Alert archive / New York / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 92, NWS Buffalo, NY

July 20, 2021Allegany County, Cattaraugus County, Chautauqua County, New York

NWS Buffalo, NY issued this severe thunderstorm warning at Jul 20, 2021, 11:29 PM EDT for Allegany County, Cattaraugus County, Chautauqua County, New York. It was in force for 61 min. 2 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
Jul 20, 2021, 11:29 PM EDT (03:29 UTC)
Expired
Jul 21, 2021, 12:30 AM EDT
In force
61 min
Issued by
NWS Buffalo, NY
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties Allegany County, NY, Cattaraugus County, NY, Chautauqua County, NY

The radar

The Buffalo radar (KBUF), 84 km from the middle of the area, began a volume at 03:34 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
Jul 20, 11:30 PM EDTTSTM WND DMG6 Wsw Cattaraugus, NYMULTIPLE REPORTS OF TREES DOWN IN LEON AREA.
Jul 21, 12:21 AM EDTTSTM WND DMGOlean, NYMULTIPLE REPORTS OF WIRES DOWN IN AND AROUND OLEAN.

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

The nearest sounding before it

Buffalo Intl Airport, NY (KBUF), launched 00:00Z, 3.5 hours before the alert went out and 82 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 00:00Z on 2021-07-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Buffalo Intl Airport, NY at 00:00Z on 2021-07-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -176 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1459 m above ground
0-6 km bulk shear
38 kt
0-1 km storm-relative helicity
-176 m²/s²
0-3 km storm-relative helicity
87 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.2

Open this sounding in Storm Lab

The text

As transmitted.

829 
WUUS51 KBUF 210329
SVRBUF
NYC003-009-013-210430-
/O.NEW.KBUF.SV.W.0092.210721T0329Z-210721T0430Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Buffalo NY
1129 PM EDT Tue Jul 20 2021

The National Weather Service in Buffalo has issued a

* Severe Thunderstorm Warning for...
  Cattaraugus County in western New York...
  East central Chautauqua County in western New York...
  West central Allegany County in western New York...

* Until 1230 AM EDT..

* At 1128 PM EDT, severe thunderstorms were located along a line
  extending from 6 miles southeast of Gowanda to near Falconer,
  moving east at 35 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees.

* Locations impacted include...
  Olean, Salamanca, Allegany State Park, Ashford, Allegany,
  Franklinville, Cuba, St. Bonaventure, Ashford Hollow and Weston
  Mills.

 This includes Interstate 86 between exits 13 and 31.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

To report severe weather, contact your nearest law enforcement
agency. They will send your report to the National Weather Service
office in Buffalo.

Damaging winds and continuous cloud to ground lightning is occurring 
with these storms. Move indoors immediately.
Lightning is one of nature's leading killers. Remember, if you can
hear thunder, you are close enough to be struck by lightning.

&&

LAT...LON 4200 7892 4215 7924 4244 7889 4246 7880
      4231 7796 4200 7834
TIME...MOT...LOC 0328Z 290DEG 29KT 4242 7883 4215 7915 

HAIL...<.75IN
WIND...60MPH
 
$$

Welch
3 follow-up statements
362 
WWUS51 KBUF 210402
SVSBUF

Severe Weather Statement
National Weather Service Buffalo NY
1202 AM EDT Wed Jul 21 2021

NYC013-210410-
/O.CAN.KBUF.SV.W.0092.000000T0000Z-210721T0430Z/
Chautauqua NY-
1202 AM EDT Wed Jul 21 2021

...THE SEVERE THUNDERSTORM WARNING FOR EAST CENTRAL CHAUTAUQUA COUNTY
IS CANCELLED...
    
The severe thunderstorm which prompted the warning has moved out of 
the warned area. Therefore, the warning has been cancelled.

LAT...LON 4200 7892 4215 7887 4222 7877 4227 7864
      4220 7809 4200 7834
TIME...MOT...LOC 0400Z 292DEG 25KT 4214 7867 

$$

NYC003-009-210430-
/O.CON.KBUF.SV.W.0092.000000T0000Z-210721T0430Z/
Cattaraugus NY-Allegany NY-
1202 AM EDT Wed Jul 21 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1230 AM EDT
FOR SOUTHEASTERN CATTARAUGUS AND WEST CENTRAL ALLEGANY COUNTIES...

