Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2019

Severe Thunderstorm Warning 293, NWS Pittsburgh, PA

September 11, 2019Allegheny County, Beaver County, Butler County, Pennsylvania

NWS Pittsburgh, PA issued this severe thunderstorm warning at Sep 11, 2019, 4:59 PM EDT for Allegheny County, Beaver County, Butler County, Pennsylvania. It was in force for 46 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
Sep 11, 2019, 4:59 PM EDT (20:59 UTC)
Expired
Sep 11, 2019, 5:45 PM EDT
In force
46 min
Issued by
NWS Pittsburgh, PA
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties Allegheny County, PA, Beaver County, PA, Butler County, PA

The radar

The Pittsburgh radar (KPBZ), 21 km from the middle of the area, began a volume at 20:58 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 nearest sounding before it

Pittsburgh, PA (KPIT), launched 12:00Z, 9.0 hours before the alert went out and 31 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, Pittsburgh, PA at 12:00Z on 2019-09-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 229 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, Pittsburgh, PA at 12:00Z on 2019-09-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 92 square meters per square second.193958Sfc1 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
229 J/kg
Mixed-layer CIN
-94 J/kg
Mixed-layer LCL
1607 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
92 m²/s²
0-3 km storm-relative helicity
91 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

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 Pittsburgh, PA wrote its last area forecast discussion before this severe thunderstorm warning went out at Sep 11, 4:01 PM EDT, 58 minutes earlier.

Area forecast discussion, Sep 11, 4:01 PM EDT, 58 minutes before
Area Forecast Discussion
National Weather Service Pittsburgh PA
401 PM EDT Wed Sep 11 2019

.SYNOPSIS...
Warm and humid conditions will be in place through Friday, with
periodic chances for showers and thunderstorms. A crossing cold front
will filter in drier air in high pressure for the weekend.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Strong daytime heating in a buoyant airmass, combined with lift from
an encroaching Great Lakes trough has led to the development of
scattered showers and thunderstorms this afternoon.

Cooling mid-levels associated with the upper trough, combined with
strong surface heating suggests steep lapse rates, with mixed layer
CAPE values progged between 1500-2000 J/kg. These values are realized
in AMDAR soundings out of KPIT. Recent soundings and SPC RAP
analysis also suggest sufficient dry air at mid-levels supporting a
damaging wind threat given stronger updrafts. Hail will also be
possible given the deep CAPE profile, although the lack of shear and
warm layer exceeding 12,000ft should keep it mostly sub-severe.

The severe threat should wane with the loss of daytime heating this
evening, though, periodic showers remain possible through the night
given a very warm, humid airmass and continued shortwave support
associated with the aforementioned trough. Summerlike minimums in
the mid and upper 60s are forecast.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
On Thursday, a weak cold front is progged to push south across the
region, although its progress will likely be hindered by the still-
strong ridge in place across the southeast CONUS and lack of jet
support. This boundary should serve as a mechanism for additional
shower and thunderstorm development during the afternoon and evening.
Lingering morning clouds should hinder destabilization, limiting the
overall severe threat.

The boundary is anticipated to lift north as a warm front as the
southeast ridge expands north once again on Friday. Deepening low
pressure across the upper Midwest will push a stronger cold front
through the region Friday night. Numerous showers and thunderstorms
should accompany this system, and likely PoPs were maintained.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
The front will continue its passage on Saturday, with rain chances
ending from west to east during the day. A brief period of zonal flow
will be in place Sunday, with high pressure providing dry weather but
still above-normal temperatures.

Early next week, ridging should become established again, although
models differ on where the axis sets up. This may have implications
for PoPs, as ripples riding over the ridge may provide rain chances.
Chances were kept quite low for now due to uncertainty. In any case,
our September warm spell looks set to continue.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
Medium confidence forecast save for the 6Z-14Z time window where
confidence is low given CIGS could be lower than forecast.

CU has developed and storms are not that far behind as of the 18Z
hour. Things are coming together for a line of showers and storms to
develop across northeast Ohio into northwestern Pennsylvania then
move southeast through the afternoon hours. Activity will wane with
the loss of heating between 0Z-2Z. Continued mention of VCTS at all
terminals through 3Z save for FKL and DUJ where any storm should be
out by 22Z. Would not be surprised for a brief drop to IFR vis in any
storm, but did not include any tempos at this time. Do not expect
showers during the night through the end of the forecast time frame.

After the storms fizzle out, what if any fog will develop during the
predawn hours? For now, thinking it will be more of a stratus event
given we won't totally clear out. Dropped CIGS to low end MVFR at FKL
and DUJ, but those could be lowered to IFR with future forecasts,
elsewhere ran with BKN015-025 around daybreak through mid morning.
Moisture is locked in at low levels with the boundary lingering
around.

