763  
FXUS64 KEWX 231155 AAA  
AFDEWX  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX  
655 AM CDT SAT SEP 23 2017  
   
AVIATION
 
 
/12Z TAFS/  
CIGS ARE EXPECTED TO BE BETWEEN MVFR AND IFR CATEGORIES ALONG THE  
I-35 TERMINALS FOR THE NEXT SEVERAL HOURS BEFORE THEY LIFT TO VFR  
LATE THIS MORNING. PATCHY TO AREAS OF FOG HAVE DEVELOPED TO THE SOUTH  
AND EAST OF THE I-35 SITES THIS MORNING AND EXPECTED TO LIFT WITHIN  
THE NEXT COUPLE OF HOURS. WIND SHOULD STAY FROM THE SOUTHEAST AT 8 TO  
12 KNOTS WITH GUSTS UP TO 25 KNOTS ALONG THE RIO GRANDE. ISOLATED  
SHOWERS AND STORMS ARE EXPECTED EAST OF THE I-35 WITH NO IMPACT TO  
THE AREA TERMINALS.  
 

 
   
PREV DISCUSSION
 
/ISSUED 508 AM CDT SAT SEP 23 2017/  
 
SHORT TERM (TODAY THROUGH SUNDAY)...  
EARLY MORNING SURFACE OBSERVATIONS SHOW PLENTY OF LOW-LEVEL MOISTURE  
IN PLACE WITH DEWPOINT TEMPERATURES CURRENTLY IN THE UPPER 60S AND  
LOWER 70S FOR MOST AREAS. WINDS ARE ALSO FAIRLY LIGHT EAST OF I-35  
AND THIS HAS ALLOWED SOME PATCHY FOG TO DEVELOP. THE FOG WILL  
CONTINUE THROUGH MID-MORNING, THEN DISSIPATE QUICKLY AS DAYTIME  
HEATING AND MIXING COMMENCE. WE WILL LIKELY SEE A FEW SHOWERS EARLY  
THIS MORNING GIVEN PLENTY OF MOISTURE ALONG WITH THE PRESENCE OF A  
LOW-LEVEL JET. THE TEXAS TECH WRF AND HRRR MODELS ARE CONSISTENT IN  
SHOWING THE BETTER RAIN CHANCES THIS MORNING ALONG HIGHWAY 83. FOR  
THE AFTERNOON HOURS, LOOK FOR HIGH TEMPERATURES NEAR CLIMATOLOGICAL  
NORMALS ALONG WITH A LOW CHANCE FOR SHOWERS AND THUNDERSTORMS. ANY  
SHOWERS AND STORMS SHOULD DISSIPATE FAIRLY QUICKLY WITH THE LOSS OF  
DAYTIME HEATING. THE ONE EXCEPTION TO THIS COULD BE OUT WEST ALONG  
THE RIO GRANDE WHERE SOME CONVECTION ACROSS THE LOWER TRANS-PECOS MAY  
IMPACT WESTERN VAL VERDE COUNTY. THE WEATHER PATTERN WILL CHANGE  
LITTLE ON SUNDAY AND WE SHOULD SEE ANOTHER ROUND OF MAINLY ISOLATED  
AFTERNOON CONVECTION ACROSS THE REGION ALONG WITH NEAR NORMAL  
TEMPERATURES.  
 
