Flood Potential Outlook
Issued by NWS Austin/San Antonio, TX
FGUS74 KEWX 201947
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
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
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.