June Drought Information Statement

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DROUGHT INFORMATION STATEMENT
NATIONAL WEATHER SERVICE RIVERTON WY
852 AM MDT SUN JUN 15 2008

...MUCH ABOVE NORMAL PRECIPITATION IN MAY EASES DROUGHT CONDITIONS
ACROSS SOUTHWEST AND WEST CENTRAL WYOMING...

SYNOPSIS...

THE LATEST U.S. DROUGHT MONITOR FOR WYOMING ISSUED ON
JUNE 12 SHOWED THE AREA OF MODERATE /D1/ TO SEVERE /D2/ DROUGHT
HAD RETREATED...ESPECIALLY ACROSS FREMONT COUNTY AND THE UPPER
GREEN RIVER BASIN. THE AREA CLASSIFIED AS SEVERE DROUGHT WAS
CONFINED TO THE NORTHWEST TWO-THIRDS OF SWEETWATER COUNTY AND
SOUTHEAST LINCOLN COUNTY. MOST OTHER AREAS IN SOUTHWEST
WYOMING WITH THE EXCEPTION OF THE UPPER GREEN RIVER BASIN
REMAINED IN MODERATE DROUGHT. NORTH AND CENTRAL WYOMING WERE FREE OF
DROUGHT WITH SOUTHERN PARTS OF NATRONA...FREMONT AND TETON COUNTIES
AS WELL AS THE UPPER GREEN RIVER BASIN CLASSIFIED AS ABNORMALLY DRY.
BASIN-WIDE AVERAGE PRECIPITATION IN MAY WAS 110 TO 210 PERCENT OF
NORMAL. AT THE END OF MAY ALL BASINS WITH THE EXCEPTION OF THE UPPER
GREEN RIVER BASIN HAD ABOVE AVERAGE SNOWPACK.

SUMMARY OF IMPACTS...

HYDROLOGIC CONDITIONS HAVE IMPROVED SIGNIFICANTLY FROM ONE YEAR
AGO...ESPECIALLY AFTER A MAY WITH OVERALL MUCH ABOVE NORMAL
PRECIPITATION IN CONTRAST TO MAY 2007 IN WHICH MOST AREAS RECEIVED
BELOW NORMAL PRECIPITATION. THE FOLLOWING TABLE SHOWS THE LATEST AND
LAST YEAR PERCENT OF AVERAGE SNOW WATER EQUIVALENT (SWE) AMOUNTS FOR
WYOMING BASINS. THE AVERAGE IS BASED ON ALL REPORTING SNOTEL SITES IN
THE BASIN AND THE REFERENCE PERIOD FOR AVERAGE COMPARISON IS 1971-
2000.

DRAINAGE BASIN 5/26/2008 5/26/2007

SNAKE RIVER 134 15
UPPER YELLOWSTONE 151 36
WIND RIVER 128 20
BIG HORN BASIN 138 38
SHOSHONE 124 23
POWDER-TONGUE 211 48
BELLE FOURCHE MELTED OUT
UPPER NORTH PLATTE 124 43
LOWER NORTH PLATTE, SWT 133 37
LITTLE SNAKE RIVER 154 33
UPPER GREEN RIVER 97 18
LOWER GREEN RIVER 126 23
UPPER BEAR RIVER 102 0

WEIGHTED STATE AVERAGE 132 30

FIRE WEATHER IMPACTS.
MANY AREAS RECEIVED SIGNIFICANT MOISTURE IN MAY THROUGH EARLY JUNE
ALONG WITH COOL CONDITIONS. ALL FIRE WEATHER ZONES WERE IN GREEN-UP
OR DELAYED GREEN-UP AT THE HIGHER ELEVATIONS DUE TO COOL CONDITIONS
AND DELAYED MELTOFF OF SNOWPACK AND RUNOFF. NO FIRE WEATHER ZONES
WERE ASSESSED AS CRITICAL OR FAVORABLE FOR LARGE FIRE GROWTH AS OF
JUNE 14. CHECK WITH YOUR COUNTY OFFICIALS FOR THE LATEST BURNING
RESTRICTIONS.

CLIMATE SUMMARY...

