MESOSCALE PRECIPITATION DISCUSSION 0626
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
936 PM EDT FRI OCT 30 2015
 
AREAS AFFECTED...BIG BEND OF TX...CENTRAL TX 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 310130Z - 310615Z
 
SUMMARY...STRONG CONVECTIVE BANDS WILL TEND TO REDEVELOP OVER THE
NEXT COUPLE OF HOURS AND PRODUCE ADDITIONAL VERY HEAVY SHOWERS AND
THUNDERSTORMS. ADDITIONAL FLASH FLOODING WILL BE POSSIBLE...AND
ESPECIALLY OVER AREAS THAT SAW EARLIER HEAVY RAINS.

DISCUSSION...THE WV AND GOES-RGB AIRMASS IMAGERY SHOWS A
WELL-DEFINED UPPER TROUGH EJECTING OUT INTO WESTERN TX THIS
EVENING WHICH IS FOSTERING A REDEVELOPMENT OF CONVECTION NEAR THE
BIG BEND OF TX AND IS HELPING TO SUSTAIN THE ONGOING CONVECTIVE
BAND ACROSS CENTRAL TX. MUCH OF THIS ACTIVITY IS IN THE WARM
SECTOR AHEAD OF A COLD FRONT WHERE THERE IS AT LEAST A MODESTLY
UNSTABLE AIRMASS IN PLACE. MUCH OF THE CONVECTIVE DEVELOPMENT HAS
TENDED TO BE ASSOCIATED WITH THE STRONGER UPPER LEVEL
FORCING/DIVERGENT FLOW ALOFT AHEAD OF THE TROUGH...BUT IT IS ALSO
TAKING ADVANTAGE OF A VERY MOIST AIRMASS COURTESY OF DUAL MOISTURE
FEEDS INVOLVING THE EASTERN TROPICAL PACIFIC OCEAN AND THE GULF OF
MEXICO. THIS IS SEEN VERY WELL IN THE H7/H3 LAYER AS DEPICTED BY
THE 00Z CIRA LAYERED PW PRODUCT.

THE LAST COUPLE RUNS OF THE HRRR HAVE BEEN SUGGESTING THAT
CONVECTION WILL TEND TO ORGANIZE A BIT MORE IN A SW/NE ORIENTED
FASHION ACROSS CENTRAL TX AS ADDITIONAL SHORTWAVE ENERGY EJECTING
OUT OF THE BASE OF THE UPPER TROUGH INTERACTS WITH THE
AFOREMENTIONED FRONTAL ZONE AND A FAVORABLE THERMODYNAMIC
ENVIRONMENT. CONTRIBUTING TO THIS WILL BE A PERSISTENTLY
MOIST/UNSTABLE SOUTHERLY LOW LEVEL JET REACHING AS HIGH AS 50 KTS.

EXPECT RAINFALL RATES TO LOCALLY BE AS HIGH AS 2 TO 3
INCHES/HR....WITH ADDITIONAL STORM TOTALS THROUGH 06Z OF 3 TO 4
INCHES WITH ISOLATED HEAVIER AMOUNTS. THESE RAINS WILL PROMOTE
ADDITIONAL CONCERNS FOR FLASH FLOODING AND ESPECIALLY OVER AREAS
THAT SAW EARLIER HEAVY RAINS.

ORRISON

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

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

LAT...LON   33789651 33649602 33299575 32669578 31939633 
            31299703 30529795 29769926 29340058 29770147 
            30610115 31640006 32429900 33129807 33659726