Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 21, NWS Pittsburgh, PA

April 20, 2017Allegheny County, Westmoreland County, Pennsylvania

NWS Pittsburgh, PA issued this severe thunderstorm warning at Apr 20, 2017, 12:41 PM EDT for Allegheny County, Westmoreland County, Pennsylvania. It was in force for 49 min. 9 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Apr 20, 2017, 12:41 PM EDT (16:41 UTC)
Expired
Apr 20, 2017, 1:30 PM EDT
In force
49 min
Issued by
NWS Pittsburgh, PA
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

Counties Allegheny County, PA, Westmoreland County, PA

The radar

The Pittsburgh radar (KPBZ), 55 km from the middle of the area, began a volume at 16:41 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.

What was reported inside it

TimeReportWhereRemark
Apr 20, 12:41 PM EDTHAIL 1.25Mount Vernon, PASPECIFIC LOCATION AND TIME ADJUSTED. PHOTOS SUBMITTED THROUGH NWS FACEBOOK
Apr 20, 12:43 PM EDTHAIL 2West New Kensington, PA
Apr 20, 12:45 PM EDTHAIL 1Arnold, PA
Apr 20, 12:46 PM EDTHAIL 1.251 E Logans Ferry Height, PA
Apr 20, 12:50 PM EDTHAIL 15 Se New Kensington, PA
Apr 20, 1:00 PM EDTHAIL 1.251 E Logans Ferry Height, PA
Apr 20, 1:03 PM EDTHAIL 17 Ese New Kensington, PA
Apr 20, 1:08 PM EDTHAIL 1.52 Se North Washington, PA
Apr 20, 1:15 PM EDTHAIL 1.252 Sw Salina, PA

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Pittsburgh, PA (KAGC), launched 12:00Z, 4.7 hours before the alert went out and 48 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 2017-04-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 59 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Pittsburgh, PA at 12:00Z on 2017-04-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 186 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
59 J/kg
Mixed-layer CIN
-86 J/kg
Mixed-layer LCL
791 m above ground
0-6 km bulk shear
38 kt
0-1 km storm-relative helicity
186 m²/s²
0-3 km storm-relative helicity
182 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

761 
WUUS51 KPBZ 201641
SVRPBZ
PAC003-129-201730-
/O.NEW.KPBZ.SV.W.0021.170420T1641Z-170420T1730Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Pittsburgh PA
1241 PM EDT THU APR 20 2017

The National Weather Service in Pittsburgh has issued a

* Severe Thunderstorm Warning for...
  Northeastern Allegheny County in southwestern Pennsylvania...
  Northwestern Westmoreland County in southwestern Pennsylvania...

* Until 130 PM EDT.

* At 1241 PM EDT, a severe thunderstorm was located over New
  Kensington, or near Penn Hills, moving east at 20 mph.

  HAZARD...60 mph wind gusts and quarter-size hail. 

  SOURCE...Radar. 

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to trees and power lines, resulting in some power 
           outages. 

* Locations impacted include...
  Penn Hills...                     Vandergrift...
  Apollo...                         Plum...
  Murrysville...                    New Kensington...
  Lower Burrell...                  Harrison Township...
  Oakmont...                        Arnold...
  Tarentum...                       Natrona Heights...

This includes  Pennsylvania Turnpike between mile markers 46 and 52.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is occurring with this storm and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

Move to an interior room on the lowest floor of a building.

Please report severe weather by calling 412-262-1988, posting to 
the NWS Pittsburgh Facebook page, or using Twitter @NWSPITTSBURGH. 

&&

LAT...LON 4044 7946 4050 7985 4066 7984 4066 7964
      4064 7961 4062 7961 4063 7959 4060 7958
      4060 7956 4059 7957 4056 7956 4054 7951
      4053 7950 4054 7948 4053 7945 4052 7946
      4047 7945
TIME...MOT...LOC 1641Z 278DEG 19KT 4056 7976 

HAIL...1.00IN
WIND...60MPH
 
$$
4 follow-up statements
151 
WWUS51 KPBZ 201653
SVSPBZ

Severe Weather Statement
National Weather Service Pittsburgh PA
1253 PM EDT THU APR 20 2017

PAC003-129-201730-
/O.CON.KPBZ.SV.W.0021.000000T0000Z-170420T1730Z/
Allegheny PA-Westmoreland PA-
1253 PM EDT THU APR 20 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 130 PM EDT
FOR NORTHEASTERN ALLEGHENY AND NORTHWESTERN WESTMORELAND COUNTIES...

