MESOSCALE PRECIPITATION DISCUSSION 0584
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
312 PM EDT SAT AUG 20 2016
 
AREAS AFFECTED...CENTRAL AND SOUTHERN TX 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 201910Z - 210000Z
 
SUMMARY...HEAVY RAIN AND FLASH FLOODING WILL BECOME AN INCREASING
CONCERN THIS EVENING ACROSS THE TX HILL COUNTRY AND POSSIBLY TO
THE RIO GRANDE VALLEY.

DISCUSSION...COOLING CONVECTIVE TOPS ARE SEEN IN BETWEEN SAN
ANGELO AND JUNCTION TX OVER THE LAST HOUR...AS HEAVY RAINS ARE
SETTING UP AGAIN AROUND THE NORTHWEST FLANK OF A VERY WELL-DEFINED
MCV WHICH IS CENTERED NEAR SAN ANTONIO. THE CONVECTION IS ALSO
COINCIDING WITH PRESENCE OF A VERY SLOW-MOVING COLD FRONT SETTLING
DOWN INTO THE TX HILL COUNTRY AND INTERACTION WITH A SURFACE LOW
JUST NORTHEAST OF THE BIG BEND AREA.

OVER THE NEXT FEW HOURS...CONVECTION IS LIKELY TO BECOME A BIT
MORE FOCUSED/WIDESPREAD AS INSTABILITY RECOVERS A BIT MORE OVER
THE REGION IN THE WAKE OF EARLIER CONVECTION TODAY. THIS WILL
INCLUDE AN EXPANSION CLOSER INTO TOWARD THE SAN ANTONIO AREA
TOWARD EARLY EVENING. VERY HEAVY RAINFALL RATES ARE LIKELY
COURTESY OF THE PWATS BETWEEN 2.0 TO 2.2 INCHES...AND A
CONCENTRATED LAYER OF HIGH LEVEL TROPICAL MOISTURE IN THE 500/300
MB LAYER AS PER CIRA-LPW DATA. THE CIRA-LPW PRODUCT SHOWS A CLEAR
CONNECTION TO TROPICAL MOISTURE EMANATING FROM T.S. KAY OVER THE
EASTERN TROPICAL PACIFIC OCEAN SOUTHWEST OF THE BAJA PENINSULA.

EXPECT AS MUCH AS 2.5 INCH/HR RAINFALL RATES...WITH ADDITIONAL
STORM TOTALS THROUGH 00Z OF 4 TO 6 INCHES POSSIBLE. THE HIRES
GUIDANCE SUGGESTS AN INCREASINGLY CONCENTRATED POTENTIAL FOR VERY
HEAVY RAINFALL NOT ONLY THROUGH 00Z...BUT WELL BEYOND THIS PERIOD.
CONDITIONS ARE EXPECTED TO BECOME MORE CONDUCIVE FOR ENHANCED AND
LIKELY SIGNIFICANT FLASH FLOODING THROUGH THE EVENING.

ORRISON

ATTN...WFO...EWX...FWD...SJT...

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

LAT...LON   31479902 31229826 30719786 30019774 29579782 
            29219822 29189881 29679965 29850020 29980085 
            30230126 30460135 30760116 31200047 31439968