Extended Streamflow Guidance
Issued by NWS West Gulf RFC

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SPRING FLOOD OUTLOOK
NATIONAL WEATHER SERVICE
WEST GULF RIVER FORECAST CENTER, FORT WORTH, TX
1 PM CST WED FEBRUARY 18, 2015

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, IS BELOW AVERAGE
BASED UPON CURRENT ANTECEDENT CONDITIONS.  FOR THE SOUTHERN ROCKY
MOUNTAINS AND SANGRE DE CRISTOS SNOWMELT RUNOFF DRAINING INTO THE UPPER
RIO GRANDE AND PECOS RIVER BASINS, THE POTENTIAL FOR SPRING FLOODING
IS UNLIKELY AND NOT EXPECTED.

THIS OUTLOOK CONSIDERS ANTECEDENT RAINFALL, SNOWPACK, SOIL MOISTURE,
STREAMFLOW, AND WATERSUPPLY CONDITIONS COMPARED TO CLIMATOLOGY
COMBINED WITH LONGER-TERM 90-DAY FORECASTS FOR TEMPERATURES AND
PRECIPITATION ACROSS THE FORECAST AREA.

THE PRIMARY FACTOR IN DEVELOPMENT OF 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.  HOWEVER, THE MOUNTAINOUS AREA
IN THE NORTHWEST PORTION OF THE FORECAST AREA CAN BE AFFECTED BY
RAPID SNOWMELT, USUALLY OCCURRING IN THE SPRING MONTHS.  THESE
MOUNTAINOUS AREAS OF SOUTHERN COLORADO AND NORTHERN NEW MEXICO CAN
RECEIVE SIGNIFICANT WINTER SNOWPACK ACCUMULATION.  ALTHOUGH, NORMAL
WEATHER REGIMES PRODUCING RAPID SNOWMELT AND/OR HEAVY RAIN ON SNOW
EVENTS STATISTICALLY HAVE A LOW PROBABILITY IN THIS AREA.  HEAVY
SNOWPACK IS CURRENTLY NOT OBSERVED OR FORECAST WITHIN THE SOUTHERN
COLORADO AND NORTHERN NEW MEXICO MOUNTAINS.

THE GENERAL OUTLOOK FOR SPECIFIC BASIN AREAS IN THE REGION FOLLOW:

...UPPER RIO GRANDE AND PECOS BASIN, COLORADO AND NEW MEXICO

THE CURRENT GENERAL BASIN WIDE CONDITIONS WITHIN THE UPPER RIO GRANDE IN COLORADO
AND NEW MEXICO ARE TRACKING BELOW AVERAGE OVER THE PAST 60 DAY PERIOD. IN CONTRAST,
THE PECOS RIVER BASIN RECEIVED SOME UNUSUALLY HEAVY RAINFALL AMOUNTS BEFORE
THE END OF THE YEAR ALONG WITH ADDITIONAL EVENTS BOOSTING THE AVERAGES OVER THE BASIN
TO VALUES RANGING FROM 150-600% ABOVE AVERAGE OVER THE PAST 60 DAYS.

RECENT STORMS HAVE ALSO DROPPED MUCH NEEDED SNOW OVER THE MOUNTAINOUS REGIONS
THROUGHOUT SOUTH CENTRAL COLORADO AND NORTHERN NEW MEXICO BUT NOT ENOUGH TO
SIGNIFICANTLY INCREASE SEASONAL FORECAST STREAMFLOWS, NOR INCREASE THE POTENTIAL
FOR SPRING FLOODING.

LOOKING AT SNOWPACK, THE UPPER RIO GRANDE BASIN IN COLORADO IS CURRENTLY 65-80 PERCENT
OF NORMAL FOR SNOW WATER EQUIVALENT BASIN-WIDE WITH LOCALIZED ABOVE AND BELOW OUTLIERS.
ACROSS NEW MEXICO IN THE RIO GRANDE AND PECOS BASINS, SNOW WATER EQUIVALENTS RANGE FROM
60-80% PERCENT OF NORMAL.