LONG TERM (SUNDAY NIGHT THROUGH FRIDAY)...  
EARLY NEXT WEEK, A BROAD UPPER TROUGH WILL GRADUALLY APPROACH FROM  
THE WEST. AHEAD OF THIS TROUGH, WE WILL CONTINUE TO SEE A STRONG  
SOUTHEASTERLY FLOW IN THE LOW-LEVELS AND THIS WILL HELP MAINTAIN OR  
INCREASE MOISTURE LEVELS ACROSS THE REGION. IN THE MID AND UPPER  
LEVELS, WE WILL CONTINUE TO SEE AN INCREASINGLY ACTIVE SOUTHWEST  
FLOW AS AN UPPER TROUGH REMAINS TO OUR WEST. IN ADDITION, A COLD  
FRONT WILL MOVE IN EITHER LATE TUESDAY OR WEDNESDAY. THE GFS AND  
ECMWF ARE BEGINNING TO SHOW SOME AGREEMENT WITH REGARDS TO TIMING,  
WITH THE GFS TRENDING TOWARD THE FASTER ECMWF SOLUTION WITH THE  
FRONT. THE COLD FRONT IS EXPECTED TO SLOW IT'S SOUTHWARD PROGRESS OR  
PERHAPS EVEN STALL OVER THE REGION WEDNESDAY OR WEDNESDAY NIGHT.  
THIS PATTERN STILL REMAINS FAVORABLE FOR A HEAVY RAINFALL EVENT  
ACROSS PORTIONS OF SOUTH CENTRAL TEXAS. AT THIS TIME, IT APPEARS  
AREAS ALONG THE RIO GRANDE AND SOUTHERN EDWARDS PLATEAU WILL SEE THE  
HEAVIEST RAINFALL TOTALS LATE TUESDAY AND WEDNESDAY. HOWEVER, THE  
POTENTIAL FOR HEAVY RAINFALL COULD PERSIST WELL INTO THURSDAY. MODEL  
QPF AMOUNTS ARE QUITE IMPRESSIVE ALONG THE RIO GRANDE. WHILE THESE  
TOTALS ARE LIKELY TOO HIGH, AM STILL CONCERNED ABOUT THE HEAVY  
RAINFALL AND FLOODING THREAT ALONG THE RIO GRANDE AND SOUTHERN  
EDWARDS PLATEAU DURING THE MIDDLE OF THE UPCOMING WEEK. THE GFS  
ENSEMBLE PLUMES ALONG WITH MOS GUIDANCE NUMBERS CONTINUE TO SHOW  
GOOD CONFIDENCE FOR SOME HEAVY RAINFALL AND WE WILL CONTINUE TO  
MENTION THIS IN THE HAZARDOUS WEATHER OUTLOOK. FOR THE REMAINDER OF  
SOUTH CENTRAL TEXAS, WE DO EXPECT A DECENT CHANCE OF RAIN, BUT SHOULD  
SEE LESSER AMOUNTS AS THE MAIN SOURCE OF LIFT SHOULD REMAIN FOCUSED  
ALONG THE RIO GRANDE.  
 
SOME DRIER AIR IS EXPECTED TO MOVE IN BEHIND THE FRONT ON FRIDAY AND  
WE WILL SEE DECREASING RAIN CHANCES.  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
AUSTIN CAMP MABRY 91 73 90 73 89 / 20 - 20 10 20  
AUSTIN BERGSTROM INTL AIRPORT 91 72 90 72 89 / 20 - 20 10 20  
NEW BRAUNFELS MUNI AIRPORT 90 72 90 72 89 / 20 10 30 10 30  
BURNET MUNI AIRPORT 89 70 87 70 85 / 10 - 10 10 20  
DEL RIO INTL AIRPORT 93 75 91 74 89 / 20 20 30 50 50  
GEORGETOWN MUNI AIRPORT 91 71 90 71 88 / 10 - 10 10 20  
HONDO MUNI AIRPORT 94 73 94 73 93 / 20 10 30 10 30  
SAN MARCOS MUNI AIRPORT 91 72 91 72 89 / 20 10 30 10 20  
LA GRANGE - FAYETTE REGIONAL 91 72 91 72 90 / 20 - 20 10 20  
SAN ANTONIO INTL AIRPORT 90 74 89 74 88 / 20 20 30 10 30  
STINSON MUNI AIRPORT 89 74 89 74 89 / 20 10 30 10 30  
 

 
   
EWX WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  

 
 

 
 
MESOSCALE/AVIATION...17  
SYNOPTIC/GRIDS...24  
 
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