Thunderstorms developed along various boundaries within a warm and moist air mass over the region. Storms first developed across the Finger Lakes midday along the Lake Ontario lake breeze and then in the mid afternoon along the Lake Erie lake breeze boundary as it pushed inland across the Southern Tier. The strongest storms produced one to two inch hailstones.  Specific hail reports were received from Stanley, Geneva, Newark, Walworth, Marion, and Brockport. In several of those locations, automobiles were damage by the hail stones.  Later in the afternoon thunderstorms rolled across the North Country with downed trees and power poles reported.

Hail in ONTARIO, NEW YORK
From 21-MAY-13 11:38:00 to 21-MAY-13 11:38:00 (EST-5)
Location: ENNERDALE
Magnitude: 0.75 
Reported by: Social Media

Hail in WAYNE, NEW YORK
From 21-MAY-13 14:17:00 to 21-MAY-13 14:17:00 (EST-5)
Location: MUD MILLS
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 8.00K
Reported by: Storm Chaser

Hail in WAYNE, NEW YORK
From 21-MAY-13 14:36:00 to 21-MAY-13 14:36:00 (EST-5)
Location: WALWORTH
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 10.00K
Reported by: Post Office

Hail in WAYNE, NEW YORK
From 21-MAY-13 14:45:00 to 21-MAY-13 14:45:00 (EST-5)
Location: MARION
Magnitude: 0.88 
Reported by: Trained Spotter

Hail in MONROE, NEW YORK
From 21-MAY-13 14:58:00 to 21-MAY-13 14:58:00 (EST-5)
Location: CLARKSON
Magnitude: 1.75 
Property damage: 5.00K
Crop damage: 5.00K
Reported by: Social Media

Thunderstorm Wind in ONTARIO, NEW YORK
From 21-MAY-13 11:39:00 to 21-MAY-13 11:39:00 (EST-5)
Location: MANCHESTER CENTER
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Post Office

A postal carrier reported trees downed by thunderstorm winds.

Hail in MONROE, NEW YORK
From 21-MAY-13 15:03:00 to 21-MAY-13 15:03:00 (EST-5)
Location: HILTON PONDEROSA ARP
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 5.00K
Reported by: Public

Hail in MONROE, NEW YORK
From 21-MAY-13 15:07:00 to 21-MAY-13 15:07:00 (EST-5)
Location: PARMA CENTER
Magnitude: 1.50 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Social Media

Hail in LIVINGSTON, NEW YORK
From 21-MAY-13 15:55:00 to 21-MAY-13 15:55:00 (EST-5)
Location: LAKEVILLE
Magnitude: 1.75 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in MONROE, NEW YORK
From 21-MAY-13 15:07:00 to 21-MAY-13 15:07:00 (EST-5)
Location: HILTON
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm Wind in JEFFERSON, NEW YORK
From 21-MAY-13 17:10:00 to 21-MAY-13 17:10:00 (EST-5)
Location: SACKETS HARBOR
Magnitude: 50.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement reported trees downed by thunderstorm winds.

Hail in OSWEGO, NEW YORK
From 21-MAY-13 17:05:00 to 21-MAY-13 17:05:00 (EST-5)
Location: FULTON
Magnitude: 0.75 
Reported by: Public

Thunderstorm Wind in JEFFERSON, NEW YORK
From 21-MAY-13 17:22:00 to 21-MAY-13 17:22:00 (EST-5)
Location: HERRINGS
Magnitude: 50.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement reported trees downed by thunderstorm winds.

Thunderstorm Wind in ONTARIO, NEW YORK
From 21-MAY-13 16:45:00 to 21-MAY-13 16:45:00 (EST-5)
Location: BILSBORO
Magnitude: 50.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Social Media

Reports of trees and power poles down were posted on Facebook.

Hail in ONTARIO, NEW YORK
From 21-MAY-13 16:45:00 to 21-MAY-13 16:45:00 (EST-5)
Location: BILSBORO
Magnitude: 1.75 
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Social Media

Hail in ONTARIO, NEW YORK
From 21-MAY-13 16:47:00 to 21-MAY-13 16:47:00 (EST-5)
Location: BILSBORO
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in CAYUGA, NEW YORK
From 21-MAY-13 16:51:00 to 21-MAY-13 16:51:00 (EST-5)
Location: NORTH VICTORY
Magnitude: 0.75 
Reported by: Public

Hail in ONTARIO, NEW YORK
From 21-MAY-13 11:45:00 to 21-MAY-13 11:45:00 (EST-5)
Location: STANLEY
Magnitude: 1.75 
Property damage: 5.00K
Crop damage: 10.00K
Reported by: Trained Spotter

Hail in ONTARIO, NEW YORK
From 21-MAY-13 11:45:00 to 21-MAY-13 11:45:00 (EST-5)
Location: SENECA CASTLE
Magnitude: 2.00 
Property damage: 5.00K
Crop damage: 10.00K
Reported by: Social Media

Hail in ONTARIO, NEW YORK
From 21-MAY-13 12:00:00 to 21-MAY-13 12:00:00 (EST-5)
Location: GENEVA
Magnitude: 1.75 
Property damage: 5.00K
Crop damage: 10.00K
Reported by: Social Media

Hail in WAYNE, NEW YORK
From 21-MAY-13 14:10:00 to 21-MAY-13 14:10:00 (EST-5)
Location: MUD MILLS
Magnitude: 0.88 
Reported by: Trained Spotter