Flood Potential Outlook
Issued by NWS Corpus Christi, TX

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FGUS74 KCRP 052028
ESFCRP
TXC007-025-057-131-175-249-273-283-297-311-355-391-409-469-479-
072030-

HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE CORPUS CHRISTI TX
228 PM CST THU MAR 5 2015

...SPRING FLOOD OUTLOOK FOR SOUTH TEXAS...

...THE SPRING FLOOD POTENTIAL FOR THE RIO GRANDE BASIN...NUECES
RIVER BASIN AND FRIO RIVER BASIN IS BELOW AVERAGE...

...THE SPRING FLOOD POTENTIAL FOR THE GUADALUPE RIVER
BASIN...SAN ANTONIO RIVER BASIN AND THE COASTAL CREEKS IS ABOUT
AVERAGE...

FOR THE SPRING OF 2015...THE WEST GULF RIVER FORECAST CENTER IS
FORECASTING A BELOW AVERAGE POTENTIAL FOR SPRING FLOODING RIVERS
AND CREEKS IN THE FOLLOWING BASINS...NUECES RIVER...FRIO RIVER AND
THE RIO GRANDE. HOWEVER...A NEAR AVERAGE SPRING FLOOD POTENTIAL IS
FORECAST FOR THE LOWER GUADALUPE RIVER BASIN...THE LOWER SAN
ANTONIO RIVER BASIN...AND COASTAL RIVERS AND CREEKS.


EXISTING CONDITIONS...
SOIL MOISTURE...NEAR NORMAL SOIL MOISTURE CONDITIONS EXIST OVER
MOST OF SOUTH TEXAS...WITH SLIGHTLY BELOW NORMAL SOIL MOISTURE
OVER THE EXTREME NORTHERN PORTIONS OF THE VICTORIA AREA...COASTAL
BEND...BRUSH COUNTRY AND RIO GRANDE PLAINS. BELOW NORMAL SOIL
MOISTURE CONDITIONS ALSO EXIST IN THE UPPER PORTIONS OF THE
FRIO...RIO GRANDE AND NUECES RIVER BASINS NORTH OF SOUTH TEXAS.
RAINFALL DURING THE PAST 90 DAYS HAS KEPT NEAR SURFACE SOIL
MOISTURE AT NEAR TO SLIGHTLY BELOW NORMAL VALUES. HOWEVER...DEEPER
SOIL MOISTURE REMAINS BELOW NORMAL...DUE TO THE PERSISTENT
DROUGHT CONDITIONS OVER THE PAST FEW YEARS.

STREAMFLOW...MOST SOUTH TEXAS RIVERS AND CREEKS HAVE HAD BELOW TO
WELL BELOW NORMAL FLOWS DURING THE PAST FEW MONTHS. IN FACT...NO
RIVER FLOODING HAS BEEN OBSERVED IN SOUTH TEXAS SINCE JUNE 2014.
ALTHOUGH NEAR TO ABOVE NORMAL RAINFALL HAS OCCURRED DURING FROM
TIME TO TIME SINCE THE FALL OF 2014...MOST OF THE RAIN HAS BEEN
STRATIFORM IN NATURE. AS A RESULT...EXCESSIVE RAINFALL RESULTING
IN SIGNIFICANT RISES IN RIVERS AND CREEKS HAS NOT OCCURRED. MOST
RIVERS AND CREEKS IN THE NUECES RIVER...GUADALUPE RIVER...FRIO
RIVER...AND MISSION RIVER BASINS ARE RUNNING BELOW TO WELL BELOW
NORMAL. OTHER RIVERS AND CREEKS IN SOUTH TEXAS ARE RUNNING NEAR
TO SLIGHTLY BELOW NORMAL FOR THIS TIME OF YEAR.

