Alert archive / Pennsylvania / Special Weather Statements in 2021

Special Weather Statement, NWS Pittsburgh, PA

August 13, 2021Mercer County, Pennsylvania

NWS Pittsburgh, PA issued this special weather statement at Aug 13, 2021, 8:41 PM EDT for Mercer County, Pennsylvania. It was in force for 34 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Aug 13, 2021, 8:41 PM EDT (00:41 UTC)
Expired: Aug 13, 2021, 9:15 PM EDT
In force: 34 min
Issued by: NWS Pittsburgh, PA
Hail: 0.25 in
Wind: 50

County Mercer County, PA

The radar

The Pittsburgh radar (KPBZ), 92 km from the middle of the area, began a volume at 00:43 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 00:00Z, 0.7 hours before the alert went out and 107 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1815 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 1196 m above ground
0-6 km bulk shear: 43 kt
0-1 km storm-relative helicity: 73 m²/s²
0-3 km storm-relative helicity: 111 m²/s²
Significant tornado parameter: 0.7
Supercell composite: 5.8

Open this sounding in Storm Lab

The text

As transmitted.

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What forecasters said that day

The local office's own words before this special weather statement 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 special weather statement went out at Aug 13, 4:56 PM EDT, 3 hours 45 minutes earlier.

Area forecast discussion, Aug 13, 4:56 PM EDT, 3 hours 45 minutes before

Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
456 PM EDT Fri Aug 13 2021

.SYNOPSIS...
Warmth, humidity, and periodic showers and thunderstorms
can be expected until cold frontal passage late tonight.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Severe Thunderstorm Watch has been issued for the region with no
changes to the discussion issued just a bit ago...

Buoyancy remains quite notable this afternoon, but very little
convection has formed in the region so far owing to subsidence in the
wake of a morning mesoscale convective vortex (MCV). A second such
MCV is approaching swrn OH, which will increase broad lift across the
OH Valley late this afternoon and evening while abundant afternoon
sunshine will help with airmass recovery. In truth, very little
recovery appears to be needed, since a RAOB launched at 20Z indicates
minimal CINH remaining amid moderate CAPE and DCAPE sufficient for
severe downbursts.

Scattered strong to severe storms capable of damaging wind gusts are
forming at this time as the wrn OH MCV approaches, with increasing
coverage as a cold front impinges on the area. Given prior rainfall,
flash flooding also may be a concern. Prior discussion follows...

Broken record forecast continues with scattered storms expected to
develop again this afternoon and tonight with the passage of a cold
front. Convection has largely been contained by warmer air aloft but
eventually will begin to fire as convective temperatures are met and
an upstream MCV apparent in latest satellite imagery begins to have
an impact later this afternoon. CAMs continue to have difficulty but
overall the severe threat remains, with MLCAPE near 2000J/KG, 25kts
effective shear, and sufficient dry air aloft. Damaging winds are the
primary threat. Flooding is also a concern, especially for areas
that observed a lot of rain during yesterday's convection. One hour
FFG values are 1-1.5" in areas of SW PA...lower in metro areas. The
trough axis will pass through late tonight and drag the surface cold
front southeastward. Until the trough and surface boundary pass, the
risk for showers and storms continues.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/...
A lingering shower or storm is possible in the southeast Saturday
morning until the front finally exits. Conditions will quickly
improve Saturday, with decreasing cloud cover and much more
comfortable conditions.

Broad high pressure will settle in on Sunday. Expect sunshine through
high clouds with near seasonable temperatures and comfortable
conditions.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
The western side of the high will move into the area on Monday and
Tuesday allowing warm and moist air to once again flow back into the
region. This will bring active weather to the region for the later
part of the extended period.

&&

.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
VFR should prevail until the approach of a cold front, with
scattered thunderstorms developing from mid to late afternoon
through this evening. Local MVFR/IFR restrictions may be realized in
convective activity in conjunction with strong to severe storms
capable of producing damaging wind gusts.

MVFR/IFR cigs will then settle across the region once the cold front
arrives tonight, provided excess llvl moisture and cooling aloft,
with scattered showers lingering through dawn Saturday. The FROPA
should finally be denoted by a nwly wind shift, with gradual cig
improvement to VFR toward midday.

.Outlook... Gradual improvement to VFR is expected under building
high pressure Saturday, with favorable flight conditions expected to
persist into Sunday.

&&

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

&&

Update...Kramar

Hazardous weather outlook, Aug 13, 5:13 PM EDT, 3 hours 28 minutes before

Hazardous Weather Outlook...UPDATED
National Weather Service Pittsburgh PA
513 PM EDT Fri Aug 13 2021

OHZ039>041-048>050-057>059-068-069-PAZ013-014-020>023-029-031-
073>076-WVZ001>004-012-021-509>514-142115-
Tuscarawas-Carroll-Columbiana-Coshocton-Harrison-Jefferson OH-
Muskingum-Guernsey-Belmont-Noble-Monroe-Lawrence-Butler-Beaver-
Allegheny-Armstrong-Indiana-Washington-Greene-Westmoreland-
Higher Elevations of Westmoreland-Fayette-
Higher Elevations of Fayette-Hancock-Brooke-Ohio-Marshall-Wetzel-
Marion-Monongalia-
Ridges of Eastern Monongalia and Northwestern Preston-Preston-
Eastern Preston-Western Tucker-Eastern Tucker-
513 PM EDT Fri Aug 13 2021

...SEVERE THUNDERSTORM WATCH 438 IN EFFECT UNTIL 11 PM EDT THIS
EVENING...