Wind will light from the west. We could see gusts nearing 20 knots
for a short time period this afternoon.

.Outlook...
Isolated storms are possible Thursday while they will more widespread
restrictions Friday night into Saturday with a cold front.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...None.
OH...None.
PA...None.
WV...None.

&&
Hazardous weather outlook, Sep 11, 3:03 PM EDT, 1 hour 56 minutes before
Hazardous Weather Outlook
National Weather Service Pittsburgh PA
303 PM EDT Wed Sep 11 2019

MDZ001-OHZ039>041-048>050-057>059-068-069-PAZ007>009-013>016-020>023-
029-031-073>076-WVZ001>004-012-021-509>514-121915-
Garrett-Tuscarawas-Carroll-Columbiana-Coshocton-Harrison-
Jefferson OH-Muskingum-Guernsey-Belmont-Noble-Monroe-Mercer-Venango-
Forest-Lawrence-Butler-Clarion-Jefferson PA-Beaver-Allegheny-
Armstrong-Indiana-Washington-Greene-Westmoreland-Westmoreland Ridges-
Fayette-Fayette Ridges-Hancock-Brooke-Ohio-Marshall-Wetzel-Marion-
Monongalia-Ridges of Eastern Monongalia and Northwestern Preston-
Preston-Eastern Preston-Western Tucker-Eastern Tucker-
303 PM EDT Wed Sep 11 2019

This Hazardous Weather Outlook is for western Maryland, east
central Ohio, northwest Pennsylvania, southwest Pennsylvania, west
central Pennsylvania, western Pennsylvania, northern West Virginia
and northern panhandle of West Virginia.

.DAY ONE...This afternoon and tonight.

Scattered thunderstorms will continue through tonight, with isolated
incidents of severe weather possible. The primary hazard will be
damaging wind, however small hail and localized heavy rainfall
cannot be ruled out.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

In the hours before

Special weather statement, Sep 11, 3:19 PM EDT, 1 hour 40 minutes before
Special Weather Statement
National Weather Service Pittsburgh PA
319 PM EDT Wed Sep 11 2019

MDZ001-WVZ511-512-111945-
Garrett-Eastern Preston-Preston-
319 PM EDT Wed Sep 11 2019

...A STRONG THUNDERSTORM WILL AFFECT NORTHWESTERN GARRETT AND
NORTHEASTERN PRESTON COUNTIES...

At 319 PM EDT, a strong thunderstorm was located 8 miles southwest of
Friendsville, or 9 miles north of Terra Alta, moving east at 15 mph.

Locations impacted include...
Friendsville...                   Accident...
Deep Creek Lake State Park...     Swallow Falls State Park...
McHenry...                        Cranesville...
McComas Beach...

This includes  Interstate 68 in MARYLAND mile marker 2 and near mile
marker 5.

LAT...LON 3953 7961 3959 7961 3964 7958 3968 7926
      3943 7927
TIME...MOT...LOC 1919Z 274DEG 13KT 3958 7953

Kramar
Special weather statement, Sep 11, 3:45 PM EDT, 1 hour 14 minutes before
Special Weather Statement
National Weather Service Pittsburgh PA
345 PM EDT Wed Sep 11 2019

PAZ007-112015-
Mercer-
345 PM EDT Wed Sep 11 2019

...A STRONG THUNDERSTORM CAPABLE OF PRODUCING GUSTY WIND WILL AFFECT
NORTHWESTERN MERCER COUNTY...

At 344 PM EDT, a strong thunderstorm was located over Kinsman, or 12
miles northwest of Sharpsville, moving east at 20 mph.

Wind gusts up to 55 mph are possible with this storm.

Locations impacted include...
Greenville...                     Clark...
Jamestown...

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

LAT...LON 4149 8034 4148 8025 4137 8022 4126 8033
      4131 8052 4149 8052
TIME...MOT...LOC 1944Z 284DEG 16KT 4143 8060

Kramar
Special weather statement, Sep 11, 4:10 PM EDT, 49 minutes before
Special Weather Statement
National Weather Service Pittsburgh PA
410 PM EDT Wed Sep 11 2019

PAZ007-013-112045-
Lawrence-Mercer-
410 PM EDT Wed Sep 11 2019

...A STRONG THUNDERSTORM CAPABLE OF PRODUCING GUSTY WIND WILL AFFECT
SOUTHWESTERN MERCER AND NORTH CENTRAL LAWRENCE COUNTIES...

At 409 PM EDT, a strong thunderstorm was located over Farrell, or
over Hermitage, moving east at 20 mph.

Wind gusts up to 55 mph are possible with this storm.

