MESOSCALE PRECIPITATION DISCUSSION 0459
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
746 AM EDT THU AUG 20 2015
 
AREAS AFFECTED......SOUTH TEXAS... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 201145Z - 201545Z
 
SUMMARY...HIGHLY EFFICIENT WARM RAIN PROCESSES WILL LEAD TO
CONTINUED INTENSE SHORT TERM RAINFALL RATES ACROSS THE RIO GRAND
VALLEY THIS MORNING.

DISCUSSION...THE MCS EARLIER THIS MORNING IS CURRENTLY RECYCLING
ACROSS THE RIO GRAND VALLEY...WITH THE NEW ORGANIZED CONVECTION
AIDED BY CONTINUED LOW LEVEL INFLOW AROUND 30 KTS WITH MUCAPES OF
2000 J/KG. DEEP WARM RAIN PROCESSES ARE IN PLAY WITH OBSERVED
PRECIPITABLE WATER VALUES AROUND 2.25 INCHES PER THE GPS...ALONG
WITH VERY HIGH WET BULB ZERO HEIGHTS (OVER 14,000 KFT) AND WARM
CLOUD DEPTHS OVER 10,000 FEET. 

THE MESOSCALE-ENHANCED VORT CENTER CURRENTLY OVER SOUTH TEXAS PER
THE LATEST WV LOOPS WILL MOVE VERY LITTLE THIS MORNING PER THE
LATEST MODEL GUIDANCE. THIS ALONG WITH THE CONTINUED SUFFICIENT
LOW LEVEL INFLOW ABOVE THE SURFACE LAYER WILL MAINTAIN ORGANIZED
MULTICELLULAR CONVECTION...AT LEAST THROUGH LATE MORNING BEFORE
DIURNAL/DIFFERENTIAL HEATING WILL BEGIN TO DISRUPT THE CURRENT
ORGANIZED LOW LEVEL MOIST INFLOW. 

ADDITIONAL BACK-BUILDING AND THUS CELL TRAINING ARE EXPECTED WITH
THE STATIONARY MCV AND STRONG LOW LEVEL INFLOW RELATIVE TO THE
MEAN 850-300 LAYER FLOW. BASED ON THIS ALONG WITH THE DEGREE/
DEPTH OF MOISTURE AND INSTABILITY...HOURLY RAINFALL RATES OF 2-2.5
INCHES ARE ANTICIPATED UNDER THE HEAVIER CORES... WITH SOME OF THE
LATEST CAM GUIDANCE (INCLUDING THE EXPERIMENTAL
HRRR...WRF-ARW...AND WRF-NMMB) INDICATING POCKETS OF 3-6" THROUGH
15Z. 

HURLEY

ATTN...WFO...BRO...CRP...

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

LAT...LON   28169739 27699661 26749612 25809630 25219722 
            25299823 25829906 26739934 27469906 28129825