CLIMATE REGIME...OVER THE PAST SEVERAL WEEKS...EQUATORIAL SEA
SURFACE TEMPERATURES (SSTS) HAVE BEEN ABOVE NORMAL OVER THE
WESTERN AND CENTRAL PACIFIC...BUT ARE NEAR TO SLIGHTLY BELOW
NORMAL OVER THE EASTERN PACIFIC. THIS HAS RESULTED IN NEAR EL-
NINO CONDITIONS OVER THE EQUATORIAL PACIFIC OVER THE PAST FEW
MONTHS. IN FACT...AN EL-NINO ADVISORY HAS JUST BEEN ISSUED. THE
CLIMATE PREDICTION CENTER NOW FORECASTS A 50 TO 60 PERCENT CHANCE
FOR EL-NINO CONDITIONS TO CONTINUE THROUGH THE NORTHERN
HEMISPHERIC SUMMER OF 2015. EL-NINO CONDITIONS WOULD MORE LIKELY
PRODUCE AN ABOVE NORMAL RAINFALL AND A BELOW NORMAL TEMPERATURE
WEATHER PATTERN TO SOUTH TEXAS AT LEAST THROUGH THE FIRST PART OF
SPRING.

RAINFALL...ACCORDING TO THE ADVANCED HYDROLOGIC PREDICTION
SERVICE (AHPS) 90 DAY RAINFALL ANALYSIS...RAINFALL HAS BEEN NEAR
TO SLIGHTLY ABOVE NORMAL OVER THE COASTAL AREAS OF SOUTH
TEXAS...BUT MAINLY BELOW NORMAL OVER INLAND AREAS OF SOUTH TEXAS.
OVER THE RIO GRANDE...FRIO RIVER...AND NUECES RIVER BASINS...MANY
AREAS HAVE RECEIVED NO MORE THAN 75 PERCENT OF THEIR NORMAL
RAINFALL IN THE PAST THREE MONTHS. ALTHOUGH THE SAN ANTONIO AND
GUADALUPE RIVER BASINS HAVE FARED SLIGHTLY BETTER...MOST AREAS IN
THESE RIVER BASINS HAVE RECEIVED BETWEEN 75 AND 90 PERCENT OF
THEIR NORMAL RAINFALL IN THE PAST 90 DAYS.

RESERVOIR CONSIDERATIONS...POOL LEVELS AT CHOKE CANYON DAM ARE
VERY LOW...WITH A POOL CAPACITY JUST ABOVE 24 PERCENT. LAKE
CORPUS CHRISTI IS NOT AS LOW...WITH ITS PERCENT CAPACITY NEAR 46
PERCENT. COLETO CREEK IS MORE THAN 4 FEET BELOW NORMAL POOL
LEVEL...WHILE LAKE TEXANA IS AROUND 84 PERCENT CAPACITY. FARTHER
NORTH...LAKE AMISTAD IS AROUND 52 PERCENT CAPACITY...WHILE CANYON
DAM IS 77 PERCENT OF NORMAL POOL ELEVATION. THUS...ALTHOUGH
WIDESPREAD HEAVY RAINFALL COULD POSE A CONCERN FOR FLOODING
UPSTREAM OF THESE RESERVOIRS...THERE IS PLENTY OF STORAGE
AVAILABLE DOWNSTREAM OF THESE DAMS...MAKING RIVER FLOODING LESS
LIKELY SOUTH AND EAST OF THE RESERVOIRS. FINALLY...BELOW NORMAL
RAINFALL OVER NEARLY ALL OF THE RIO GRANDE...FRIO AND NUECES RIVER
BASINS WILL MEAN THAT THERE WILL BE SOME CAPACITY FOR RAINFALL TO
PERCOLATE DEEPER IN THE SOIL UPSTREAM OF THE RESERVOIRS (SHOULD
HEAVY RAINFALL OCCUR). THIS WOULD DECREASE THE CHANCES FOR THE
RIVERS AND CREEKS IN THESE BASINS TO FLOOD.


