FGUS64 KFWR 101653 ESGFWR PROBABILISTIC HYDROLOGIC OUTLOOK NATIONAL WEATHER SERVICE WEST GULF RIVER FORECAST CENTER, FORT WORTH, TX 11 AM CST WED MAR 10 2021 ...SPRING FLOOD POTENTIAL OUTLOOK.... ...FLOOD RISK IS BELOW AVERAGE FOR WEST TEXAS, COLORADO AND NEW MEXICO.... ...FLOOD RISK IS NEAR AVERAGE FOR NORTH AND EAST TEXAS... THE SPRING FLOOD POTENTIAL FOR THE WEST GULF RIVER FORECAST CENTER DRAINAGE AREA COVERING PORTIONS OF SOUTHERN COLORADO, NEW MEXICO, AND TEXAS THAT FLOWS INTO THE GULF OF MEXICO VARIES QUITE A BIT BASED UPON CURRENT ANTECEDENT CONDITIONS. FOR THE SOUTHERN ROCKY MOUNTAINS, WHICH INCLUDES THE SAN JUANS AND SANGRE DE CRISTOS THAT DRAIN INTO THE UPPER RIO GRANDE AND PECOS RIVER BASINS, SPRING FLOODING DRIVEN BY SNOW MELT RUNOFF IS NOT EXPECTED WITH THE CURRENT BELOW AVERAGE SNOWPACK CONDITIONS. AT THE LOWER ELEVATIONS, THE SNOWPACK HAS ALREADY STARTED THE MELT-OUT PROCESS. THIS OUTLOOK CONSIDERS ANTECEDENT RAINFALL, SNOWPACK, SOIL MOISTURE CONDITIONS, CURRENT STREAMFLOW, AND WATER SUPPLY CONDITIONS COMPARED TO CLIMATOLOGY COMBINED WITH LONGER-TERM 90-DAY CLIMATE OUTLOOK FORECASTS FOR TEMPERATURES AND PRECIPITATION ACROSS THE FORECAST AREA. OVERVIEW THE PRIMARY FACTOR TO CONSIDER FOR SIGNIFICANT RIVER FLOODING OVER MOST OF THE REGION IS THE OCCURRENCE OF EXCESSIVE RAINFALL IN RELATIVELY SHORT PERIODS OF TIME, EVEN FOR AREAS WHERE DROUGHT CONDITIONS PERSIST OR HAVE DEVELOPED. IN ADDITION, THE MOUNTAINOUS AREAS IN THE NORTHWEST PORTIONS OF THE WGRFC FORECAST AREA CAN BE AFFECTED BY TIMING OF SNOW MELT OCCURRING AS EARLY AS MID-MARCH THROUGH THE APRIL TIME FRAME. THESE MOUNTAINOUS AREAS OF SOUTHERN COLORADO AND NORTHERN NEW MEXICO CAN ACCUMULATE A SIGNIFICANT WINTER SNOWPACK. THE MOST SIGNIFICANT FACTORS FOR SPRING FLOODING IN MOUNTAINOUS TERRAIN ARE THE AMOUNT OF WATER IN THE SNOWPACK AND THE TIMING OF THE MELT, WHICH CAN BE COMBINED WITH PERIODS OF RUNOFF FROM HEAVY RAINFALL. HOWEVER, NORMAL WEATHER REGIMES PRODUCING RAPID SNOW MELT AND/OR HEAVY RAIN-ON-SNOW EVENTS HAVE A STATISTICALLY LOW PROBABILITY OF OCCURRENCE IN THIS AREA EVEN DURING EL NIÑO OR LA NIÑA DRIVEN WEATHER PATTERNS. CURRENT MAJOR POINTS - LA NIÑA CONDITIONS ARE EXPECTED TO PERSIST THIS SNOW-MELT SEASON - AFTER SPRING THE OUTLOOK FOR A LA NIÑA IS A BIT MORE UNCERTAIN - ABNORMALLY WARM TEMPERATURES AND DRY CONDITIONS ARE ANTICIPATED FOR THE NEXT FEW MONTHS. THE GENERAL OUTLOOK FOR SPECIFIC BASIN AREAS IN THE REGION FOLLOW: ...UPPER RIO GRANDE