At 1253 PM EDT, a severe thunderstorm was located over New
Kensington, or near Penn Hills, moving east at 20 mph.

HAZARD...60 mph wind gusts and half dollar-size hail. 

SOURCE...Public. 

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         trees and power lines, resulting in some power outages. 

Locations impacted include...
Vandergrift...                    Apollo...
Plum...                           Murrysville...
New Kensington...                 Lower Burrell...
Harrison Township...              Arnold...
Tarentum...                       Natrona Heights...
Springdale...                     Brackenridge...

This includes  Pennsylvania Turnpike near mile marker 52.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

Large hail has been reported!  Seek shelter indoors and stay away
from windows!

Torrential rainfall is occurring with this storm and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

Please report severe weather by calling 412-262-1988, posting to 
the NWS Pittsburgh Facebook page, or using Twitter @NWSPITTSBURGH. 

&&

LAT...LON 4049 7979 4062 7978 4063 7966 4064 7961
      4062 7961 4063 7959 4060 7958 4060 7956
      4059 7957 4056 7956 4054 7951 4053 7950
      4054 7948 4053 7945 4052 7946 4047 7945
      4044 7946
TIME...MOT...LOC 1653Z 278DEG 19KT 4056 7974 

HAIL...1.25IN
WIND...60MPH
 
$$
924 
WWUS51 KPBZ 201705
SVSPBZ

Severe Weather Statement
National Weather Service Pittsburgh PA
105 PM EDT THU APR 20 2017

PAC003-201714-
/O.CAN.KPBZ.SV.W.0021.000000T0000Z-170420T1730Z/
Allegheny PA-
105 PM EDT THU APR 20 2017

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN ALLEGHENY COUNTY
IS CANCELLED...
    
The storm that prompted the warning has moved out of the area.
Therefore, the warning has been cancelled.

LAT...LON 4044 7946 4048 7970 4051 7970 4061 7966
      4063 7966 4064 7961 4062 7961 4060 7958
      4060 7956 4059 7957 4056 7956 4054 7951
      4053 7950 4054 7948 4053 7945 4052 7946
      4047 7945
TIME...MOT...LOC 1704Z 286DEG 21KT 4052 7961 

$$

PAC129-201730-
/O.CON.KPBZ.SV.W.0021.000000T0000Z-170420T1730Z/
Westmoreland PA-
105 PM EDT THU APR 20 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 130 PM EDT
FOR NORTHWESTERN WESTMORELAND COUNTY...

At 104 PM EDT, a severe thunderstorm was located near Murrysville, or
near Apollo, moving east at 25 mph.

HAZARD...Golf ball size-hail and 60 mph wind gusts. 

SOURCE...Public. 

IMPACT...People and animals outdoors will be injured. Expect hail 
         damage to roofs, siding, windows, and vehicles. Expect wind 
         damage to trees and power lines, resulting in some power 
         outages. 

Locations impacted include...
Vandergrift...                    Apollo...
Murrysville...                    West Leechburg...
Avonmore...                       Saltsburg...
Oklahoma...                       East Vandergrift...
Slickville...                     North Washington...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Seek shelter indoors and stay away from windows.

Large hail has been reported!  Seek shelter indoors and stay away
from windows!

Torrential rainfall is occurring with this storm and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

Please report severe weather by calling 412-262-1988, posting to 
the NWS Pittsburgh Facebook page, or using Twitter @NWSPITTSBURGH. 