METEOROLOGICAL OUTLOOK...
THE CLIMATE PREDICTION CENTER (CPC) HAS THE FOLLOWING FORECASTS FOR
SOUTH TEXAS. THE MARCH 2015 RAINFALL OUTLOOK CALLS FOR EQUAL
CHANCES FOR NEAR/ABOVE/BELOW NORMAL PRECIPITATION OVER ALL OF
SOUTH TEXAS. HOWEVER...THE THREE MONTH PRECIPITATION OUTLOOK FOR
THE PERIOD MARCH THROUGH MAY 2015 SHOWS A GREATER PROBABILITY FOR
ABOVE NORMAL RAINFALL OVER ALL OF SOUTH TEXAS. BOTH THE
AFOREMENTIONED MONTHLY AND THREE MONTH TEMPERATURE OUTLOOKS
PREDICT THAT BELOW NORMAL TEMPERATURES ARE LIKELY. FOR THE
REMAINDER OF THE SPRING...CPC FORECASTS EQUAL CHANCES FOR
ABOVE/BELOW/NEAR NORMAL RAINFALL DURING THE APRIL THROUGH JUNE
TIME FRAME.


...SPRING FLOOD OUTLOOK...
SINCE RAINFALL HAS BEEN BELOW NORMAL OVER MUCH OF THE MID AND
UPPER PORTIONS OF THE NUECES...FRIO AND RIO GRANDE RIVER BASINS
DURING THE LAST SEVERAL MONTHS...THE SPRING FLOOD POTENTIAL FOR
THE RIO GRANDE BASIN...NUECES RIVER BASIN AND FRIO RIVER BASIN
IS BELOW AVERAGE.

ON THE OTHER HAND...SINCE RAINFALL HAS BEEN CLOSER TO (BUT STILL
BELOW) NORMAL OVER THE LOWER GUADALUPE AND LOWER SAN ANTONIO RIVER
BASINS...AS WELL AS THE COASTAL RIVER AND CREEK LOCATIONS...AND
SINCE ABOVE NORMAL RAINFALL IS MORE LIKELY OVER THE AREA FROM
MARCH THROUGH MAY...THE SPRING FLOOD POTENTIAL FOR THE LOWER
GUADALUPE RIVER BASIN...THE LOWER SAN ANTONIO RIVER BASIN...AND
THE COASTAL RIVERS AND CREEKS IS ABOUT AVERAGE.

&&

REFERENCES/LINKS:
(USE ALL LOWER CASE)

FOR DETAILED INFORMATION CONCERNING RIVER STAGES AND FORECASTS
FOR SOUTH TEXAS...GO TO (ALL LOWER CASE):

HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?CRP

FOR THE WEST GULF RIVER FORECAST CENTER...GO TO (LOWER CASE):
WWW.SRH.NOAA.GOV/WGRFC

PRECIPITATION ANALYSIS:
WATER.WEATHER.GOV/PRECIP/

STREAMFLOW CONDITIONS:
WATERWATCH.USGS.GOV/

RESERVOIR SUMMARIES:
WATERFORTEXAS.ORG/RESERVOIRS/STATEWIDE

US DROUGHT MONITOR AND OUTLOOK:
DROUGHTMONITOR.UNL.EDU
CPC.NCEP.NOAA.GOV/

TX DROUGHT INFORMATION:
WATERDATAFORTEXAS.ORG/DROUGHT/
CLIMATEXAS.TAMU.EDU

CLIMATE GRAPHICS:
CPC.NCEP.NOAA.GOV
CPC.NCEP.NOAA.GOV/PRODUCTS/PREDICTIONS/

LOCAL WEATHER...RIVER...CLIMATE AND FORECAST INFORMATION FOR
SOUTH TEXAS:
WWW.WEATHER.GOV/CRP

ENSO CONDITIONS AND FORECASTS...RAINFALL OUTLOOKS...AND SOIL
MOISTURE CONDITIONS CAN BE FOUND ON THE CLIMATE PREDICTION CENTER
WEB PAGE:
HTTP://WWW.CPC.NCEP.NOAA.GOV

$$

GW





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