National Weather Service Text Product Display

Flood Potential Outlook
Issued by NWS Boise, ID
Versions: 1 2
000
FGUS75 KBOI 211821
ESFBOI

210600-

WATER SUPPLY OUTLOOK
NATIONAL WEATHER SERVICE
1220 PM MDT TUE MAY 21 2013

...IDAHO WATER SUPPLY AND SPRING FLOOD OUTLOOK AS OF MAY 2013...

...NEAR NORMAL TO BELOW NORMAL RUNOFF VOLUMES ACROSS IDAHO...
...SPRING FLOOD RISK FOR NORTHERN IDAHO IS NEAR AVERAGE...
...SPRING FLOOD RISK FOR SOUTHERN IDAHO IS BELOW AVERAGE...

THE NATIONAL WEATHER SERVICE WATER SUPPLY OUTLOOK FOR IDAHO FOR THE
2013 WATER YEAR PROJECTS NEAR NORMAL TO BELOW NORMAL RUNOFF VOLUMES
ACROSS THE STATE AS OF MAY 21. WATER SUPPLY PROJECTIONS ARE MOST
FAVORABLE FOR THE NORTHERN PORTION OF THE STATE...AND BECOME
PROGRESSIVELY LESS FAVORABLE ACROSS CENTRAL AND SOUTHERN IDAHO.

AFTER A REASONABLY GOOD START TO THE 2013 WATER YEAR...CONSECUTIVE
MONTHS OF WELL BELOW NORMAL PRECIPITATION HAVE OCCURRED ACROSS
CENTRAL AND SOUTHERN IDAHO SINCE JANUARY...RESULTING IN ABNORMALLY
DRY CONDITIONS ACROSS CENTRAL AND SOUTHERN IDAHO...WITH POCKETS OF
MODERATE DROUGHT ACROSS THE SOUTH. THE STORM TRACK HAS BEEN A LITTLE
MORE FAVORABLE FOR NORTHERN IDAHO THIS SPRING...RESULTING IN AREAS
OF NORMAL TO ABOVE NORMAL PRECIPITATION IN APRIL...BUT IT HAS BEEN
QUITE DRY IN MAY. TEMPERATURES OVER THE PAST 30 DAYS HAVE GENERALLY
BEEN ABOVE NORMAL FOR THE WEST CENTRAL AND PANHANDLE REGIONS OF
IDAHO...AND NEAR NORMAL ELSEWHERE.

THE SEASONAL TRANSITION TO WARMER WEATHER BROUGHT INCREASED SNOWMELT
ALONG WITH HIGHER FLOWS TO MANY IDAHO RIVERS AND STREAM IN LATE
APRIL AND MAY. HOWEVER...SOME BASINS ACROSS SOUTHERN IDAHO WHERE
WINTER SNOWPACK WAS THE POOREST...HAVE ALREADY EXPERIENCED THEIR
SNOWMELT PEAK FLOWS...AND HAVE EITHER ALREADY MELTED OUT...OR ARE ON
PACE TO MELT OUT SEVERAL WEEKS AHEAD OF NORMAL.

THE SPRING FLOOD THREAT FOR SOUTHERN IDAHO IS BELOW AVERAGE DUE TO
THE POOR SNOWPACK AND EARLY MELT. BETTER SNOW CONDITIONS ACROSS
NORTHERN IDAHO SUPPORT ABOUT AVERAGE SPRING FLOOD THREAT...ALTHOUGH
LARGELY DEPENDENT ON SPRING RAINS.

AS HIGH ELEVATION SNOWMELT CONTINUES OVER THE NEXT MONTH...REMEMBER
THAT IT IS NOT ALWAYS POSSIBLE TO FORECAST SPECIFIC RAIN STORMS...OR
RAIN AND SNOWMELT EVENTS MORE THAN 4 TO 7 DAYS INTO THE FUTURE.
THEREFORE...SHORT RANGE RIVER FORECASTS SHOULD BE MONITORED CLOSELY
IF A RAIN EVENT OCCURS. DETAILS REGARDING POSSIBLE OR RESULTING
FLOODING WILL BE AVAILABLE IN SHORT TERM OUTLOOKS...FLOOD WATCHES
AND FLOOD WARNINGS ISSUED BY THE NATIONAL WEATHER SERVICE.

REFER TO SECTIONS BELOW AND LINKS PROVIDED FOR THE LATEST DETAILS
REGARDING WATER SUPPLY FORECASTS FOR SPECIFIC LOCATIONS...
SNOWPACK...PRECIPITATION...RESERVOIR CONDITIONS...DROUGHT...AND
LONG TERM WEATHER OUTLOOKS.


WATER SUPPLY FORECASTS...

WATER SUPPLY FORECASTS ISSUED BY THE NORTHWEST RIVER FORECAST CENTER
AND THE COLORADO BASIN RIVER FORECAST CENTER ARE ISSUED
FREQUENTLY...ON EITHER A WEEKLY OR DAILY BASIS.

FOR THE LATEST WATER SUPPLY FORECASTS FOR IDAHO PLEASE REFER TO THE
FOLLOWING WEB SITES.

NATIONAL WEATHER SERVICE-NORTHWEST RIVER FORECAST CENTER
WWW.NWRFC.NOAA.GOV/WS

NATIONAL WEATHER SERVICE-COLORADO BASIN RIVER FORECAST CENTER
WWW.CBRFC.NOAA.GOV/GMAP/CMAP2.PHP?CON=WSUP

USDA-NATURAL RESOURCES CONSERVATION SERVICE
WWW.ID.NRCS.USDA.GOV/SNOW/WATERSUPPLY


SNOWPACK INFORMATION...

