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Drought Information Statement
Issued by NWS Boise, ID

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DROUGHT INFORMATION STATEMENT
NATIONAL WEATHER SERVICE BOISE IDAHO
1250 PM MDT Thu Apr 22 2021

...DROUGHT PERSISTS ACROSS MUCH OF CENTRAL AND SOUTHERN IDAHO WITH
DROUGHT DEVELOPMENT ACROSS NORTHERN IDAHO...

Synopsis...

Areas of drought continue across the southern half of Idaho while
drought development has occurred across northern Idaho in the
Panhandle Region. The lack of spring precipitation, below normal
winter snowpack, and dry conditions last fall have resulted in both
meteorological drought and longer term hydrologic drought conditions.
According to the U.S. Drought Monitor released on April 22...42
percent of Idaho was experiencing some level of drought. Moderate to
extreme drought exists across much of the Central Idaho Mountains
with a focus in Blaine and Custer Counties. Moderate to severe
drought is present across far southern Idaho near the Utah and
Nevada border while moderate drought development has occurred across
the northern Idaho Panhandle. The latest seasonal drought outlook
(April 15, 2021-July 31, 2021) indicates that drought will persist
in areas already being impacted by drought, and drought development
is likely across the rest of Idaho.

SUMMARY OF REPORTED IMPACTS...

Much below normal water supply runoff volumes are forecast for
watersheds across the southern half of Idaho for the April through
September period. The lowest forecasts are in the Big Wood, Little
Wood, and Big Lost Basins of the Central Mountains, and Southside
Snake River Basins of far southern Idaho where only 20 to 40 percent
of normal runoff is expected. Elsewhere across Idaho from the Salmon
River Basin south to the Utah and Nevada border the water supply
forecasts range from 55 to 75 percent of normal while forecasts for
northern Idaho basins generally range from 75 to 95 percent of
normal. As of April 20, drought declaration requests have been
submitted to the Idaho Department of Water Resources by Blaine,
Butte, Custer, Gooding, and Lincoln Counties. Low snowpack and poor
streamflows may lead to water supply concerns for other areas of
southern Idaho, especially for those relying on natural flows.
According to the USDA, the combination of wind and little
precipitation so far in April has brought some early deterioration
to pasture and range conditions. A number of lower elevation SNOTEL
sites have melted out a month earlier than normal.

Drought Impacts Reports can be found via the U.S. Drought Portal in
the related websites section.

Climate Summary...

Water Year 2021 precipitation (October 1, 2020-April 20, 2021)
varies considerably across the state. North-central Idaho near the
Montana border and pockets of west-central Idaho have received 100
to 130 percent of average precipitation. Otherwise, below normal
precipitation has occurred across Idaho through the first half of
the Water Year. Much of southern Idaho has only received 50 to 70 of
normal precipitation with areas of the Central Mountains and near
the Nevada border having received less than 50 percent. The
Panhandle Region has generally received 70 to 90 percent of normal
precipitation.

Average temperatures for the 2021 Water Year so far have been within
a couple degrees of normal except for a portion of south-central
Idaho (Magic Valley area) where temperatures have been 4 to 6
degrees above normal.

Below is a list of precipitation data for selected locations in
Idaho for the 2021 Water Year.

        Oct 1, 2020-Apr 20, 2021    Normal     Departure    Last
          Total Precip(Inches)      Value     From Normal   Year

BOISE             6.52              8.08        -1.56       6.96

MCCALL           15.06             13.15         1.91      15.22

TWIN FALLS        3.49              6.81        -3.32       5.02

POCATELLO         4.88              7.16        -2.28       6.11

IDAHO FALLS       3.93              5.46        -1.53       5.08

CHALLIS           2.15              4.26        -2.11       3.10

STANLEY          10.67             11.11        -0.44       8.09

LEWISTON          6.03              6.97        -0.94       7.94


Hydrologic Summary...

