Alert archive / New York / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 83, NWS Buffalo, NY

July 20, 20214 counties in New York

NWS Buffalo, NY issued this severe thunderstorm warning at Jul 20, 2021, 5:30 PM EDT for 4 counties in New York. It was in force for 60 min. 4 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, 5:30 PM EDT (21:30 UTC)
Expired
Jul 20, 2021, 6:30 PM EDT
In force
60 min
Issued by
NWS Buffalo, NY
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

Counties Erie County, NY, Genesee County, NY, Niagara County, NY, Orleans County, NY

The radar

The Buffalo radar (KBUF), 20 km from the middle of the area, began a volume at 21:31 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, 5:50 PM EDTHAIL 0.5Lockport, NYHALF INCH (0.50IN) HAIL REPORTED IN THE TOWN OF LOCKPORT. NUMEROUS BRANCHES DOWN REPORTED AS WELL.
Jul 20, 5:51 PM EDTTSTM WND DMGPendleton, NYTREES DOWN IN PENDLETON.
Jul 20, 6:02 PM EDTHAIL 0.5Lewiston, NYGOLF BALL TO TENNIS BALL SIZED HAIL REPORTED IN THE TOWN OF LEWISTON.
Jul 20, 6:02 PM EDTHAIL 2.5Lewiston, NYCORRECTS PREVIOUS HAIL REPORT FROM LEWISTON. GOLF BALL TO TENNIS BALL SIZED HAIL REPORTED IN THE TOWN OF LEWISTON.

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

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Jul 20, 3:05 PM EDTSevere Thunderstorm WatchSPC8 hr

The nearest sounding before it

Buffalo Intl Airport, NY (KBUF), launched 12:00Z, 9.5 hours before the alert went out and 23 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 12:00Z on 2021-07-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 574 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, Buffalo Intl Airport, NY at 12:00Z on 2021-07-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 38 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
574 J/kg
Mixed-layer CIN
-62 J/kg
Mixed-layer LCL
893 m above ground
0-6 km bulk shear
23 kt
0-1 km storm-relative helicity
38 m²/s²
0-3 km storm-relative helicity
56 m²/s²
Significant tornado parameter
0.1
Supercell composite
0.7

Open this sounding in Storm Lab

The text

As transmitted.

108 
WUUS51 KBUF 202130
SVRBUF
NYC029-037-063-073-202230-
/O.NEW.KBUF.SV.W.0083.210720T2130Z-210720T2230Z/

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

The National Weather Service in Buffalo has issued a

* Severe Thunderstorm Warning for...
  Northeastern Erie County in western New York...
  Niagara County in western New York...
  Western Orleans County in western New York...
  Western Genesee County in western New York...

* Until 630 PM EDT..

* At 529 PM EDT, a severe thunderstorm was located over Lewiston, or
  near Niagara Falls, moving east at 20 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...
  Buffalo, Cheektowaga, North Tonawanda, Clarence, Lockport, Kenmore,
  Depew, Tonawanda, Amherst and Medina.

 This includes Interstate 90 between exits 51 and 48A.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 4328 7906 4335 7828 4289 7834 4294 7891
      4296 7893 4296 7896 4299 7901 4302 7902
      4303 7901 4306 7900 4307 7901 4307 7904
      4315 7904
TIME...MOT...LOC 2129Z 277DEG 18KT 4317 7898 

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

Reynolds
2 follow-up statements
336 
WWUS51 KBUF 202202
SVSBUF

Severe Weather Statement
National Weather Service Buffalo NY
602 PM EDT Tue Jul 20 2021

NYC029-037-063-073-202230-
/O.CON.KBUF.SV.W.0083.000000T0000Z-210720T2230Z/
Erie NY-Niagara NY-Orleans NY-Genesee NY-
602 PM EDT Tue Jul 20 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 630 PM EDT
FOR NORTHEASTERN ERIE...NIAGARA...WESTERN ORLEANS AND WESTERN GENESEE
COUNTIES...

At 601 PM EDT, a severe thunderstorm was located near Lockport,
moving east at 20 mph.

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

SOURCE...Radar indicated.

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

Locations impacted include...
Buffalo, Cheektowaga, North Tonawanda, Clarence, Lockport, Kenmore,
Depew, Tonawanda, Amherst and Medina.

 This includes Interstate 90 between exits 51 and 48A.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm is producing large hail. SEEK SHELTER NOW inside a sturdy
structure 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.

