000 FGUS74 KBRO 131922 ESFBRO TXC047-061-215-247-261-427-489-505-132300- HYDROLOGIC OUTLOOK NATIONAL WEATHER SERVICE BROWNSVILLE TX 220 PM CDT FRI MAR 13 2009 ...SPRING FLOOD OUTLOOK FOR DEEP SOUTH TEXAS... THE POTENTIAL FOR FLOOD CONDITIONS WILL BE LOW THIS SPRING ACROSS THE HYDROLOGIC SERVICE AREA. ...EXISTING CONDITIONS... BELOW NORMAL RAINFALL AND ABOVE NORMAL TEMPERATURES PERSIST ACROSS DEEP SOUTH TEXAS. RAINFALL THE PAST 90 DAYS AVERAGED NEAR ONE INCH OR LESS. THE LAST SIGNIFICANT WIDESPREAD RAINFALL OVER THE REGION OCCURRED BACK IN AUGUST 2008. RAINFALL DEFICITS THE PAST 90 DAYS ARE 2 TO 3 INCHES BELOW NORMAL. ...SOIL MOISTURE CONDITIONS... DUE TO THE PROLONG WARM, DRY AND WINDY PERIODS, SOIL MOISTURE OVER DEEP SOUTH TEXAS IS ABNORMALLY DRY. ACCORDING TO THE UNITED STATES DEPARTMENT OF AGRICULTURAL...AND TEXAS AGRILIFE EXTENSION SERVICE AGENTS..."VERY SHORT SOIL MOISTURE, DRY AND WINDY CONDITIONS CONTINUED TO BE THE RULE OVER THE REGION. WINDY CONDITIONS ACCELERATE THE DRYING OUT OF TOP SOILS AND CROPS. THE LACK OF SIGNIFICANT RAINFALL HAS KEPT SOIL MOISTURE CONDITIONS CRITICAL. SPRING PLANTING WAS DELAYED EXCEPT WHERE PRODUCERS DECIDED TO INVEST ON PRE-PLANTING IRRIGATION. THE FORAGE SUPPLY FOR LIVESTOCK WAS DECLINING, WHILE SUPPLEMENTAL FEEDING INCREASED. SOME LIVESTOCK PRODUCERS LIQUIDATED THEIR HERDS, A PRACTICE LIKELY TO CONTINUE IF THE DROUGHT PERSISTS." CURRENT DAILY EVAPORATION RATES OVER THE LOWER RIO GRANDE VALLEY ARE AVERAGING A QUARTER TO HALF AN INCH. ...RIVER AND STREAMS... RIVER AND STREAMS LEVELS ARE BELOW NORMAL. INCREASED RIVER FLOWS HAVE NOT BEEN OBSERVED SINCE OCTOBER 2008. THIS WAS DUE TO RESERVOIR RELEASES FROM NEARBY MEXICAN RESERVOIRS. ...RESERVOIRS LEVELS... FALCON AND AMISTAD RESERVOIRS PROVIDE MUCH OF THE WATER FOR THE LOWER RIO GRANDE VALLEY. CURRENTLY...STORAGE AT AMISTAD AND FALCON RESERVOIRS REMAIN JUST ABOVE NORMAL CONSERVATIONS LEVELS. ACCORDING TO THE TEXAS COMMISSION ON ENVIRONMENTAL QUALITY (TCEQ), "THE LOWER RIO GRANDE VALLEY IS IN A UNIQUE SITUATION AT THIS POINT BECAUSE BOTH OF THE U.S. RESERVOIRS ARE CONSIDERED FULL AND SO ARE THE MAJORITY OF MEXICAN RESERVOIRS IN THE RIO GRANDE BASIN." HOWEVER, RESERVOIR LEVELS AT FALCON ARE EXPECTED TO BEGIN TO DECREASE DURING THE NEXT SEVERAL WEEKS AS IRRIGATION SEASON PEAKS OVER THE LOWER RIO GRANDE VALLEY. ...DROUGHT CONDITIONS... ACCORDING TO THE LATEST UNITED STATES DROUGHT MONITOR, DUE TO THE CURRENT RAINFALL DEFICITS OVER THE REGION, AND ABOVE NORMAL TEMPERATURES MODERATE DROUGHT CONDITIONS HAVE EXTENDED SOUTH TO ALONG THE MEXICAN BORDER. MODERATE CONDITIONS ARE NOW AFFECTING ZAPATA, JIM HOGG, BROOKS, KENEDY, WILLACY, CAMERON