Snow water equivalent percentages have dropped considerably over the
past month in many basins across southern Idaho. The lowest
percentages continue to be in the Big Lost and Little Wood River
Basins at 48 and 43 percent of normal. Many SNOTEL sites in the
Central Mountains are in the 5th to 10th percentile for low snow
water equivalent with one location setting a new record low. Twenty-
eight day average streamflows for many USGS gaging stations across
southern Idaho and the Panhandle Region are below normal to much
below normal.

Below is a summary of major reservoir system storage across Idaho.

                April 1, 2021 NRCS Reservoir Data

                                  Percent of      Percent of
                                   Capacity        Average

Idaho Panhandle Region                59             106
Hungry Horse...Flathead Lake...Noxon Rapids...Lake Pend Orelle...
Priest Lake...Lake Coeur D Alene)

Dworshak                              60              86

West Central Basins                   65             105
Anderson Ranch...Arrowrock...Lucky Peak...Lake Lowell...
Deadwood...Cascade...Mann Creek)

Wood and Lost Basins                  31              58
(Mackay...Little Wood...Magic)

Upper Snake River Basin               87             122
(Jackson...Palisades...Henrys...Grassy...Island Park...Ririe
...Blackfoot...American Falls)

Southside Snake River Basins          60              86
(Oakley...Salmon Falls...Wild Horse...Lake Owyhee...Brownlee)

Bear River Basin                      63             135
(Bear Lake...Montpelier)


Precipitation and Temperature Outlook...

The three month outlook from the Climate Prediction Center for May
through July favors above normal temperatures and below normal
precipitation for the entire state.


Next Issuance...

Updates to this product are generally made on a monthly basis.

Related Websites...

U.S. DROUGHT PORTAL: HTTP://WWW.DROUGHT.GOV

NATIONAL DROUGHT MITIGATION CENTER: HTTP://DROUGHT.UNL.EDU

STREAM FLOWS: AHPS HTTP://WATER.WEATHER.GOV/AHPS USGS
HTTP://WATERWATCH.USGS.GOV

NWS WATER SUPPLY FORECASTS: HTTP://WWW.NWRFC.NOAA.GOV
HTTP://WWW.CBRFC.NOAA.GOV

NRCS WATER SUPPLY FORECASTS:
HTTP://WWW.WCC.NRCS.USDA.GOV/WSF/WSF.HTML

IDAHO DEPARTMENT OF WATER RESOURCES: HTTP://WWW.IDWR.IDAHO.GOV

OREGON WATER RESOURCES DEPARTMENT (DROUGHT INFORMATION):
HTTP://WWW.OREGON.GOV/OWRD/PAGES/WR/DROUGHT.ASPX

LONG TERM WEATHER AND CLIMATE OUTLOOKS: HTTP://WWW.CPC.NCEP.NOAA.GOV

WESTERN REGION CLIMATE CENTER (CLIMATE ANOMALY MAPS):
HTTP://WWW.WRCC.DRI.EDU/MONITORING-MAPS/

NATIONAL INTERAGENCY COORDINATION CENTER (FIRE DANGER AND OUTLOOKS):
 HTTP://WWW.NIFC.GOV/NICC

RESERVOIR INFORMATION: NRCS HTTP://WWW.WCC.NRCS.USDA.GOV/BASIN.HTML
BUREAU OF RECLAMATION HTTP://WWW.USBR.GOV/PN/HYDROMET/SELECT.HTML

UNITED STATES DEPARTMENT OF AGRICULTURE: DISASTER ASSISTANCE
HTTP://WWW.USDA.GOV/WPS/PORTAL/USDA/USDAHOME

Acknowledgments... The Drought Monitor is a multi-agency effort
involving NOAA`s National Weather Service and National Climatic Data
Center...The U.S. Department Of Agriculture...State and Regional
Centers...Climatologists...and the National Drought Mitigation
Center.

Information for this statement has been gathered from the NWS and
FFA observation sites...State Agencies...USDA...NRCS...USACE AND
USGS.

Questions or comments...If you have questions or comments about this
Drought Information Statement please contact...

National Weather Service
3833 South Development Avenue
Boise, ID 83705-5354
Phone: 208-334-9860
Email: w-boi.webmaster@noaa.gov

$$