MESOSCALE PRECIPITATION DISCUSSION 0609
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
512 PM EDT SAT OCT 24 2015
 
AREAS AFFECTED...SOUTHEAST TX 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 242115Z - 250130Z
 
SUMMARY...EFFICIENT WARM PROCESS HEAVY RAINFALL THREAT CONTINUES
INTO THE EVENING HOURS...RESULTING IN ADDITIONAL FLASH FLOODING. 

DISCUSSION...A DEEP MOIST FLOW CONTINUES AHEAD OF A COLD FRONT
CROSSING CENTRAL INTO SOUTH TX. IN ADVANCE OF THE FRONT...A 20 TO
30 KNOT LOW LEVEL SOUTHERLY INFLOW PUMPS 2.25 TO 2.50 INCH
PRECIPITABLE
WATER AIR (WHICH IS ABOUT THREE STANDARD DEVIATIONS ABOVE THE
MEAN) INTO SOUTHEAST TX. DEEPER INSTABILITY IS IN THE PROCESS OF
BEING PUSHED TO THE SOUTHEAST TX COAST BY THE COLD
FRONT...LIMITING THE DEEP...WARM RAIN PROCESS DOMINATED CONVECTION
TO SOUTHEAST TX. 

HOURLY RAINFALL RATES (PER THE KBRO RADAR AND THE MRMS RAINFALL
RATE PRODUCT) BETWEEN 2.00 AND 2.50 INCHES WILL RESULT IN
ADDITIONAL FLASH FLOODING AHEAD OF THE FRONT FROM KBRO TO KVCT
THROUGH ABOUT 25/00Z. AFTER THAT TIME...THE DEEPEST MOISTURE
SHOULD BE PUSHED JUST OFF THE FAR SOUTH TX COAST.

SURFACE LOW PRESSURE FORMING ON THE FRONT OFF THE FAR SOUTH TX
COAST SHOULD BEGIN TO FOCUS THE 25 TO 35 KNOT LOW LEVEL INFLOW
FURTHER NORTH (BETWEEN KVCT AND KIAH) BEFORE 25/01Z. INSTABILITY
OVER LAND IN THESE AREAS WILL BE FAIRLY MEAGER...BUT THE LOW LEVEL
INFLOW SHOULD TRANSPORT ENOUGH MUCAPE BASED INSTABILITY TO THE
COAST TO SUSTAINED LOW TOPPED WARM PROCESS CONVECTION INTO THE
EARLY EVENING. 

THERE IS A FAIRLY STRONG HIGH RESOLUTION GUIDANCE SIGNATURE
(INCLUDING THE LATEST HRRR/RAP/12Z WRF-ARW/NMMB/12Z REGIONAL GEM)
FOR HEAVY RAINFALL OVER THE MID TX COAST...WITH LOCAL 3-5 INCH
AMOUNTS POSSIBLE. WHILE THREE HOUR FLASH FLOOD GUIDANCE VALUES ARE
RELATIVELY HIGH HERE...HIGH RAINFALL RATES IN THE HIGH MOISTURE
CONTENT AIRMASS SHOULD PRODUCE FLASH FLOODING.

HAYES

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

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

LAT...LON   31039590 30889477 29539408 28399616 27849656 
            26219704 25879736 25949856 26549908 28249825 
            28389823 28779786 29399715 30119648 30709605