Saturday, June 12, 2010

Monster Size Hail in the Texas Panhandle

A severe thunderstorm in the far northern Texas Panhandle has produced hailstones up to 6 inches in diameter (yes, 6 inches!!!) just south of Sunray, TX.  Below is a reflectivity image of the cell near the time the report was received:
AMA NEXRAD Reflectivity image at 3:19 PM CDT

The Storm Attributes algorithm on the radar attempted to estimate the maximum potential hailstone size as 2.75 inches, as depicted by the solid green triangle in the image below (near Sunray):

In my earlier post regarding the new Phased Array Radar (PAR) system that is being tested in Norman, OK, I pointed out that PAR samples the atmosphere about once every minute, whereas the current NEXRAD network samples the atmosphere once every 4 to 6 minutes.  In situations like this afternoon's, the PAR would have had a better chance at "catching" the rapid intensification of the hail producing thunderstorm, and perhaps could have given stronger indication that the hail diameter potential was larger than 2.75 inches estimated by the NEXRAD algorithm.  Only time (and testing) will tell for sure, but there's little doubt that we would have had more information with a once per minute sampling vs. a once every 4-6 minute sampling of this storm!

Below is an image of the AMA Vertically Integrated Liquid (VIL) scan at about the same time as the image above.  VIL estimates the amount of liquid that is located in the air column at a given point.  In this particular case, the radar indicated a VIL value near 80 (denoted by the bright white colored area immediately Southeast of Sunray).  An 80 VIL is extremely high, and is more indicative of the super-size hail potential with this storm, even more so than the hail detection algorithm that predicted 2.75 inch hail:

Below is a snapshot of the GRLevel2 vertical cross-section of this storm shortly after it moved Northeast of Sunray:

On a reflectivity image (such as the cross section above), rain, hail, etc. are sending back echoes to the radar measured in "decibels of Z" (also known as dBZ).  To put some sort of generic perspective in place, 10-20 dBZ echoes would be considered light, 20-40 would be considered moderate, 40-60 heavy and anything above 60 would be considered "intense".  I've noted on the above image where a fairly good size core of 70 dBZ (getting toward the top of the intense scale) echoes were noted about 10,000 feet above ground level.  This is undoubtedly representing the heart of the intense hail core associated with this particular storm.

UPDATE 6/13/10:  Here is an impressive video of the hail from yesterday on YouTube:

Personally, I can't wait until Phased Array Radar comes onboard across the country and we can hopefully get a better handle on this type of situation.  Again, I'm not saying we don't already do a better job than we did even 5 or 10 years ago, but a more frequently updating radar system would result in even further improvement - and likely save additional lives each year as well!

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