MESOSCALE PRECIPITATION DISCUSSION 0278
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
524 PM EDT TUE MAY 31 2016
 
AREAS AFFECTED...SOUTH TEXAS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 312124Z - 010124Z
 
SUMMARY...COLD POOL AND OUTFLOW GRAVITY WAVES FROM CONVECTION TO
THE NORTH HAS PERTURBED ENVIRONMENT FOR DEEP CONVECTIVE EXPANSION
SOUTHWARD OF CONVECTION  CAPABLE OF FLASH FLOODING DUE TO HIGH
RATES AND CELL MERGERS. 

DISCUSSION...LARGE COMPLEX ACROSS HILL COUNTY HAS GENERATED A
EASTWARD PROPAGATING MCS AS WELL AS GENERATING GRAVITY WAVES THAT
PERTURBED THE CAPPED ENVIRONMENT ENOUGH FOR NEW CONVECTIVE
DEVELOPMENT SOUTH OF THE COMPLEX.   DEEP SOUTHERLY FLOW
ILLUSTRATED WELL BY NUMEROUS CU FEEDER BANDS SEEN IN VISIBLE
IMAGERY LEAD TO VERY STRONG 25-30 UNITS OF SURFACE MST CONVERGENCE
ALONG THE LOW LEVEL OUTFLOW BOUNDARY AS WELL AS ALONG THE SW-NE
BOUNDARY THAT BISECTS THE RIO GRANDE IN MAVERICK COUNTY.  WITHIN
THIS FEEDER BAND AREA 4500 SBCAPES AND TPWS TO 1.9" ARE QUITE
CAPABLE OF GENERATING RAIN RATES IN EXCESS OF 2.5"/HR UP TO 4"/HR
IF MST FLUX IS LOCALLY MAXIMIZED DUE TO STORM SCALE
INTERACTIONS...QUICKLY LEADING TO FLASH FLOODING CONCERNS ACROSS
SOUTH TEXAS.

WITH PERSISTENT HEIGHT FALLS TO THE WEST FORCING WILL CONTINUE TO
REESTABLISH FURTHER WEST AS WELL DRAWING MOISTURE/FLOW THROUGH THE
COMPLEX TOWARD ANY NEW COMPLEXES ADVANCING FROM THE SIERRA
MADRE...THIS CURRENT ACTIVITY IS LIKELY TO LIMIT THE STRENGTH OF
THE NEXT ROUND LIKELY FOCUSING IT FURTHER SOUTH OVERNIGHT COMPARED
TO MUCH OF THE HI-RES CAMS SUGGESTING ROLLING THROUGH BY 06Z. AS
SUCH WILL REASSESS THE CONVECTIVE SETUP LATER. 
 
EAST OF THE COMPLEX ALONG I-10...LOW LEVEL ANALYSIS INDICATES
WEAKER WINDS BELOW 10KTS FROM SFC TO 7H...WITH HIGHER LOW LEVEL
TEMPS (CAPPING) AND LOWER MST AVAILABILITY LEADING TO CAPES BELOW
1500 J/KG (MLCAPES) EAST OF 96W; SHOULD LIMIT HIGHER RAINFALL
RATES AND SUPPORT STRONGER DOWNDRAFTS/FASTER EASTWARD PROPAGATION
LIMITING HIGH RAINFALL TOTALS.  HOWEVER...ANY MODERATE RAINFALL
COULD COMPOUNDING ONGOING FLOODING RIVER CONDITIONS ACROSS SE
TEXAS INCLUDING THE COLORADO/TRINITY/BRAZOS RIVERS. 

GALLINA

ATTN...WFO...BRO...CRP...EWX...FWD...HGX...

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

LAT...LON   30809780 30479629 29239598 28719609 27979687 
            27069749 26969809 27059932 27579956 28470034 
            29099985 29689871 30479861