Locations impacted include...
Hermitage...                      Sharon...
Sharpsville...                    Farrell...
New Wilmington...                 West Middlesex...
Clark...                          Wheatland...

This includes  Interstate 80 in Pennsylvania between mile markers 0
and 15.

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

LAT...LON 4119 8023 4111 8028 4114 8052 4125 8052
      4130 8030
TIME...MOT...LOC 2009Z 267DEG 17KT 4119 8046

Kramar
Special weather statement, Sep 11, 4:19 PM EDT, 40 minutes before
Special Weather Statement
National Weather Service Pittsburgh PA
419 PM EDT Wed Sep 11 2019

PAZ008-009-015-112045-
Forest-Clarion-Venango-
419 PM EDT Wed Sep 11 2019

...A STRONG THUNDERSTORM CAPABLE OF PRODUCING GUSTY WIND WILL AFFECT
EAST CENTRAL VENANGO...NORTHWESTERN CLARION AND WEST CENTRAL FOREST
COUNTIES...

At 419 PM EDT, a strong thunderstorm was located over Oil City,
moving east at 15 mph.

Wind gusts up to 45 mph are possible with this storm.

Locations impacted include...
Oil City...                       Sugarcreek...
Hasson Heights...                 Seneca...
Rouseville...                     Woodland Heights...
Cranberry Township...             Oil Creek State Park...

LAT...LON 4137 7982 4149 7980 4152 7951 4139 7946
      4127 7955
TIME...MOT...LOC 2019Z 279DEG 11KT 4142 7973

Kramar
Special weather statement, Sep 11, 4:39 PM EDT, 20 minutes before
Special Weather Statement
National Weather Service Pittsburgh PA
439 PM EDT Wed Sep 11 2019

PAZ007-008-112115-
Venango-Mercer-
439 PM EDT Wed Sep 11 2019

...A LINE OF STRONG THUNDERSTORMS CAPABLE OF PRODUCING GUSTY WIND
WILL AFFECT NORTHERN MERCER AND WEST CENTRAL VENANGO COUNTIES...

At 439 PM EDT, radar indicated strong thunderstorms in a cluster
from 9 miles west of Sugarcreek to near Hermitage. Movement was east
at 15 mph.

Wind gusts up to 45 mph are possible with these storms.

Locations impacted include...
Hermitage...                      Franklin...
Sugarcreek...                     Mercer...
Stoneboro...                      Polk...
Sandy Lake...                     Clark...
Fredonia...                       Cooperstown...
Jackson Center...                 Utica...

This includes  Interstate 79 in Pennsylvania between mile markers 119
and 135.

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

LAT...LON 4136 7982 4120 8012 4123 8041 4133 8037
      4149 8009 4150 7981
TIME...MOT...LOC 2039Z 260DEG 15KT 4140 8005 4127 8035

Kramar
Special weather statement, Sep 11, 4:53 PM EDT, 6 minutes before
<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 11, 3:08 PM EDTSpecial Weather StatementPBZBeaver37 min
Sep 11, 3:28 PM EDTSevere Thunderstorm WarningPBZBeaver, Lawrence47 min
Sep 11, 3:45 PM EDTSpecial Weather StatementPBZMercer30 min
Sep 11, 4:00 PM EDTSevere Thunderstorm WarningPBZButler, Lawrence, Mercer45 min
Sep 11, 4:10 PM EDTSpecial Weather StatementPBZMercer35 min
Sep 11, 4:19 PM EDTSpecial Weather StatementPBZVenango26 min
Sep 11, 4:34 PM EDTSevere Thunderstorm WarningPBZBeaver, Butler, Lawrence41 min
Sep 11, 4:39 PM EDTSpecial Weather StatementPBZMercer36 min
Sep 11, 4:53 PM EDTSpecial Weather StatementPBZArmstrong37 min
Sep 11, 5:10 PM EDTSevere Thunderstorm WarningPBZArmstrong, Butler, Clarion, Venango50 min
Sep 11, 5:22 PM EDTSpecial Weather StatementPBZButler38 min
Sep 11, 5:35 PM EDTSevere Thunderstorm WarningPBZClarion, Jefferson, Venango26 min
Sep 11, 5:37 PM EDTSpecial Weather StatementPBZJefferson23 min
Sep 11, 6:56 PM EDTSevere Thunderstorm WarningPBZIndiana19 min
Sep 11, 7:05 PM EDTSpecial Weather StatementPBZWestmoreland25 min
Sep 11, 7:09 PM EDTSevere Thunderstorm WarningPBZWestmoreland17 min
Sep 11, 7:12 PM EDTSpecial Weather StatementPBZMercer33 min
Sep 11, 3:17 PM EDTSpecial Weather StatementPBZColumbiana28 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2019Every severe thunderstorm warning in 2019

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.