MESOSCALE PRECIPITATION DISCUSSION 0582
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
745 AM EDT SAT AUG 20 2016
 
AREAS AFFECTED...CENTRAL TEXAS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 201145Z - 201745Z
 
SUMMARY...HIGHLY EFFICIENT RAINFALL PRODUCING MCC SLOWLY DRIFTING
EAST LIKELY TO MAINTAIN STRENGTH THROUGH THE EARLY MORNING POSING
A LIKELY FLASH FLOOD THREAT. 

SUMMARY...ENVIRONMENT SETUP GENERALLY IDEAL FOR MAINTAINING STRONG
MESOSCALE CONVECTIVE COMPLEX WITH CONTINUED OVERSHOOTING TOPS
COLDER THAN -80C.  WV LOOP INDICATES MCC HAS STRONG UPPER LEVEL
DIVERGENCE PATTERN AT AN ANTICYCLONICALLY CURVING LEFT EXIT REGION
200MB SUBTROPICAL JET ACROSS NW MEXICO...AS WELL AS SOME RIGHT
ENTRANCE UVV DYNAMICS AT THE PERIPHERY OF 30-35KT 3H ENHANCING
POLAR JET.  ADDITIONALLY THE 3H PATTERN IS HIGHLY DIFFLUENT WITH
VERY CLOSE IN PROXIMITY TO THE 3H RIDGE AXIS ALONG THE CENTRAL TX
GULF COAST.  THIS STRONG DIVERGENCE WILL MAINTAIN SOLID EVACUATION
ALOFT SUPPORTING STRENGTHENING MCV DRIVEN BY STRONG LATENT HEAT
RELEASE.  DUAL CHANNEL MST TRANSPORT WITH SFC TO 850 VEERED
SOUTHERLY WIND PROFILE WITH MID 70S SFC TD TRANSPORTS NORTHWARD
TOWARD THE COMPLEX WHILE CIRA LAYERED TPW VALUES ABOVE 7H ARE NEAR
1" ALONE WITH LITTLE DRY INTRUSION DUE TO THE TROPICAL CONNECTION
TO KEEP DOWNDRAFTS GENERALLY WEAK AND LIMIT FORWARD PROPAGATION. 
THIS ALLOWS SLOWER FORWARD MOTIONS FOR DEEP CONVECTION CAPABLE OF
RATES NEAR OR ABOVE 2"/HR TO COMPOUND TOTALS QUICKLY. 

AS THE MORNING PROGRESSES...HI-RES CAMS AND RAP FORECASTS SUGGEST
SLOW EASTWARD DRIFT THOUGH THERE SHOULD BE INCREASING CONVECTIVE
GROWTH ALONG NEWARD EXTENDING LOW TO MID LEVEL CONVERGENCE
BAND/SFC TROF ACROSS SE EDWARDS PLATEAU AFFECTING SOME OF THE HILL
COUNTY OF CENTRAL TX...ALONG NOSE OF 35-40KT 850 LLJ...EXPANDING
FLASH FLOOD THREAT THROUGH THIS AXIS POTENTIALLY CONNECTING TOWARD
DEVELOPING COMPLEX/DEFORMATION ZONE FURTHER NORTH (PLEASE SEE MPD
583 FORTHCOMING).

THOUGH THE HI-RES AND GLOBAL GUIDANCE ARE SCATTERED WITH LOCATION
OF THE HEAVIEST TOTALS THERE IS GENERAL CONSENSUS OF HIGH TOTALS
OF 3-6" OVER THE NEXT 6HRS WITH RADAR AND SATELLITE TRENDS
SUGGESTING LIKELY MAXIMA IN AN AREA ALONG SOUTH AND EAST OF 30N
AND 100W (NEARING WESTERN AND NORTHERN PORTIONS OF THE SAN ANTONIO
METRO) THOUGH HIGHER LOCALIZED TOTALS ARE POSSIBLE CAUSING A HIGH
LIKELIHOOD OF FLASH FLOODING CONDITIONS. 

GALLINA

ATTN...WFO...CRP...EWX...SJT...

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

LAT...LON   31119886 30529764 29359814 28689869 27889969 
            28450075 29110092 30060045 30789945