More large hail falls across the Lower Rio Grande Valley, May 12th 2012

Loop of 1.4° radar base reflectivity between 404 PM and 545 PM across the Lower Rio Grande Valley on May 12th. Note the rapid development of cells in Cameron County, with others forming rapidly near Weslaco (southeast Hidalgo). South moving boundaries from earlier storms near Raymondville triggered the newer development.

Atmospheric profile from Brownsville, posted at 7 PM with initial data sampled closer to 6 PM, soon after hailstorms raced through the Lower Valley. Click for larger version. The combination of dry air aloft, a very steep temperature drop with height, and a trigger in the form of a boundary between much drier and much more humid air near the surface aided rapid updraft formation.

Oh, Yes it Did...
...Hail (Again) in portions of the Rio Grande Valley on May 12th 2012

Recap
A little more than a day after a thunderstorm system brought more severe weather to the Rio Grande Valley, the last vestige of very unstable air held forth mainly along and east of Highway 77. Despite unfavorable upper level conditions, the combination of the unstable air with a trigger in the form of a wind shift/dry line which moved within striking distance of Highway 77 allowed a small but potent cluster of thunderstorms to explosively grow initially in northern Willacy County just before 4 PM CDT. These storms would produce south–moving outflows, which added to the dryline trigger. Additional storms would fire in only a half hour, working on the very unstable atmosphere (above right) to increase updraft speed and develop quarter to half dollar sized hail – at least – between west Harlingen and La Feria and points south between 515 and 545 PM. Once again, there was some damage to vehicles caught in the hail, much containing jagged edges. Many residents caught by surprise by the rapid development moved their vehicles under gas station canopies, car washes, and highway underpasses.

A preliminary storm report follows. Note that some times are estimated after reconciliation with radar, and may not match earlier preliminary reports that can be found online.

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE BROWNSVILLE TX
731 PM CDT SAT MAY 12 2012

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0705 PM     HAIL             FALFURRIAS              27.22N  98.14W
05/11/2012  E1.00 INCH       BROOKS             TX   LAW ENFORCEMENT 

0406 PM     HAIL             E RAYMONDVILLE          26.48N  97.78W
05/12/2012  E0.88 INCH       WILLACY            TX   PUBLIC          

            NICKLE SIZE HAIL NEAR RAYMONDVILLE ABOUT 2 MILES EAST 
            OF HWY 77 

0425 PM     HAIL             1 N RAYMONDVILLE        26.49N  97.78W
05/12/2012  E1.00 INCH       WILLACY            TX   PUBLIC          

            PUBLIC REPORTED QUARTER SIZE HAIL ON NORTH SIDE OF 
            RAYMONDVILLE 

0425 PM     HAIL             7 N RAYMONDVILLE        26.58N  97.78W
05/12/2012  E1.00 INCH       WILLACY            TX   EMERGENCY MNGR  

            EMERGENCY MANAGER REPORTED QUARTER SIZE HAIL NEAR 
            YTURRIA 

0434 PM     HAIL             RAYMONDVILLE            26.48N  97.78W
05/12/2012  M0.88 INCH       WILLACY            TX   BROADCAST MEDIA 

            PUBLIC VIA BROADCAST METEOROLOGIST REPORTED NICKEL SIZE 
            HAIL AT THE CORNER OF 1ST AND TAMPICO 

0500 PM     HAIL             RAYMONDVILLE            26.48N  97.78W
05/12/2012  E1.00 INCH       WILLACY            TX   PUBLIC          

            PUBLIC REPORTED QUARTER SIZE HAIL ON BUS NEAR 
            RAYMONDVILLE 

0510 PM     HAIL             2 W HARLINGEN           26.20N  97.72W
05/12/2012  M0.75 INCH       CAMERON            TX   PUBLIC          

            PALM VALLEY RESIDENT REPORTED 5 PALM TREES SET ON FIRE 
            BY LIGHTNING. 

0515 PM     HAIL             2 W HARLINGEN           26.20N  97.72W
05/12/2012  M0.88 INCH       CAMERON            TX   PUBLIC          

            WEST SIDE OF HARLINGEN ALONG HIGHWAY 77 83 REPORTED 
            NICKEL SIZE HAIL 

0520 PM     HAIL             HARLINGEN               26.20N  97.69W
05/12/2012  M0.75 INCH       CAMERON            TX   PUBLIC          

            PENNY SIZE HAIL AT HARRISON AND HWY 77 

0520 PM     HAIL             HARLINGEN               26.20N  97.69W
05/12/2012  M0.75 INCH       CAMERON            TX   AMATEUR RADIO   

            PENNY HAIL RELAYED BY HAM OPERATER FROM GENERAL PUBLIC 

0525 PM     HAIL             3 W HARLINGEN           26.20N  97.73W
05/12/2012  M1.00 INCH       CAMERON            TX   PUBLIC          

            NICKEL TO QUARTERS AT ALTAS PALMAS AND HWY 83 

0532 PM     HAIL             2 W HARLINGEN           26.20N  97.72W
05/12/2012  M1.00 INCH       CAMERON            TX   PUBLIC          

            RELAYED REPORTED FROM SPOUSE OF NWS EMPLOYEE. QUARTER 
            SIZE HAIL BROKE CAR WINDSHEILD ALONG HWY 83 WEST SIDE OF 
            HARLINGEN 

0532 PM     HAIL             HARLINGEN               26.20N  97.69W
05/12/2012  M1.00 INCH       CAMERON            TX   EMERGENCY MNGR  

            CAMERON COUNTY EM HUMBERTO BARRERA REPORTED QUARTER 
            SIZE HAIL AT COUNTY ROAD 800 AND RANGERVILLE RD. 

0545 PM     HAIL             LA FERIA                26.16N  97.82W
05/12/2012  E1.00 INCH       CAMERON            TX   PUBLIC          

            PUBLIC REPORTED QUARTER SIZE HAIL NEAR LA FERIA. 

0600 PM     HAIL             6 SE LA FERIA           26.09N  97.77W
05/12/2012  M1.00 INCH       CAMERON            TX   TRAINED SPOTTER 

            SKYWARN SPOTTER NEAR REPORTED QUARTER SIZE HAIL NEAR 
            RANGERVILLE