At 1200 AM EDT, a severe thunderstorm was located near Salamanca,
moving southeast at 30 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Expect damage to roofs, siding, and trees.

Locations impacted include...
Olean, Salamanca, Allegany State Park, Allegany, Cuba, St.
Bonaventure, Weston Mills, Hinsdale, Friendship and Great Valley.

 This includes Interstate 86 between exits 18 and 27.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

To report severe weather contact your nearest law enforcement agency.
They will send your report to the National Weather Service office in
Buffalo.

Frequent cloud to ground lightning is occurring with this storm.
Move indoors immediately. Lightning is one of nature's leading
killers. Remember, if you can hear thunder, you are close enough to
be struck by lightning.

&&

LAT...LON 4200 7892 4215 7887 4222 7877 4227 7864
      4220 7809 4200 7834
TIME...MOT...LOC 0400Z 292DEG 25KT 4214 7867 

HAIL...<.75IN
WIND...60MPH
 
$$

Welch
195 
WWUS51 KBUF 210413
SVSBUF

Severe Weather Statement
National Weather Service Buffalo NY
1213 AM EDT Wed Jul 21 2021

NYC003-009-210430-
/O.CON.KBUF.SV.W.0092.000000T0000Z-210721T0430Z/
Cattaraugus NY-Allegany NY-
1213 AM EDT Wed Jul 21 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1230 AM EDT
FOR SOUTHEASTERN CATTARAUGUS AND WEST CENTRAL ALLEGANY COUNTIES...

At 1213 AM EDT, a severe thunderstorm was located over Allegany, or
near Olean, moving southeast at 35 mph.

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

SOURCE...Radar indicated.

IMPACT...Minor damage to vehicles is possible. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
Olean, Allegany State Park, Allegany, Cuba, St. Bonaventure, Weston
Mills, Hinsdale, Friendship, Carrollton and Portville.

 This includes Interstate 86 between exits 23 and 27.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

To report severe weather contact your nearest law enforcement agency.
They will send your report to the National Weather Service office in
Buffalo.

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

&&

LAT...LON 4200 7879 4211 7873 4225 7850 4220 7809
      4200 7834
TIME...MOT...LOC 0413Z 314DEG 29KT 4206 7853 

HAIL...1.00IN
WIND...60MPH
 
$$

Mitchell
050 
WWUS51 KBUF 210430
SVSBUF

Severe Weather Statement
National Weather Service Buffalo NY
1230 AM EDT Wed Jul 21 2021

NYC003-009-210440-
/O.EXP.KBUF.SV.W.0092.000000T0000Z-210721T0430Z/
Cattaraugus NY-Allegany NY-
1230 AM EDT Wed Jul 21 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN CATTARAUGUS AND
WEST CENTRAL ALLEGANY COUNTIES HAS EXPIRED...
        
The storm which prompted the warning has moved out of the area.
Therefore, the warning has been allowed to expire.  However small
hail and gusty winds are still possible with this thunderstorm.

LAT...LON 4200 7879 4211 7873 4225 7850 4220 7809
      4200 7834
TIME...MOT...LOC 0430Z 290DEG 29KT 4203 7842 

$$

Mitchell

The office that day

Everything else NWS Buffalo, NY issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 20, 8:07 PM EDTAreal Flood WarningBUFLivingston, Monroe, Ontario, Wayne81 min
Jul 20, 8:28 PM EDTSevere Thunderstorm WarningBUFAllegany, Cattaraugus62 min
Jul 20, 8:39 PM EDTSevere Thunderstorm WarningBUFAllegany, Cattaraugus, Erie, Livingston, Wyoming53 min
Jul 20, 9:16 PM EDTSevere Thunderstorm WarningBUFAllegany36 min
Jul 20, 9:45 PM EDTSpecial Marine WarningBUF60 min
Jul 20, 10:14 PM EDTAreal Flood WarningBUFNiagara9 hr
Jul 20, 10:19 PM EDTSevere Thunderstorm WarningBUFChautauqua56 min
Jul 20, 11:10 PM EDTSpecial Weather StatementBUFCattaraugus35 min
Jul 21, 12:31 AM EDTSpecial Weather StatementBUFAllegany44 min

Nearby

Severe Thunderstorm Warnings in New York, 2021Every severe thunderstorm warning 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.