&&

LAT...LON 4335 7828 4289 7834 4294 7891 4296 7893
      4296 7896 4299 7901 4302 7902 4306 7900
      4307 7901 4307 7904 4315 7904 4326 7906
TIME...MOT...LOC 2201Z 277DEG 18KT 4315 7876 

HAIL...1.25IN
WIND...60MPH
 
$$

Reynolds
595 
WWUS51 KBUF 202232
SVSBUF

Severe Weather Statement
National Weather Service Buffalo NY
632 PM EDT Tue Jul 20 2021

NYC029-037-063-073-202241-
/O.EXP.KBUF.SV.W.0083.000000T0000Z-210720T2230Z/
Erie NY-Niagara NY-Orleans NY-Genesee NY-
632 PM EDT Tue Jul 20 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN ERIE...NIAGARA...
WESTERN ORLEANS AND WESTERN GENESEE COUNTIES HAS EXPIRED...
    
The severe thunderstorm which prompted the warning has weakened. 
Therefore, the warning has been allowed to expire.

A Severe Thunderstorm Watch remains in effect until 1100 PM EDT for
western New York.

LAT...LON 4335 7828 4289 7834 4294 7891 4296 7893
      4296 7896 4299 7901 4302 7902 4306 7900
      4307 7901 4307 7904 4315 7904 4326 7906
TIME...MOT...LOC 2231Z 277DEG 18KT 4314 7859 

$$

EAJ

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 20, 2:13 PM EDTSpecial Marine WarningBUF62 min
Jul 20, 2:57 PM EDTSpecial Weather StatementBUFNiagara48 min
Jul 20, 3:14 PM EDTSpecial Marine WarningBUF61 min
Jul 20, 3:23 PM EDTSevere Thunderstorm WarningBUFNiagara67 min
Jul 20, 3:39 PM EDTSpecial Marine WarningBUF81 min
Jul 20, 3:48 PM EDTSpecial Marine WarningBUF87 min
Jul 20, 4:08 PM EDTSevere Thunderstorm WarningBUFJefferson, Lewis67 min
Jul 20, 4:23 PM EDTSevere Thunderstorm WarningBUFErie, Genesee, Niagara, Orleans67 min
Jul 20, 4:42 PM EDTSevere Thunderstorm WarningBUFNiagara48 min
Jul 20, 4:46 PM EDTSpecial Marine WarningBUF59 min
Jul 20, 4:49 PM EDTFlash Flood WarningBUFNiagara6 hr
Jul 20, 4:55 PM EDTSpecial Marine WarningBUF48 min
Jul 20, 4:58 PM EDTSpecial Marine WarningBUF92 min
Jul 20, 5:00 PM EDTSpecial Weather StatementBUFGenesee30 min
Jul 20, 5:10 PM EDTSpecial Marine WarningBUF2 hr
Jul 20, 5:13 PM EDTSevere Thunderstorm WarningBUFJefferson, Lewis, Oswego62 min
Jul 20, 5:28 PM EDTSpecial Weather StatementBUFOswego47 min
Jul 20, 5:43 PM EDTSpecial Marine WarningBUF92 min
Jul 20, 5:43 PM EDTSevere Thunderstorm WarningBUFOswego62 min
Jul 20, 5:56 PM EDTSpecial Weather StatementBUFGenesee, Monroe, Ontario, Orleans34 min
Jul 20, 6:07 PM EDTSevere Thunderstorm WarningBUFCayuga, Jefferson, Lewis, Oswego, Wayne38 min
Jul 20, 6:21 PM EDTFlash Flood WarningBUFErie, Niagara4 hr
Jul 20, 6:26 PM EDTSpecial Marine WarningBUF34 min
Jul 20, 6:30 PM EDTSpecial Weather StatementBUFErie, Genesee30 min
Jul 20, 6:37 PM EDTSevere Thunderstorm WarningBUFErie, Genesee, Niagara46 min
Jul 20, 6:46 PM EDTSpecial Weather StatementBUFLewis29 min
Jul 20, 6:52 PM EDTSpecial Marine WarningBUF67 min
Jul 20, 7:24 PM EDTSpecial Weather StatementBUFErie, Genesee, Livingston, Ontario, Wyoming36 min
Jul 20, 7:38 PM EDTSevere Thunderstorm WarningBUFLivingston, Monroe, Ontario, Wayne31 min
Jul 20, 7:58 PM EDTSpecial Weather StatementBUFLivingston, Wyoming92 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.