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Stormy Weather in the Northwest; Fire Weather Threat Redeveloping in Southern California this Weekend

An active fall storm pattern in the Pacific Northwest is bringing heavy rain and high elevation snow to the region which will persist through this weekend. Strong winds associated with this system will bring a renewed period of critical fire weather to southern California later this weekend into next week. Read More >

Summary

 

On May 23, 2011 a strong supercell thunderstorm moved across northern Kiowa County producing large, damaging hail. A hail research team (HailSTONE) recovered a large hailstone 2 miles north of Gotebo, OK that measured 6 inches in diameter (see image below). The hailstone was so large that it significantly caved in the roof of the vehicle that captured it (see image). Investigation and coordination between the National Weather Service in Norman, OK and the Oklahoma Climatological Survey (OCS) determined that this is the new record holder for largest hailstone in Oklahoma.

6 Inch Hailstone Falls on May 23, 2011
6" Hailstone near Gotebo, OK
Vehicle Roof Caved in from the 6
Caved in roof of the automobile that captured the hailstone.
 

The process for determining the record was a lengthy process. The hailstone itself had to be saved in accord with best practices by the HailSTONE group, which it was. Next, representatives from NWS Norman and OCS had to research the National Climatic Data Center's (NCDC) official database to see if any archived hail events at or above 6” could be verified. Four hail events were found in the database and are listed below (since 1950):

Location or County Date Time (CST) Size (inches)
Canadian 4/30/1961 1815 7.0
Garfield 4/26/1971 1600 8.0
McClain 5/1/1980 2130 5.5
Eufaula 6/16/1997 1715 5.5
 

Further research concluded that neither the 7” hailstone at Canadian County on 4/30/1961, nor the 8” hailstone at Garfield County on 4/26/1971 could be reasonably validated or verified. Other local research of large hail events in the area failed to turn up sufficient verification of any hailstones larger than 6”.

Finally, in accordance with the National Weather Service Directives, a State Climate Extremes Committee (SCEC) was established to consider this potential record-setting hailstone. The SCEC weighed the lack of quantifiable verification of any hailstones in excess of 6” as recorded in NCDC, as well as the sound and valid approach used by the HailSTONE group. It was determined that the 6” hailstone recorded 2 miles north of Gotebo, OK on 5/23/2011 is the new state record largest hailstone for the state of Oklahoma. The national record for largest hailstone is 8". That hailstone fell near Vivian, South Dakota on July 23, 2010.

 

Additional Information

 

Public Information Statement (issued by the NWS Norman)

HailSTONE (A Hail Spatial and Temporal Observing Network Effort) Project