SPRING FLOOD OUTLOOK NATIONAL WEATHER SERVICE WEST GULF RIVER FORECAST CENTER, FORT WORTH, TX 3 PM CST THURSDAY MARCH 9, 2006
THE SPRING FLOOD POTENTIAL FOR THE WEST GULF RIVER FORECAST DRAINAGE AREA COVERING PORTIONS OF SOUTHERN COLORADO, NEW MEXICO, AND TEXAS, THAT FLOWS INTO THE GULF OF MEXICO, IS BELOW AVERAGE AVERAGE BASED UPON CURRENT ANTECEDENT FACTORS.
THE MAIN FACTOR IN DEVELOPMENT OF SIGNIFICANT RIVER FLOODING IN THIS REGION IS THE OCCURRENCE OF EXCESSIVE RAINFALL OVER RELATIVELY SHORT PERIODS OF TIME, EVEN WITH INITIAL NEAR DROUGHT CONDITIONS. THE ONLY PORTION OF THE AREA OF RESPONSIBILITY HAVING SIGNIFICANT WINTER SNOWPACK ACCUMULATION IS THE MOUNTAINOUS AREAS OF SOUTHERN COLORADO AND NEW MEXICO, BUT WEATHER REGIMES THAT PRODUCE RAPID MELT OF A LARGE PERCENTAGE OF THE SNOWPACK, OR HEAVY RAINS ON TOP OF THE SNOWPACK, ARE A LOW PROBABILITY.
THE GENERAL OUTLOOK FOR SPECIFIC BASIN AREAS IN THE REGION FOLLOW.
... RIO GRANDE BASIN, COLORADO AND NEW MEXICO
AFTER HAVING ABOVE AVERAGE PRECIPITATION AND MOUNTAIN SNOWPACK FOR THE 2005 WATER YEAR, THIS AREA HAS EXPERIENCED A REVERSAL TO DROUGHT WITH MUCH BELOW AVERAGE PRECIPITATION TOTALS AND MOUNTAIN SNOWPACK.
THE POTENTIAL FOR FLOODING FROM SPRINGTIME SNOWMELT IN THE UPPER RIO GRANDE BASIN IS VERY LOW. CURRENT MOUNTAIN SNOWPACK IS MUCH BELOW AVERAGE, WITH CURRENT DEPTHS BEING ABOUT 40 PERCENT OF AVERAGE IN THAT PORTION OF THE BASIN IN COLORADO, AND 23 PERCENT OF AVERAGE IN NEW MEXICO.
FORECAST SEASONAL VOLUME STREAMFLOW TOTALS ARE WELL BELOW AVERAGE, WITH CURRENT PREDICTIONS BEING ONLY 10 TO 60 PERCENT OF AVERAGE. CURRENT BASIN STREAMFLOWS ALONG THE MAINSTEM AND TRIBUTARIES ARE BELOW AVERAGE , AND RESERVOIR STORAGE IS ABOUT 72 PERCENT OF THE LONG TERM AVERAGE IN BASIN RESERVOIRS IN COLORADO, AND 53 PERCENT IN NEW MEXICO.
THE LATEST CLIMATE PREDICTION CENTER CROP DROUGHT SEVERITY INDICES INDICATE MODERATE TO SEVERE DROUGHT OVER FOR MOST OF THE BASIN AREA.
EXTENDED OUTLOOKS PROJECT ABOVE AVERAGE TEMPERATURES AND NEAR AVERAGE PRECIPITATION FOR THE NEXT 90 DAYS.
... WEST AND SOUTH TEXAS GENERALLY WEST OF A CHILDRESS TO SAN ANGELO LINE TO SAN ANTONIO TO CORPUS CHRISTI LINE, INCLUDING PORTIONS OF THE UPPER BRAZOS, UPPER COLORADO, NUECES, SAN ANTONIO, AND RIO GRANDE BASINS
THE POTENTIAL FOR SIGNIFICANT FLOODING OVER THESE BASINS IN TEXAS IS LOW AT THIS TIME.
MUCH BELOW AVERAGE PRECIPITATION HAS BEEN THE RULE IN THIS REGION FOR ALL OF THE CALENDAR YEAR 2005 AND THE EARLY MONTHS OF 2006. AT THE CURRENT TIME, STREAMFLOWS ARE NEAR BASEFLOW, AND MAJOR RESERVOIRS ARE BELOW TO WELL BELOW CONSERVATION LEVELS.
EXTENDED OUTLOOKS CALL FOR BELOW TO NEAR AVERAGE PRECIPITATION FOR THE NEXT 90 DAYS.
... THE EASTERN HALF OF TEXAS INCLUDING THE GUADALUPE, NECHES, SABINE, LOWER COLORADO, LOWER BRAZOS, SAN JACINTO, AND TRINITY RIVER BASINS.
THE POTENTIAL FOR SIGNIFICANT FLOODING OVER PORTIONS OF THESE BASINS IN TEXAS IS BELOW TO NEAR AVERAGE.
SOME AREAS OF CENTRAL THROUGH EASTERN TEXAS HAVE RECEIVED BENEFICIAL RAINFALL SINCE THE BEGINNING OF CALENDAR YEAR 2006, INTERRUPTING THE NEAR RECORD LOW PRECIPITATION TOTALS EXPERIENCED BY MUCH OF THE AREA FOR 2005. SOME HIGH RUNOFF AND CORRESPONDING STREAMFLOWS OCCURRED ALONG SOME SMALL AREAS OF THE TRINITY AND NECHES RIVER BASINS DURING LATE FEBRUARY, BUT THESE AREAS HAVE NOW RECEDED TO NEAR BASEFLOW LEVELS.
SOIL MOISTURE HAS INCREASED OVER PORTIONS OF THE TRINITY, NECHES, SABINE, AND BRAZOS BASINS, BUT DROUGHT INDICES REMAIN IN THE EXTREME TO SEVERE RANGE. FLOOD CONTROL RESERVOIRS IN THESE AREAS HAVE CURRENT WATER STORAGES BELOW CONSERVATION LEVELS.
CURRENT EXTENDED OUTLOOKS CALL BELOW AVERAGE PRECIPITATION FOR THE APRIL THROUGH JUNE PERIOD.
ALTHOUGH MOST ANTECEDENT CONDITIONS ARE CURRENTLY RELATIVELY LOW FOR THE GENERATION OF WIDESPREAD FLOODING, DEVELOPMENT AND SUSTAINMENT OF HEAVY RAINFALL DURING THE SPRING SEASON CAN REVERSE THE CURRENT CONDITIONS, AND PRODUCE LOCALIZED FLOODING RAPIDLY, PARTICULARLY IN URBAN AREAS.
END WGRFC/55