AND PECOS BASIN, COLORADO AND NEW MEXICO THE INFORMATION BELOW REFLECTS CONDITIONS THROUGH EARLY MARCH. CONDITIONS ACROSS THE AREA HAVE NEAR TO BELOW NORMAL SNOWPACK. THE 90 DAY CLIMATE OUTLOOK INDICATES A TREND TOWARD ABOVE NORMAL TEMPERATURES AND BELOW NORMAL PRECIPITATION WHICH MAY ACCELERATE MELT-OUT THIS SEASON WITH EARLIER, BELOW NORMAL PEAK FLOWS. REGIONALLY, SNOWPACK SNOW WATER EQUIVALENT (SWE) CONDITIONS WITHIN THE UPPER RIO GRANDE AND PECOS IN COLORADO AND NEW MEXICO ARE TRACKING NEAR/BELOW THE 30-YEAR MEDIAN. PRECIPITATION RECEIVED FOR THE WATER-YEAR-TO-DATE IS BELOW NORMAL. CURRENT OBSERVED BASIN STREAMFLOWS ALONG THE MAINSTEM AND TRIBUTARIES WITHOUT ICE IMPAIRMENT ARE BELOW NORMAL. RESERVOIR CONDITIONS ARE BELOW NORMAL IN NEW MEXICO. THE ELEPHANT BUTTE RESERVOIR IS AT 9.5% OF STORAGE WITH A DECREASE OF 20% FROM LOW 2020 RUNOFF AMOUNTS. RED BLUFF RESERVOIR ON THE PECOS IS AT 50.2% OF ITS STORAGE - A DROP OF 17% FROM LAST YEAR. HISTORICALLY, MOUNTAINOUS SNOWPACK, PARTICULARLY IN THE HIGHER ELEVATIONS, INCREASES INTO APRIL WITH ADDITIONAL STORMS, BUT RECENT TRENDS INDICATE THE TIMING OF PEAK ACCUMULATIONS AND MELT-OUT ARE OCCURRING WEEKS EARLIER. EARLIER MELT-OUT MAY ALSO BE ATTRIBUTED IN PART TO DUST-ON-SNOW EVENTS COMING FROM AN INCREASING NUMBER OF BURN SCAR AREAS. AS STATED ABOVE THE CLIMATE PREDICTION CENTER 90-DAY EXTENDED CLIMATE OUTLOOKS INDICATE AN ABOVE NORMAL CHANCE FOR ABOVE NORMAL TEMPERATURES AND BELOW NORMAL PRECIPITATION. THE U.S. DROUGHT MONITOR HAS 50% SEVERE DROUGHT CONDITIONS OR WORSE CURRENTLY DESIGNATED FOR THE UPPER RIO GRANDE AND PECOS BASINS IN COLORADO AND NEW MEXICO. THIS IS A CONSIDERABLE DEGRADATION FROM 32% A YEAR AGO. THE U.S. SEASONAL DROUGHT OUTLOOK INDICATES THAT THE SEVERE DROUGHT CONDITIONS WILL REMAIN OVER NORTHERN NEW MEXICO AND SOUTHERN COLORADO, THE WEAK 2020 MONSOON SEASON LEFT SOIL MOISTURE WELL BELOW NORMAL. ...WEST AND SOUTH TEXAS GENERALLY WEST OF WICHITA FALLS TO SAN ANTONIO TO BROWNSVILLE LINE, INCLUDING PORTIONS OF THE UPPER BRAZOS, UPPER COLORADO, UPPER GUADALUPE, NUECES, SAN ANTONIO AND LOWER RIO GRANDE BASINS THE POTENTIAL FOR SIGNIFICANT SPRING FLOODING OVER THESE BASIN AREAS IN TEXAS IS BELOW AVERAGE THIS YEAR. IN THE PAST 60 DAYS, MOST OF THESE BASINS HAVE RECEIVED BELOW AVERAGE RAINFALL RANGING AROUND 25-50% PERCENT OF NORMAL. CURRENT BASIN STREAMFLOWS ARE NEAR TO BELOW AVERAGE SEASONAL BASEFLOW BASED ON THE LATEST USGS STREAMFLOW INDEX. RESERVOIR STORAGE IN