294  
AWUS01 KWNH 130226  
FFGMPD  
TXZ000-130825-  
 
MESOSCALE PRECIPITATION DISCUSSION 0665  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1025 PM EDT SAT JUL 12 2025  
 
AREAS AFFECTED...CENTRAL TEXAS  
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY  
 
VALID 130225Z - 130825Z  
 
SUMMARY...A SERIOUS RISK OF HIGH-IMPACT FLASH FLOODING FROM  
SLOW-MOVING, AND LOCALLY TRAINING SHOWERS AND THUNDERSTORMS WILL  
EXIST LATER TONIGHT ACROSS CENTRAL TX, INCLUDING PORTIONS OF THE  
EDWARDS PLATEAU/HILL COUNTRY.  
 
DISCUSSION...THE GOES-E PROXY VISIBLE SATELLITE IMAGERY SHOWS A  
SLOW-MOVING VORT CENTER GRADUALLY DRIFTING EAST ACROSS THE CONCHO  
VALLEY WHICH OVERNIGHT WILL EVENTUALLY ADVANCE INTO THE BROADER  
HILL COUNTRY REGION. BASED ON THE LATEST CIRA-ALPW DATA, THIS  
ENERGY IS EMBEDDED WITHIN A CONCENTRATED CORRIDOR OF DEEPER  
MOISTURE LIFTING UP ACROSS CENTRAL TX, WITH STRONG CONCENTRATIONS  
SEEN IN THE 850/500 MB LAYER WITH OVERALL VALUES OF 1.5 TO 1.75+  
INCHES.  
 
MEANWHILE, THE AIRMASS MORE BROADLY POOLED ACROSS THE HILL COUNTRY  
REGION IS QUITE UNSTABLE WITH MLCAPE VALUES OF 1500 TO 2500 J/KG.  
THIS INSTABILITY IS SEEN POOLING ALONG A WEAK SURFACE TROUGH OUT  
AHEAD OF A STATIONARY FRONT, AND THIS COUPLED WITH THE ARRIVAL OF  
THE AFOREMENTIONED VORT ENERGY ALONG WITH A GRADUALLY INCREASING  
SOUTHERLY LOW-LEVEL JET SHOULD HELP DRIVE DEVELOPING AREAS OF  
SHOWERS AND THUNDERSTORMS WITH HIGH RAINFALL RATES.  
 
A NOCTURNAL TIGHTENING OF THE MID-LEVEL VORT ENERGY ALONG WITH  
INCREASINGLY CONVERGENT FLOW ALONG ITS SOUTHERN AND EASTERN FLANKS  
NEAR THE SURFACE TROUGH WILL FAVOR CONVECTION GROWING GRADUALLY  
UPSCALE, BUT IN A VERY CONCENTRATED MANNER IN A SOUTHWEST TO  
NORTHEAST FASHION ACROSS CENTRAL TX. THIS REGION WILL ALSO BE IN  
THE RIGHT-ENTRANCE REGION OF AN UPPER-LEVEL JET TO FURTHER SUPPORT  
ASCENT FOR CONVECTION.  
 
RAINFALL RATES ARE EXPECTED TO BE ON THE ORDER OF 2 TO 4  
INCHES/HOUR WITH THE STRONGER STORMS, AND THE LATEST HRRR/RRFS  
GUIDANCE ALONG WITH SUPPORT FROM THE 18Z HREF AND 12Z REFS SUITES  
SUPPORT THESE RATES. AN EXCELLENT ENVIRONMENT WILL DEVELOP LATER  
TONIGHT FOR BACK-BUILDING AND TRAINING CONVECTION, WITH SLOW  
CELL-MOTIONS. FAVORABLE CORFIDI VECTORS WITH WEAK STEERING FLOW  
ARE EXPECTED TO ALIGN THAT WILL FACILITATE THIS CONVECTIVE  
EVOLUTION ESPECIALLY AFTER MIDNIGHT.  
 
SOME RAINFALL TOTALS BY 08Z (3AM CDT) MAY REACH AS HIGH AS 4 TO 6+  
INCHES, BUT WITH ADDITIONAL VERY HEAVY RAINFALL EXPECTED AFTER  
THIS TIME FRAME GOING THROUGH DAWN. A SERIOUS RISK OF HIGH-IMPACT  
FLASH FLOODING IS EXPECTED OVERNIGHT ACROSS THE SENSITIVE HILL  
COUNTRY REGION, WITH DANGEROUS AND LIFE-THREATENING FLASH FLOODING  
LIKELY BY LATER TONIGHT. ADDITIONAL MPDS WILL BE ISSUED  
ACCORDINGLY AS THIS EVENT UNFOLDS.  
 
ORRISON  
   
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
 
 
ATTN...WFO...EWX...FWD...MAF...SJT...  
 
ATTN...RFC...FWR...NWC...  
 
LAT...LON 32939718 32759622 32189589 31489612 30639713  
29949852 29579995 29690106 30260173 30930152  
31320091 31669989 32209880  
 
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