ACCORDING TO NRCS SNOTEL DATA...AS OF MAY 21...FROM THE CLEARWATER
BASIN TO THE CANADIAN BORDER SNOWPACK PERCENTAGES WERE 73 TO 84
PERCENT OF NORMAL. TO THE SOUTH...SEVERAL SUB BASINS IN THE UPPER
SNAKE REGION WERE NEAR 55 PERCENT OF NORMAL. FOR THE REST OF
SOUTHERN IDAHO...INCLUDING THE SALMON BASIN...SNOWPACK WAS GENERALLY
LESS THAN 45 PERCENT OF NORMAL WITH SOME BASINS ALREADY MELTED OUT.

CURRENT DAY SNOW WATER EQUIVALENT AND PERCENT OF NORMAL SNOWPACK
INFORMATION CAN BE FOUND AT THE FOLLOWING WEB SITES.

NATIONAL WEATHER SERVICE-NORTHWEST RIVER FORECAST CENTER
WWW.NWRFC.NOAA.GOV/SNOW

NATIONAL WEATHER SERVICE-COLORADO BASIN RIVER FORECAST CENTER
WWW.CBRFC.NOAA.GOV/GMAP/CMAP2.PHP?CON=SNOW

NATIONAL WEATHER SERVICE-NATIONAL HYDROLOGIC REMOTE SENSING CENTER
WWW.NOHRSC.NWS.GOV

USDA-NATURAL RESOURCES CONSERVATION SERVICE
WWW.ID.NRCS.USDA.GOV/SNOW/DATA/CURRENT.HTML


RESERVOIR INFORMATION...

MOST RESERVOIRS IN IDAHO WERE HOLDING NEAR AVERAGE STORAGE AT THE
BEGINNING OF MAY. THERE WERE SOME EXCEPTIONS ACROSS SOUTHERN
IDAHO...WHERE RESERVOIR STORAGE WAS ONLY 45 TO 70 PERCENT OF AVERAGE.

THE LATEST RESERVOIR STORAGE INFORMATION CAN BE FOUND AT THE
FOLLOWING WEB SITES

BUREAU OF RECLAMATION RESERVOIR STORAGE
WWW.USBR.GOV/PN/HYDROMET/SELECT.HTML

USDA-NATURAL RESOURCES CONSERVATION SERVICE
WWW.WCC.NRCS.USDA.GOV/CGIBIN/RESV-GRAPH.PL?STATE=ID


DROUGHT CONDITIONS...

ACCORDING TO THE U.S. DROUGHT MONITOR...AS OF MAY 21...ABNORMALLY
DRY CONDITIONS EXISTED ACROSS MOST OF CENTRAL AND SOUTHERN
IDAHO...WITH AREAS OF MODERATE DROUGHT CONDITIONS ACROSS SOUTHEAST
IDAHO...AND THE TREASURE VALLEY AND OWYHEE MOUNTAINS IN SOUTHWEST
IDAHO. THE IDAHO DEPARTMENT OF WATER RESOURCES POSTED DROUGHT
DECLARATIONS FOR FOUR COUNTIES IN SOUTH CENTRAL AND SOUTHEAST IDAHO
ON MAY 14.

THE LATEST DROUGHT CONDITIONS AND COUNTY DROUGHT DECLARATIONS CAN BE
FOUND AT THE FOLLOWING WEB SITES.

U.S. DROUGHT MONITOR
WWW.DROUGHTMONITOR.UNL.EDU

U.S. DROUGHT PORTAL
WWW.DROUGHT.GOV

IDAHO DEPARTMENT OF WATER RESOURCES
WWW.IDWR.IDAHO.GOV/NEWS/DROUGHT/DROUGHT.HTM


PEAK FLOW FORECASTS...

THE LATEST PEAK FLOW FORECASTS CAN BE FOUND AT THE FOLLOWING WEB
SITES.

NORTHWEST RIVER FORECAST CENTER PEAK FLOW
WWW.NWRFC.NOAA.GOV/PEAK

COLORADO BASIN RIVER FORECAST CENTER PEAK FLOW
WWW.CBRFC.NOAA.GOV/GMAP/LIST/LIST.PHP?TYPE=PEAK


TEMPERATURE AND PRECIPITATION OUTLOOKS...

ACCORDING TO THE CLIMATE PREDICTION CENTER JUNE OUTLOOK...
PROBABILITIES FAVOR WARMER THAN NORMAL TEMPERATURES AND BELOW NORMAL
PRECIPITATION ACROSS IDAHO.

FOR JULY THROUGH SEPTEMBER...PROBABILITIES FAVOR WARMER THAN NORMAL
TEMPERATURES ACROSS IDAHO...AND BELOW NORMAL PRECIPITATION FOR ALL
BUT THE SOUTHEAST PORTION OF THE STATE.

THE LATEST LONG RANGE AND SEASONAL OUTLOOKS ISSUED BY THE NATIONAL
WEATHER SERVICE CLIMATE PREDICTION CENTER CAN BE FOUND AT THE
FOLLOWING WEB SITE.

WWW.CPC.NCEP.NOAA.GOV

$$

TAL
National Weather Service National Headquarters
