809  
FGUS74 KEWX 201947  
ESFEWX  
211347-  
PROBABILISTIC HYDROLOGIC OUTLOOK  
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX  
247 PM CDT THU APR 20 2017  
 
...ADVANCED HYDROLOGIC PREDICTION SERVICE (AHPS) LONG RANGE  
PROBABILISTIC OUTLOOK FOR THE BRAZOS RIVER BASIN IN SOUTH  
CENTRAL TEXAS...  
 
THE AUSTIN/SAN ANTONIO TEXAS NATIONAL WEATHER SERVICE OFFICE  
HAS IMPLEMENTED ADVANCED HYDROLOGIC PREDICTION SERVICE  
(AHPS) FOR THE BRAZOS RIVER BASIN IN SOUTH CENTRAL TEXAS.  
AHPS ENABLES THE NATIONAL WEATHER SERVICE TO PROVIDE LONG-RANGE  
PROBABILISTIC OUTLOOKS. THIS SERVICE IS ALSO AVAILABLE ON THE  
INTERNET.  
 
IN THE TABLE BELOW, THE 90 THROUGH 10 PERCENT COLUMNS INDICATE  
THE CHANCE THE RIVER COULD RISE ABOVE THE LISTED STAGE LEVELS  
IN THE NEXT 90 DAYS. EXAMPLE: THE SOUTH FORK SAN GABRIEL RIVER  
AT GEORGETOWN HAS A FLOOD STAGE OF 9 FEET. THERE IS A 50 PERCENT  
CHANCE THE GEORGETOWN FORECAST POINT WILL RISE ABOVE  
4.7 FEET DURING THE NEXT 90 DAYS.  
 
CHANCE OF EXCEEDING STAGES AT SPECIFIC LOCATIONS  
VALID 4/20/2017 - 7/18/2017  
 
LOCATION FS(FT) 90% 80% 70% 60% 50% 40% 30% 20% 10%  
-------- ------ --- --- --- --- --- --- --- --- ---  
SOUTH FORK SAN GABRIEL RIVER  
GEORGETOWN 9.0 3.0 3.6 4.0 4.3 4.7 4.9 5.2 5.4 8.9  
 
THIS LONG-RANGE PROBABILISTIC OUTLOOK CONTAINS NUMBERS THAT ARE  
CALCULATED USING MULTIPLE SCENARIOS FROM 50 YEARS OF HISTORICAL  
CLIMATOLOGICAL AND STREAM FLOW DATA. THESE NUMBERS ALSO TAKE  
INTO ACCOUNT CURRENT CONDITIONS OF THE RIVER AND SOIL MOISTURE.  
BY PROVIDING THE CURRENT RANGE OF PROBABILISTIC NUMBERS...THE  
LEVEL OF RISK ASSOCIATED WITH THE LONG-RANGE PLANNING DECISIONS  
CAN BE DETERMINED.  
 
ADDITIONAL SUPPORTIVE DATA AND EXPLANATION ARE AVAILABLE ON THE  
INTERNET AT: HTTP://WATER.WEATHER.GOV/AHPS2/LONG_RANGE.PHP?WFO=EWX  
 
LONG-RANGE PROBABILISTIC OUTLOOKS ARE ISSUED AROUND THE THIRD  
THURSDAY OF EVERY MONTH.  
 

 
 
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