MESOSCALE PRECIPITATION DISCUSSION 0308
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1106 AM EDT SAT JUN 04 2016
 
AREAS AFFECTED...UPPER TX COAST...SOUTHWEST LA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 041500Z - 042000Z
 
SUMMARY...VERY INTENSE RAINFALL RATES WILL CONTINUE NEAR THE UPPER
TX COAST AND GRADUALLY SPREADING INTO SOUTHWEST LA OVER THE NEXT
FEW HOURS. FLASH FLOODING WILL BE LIKELY GIVEN THE WET ANTECEDENT
CONDITIONS.

DISCUSSION...THE LATEST IR SATELLITE IMAGERY DOES SHOW SOME
EXPANSION OF COLDER CONVECTIVE TOPS OVER THE FAR NORTHWEST GULF OF
MEXICO IN ASSOCIATION WITH THE NORTHERN FLANK OF A LARGE MCS THAT
EXTENDS WELL SOUTHWEST OFF THE SOUTHEAST TX COAST. THERE IS A
RATHER WELL-DEFINED MID LEVEL CIRCULATION OVER THE SOUTHEAST TX
COASTAL PLAIN AND THIS HAS BEEN TRANSLATING DOWN TO THE SURFACE AS
WELL OVER BASED ON METAR DATA OVER THE LAST FEW HOURS.

THE CONCENTRATION OF LOW AND MID LEVEL LOW PRESSURE NEAR THE TX
COAST IS EXPECTED TO CONTINUE TO HELP TRANSPORT DEEPER MOISTURE
AND INSTABILITY IN OFF THE NORTHWEST GULF OF MEXICO AND TOWARD
AREAS OF THE FAR UPPER TX COAST AND INLAND ACROSS FAR EASTERN TX
AND SOUTHWEST LA. RAP ANALYSES ALREADY SHOW A POOL OF NEARLY 3000
J/KG OF MUCAPE ALONG THE SOUTHWEST LA COAST.

THE BLENDED-TPW PRODUCT AND GPS DATA SHOWS PWATS CLOSE TO 2 INCHES
OVER THIS REGION...AND WITH A RATHER DEEP POOL OF MOISTURE AND
COLD CONVECTIVE TOPS...THE ENHANCED RAINFALL EFFICIENCY SHOULD
HELP PUSH RAINFALL RATES EASILY IN THE 2 TO 3 INCH/HR RANGE.

THE OVERALL BETTER PERFORMING HRRR OUTPUT CONTINUES TO WANT TO
FOCUS THE HEAVIEST RAINFALL OUT OVER THE GULF OF MEXICO THROUGH
EARLY TO MID AFTERNOON...BUT THE SLOW NORTH-NORTHEAST ADVANCE OF
THE CONVECTION NEAR THE UPPER TX COAST AND LA BORDER SHOULD AFFORD
SOME OVERSPREADING OF VERY HEAVY RAINS INTO FAR EASTERN TX AND
SOUTHWEST LA OVER THE NEXT FEW HOURS. THE POTENTIAL EXISTS FOR
SOME RAINFALL TOTALS TO REACH UP TO 5 INCHES WITH ISOLATED HEAVIER
AMOUNTS THROUGH MID-AFTERNOON GIVEN THE SLOW CELL-MOTION AND SUCH
HIGH RAINFALL RATES. FLASH FLOODING IS LIKELY WITH A RISK OF
LOCALLY SIGNIFICANT RUNOFF PROBLEMS GIVEN THE WET SOIL CONDITIONS.

ORRISON

ATTN...WFO...HGX...LCH...

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

LAT...LON   30909395 30909335 30409258 29929230 29519243 
            29539302 29669358 29349451 29379481 29859477 
            30259432