AND HIDALGO COUNTIES. ABNORMALLY DRY CONDITIONS PERSIST OVER STARR COUNTY. THE DROUGHT IS MAINLY AFFECTING AGRICULTURAL INTEREST, INCLUDING CROPS, PASTURES AND GRASSLANDS. ...METEOROLOGICAL OUTLOOK... MARCH IS THE DRIEST MONTH OF THE YEAR FOR AVERAGE RAINFALL. IT IS ALSO THE SECOND LOWEST MONTH FOR THE AVERAGE PROBABILITY OF PRECIPITATION. APRIL IS THE LOWEST MONTH FOR AVERAGE PROBABILITY OF PRECIPITATION AND MAY IS THE FOURTH LOWEST MONTH. IN THE SHORT TERM...AFTER THIS WEEKEND...RAIN CHANCES WILL DIMINISH EARLY NEXT WEEK UNTIL POSSIBLY MARCH 20TH/21ST WITH A WEAK COLD FRONT APPROACHING THE AREA. RAIN CHANCES MAY LINGER NEXT WEEKEND AS A RESULT. FOR THE PERIOD OF MARCH 18TH THROUGH THE 22ND...ABOVE NORMAL TEMPERATURES AND BELOW NORMAL PRECIPITATION IS EXPECTED. FOR THE PERIOD OF MARCH 20TH THROUGH THE 26TH...ABOVE NORMAL TEMPERATURES AND EQUAL CHANCES OF BELOW NORMAL PRECIPITATION/NORMAL PRECIPITATION/ABOVE NORMAL PRECIPATION IS EXPECTED. ...LONG TERM OUTLOOK... THE LONG RANGE CLIMATE OUTLOOK FOR THE REST OF MARCH...APRIL AND MAY OF 2009...DERIVED FROM GUIDANCE FROM THE NATIONAL WEATHER SERVICE AND THE CLIMATE PREDICTION CENTER...INDICATES THAT LA NINA CONDITIONS WILL GRADUALLY WEAKEN DURING THE SPRING OF 2009. AS A RESULT OF THE PERSISTENT LA NINA CONDITIONS...BELOW NORMAL PRECIPITATION AND ABOVE NORMAL TEMPERATURES WILL BE EXPECTED ACROSS DEEP SOUTH TEXAS THROUGH MAY OF 2009. THIS WILL LIKELY RESULT IN THE PERSISTENCE OR WORSENING OF THE OVERALL DROUGHT CONDITIONS ACROSS DEEP SOUTH TEXAS THROUGH THE SPRING OF 2009. HOWEVER...WITH LA NINA CONDITIONS GRADUALLY WEAKENING...TEMPERATURES AND PRECIPITATION MAY RETURN TO NORMAL TOWARDS THE END OF SPRING INTO EARLY SUMMER OF 2009. ...SPRING FLOOD OUTLOOK... DUE TO THE CURRENT MODERATE DROUGHT CONDITIONS OVER DEEP SOUTH TEXAS AND EXPECTED LA NINA CONDITIONS PRODUCING ABOVE NORMAL TEMPERATURES AND BELOW NORMAL PRECIPITATION, SPRING FLOOD POTENTIAL OVER THE AREA WILL BE LOW. ANY PRECIPITATION ACTIVITY THAT OCCURS THROUGHOUT THIS PERIOD WILL RESULT IN ONLY SHORT TERM RELIEF FROM THE CURRENT DROUGHT CONDITIONS. HOWEVER, ANY SIGNIFICANT HEAVY RAINFALL MAY PRODUCE MINOR FLOODING IN URBAN, POOR DRAINAGE OR LOW LYING AREAS. INFORMATION USED TO COMPILE THIS FLOOD POTENTIAL OUTLOOK WAS PROVIDED COURTESY OF THE WEST GULF RIVER FORECAST CENTER, CLIMATE PREDICTION CENTER, INTERNATIONAL BOUNDARY AND WATER COMMISSION (IBWC), USDA, TEXAS AGRILIFE EXTENSION SERVICE, UNITED STATES DROUGHT MONITOR, TEXAS COMMISSION ON ENVIRONMENTAL QUALITY (TCEQ). FOR MORE SPECIFIC HYDROMETEOROLOGICAL DATA...VISIT OUR INTERNET WEB SITE AT: WWW.SRH.NOAA.GOV/BRO $$ CASTILLO/VEGA