MESOSCALE PRECIPITATION DISCUSSION 0221
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
626 AM EDT THU MAY 19 2016
 
AREAS AFFECTED...EDWARDS PLATEAU...HILL COUNTY...AND SW TEXAS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 191025Z - 191525Z
 
SUMMARY...INCREASING COVECTIVE COVERAGE AND INTENSITY WITH
POTENTIAL FOR SOME TRAINING OR SLOW MOVING CELLS MAY POSE FLASH
FLOODING THREAT.

DISCUSSION...WV LOOP SHOWS BROAD LONG WAVE TROF EJECTING IN THE
SOUTHERN PLAINS WITH MAIN CENTER IN THE OK/TX PANHANDLES BUT ALONG
THE TRAILING TROF IS ANOTHER WEAKER WAVE JUST NORTH OF THE BIG
BEND REGION.  THE TRAILING EDGE OF THE MAIN TROF AS SETUP AN AXIS
OF ACTIVE ELEVATED W-E LINE FROM W VAL VERDE COUNTY TO SAN SABA
COUNTY WITH A SMALL DRY SLOT SEPARATING  A SW-NE LINE OF
DEVELOPING CONVECTION IS ACTIVATING ON THE MID-LEVEL TROF OF THE
S/W NEAR THE BIG BEND REGION.  AN ADDITIONAL CONVECTIVE CLUSTER IS
ALSO DEVELOPING FURTHER SOUTH OVER W WEBB COUNTY WITHIN THE SPLIT
BETWEEN THE POLAR JET AND SUBTROPICAL JET THAT CLIPS DEEP SOUTH
TX.  THE BROAD HEIGHT FALLS EJECTING OUT OF THE HIGHER TERRAIN IS
SUPPORTING VEERED LOW LEVELS SUPPORTING WAA AND STRONG RETURN
MOISTURE FLOW ALONG THE RIO GRANDE VALLEY WITH TPWS RANGING FROM
1.6" NEAR KDRT AND NEARING 2" IN NE MEXICO.  THIS INCREASING LOW
LEVEL FLOW IS CURRENTLY PROVIDING SUFFICIENT ELEVATED MUCAPES TO
500 J/KG FORECAST TO INCREASE TO 1000 J/KG THROUGHOUT THE MORNING
WITH STRONG MST FLUX TO INCREASE CONVECTIVE INTENSITY AND RAINFALL
EFFICIENCY WITH RATES UP TO 2.0"/HR.  FURTHER NORTH...ORIENTATION
OF CELL MOTIONS WILL BE MORE ALIGNED TO SUPPORT SOME TRAINING;
WHILE FURTHER SOUTH CELL MOTIONS WILL BE SLOWER AND BEING CLOSER
TO THE SPLIT IN THE JET...LIKELY TO SUPPORT SOME BACKBUILDING OR
UPSTREAM DEVELOPMENT AS WELL. 

HI-RES CAMS ARE SUPPORTIVE OF THESE MULTIPLE CORRIDORS OF HIGHER
RAINFALL TOTALS WITH 3 TRACKS OF 2-3" TOTALS WITH LOCALLY HIGHER
AMOUNTS WHERE MERGERS OR SOME TRAINING OCCURS...LEADING TO FLASH
FLOODING PSBL PARTICULARLY IN THE TERRAIN OF THE EDWARDS
PLATEAU/HILL COUNTY AND URBAN CENTERS (SUCH AS SAN ANTONIO).  

GALLINA

ATTN...WFO...CRP...EWX...SJT...

ATTN...RFC...WGRFC...

LAT...LON   30869856 30809784 30539749 30449730 29859737 
            28679804 28069829 27549903 27359937 27409955 
            27989989 28750047 29450097 30370091