This Hazardous Weather Outlook is for east central Ohio, southwest
Pennsylvania, western Pennsylvania, and northern West Virginia.

.DAY ONE...Tonight.

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

   Severe Thunderstorm Watch.

Additionally, flash flooding will be possible from any storms.

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

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
conditions according to Standard Operating Procedures.

PAZ007>009-015-016-142115-
Mercer-Venango-Forest-Clarion-Jefferson PA-
513 PM EDT Fri Aug 13 2021

This Hazardous Weather Outlook is for northwest Pennsylvania and
western Pennsylvania.

.DAY ONE...Tonight.

Isolated severe storms will be possible this afternoon and evening.
the main threat will be damaging wind gusts. Storms also will be
capable of producing heavy downpours which could cause localized
flooding.

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

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

Kramar

In the hours before

Local storm report, Aug 13, 7:28 PM EDT, 1 hour 13 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PITTSBURGH PA
728 PM EDT FRI AUG 13 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0700 PM     TSTM WND DMG     IMPERIAL                40.45N  80.24W
08/13/2021                   ALLEGHENY          PA   NWS EMPLOYEE

            NUMEROUS LARGE TREES DOWN ON GRANDVIEW AND GREGG LANE

&&

EVENT NUMBER PBZ2102201

098

Local storm report, Aug 13, 7:32 PM EDT, 1 hour 9 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PITTSBURGH PA
732 PM EDT FRI AUG 13 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0549 PM     TSTM WND DMG     2 NW BUZZ               39.81N  80.35W
08/13/2021                   GREENE             PA   911 CALL CENTER

            REPORT OF TREE BLOCKING TOMS RUN ROAD NEAR INTERSECTION
            OF GRINNAGE RUN ROAD.

0619 PM     TSTM WND DMG     NINEVEH                 39.96N  80.31W
08/13/2021                   GREENE             PA   911 CALL CENTER

            REPORT OF TREE DOWN IN MORRIS TOWNSHIP.

0701 PM     TSTM WND DMG     BEAVER FALLS            40.76N  80.32W
08/13/2021                   BEAVER             PA   911 CALL CENTER

            TREES AND WIRES DOWN

0705 PM     TSTM WND DMG     WEST NEWTON             40.21N  79.77W
08/13/2021                   WESTMORELAND       PA   TRAINED SPOTTER

            NUMEROUS TREES DOWN IN ROSTRAVER TWP

&&

EVENT NUMBER PBZ2102202
EVENT NUMBER PBZ2102203
EVENT NUMBER PBZ2102204
EVENT NUMBER PBZ2102205

JF

Local storm report, Aug 13, 7:37 PM EDT, 1 hour 4 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PITTSBURGH PA
737 PM EDT FRI AUG 13 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0637 PM     TSTM WND DMG     MOUNT PLEASANT          40.18N  80.80W
08/13/2021                   JEFFERSON          OH   911 CALL CENTER

            MULTIPLE REPORTS OF TREES DOWN ACROSS THE COUNTY.
            LOCATION AND TIME ESTIMATED BASED ON RADAR.

0648 PM     TSTM WND DMG     SMITHFIELD              40.27N  80.78W
08/13/2021                   JEFFERSON          OH   911 CALL CENTER

            MULTIPLE REPORTS OF TREES DOWN ACROSS THE COUNTY.
            LOCATION AND TIME ESTIMATED BASED ON RADAR.

0650 PM     TSTM WND DMG     NEW ALEXANDRIA          40.29N  80.68W
08/13/2021                   JEFFERSON          OH   911 CALL CENTER

0701 PM     TSTM WND DMG     STEUBENVILLE            40.37N  80.65W
08/13/2021                   JEFFERSON          OH   911 CALL CENTER

            MULTIPLE REPORTS OF TREES DOWN ACROSS THE COUNTY.
            LOCATION AND TIME ESTIMATED BASED ON RADAR.

&&

EVENT NUMBER PBZ2102206
EVENT NUMBER PBZ2102207
EVENT NUMBER PBZ2102208
EVENT NUMBER PBZ2102209

JF

Local storm report, Aug 13, 7:42 PM EDT, 59 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PITTSBURGH PA
742 PM EDT FRI AUG 13 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0712 PM     TSTM WND DMG     1 NNW GAYLY             40.46N  80.15W
08/13/2021                   ALLEGHENY          PA   SOCIAL MEDIA

            REPORT OF A 40FT TREE DOWN NEAR BELLVIEW CIRCLE.

&&

EVENT NUMBER PBZ2102210

JF

Special weather statement, Aug 13, 7:52 PM EDT, 49 minutes before

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Special weather statement, Aug 13, 7:53 PM EDT, 48 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 13, 8:11 PM EDT	Severe Thunderstorm Warning	PBZ	Armstrong, Indiana, Westmoreland	31 min
Aug 13, 8:32 PM EDT	Special Weather Statement	PBZ	Indiana	28 min
Aug 13, 8:47 PM EDT	Special Weather Statement	PBZ	Venango	28 min
Aug 13, 9:00 PM EDT	Special Weather Statement	PBZ	Venango	30 min
Aug 13, 9:15 PM EDT	Flash Flood Warning	PBZ	Forest, Lawrence, Mercer, Venango	4 hr

Nearby

Special Weather Statements in Pennsylvania, 2021 Every special weather statement in 2021

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.