MESOSCALE PRECIPITATION DISCUSSION 0291
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1118 AM EDT THU JUN 02 2016
 
AREAS AFFECTED...EASTERN TX...WESTERN LA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 021515Z - 022115Z
 
SUMMARY...SIGNIFICANT FLASH FLOODING IS EXPECTED TO EVOLVE THIS
AFTERNOON AS A RESULT OF EXPECTED VERY HEAVY RAINFALL TOTALS.

DISCUSSION...AN AXIS OF DEEP TROPICAL MOISTURE AND INSTABILITY HAS
BECOME ESTABLISHED ALONG THE MIDDLE AND UPPER TX COAST AND
EXTENDING INTO EXTREME SOUTHWEST LA. THIS IS IN RESPONSE TO DEEP
LAYER SOUTHERLY FLOW UP ACROSS THE WESTERN GULF OF MEXICO OUT
AHEAD OF A DEEP LAYER TROUGH MOVING ACROSS MUCH OF CENTRAL TX AND
DOWN TO THE RIO GRANDE VALLEY.

THE LATEST BLENDED-TPW PRODUCT SHOWS PWATS EXCEEDING 2 INCHES OVER
THE NORTHWEST GULF OF MEXICO AND EXTENDING INLAND ACROSS FAR
SOUTHEAST TX AND INTO SOUTHWEST LA. MEANWHILE...A POOL OF MODERATE
TO STRONG INSTABILITY IS FOCUSED OVER THE SAME REGION WITH SBCAPE
VALUES OF 3000 TO 4000 J/KG JUST OFFSHORE. DEEP LAYER
UNIDIRECTIONAL FLOW FROM THE SOUTH SHOULD CONCENTRATE THIS
MOISTURE AND INSTABILITY UP ACROSS ESPECIALLY THE UPPER TX COAST
AND INTO SOUTHWEST LA OVER THE NEXT SEVERAL HOURS AND WILL SET THE
STAGE FOR SOME VERY IMPRESSIVE RAINFALL TOTALS.

DEEP LAYER ASCENT ASSOCIATED WITH THE APPROACHING UPPER TROUGH IN
CONJUNCTION WITH THE AFOREMENTIONED MOISTURE AND INSTABILITY
TRANSPORT SHOULD ALLOW ONGOING CONVECTION TO CONTINUE TO EXPAND
AND ORGANIZE WHICH IS STRONGLY SUPPORTED BY THE HIRES GUIDANCE AND
ESPECIALLY MULTIPLE RUNS OF THE HRRR/HRRRP OUTPUT.

RAINFALL RATES OVER 3 INCHES/HR CAN BE EXPECTED OVER THE NEXT
SEVERAL HOURS WITHIN THE STRONGER CORES...AND ESPECIALLY WHERE
OVERSHOOTING TOPS OCCUR WHICH IS ALREADY HAPPENING EAST OF THE
HOUSTON METROPOLITAN AREA. RAINFALL AMOUNTS AS PER HIRES GUIDANCE
IS EXPECTED TO BE ON THE ORDER OF 4 TO 8 INCHES THROUGH 21Z...WITH
ISOLATED TOTALS POSSIBLY APPROACHING OR EXCEEDING 10 INCHES. THIS
WILL DRIVE A SIGNIFICANT FLASH FLOOD THREAT THROUGH THE
AFTERNOON...AND ESPECIALLY IN VICINITY OF MORE URBANIZED SETTINGS.

ORRISON

ATTN...WFO...FWD...HGX...LCH...SHV...

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

LAT...LON   32709463 32209339 31019278 29679316 29239414 
            28769510 28719572 29539547 30429571 31039612 
            31689653 32569569