A cold front was to our west and stalled out. A highly unstable air mass in place. Two rounds of severe weather occurred. The first was over the North Country and St. Lawrence Valley and aided by a well-developed vortex that had traversed the Toronto area early in the afternoon. The lake breeze off of Lake Erie protected the Buffalo metro area, but it ultimately interacted with the lake breeze and instability to the east of Lake Ontario. These storms produced mostly large hail. A second round of severe storms occurred later in the evening as a couple of passing waves triggered thunderstorms due to very high instability. Wind damage and heavy rain with some flooding were the main issues.  Most of this was from the Genesee Valley to the west as thunderstorms weakened once they pushed eastward after midnight.

Thunderstorm Wind in LIVINGSTON, NEW YORK
From 21-MAY-22 19:42:00 to 21-MAY-22 19:42:00 (EST-5)
Location: NUNDA
Magnitude: 51.00 EG
Property damage: 0.50K
Crop damage: 0.00K
Reported by: 911 Call Center

A tree was downed.

Thunderstorm Wind in LIVINGSTON, NEW YORK
From 21-MAY-22 19:36:00 to 21-MAY-22 19:36:00 (EST-5)
Location: HUNT
Magnitude: 51.00 EG
Property damage: 0.50K
Crop damage: 0.00K
Reported by: 911 Call Center

A tree was downed.

Thunderstorm Wind in CHAUTAUQUA, NEW YORK
From 21-MAY-22 20:14:00 to 21-MAY-22 20:14:00 (EST-5)
Location: JAMESTOWN
Magnitude: 51.00 EG
Property damage: 0.50K
Crop damage: 0.00K
Reported by: 911 Call Center

A tree was downed.

Flash Flood in CHAUTAUQUA, NEW YORK
From 21-MAY-22 20:20:00 to 21-MAY-22 22:20:00 (EST-5)
Location: CLYMER
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

Flash flooding was reported on a portion of Plank and Corry Roads south of Clymer.

Hail in OSWEGO, NEW YORK
From 21-MAY-22 15:10:00 to 21-MAY-22 15:10:00 (EST-5)
Location: CENTRAL SQUARE
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Hail in OSWEGO, NEW YORK
From 21-MAY-22 15:05:00 to 21-MAY-22 15:05:00 (EST-5)
Location: CENTRAL SQUARE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in LEWIS, NEW YORK
From 21-MAY-22 15:02:00 to 21-MAY-22 15:02:00 (EST-5)
Location: CONSTABLEVILLE
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in LEWIS, NEW YORK
From 21-MAY-22 15:12:00 to 21-MAY-22 15:12:00 (EST-5)
Location: PORT LEYDEN
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm Wind in CHAUTAUQUA, NEW YORK
From 21-MAY-22 17:40:00 to 21-MAY-22 17:40:00 (EST-5)
Location: CELORON
Magnitude: 51.00 EG
Property damage: 0.50K
Crop damage: 0.00K
Reported by: 911 Call Center

A tree was downed onto Longview Road.

Thunderstorm Wind in CATTARAUGUS, NEW YORK
From 21-MAY-22 18:53:00 to 21-MAY-22 18:53:00 (EST-5)
Location: CADIZ
Magnitude: 51.00 EG
Property damage: 0.50K
Crop damage: 0.00K
Reported by: 911 Call Center

A tree was downed on Cadiz Road.

Thunderstorm Wind in CATTARAUGUS, NEW YORK
From 21-MAY-22 18:53:00 to 21-MAY-22 18:53:00 (EST-5)
Location: FITCH
Magnitude: 51.00 EG
Property damage: 0.50K
Crop damage: 0.00K
Reported by: 911 Call Center

A tree was downed on Lyndon Center Road.

Thunderstorm Wind in CATTARAUGUS, NEW YORK
From 21-MAY-22 18:34:00 to 21-MAY-22 18:34:00 (EST-5)
Location: ALLEGANY
Magnitude: 51.00 EG
Property damage: 0.50K
Crop damage: 0.00K
Reported by: 911 Call Center

A tree was downed on Five Mile Road.

Thunderstorm Wind in CATTARAUGUS, NEW YORK
From 21-MAY-22 18:26:00 to 21-MAY-22 18:26:00 (EST-5)
Location: LITTLE VLY
Magnitude: 51.00 EG
Property damage: 0.50K
Crop damage: 0.00K
Reported by: 911 Call Center

A tree was downed on State Route 242.