&&

LAT...LON 4044 7946 4048 7970 4051 7970 4061 7966
      4063 7966 4064 7961 4062 7961 4060 7958
      4060 7956 4059 7957 4056 7956 4054 7951
      4053 7950 4054 7948 4053 7945 4052 7946
      4047 7945
TIME...MOT...LOC 1704Z 286DEG 21KT 4052 7961 

HAIL...1.75IN
WIND...60MPH
 
$$
615 
WWUS51 KPBZ 201718
SVSPBZ

Severe Weather Statement
National Weather Service Pittsburgh PA
118 PM EDT THU APR 20 2017

PAC129-201730-
/O.CON.KPBZ.SV.W.0021.000000T0000Z-170420T1730Z/
Westmoreland PA-
118 PM EDT THU APR 20 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 130 PM EDT
FOR NORTH CENTRAL WESTMORELAND COUNTY...

At 117 PM EDT, a severe thunderstorm was located near Delmont, or 7
miles south of Apollo, moving southeast at 25 mph.

HAZARD...Ping pong ball-size hail and 60 mph wind gusts. 

SOURCE...Public. 

IMPACT...People and animals outdoors will be injured. Expect hail 
         damage to roofs, siding, windows, and vehicles. Expect wind 
         damage to trees and power lines, resulting in some power 
         outages. 

Locations impacted include...
Avonmore...                       Saltsburg...
Slickville...                     North Washington...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Seek shelter indoors and stay away from windows.

Large hail has been reported!  Seek shelter indoors and stay away
from windows!

Torrential rainfall is occurring with this storm and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

Please report severe weather by calling 412-262-1988, posting to 
the NWS Pittsburgh Facebook page, or using Twitter @NWSPITTSBURGH. 

&&

LAT...LON 4047 7962 4055 7960 4056 7955 4054 7951
      4053 7950 4054 7948 4053 7945 4052 7946
      4047 7945 4044 7946
TIME...MOT...LOC 1717Z 294DEG 22KT 4049 7952 

HAIL...1.50IN
WIND...60MPH
 
$$
682 
WWUS51 KPBZ 201726
SVSPBZ

Severe Weather Statement
National Weather Service Pittsburgh PA
126 PM EDT THU APR 20 2017

PAC129-201735-
/O.EXP.KPBZ.SV.W.0021.000000T0000Z-170420T1730Z/
Westmoreland PA-
126 PM EDT THU APR 20 2017

...THE SEVERE THUNDERSTORM WARNING FOR NORTH CENTRAL WESTMORELAND
COUNTY WILL EXPIRE AT 130 PM EDT...
        
The storm that prompted the warning has weakened below severe limits 
and is exiting the warned area. Therefore, the warning will be 
allowed to expire.  However small hail and gusty winds are still 
possible with this thunderstorm.

LAT...LON 4047 7962 4055 7960 4056 7955 4054 7951
      4053 7950 4054 7948 4053 7945 4052 7946
      4047 7945 4044 7946
TIME...MOT...LOC 1725Z 278DEG 19KT 4043 7950 

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Apr 19, 8:18 PM EDTSpecial Weather StatementPBZLawrence42 min
Apr 19, 10:03 PM EDTSpecial Weather StatementPBZAllegheny, Beaver42 min
Apr 20, 12:29 PM EDTSpecial Weather StatementPBZAllegheny31 min
Apr 20, 1:29 PM EDTSpecial Weather StatementPBZWestmoreland61 min
Apr 20, 1:38 PM EDTSpecial Weather StatementPBZBeaver52 min
Apr 20, 2:16 PM EDTSpecial Weather StatementPBZWestmoreland29 min
Apr 20, 2:27 PM EDTSevere Thunderstorm WarningPBZArmstrong, Butler, Clarion48 min
Apr 20, 2:28 PM EDTSevere Thunderstorm WarningPBZAllegheny, Fayette, Westmoreland47 min
Apr 20, 3:04 PM EDTSevere Thunderstorm WarningPBZIndiana, Westmoreland41 min
Apr 20, 3:14 PM EDTSevere Thunderstorm WarningPBZArmstrong, Clarion, Jefferson46 min
Apr 20, 3:58 PM EDTSevere Thunderstorm WarningPBZJefferson17 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2017Every severe thunderstorm warning in 2017

Sources

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