15 Feet of Hail: Tracking the Deep Stuff
UPDATE 4/21/2014: The biggest hail storm this year trapped three homeless people in three feet of hail in a drainage area in El Paso, Texas this weekend! Video below:
I read an extremely interesting article in WeatherWise magazine this month entitled Deep Hail: Tracking an Elusive Phenomenon by Thomas W. Schlatter and Nolan Doesken. The photo below has nothing to do with the article, other than the fact that it's a hilarious picture of an elderly woman holding a near-record hailstone in 2007 and I've been looking for an excuse to show it.
Big hail stones are well-documented (in fact earlier this Summer I broke the story of a new record heavy U.S. hail stone). But as an extreme weather fanatic, I am very interested in finding documentation of the world's craziest weather, so the idea of record hail depth intrigues me. This is an extremely elusive topic on which very little information can be found on the Internet. Even Chris Burt's "Extreme Weather" book did not address the question. My hat's off to the WeatherWise article authors - great job.
Part of my fascination comes from a hail storm I encountered in Winston-Salem, North Carolina during the Summer of 1991. I searched NCDC's Storm Event Database but found no hail reports between May and August 1991 in Guilford or Forsyth counties. There were a lot less weather spotters back then. Although I've blogged about extreme sleet accumulations before (hail's wintry but smaller cousin) I don't think I've ever blogged much about deep hail other than June 16, 2009 when hail was said to accumulate to between 3 and 12 inches deep in New Jersey (video).
One of the more impressive deep hail storms this year was in Nederland in Boulder County, Colorado on July 29:
The biggest hail storms that the authors uncovered included Seldon, Kansas, on June 3, 1959, where eighteen inches of hail was said to have accumulated "on the level," and Cheyenne, Wyoming, during the evening of August 1, 1985 where a foot of stones accumulated up to six feet deep in flood water.
The problem with most reports (though maybe not the first one) is that hail rolls downhill and accumulates to much higher levels in certain spots than others. The authors suggest that, like drifting snowfall, an average of several spots should be the only scientifically-sound reading.
An extreme example of this was the Union County, New Mexico hail storm of August 13, 2004, which dropped a foot of hail but piled up to 15 to 20 feet ahead of a culvert pipe. Barbara Podzemny took the picture below along with others in the New Mexico Geology magazine article about the storm, and says "It was such a sight to see in this dry county!" The hail apparently remained there for nearly a month despite summer-like temperatures.
In order to get better documentation on deep hail, the authors of the WeatherWise article recommend "broadening the definition of a severe storm to include hail that covers the ground to a depth of two inches or more, regardless of hail size." Although I agree, I think it will be tough to get that alteration of the definition through the red tape at the National Weather Service.
And now: It's time for your retro deep hail movie, this one from Germany in 1972. Keep watching, it gets crazy when hail clogs up escalators and trains!
