.

A few severe thunderstorms with damaging winds 60 mph or greater and
large hail exceeding 1 inch in diameter are possible this afternoon
and early evening.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Isolated strong to locally severe thunderstorms are possible Friday
afternoon. Locally heavy rainfall is possible on Saturday.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report significant hazardous weather.

PAZ049-051>053-058-281000-
Union-Montour-Northumberland-Columbia-Schuylkill-
309 PM EDT Thu Aug 27 2020

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...This afternoon and tonight.

A few severe thunderstorms with damaging winds 60 mph or greater and
large hail exceeding 1 inch in diameter are possible this afternoon
and early evening.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Isolated strong to locally severe thunderstorms are possible Friday
afternoon. Locally heavy rainfall is possible on Saturday.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report significant hazardous weather.

PAZ057-059-064>066-281000-
Dauphin-Lebanon-Adams-York-Lancaster-
309 PM EDT Thu Aug 27 2020

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...This afternoon and tonight.

A few severe thunderstorms with damaging winds 60 mph or greater and
large hail exceeding 1 inch in diameter are possible this afternoon
and early evening.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Isolated strong to severe thunderstorms are possible Friday and
Saturday afternoon. Locally heavy rainfall is possible on Saturday.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report significant hazardous weather.

PAZ017-024-033-281000-
Clearfield-Cambria-Somerset-
309 PM EDT Thu Aug 27 2020

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...This afternoon and tonight.

A few severe thunderstorms with damaging winds 60 mph or greater and
large hail exceeding 1 inch in diameter are possible this afternoon
and early evening.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Isolated severe thunderstorms are possible on Friday.

Locally heavy rainfall is possible on Saturday.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report significant hazardous weather.

Martin

In the hours before

Special weather statement, Aug 27, 3:06 PM EDT, 2 hours 29 minutes before
Special Weather Statement
National Weather Service State College PA
306 PM EDT Thu Aug 27 2020

PAZ005-010-011-271930-
McKean PA-Cameron PA-Elk PA-
306 PM EDT Thu Aug 27 2020

...A STRONG THUNDERSTORM WILL AFFECT PARTS OF ELK...MCKEAN...AND
CAMERON COUNTIES UNTIL 330 PM EDT...

At 305 PM EDT, Doppler radar indicated a strong thunderstorm near
Betula, moving east at 40 mph.

Wind gusts 40 to 50 mph and half inch hail are possible.

Locations impacted include...
Emporium, Betula, Elk River and Sizerville.

LAT...LON 4166 7821 4162 7821 4156 7814 4145 7819
      4164 7868 4172 7861
TIME...MOT...LOC 1905Z 291DEG 35KT 4165 7851

Evanego
Special weather statement, Aug 27, 3:29 PM EDT, 2 hours 6 minutes before
Special Weather Statement
National Weather Service State College PA
329 PM EDT Thu Aug 27 2020

PAZ006-011-272000-
Potter PA-Cameron PA-
329 PM EDT Thu Aug 27 2020

...A STRONG THUNDERSTORM WILL AFFECT PARTS OF POTTER AND CAMERON
COUNTIES UNTIL 400 PM EDT...

At 329 PM EDT, Doppler radar indicated a strong thunderstorm over Elk
River, moving southeast at 40 mph.

Wind gusts 40 to 50 mph and half inch hail are possible.

Locations impacted include...
Cameron, Wharton, Emporium, Elk River and Sizerville.

LAT...LON 4154 7793 4138 7809 4153 7842 4161 7842
      4162 7841 4162 7829
TIME...MOT...LOC 1929Z 296DEG 33KT 4157 7833

Evanego
Special weather statement, Aug 27, 5:28 PM EDT, 7 minutes before
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The office that day

Everything else NWS State College, PA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 27, 3:40 AM EDTSpecial Weather StatementCTPSullivan35 min
Aug 27, 3:06 PM EDTSpecial Weather StatementCTPCameron24 min
Aug 27, 3:29 PM EDTSpecial Weather StatementCTPCameron31 min
Aug 27, 5:00 PM EDTSevere Thunderstorm WarningCTPMcKean, Warren53 min
Aug 27, 5:28 PM EDTSpecial Weather StatementCTPClearfield47 min
Aug 27, 5:30 PM EDTSevere Thunderstorm WarningCTPClearfield75 min
Aug 27, 5:50 PM EDTSevere Thunderstorm WarningCTPCameron, Elk35 min
Aug 27, 5:58 PM EDTSevere Thunderstorm WarningCTPTioga57 min
Aug 27, 6:09 PM EDTSevere Thunderstorm WarningCTPCameron, Clearfield, Clinton32 min
Aug 27, 6:11 PM EDTSpecial Weather StatementCTPUnion34 min
Aug 27, 6:15 PM EDTSevere Thunderstorm WarningCTPBlair, Cambria, Centre, Huntingdon75 min
Aug 27, 6:38 PM EDTSevere Thunderstorm WarningCTPCentre, Clinton, Union43 min
Aug 27, 6:40 PM EDTSpecial Weather StatementCTPCentre, Lycoming, Mifflin, Snyder, Sullivan, Union35 min
Aug 27, 6:47 PM EDTSevere Thunderstorm WarningCTPSomerset58 min
Aug 27, 6:52 PM EDTSevere Thunderstorm WarningCTPSnyder39 min
Aug 27, 6:59 PM EDTSpecial Weather StatementCTPBedford, Huntingdon, Juniata, Mifflin31 min
Aug 27, 7:09 PM EDTSevere Thunderstorm WarningCTPBedford, Somerset66 min
Aug 27, 7:12 PM EDTSevere Thunderstorm WarningCTPMontour, Northumberland34 min
Aug 27, 7:16 PM EDTSpecial Weather StatementCTPSullivan14 min
Aug 27, 7:21 PM EDTSpecial Weather StatementCTPFranklin, Fulton54 min
Aug 27, 7:29 PM EDTSevere Thunderstorm WarningCTPFranklin, Fulton, Huntingdon44 min
Aug 27, 7:29 PM EDTSevere Thunderstorm WarningCTPColumbia, Schuylkill47 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2020Every severe thunderstorm warning in 2020

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.