HISTORICALLY, MOUNTAINOUS SNOWPACK, PARTICULARLY IN THE HIGHER ELEVATIONS,
INCREASES INTO APRIL WITH ADDITIONAL STORMS.  THE TIMING ON STORMS IN THE REGION
IS TRACKING NEAR NORMAL BUT THE MAGNITUDE HAS BEEN BELOW NORMAL AMOUNTS.
AS A RESULT, PEAK SNOWPACKS ARE EXPECTED TO CONTINUE BELOW NORMAL LEVELS WITH MELT
OCCURRING EARLIER THAN NORMAL IN THE SEASON.  DUE TO LOWER SNOWPACK ACCUMULATIONS AND SOME
MELT BETWEEN BETWEEN STORMS, BELOW AVERAGE STREAMFLOW IS EXPECTED THIS SPRING AND
THROUGHOUT THE SEASONAL RUNOFF PERIOD.
THE POTENTIAL FOR SIGNIFICANT FLOODING FROM SPRINGTIME SNOWMELT IN THE UPPER
RIO GRANDE AND PECOS RIVER BASINS IS SIGNIFICANTLY REDUCED FOR THE MAINSTEM
AND ASSOCIATED TRIBUTARIES.  CURRENT BASIN STREAMFLOWS ALONG THE MAINSTEM AND
TRIBUTARIES ARE BELOW NORMAL IN COLORADO AND NEW MEXICO. AS OF THE END OF JANUARY,
RESERVOIR STORAGE IS CURRENTLY LOW.

THE U.S. DROUGHT MONITOR INDICATES ABNORMALLY DRY TO MODERATE DROUGHT CONDITIONS
FOR THE UPPER RIO GRANDE BASIN IN COLORADO AND NEW MEXICO EXTENDING TO
SEVERE DROUGHT CONDITIONS ACROSS THE UPPER PECOS BASIN.  THE 60 DAY U.S. SEASONAL
DROUGHT OUTLOOK INDICATES PERSISTENCE OR SLIGHT IMPROVEMENT OF DROUGHT CONDITIONS IN
THE ENTIRE RIO GRANDE BASIN IN COLORADO AND NEW MEXICO.

EXTENDED CLIMATE OUTLOOKS CALL FOR EQUAL CHANCES OF ABOVE, BELOW, OR NEAR
NORMAL TEMPERATURES AND A 40 PERCENT CHANCE OF ABOVE AVERAGE PRECIPITATION
FOR THE NEXT 90 DAYS.  THESE CONDITIONS MAY RESULT IN MITIGATING EARLY
SNOWMELT BUT BELOW AVERAGE WATER SUPPLY, AND LOW CHANCES OF SPRING TIME
FLOODING STILL RESULT IN LOW CHANCES OF SPRING FLOODING.


REFERENCES/LINKS:

PRECIPITATION ANALYSIS:
HTTP://WATER.WEATHER.GOV/PRECIP/

SNOWPACK CONDITIONS:
HTTP://WWW.WCC.NRCS.USDA.GOV/REPORTS/SELECTUPDATEREPORT.HTML
FTP://FTP.WCC.NRCS.USDA.GOV/DATA/WATER/WCS/GIS/MAPS/WEST_SWEPCTNORMAL_UPDATE.PDF
FTP://FTP.WCC.NRCS.USDA.GOV/DATA/WATER/WCS/GIS/MAPS/WESTWIDESWEPERCENT.PDF

STREAMFLOW CONDITIONS:
HTTP://WATERDATA.USGS.GOV/NWIS/RT
HTTP://WWW.DWR.STATE.CO.US/SURFACEWATER/DEFAULT.ASPX

RESERVOIR SUMMARIES:
HTTP://WWW.WCC.NRCS.USDA.GOV/BASIN.HTML
HTTP://WWW.WATERDATAFORTEXAS.ORG/RESERVOIRS/STATEWIDE

SOIL MOISTURE CONDITIONS:
HTTP://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/SOILMST_MONITORING/US/SOILMST/SOILMST.SHTML

US DROUGHT MONITOR AND OUTLOOK:
HTTP://DROUGHTMONITOR.UNL.EDU/
HTTP://WWW.CPC.NOAA.GOV/PRODUCTS/EXPERT_ASSESSMENT/SEASON_DROUGHT.GIF

TX DROUGHT INFORMATION:
HTTP://WATERDATAFORTEXAS.ORG/DROUGHT/

CLIMATE GRAPHICS:
HTTP://WWW.CPC.NOAA.GOV/
HTTP://WWW.CPC.NOAA.GOV/PRODUCTS/PREDICTIONS/LONG_RANGE/LEAD01/OFF01_TEMP.GIF
HTTP://WWW.CPC.NOAA.GOV/PRODUCTS/PREDICTIONS/LONG_RANGE/LEAD01/OFF01_PRCP.GIF

WGRFC



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