THE REGION IS NEAR NORMAL. SEVERE OR WORSE DROUGHT CONDITIONS EXIST IN SOUTH TEXAS. THE U.S. SEASONAL DROUGHT OUTLOOK FOR THE NEXT 90 DAYS INDICATES PERSISTENCE FOR MOST OF THE REGION. EXTENDED 90-DAY CLIMATE OUTLOOKS INDICATE 40 PERCENT OR HIGHER CHANCES OF BELOW AVERAGE PRECIPITATION OVER WEST TEXAS, WITH EQUAL CHANCES OF BELOW, NEAR OR ABOVE NORMAL RAINFALL OVER CENTRAL AND EAST TEXAS. THERE IS AN ABOVE NORMAL CHANCE OF ABOVE AVERAGE TEMPERATURES. THE POTENTIAL FOR SPRING FLOODING IS EXPECTED TO BE BELOW AVERAGE OVER THE NEXT 90 DAYS. ...THE EASTERN PORTIONS OF TEXAS INCLUDING THE NECHES, SABINE, TRINITY, LOWER BRAZOS, LOWER COLORADO, LOWER GUADALUPE, AND SAN JACINTO RIVER BASINS. POTENTIAL FOR SPRING FLOODING IN THIS AREA IS NEAR NORMAL AT THIS TIME WITH HIGHER POTENTIALS ACROSS THE BASINS OVER THE NORTHERN HALF OF TEXAS. MOST OF THE RIVER BASINS IN THIS REGION HAVE RECEIVED BELOW AVERAGE RAINFALL FOR THIS TIME OF YEAR, MOST AREA RESERVOIRS ARE NEAR CONSERVATION LEVELS. THE U.S. DROUGHT MONITOR INDICATES ABNORMAL TO MODERATE DROUGHT CONDITIONS OVER NORTHERN TEXAS. ...TEXAS STATEWIDE RESERVOIR CONDITIONS AT THE END OF FEBRUARY, TOTAL STORAGE IN 114 OF THE STATE'S MAJOR WATER SUPPLY RESERVOIRS WAS 82% OF TOTAL CONSERVATION STORAGE CAPACITY. THE PERCENT FULL IS BASED ON CONSERVATION STORAGE AND CONSERVATION CAPACITY AND DOESN'T ACCOUNT FOR STORAGE IN FLOOD POOL. MORE DETAILS ARE AVAILABLE UNDER THE RESERVOIR SUMMARIES LISTED IN THE REFERENCES AND LINKS SECTION SHOWN BELOW. --------------------------------------- REFERENCES/LINKS: YOU MAY NEED TO USE LOWER CASE IN SOME LINKS PRECIPITATION ANALYSIS: HTTPS://WATER.WEATHER.GOV/PRECIP/ WATERSUPPLY CONDITIONS: HTTPS://WWW.CBRFC.NOAA.GOV/WSUP/GRAPH/WEST/MAP/ESP_MAP.HTML STREAMFLOW CONDITIONS: HTTPS://WATERDATA.USGS.GOV/NWIS/RT RESERVOIR SUMMARIES: HTTPS://WWW.WCC.NRCS.USDA.GOV/WSF/WSF-RESERVOIR.HTML HTTPS://WATERDATAFORTEXAS.ORG/RESERVOIRS/STATEWIDE SOIL MOISTURE CONDITIONS: HTTPS://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/SOILMST_MONITORING/US/SOILMST/ SOILMST.SHTML US DROUGHT MONITOR AND OUTLOOK: HTTPS://DROUGHTMONITOR.UNL.EDU/ TX DROUGHT INFORMATION: HTTPS://WATERDATAFORTEXAS.ORG/DROUGHT/ CLIMATE GRAPHICS: HTTPS://WWW.CPC.NCEP.NOAA.GOV/ HTTPS://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/PREDICTIONS/LONG_RANGE/LEAD01/ OFF01_TEMP.GIF HTTPS://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/PREDICTIONS/LONG_RANGE/LEAD01/ OFF01_PRCP.GIF WGRFC - CAZIER