Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 1991

Severe Thunderstorm Warning 21, NWS Pittsburgh, PA

May 6, 1991Allegheny County, Pennsylvania

NWS Pittsburgh, PA issued this severe thunderstorm warning at May 6, 1991, 2:02 PM EDT for Allegheny County, Pennsylvania. It was in force for 58 min. 1 report came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued: May 6, 1991, 2:02 PM EDT (18:02 UTC)
Expired: May 6, 1991, 3:00 PM EDT
In force: 58 min
Issued by: NWS Pittsburgh, PA
Area: Whole counties

County Allegheny County, PA

What was reported inside it

Time	Report	Where	Remark
May 6, 2:15 PM EDT	Thunderstorm Wind 0	Allegheny, PA

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in. Storm Data before 1996 records only tornadoes, thunderstorm wind and hail.

The nearest sounding before it

Pittsburgh, PA (KPIT), launched 12:00Z, 6.0 hours before the alert went out and 12 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: 250 J/kg
Mixed-layer CIN: -12 J/kg
Mixed-layer LCL: 604 m above ground
0-6 km bulk shear: 45 kt
0-1 km storm-relative helicity: -23 m²/s²
0-3 km storm-relative helicity: -11 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.1

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
TTAA00 KPIT 061801
SVRPIT
PAC003-061900-
 
BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE PITTSBURGH PA
202 PM EDT MON MAY 6 1991
 
THE NATIONAL WEATHER SERVICE IN PITTSBURGH HAS ISSUED A
SEVERE THUNDERSTORM WARNING EFFECTIVE UNTIL  300 PM EDT
FOR THE FOLLOWING LOCATION...
 
IN WEST PENNSYLVANIA
 
   ...ALLEGHENY COUNTY
 
A SEVERE THUNDERSTORM IS MOVING THROYUGH EASTERN ALLEGHENY COUNTY.
DOWNED TREES AND POWER LINES HAVE ALREADY BEEN REPORTED WITH THIS
STORM. IF SEVERE WEATHER APPROACHES TAKE COVER.
 
A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 215 PM FOR
GREENE AND WASHINGTON COUNTIES AND UNTIL 245 PM FOR WESTMORELAND
COUNTY.
 
 
 
SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 55
MPH...DESTRUCTIVE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN.
FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR
OF YOUR HOME OR BUSINESS.  HEAVY RAINS FLOOD ROADS QUICKLY SO
DON'T DRIVE INTO AREAS WHERE WATER COVERS THE ROAD.

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.

In the hours before

Special weather statement, May 6, 11:06 AM EDT, 2 hours 56 minutes before

PAZ001>006-013>015-WVZ001-062200-

SPECIAL WEATHER STATEMENT...THUNDERSTORMS STILL POSSIBLE IN THE
NATIONAL WEATHER SERVICE PITTSBURGH  PA        CENTRAL MOUNTAINS
1105AM EDT MON MAY 6 1991

....THUNDERSTORMS STILL POSSIBLE MAINLY IN THE CENTRAL MOUNTAINS...

SHOWERS AND THUNDERSTORMS ARE STILL POSSIBLE THROUGH EARLY AFTERNOON
FROM THE CENTRAL MOUNTAINS EAST. IN AREAS THAT INCLUDE BRADFORD SOUTH
TO SOMERSET AND EASTWARD SHOWERS AND THUNDERSTORMS...SOME STILL WITH
HEAVY DOWNPOURS...GUSTY WINDS AND DANGEROUS LIGHTNING...ARE STILL
POSSIBLE THROUGH EARLY AFTERNOON.

A COLD FRONT IS EXPECTED TO MOVE THROUGH THE CENTRAL MOUNTAINS BY
EARLY AFTERNOON BRINGING THIS ROUND OF SHOWERS AND THUNDERSTORMS.

STAY TUNED FOR FURTHER STATEMENTS AND POSSIBLE UPDATES THROUGH THE
AFTERNOON.

RWH

The office that day

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

Issued	Product	Office	Counties	Lasted
May 6, 1:11 PM EDT	Severe Thunderstorm Warning	PBZ	Washington	64 min
May 6, 1:20 PM EDT	Severe Thunderstorm Warning	PBZ	Greene	55 min
May 6, 1:44 PM EDT	Severe Thunderstorm Warning	PBZ	Westmoreland	61 min
May 6, 2:18 PM EDT	Tornado Warning	PBZ	Armstrong, Westmoreland	57 min
May 6, 2:34 PM EDT	Severe Thunderstorm Warning	PBZ	Cambria, Somerset	56 min
May 6, 2:34 PM EDT	Severe Thunderstorm Warning	PBZ	Indiana	56 min
May 6, 2:43 PM EDT	Severe Thunderstorm Warning	PBZ	Clearfield, Jefferson	62 min
May 6, 3:05 PM EDT	Severe Thunderstorm Warning	PBZ	Bedford	55 min
May 6, 3:27 PM EDT	Severe Thunderstorm Warning	PBZ	Blair	63 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 1991 Every severe thunderstorm warning in 1991

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive.