MESOSCALE PRECIPITATION DISCUSSION 0326
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1014 AM EDT TUE JUN 19 2018

AREAS AFFECTED...SOUTHERN TEXAS...

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 191415Z - 192015Z

SUMMARY...VERY MOIST/EFFICIENT RAINFALL PRODUCTION NEAR INNER
CORE/INNER MOST BAND CONTINUE TO POSE LIKELY FLASH FLOODING
ESPECIALLY NEAR/ALONG THE TX COAST.

DISCUSSION...14Z SFC ANALYSIS DENOTES WEAK LOW NEAR LIVE
OAK/MCMULLIN COUNTIES WITH KCRP RADAR SHOWING MCV SOUTHWEST OVER
DUVAL COUNTY SHIFTING SLOWLY EASTWARD AS THE CONVECTION THAT HAS
ANCHORED IT STARTS TO WANE A BIT FROM JIM WELLS TO LEE COUNTY. 
STILL WEAK INSTABILITY REMAINS IN THIS VICINITY AND GIVEN STRONG
MST CONVERGENCE/CONFLUENCE FROM DEEP SOUTH TEXAS AS WELL AS OFF
THE WESTERN GULF OF MEXICO IS STRONG ENOUGH TO MAINTAIN CONVECTION
THOUGH WEAKENING WITH TIME.  MOISTURE SOUNDINGS ARE INCREDIBLY
DEEP WITH TPWS AOA 2.6" SUPPORTED BY KCRP/KBRO 12Z SOUNDINGS AND
GPS NETWORK IN THE AREA..SO NO COLD POOL/OUTFLOW PROPAGATION WILL
BE EXPECTED SUPPORTING STATIONARY CELLS/STATIC ASCENT LOCATIONS. 
CONVERGENCE MOTIONS NEAR THE CENTER MAY SHIFT A BIT WEST AS THE
MCV SHIFTS THAT DIRECTION.  HOWEVER...LARGER SCALE RIDGING TO THE
WEST WILL DELAY/REDUCE WESTWARD MOTIONS TOO MUCH REINFORCING MORE
OF AN ELONGATED N-S MID-LEVEL TROF.  LIMITING DEEPEST INSTABILITY
WILL REDUCE RAINFALL EFFICIENCY FROM 1.5"/HR TO 1.0" OVER THE NEXT
FEW HOURS BUT DURATION WILL CONTINUE TO ALLOW FOR FLASH FLOODING
TO BE LIKELY WITH 6HR TOTALS OVER 4-6" POSSIBLE ESPECIALLY WHERE
BEST MST CONVERGENCE/INSTABILITY  IS NOT AS OBSTRUCTED ON THE
SOUTHEAST PERIPHERY OF THE MCV IN JIM HOGG/BROOKS AND S DUVAL/JIM
WELLS COUNTY.  

GOES-16 10.3UM AND 1-MINUTE VISIBLE SUITE SHOWS THE DEVELOPMENT OF
THE N-S WESTERN GULF INNER BAND.  DEEP UNIDIRECTIONAL FLOW IN THE
VICINITY OF THIS BAND SHOULD SUPPORT NORTHWARD TRAINING THOUGH
SOME STRONG SSELY INFLOW AT THE SURFACE MAY SUPPORT SOME SMALL
EASTWARD PROPAGATION OF THE BAND.   DEEP SURFACE MOISTURE AND HEAT
OVER THE OCEAN SUPPORTS GREATEST INSTABILITY OVER 2500 J/KG
ALLOWING FOR RAIN RATES/1HR TOTALS IN EXCESS OF 3"/HR GIVEN THE
TPWS OVER.  EVEN AT SHORT DURATION OR REDUCED TRAINING (IF
EASTWARD PROPAGATION IS SIGNFICANT) WHERE IT INTERSECTS WITH THE
COAST (LIKLY NEAR MATAGORDA BAY) IN THE NEXT FEW HOURS WILL LIKELY
HAVE FLOODING CONCERNS AS WELL.

THERE IS GREATER UNCERTAINTY IN COVERAGE/CONVECTIVE RESPONSE
ACROSS THE CENTRAL TO NORTHEAST TX COAST...BUT SUBSEQUENT MPD WILL
ADDRESS THIS AREA SHORTLY.

GALLINA

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

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

LAT...LON   29549681 29289586 28719562 28269639 27449717
            27069741 27159867 27639906 28329888 28929856
            29279801 29489743