OVERALL WYOMING HAD THE 17 WETTEST AND THE 37 COOLEST MAY OVER THE
LAST 114 YEARS. SOME AREAS RECEIVED RECORD OR NEAR RECORD
PRECIPITATION. LANDER HAD THE WETTEST MAY ON RECORD SINCE 1892...
DOWNTOWN RIVERTON HAD THE SECOND WETTEST MAY ON RECORD SINCE 1907...
AND CASPER HAD THE FIFTH WETTEST MAY SINCE 1948. MOST AREAS THAT
REMAINED IN MODERATE OR SEVERE DROUGHT DID NOT FARE QUITE AS WELL
ESPECIALLY IN AREAS THAT REMAIN IN SEVERE DROUGHT ACROSS SWEETWATER
COUNTY WHICH RECEIVED NEAR OR BELOW NORMAL PRECIPITATION FOR MAY.

BELOW ARE THE TOTAL PRECIPITATION AMOUNTS FROM SELECTED LOCATIONS
ACROSS WEST AND CENTRAL WYOMING FOR MAY 2008...

LOCATION MAY PRECIPITATION % AVERAGE
-------- --------------------- ---------
CASPER (AIRPORT) 4.26 179
LANDER (AIRPORT) 6.13 (RECORD WETTEST) 258
RIVERTON (AIRPORT) 4.81 253
ROCK SPRINGS (AIRPORT)* 1.42 104

AFTON* 3.84 175
BIG PINEY* 1.56 154
BITTER CREEK 4NE* 1.20 98
BUFFALO 6.21 255
CODY 4.58 234
DUBOIS 3.40 194
FARSON 5N* 1.60 113
FOSSIL BUTTE NAT MON* 1.31 75
GREEN RIVER* 0.65 54
GREYBULL 2.27 159
JACKSON 1.75 79
KAYCEE 6.25 244
KEMMERER* 0.71 60
LABARGE* 1.33 87
LAKE YELLOWSTONE 4.26 207
LOVELL 2.58 213
MOOSE 1.91 95
OLD FAITHFUL 4.12 169
PINEDALE 3.04 176
POWELL FIELD STATION 2.56 180
RIVERTON DOWNTOWN 4.75 267
THERMOPOLIS 5.01 244
WORLAND 2.67 165
YELLOWSTONE PARK (MAMMOTH) 2.47 123

*LOCATION IN SEVERE OR MODERATE DROUGHT

PRECIPITATION/TEMPERATURE OUTLOOKS...

THE OUTLOOK FOR THE METEOROLOGICAL SUMMER OR JUNE...JULY AND AUGUST
SHOWS A 40 PERCENT CHANCE OF ABOVE NORMAL TEMPERATURES ACROSS MOST OF
WEST AND CENTRAL WYOMING WITH A 50 PERCENT CHANCE OF ABOVE NORMAL
TEMPERATURES OVER THE SOUTHWEST CORNER. THE PRECIPITATION OUTLOOK
FOR THIS PERIOD SHOWS A 40 PERCENT CHANCE OF DRIER THAN NORMAL
CONDITIONS OVER ROUGHLY THE NORTH HALF OF WYOMING WITH A SLIGHT
CHANCE OF BELOW NORMAL PRECIPITATION ACROSS THE SOUTH.

LA NINA CONDITIONS CONTINUED TO WEAKEN DURING MAY. A MAJORITY OF
MODELS INDICATE A TRANSITION TO ENSO NEUTRAL CONDITIONS DURING THE
REST OF JUNE AND JULY THOUGH THERE IS STILL CONSIDERABLE UNCERTAINTY
IN REGARDS TO THIS TRANSITION.

THE U.S. SEASONAL DROUGHT OUTLOOK ISSUED ON JUNE 5 SHOWED THAT
MODERATE TO SEVERE DROUGHT CONDITIONS IN SOUTHWEST WYOMING WERE
EXPECTED TO SHOW SOME IMPROVEMENT...THOUGH DROUGHT CONDITIONS
WERE LIKELY TO PERSIST THROUGH AUGUST 2008.

HYDROLOGIC SUMMARY AND OUTLOOK...

EXCEPT FOR THE UPPER AND LOWER GREEN BASINS...ABOVE NORMAL WATER
SUPPLY NUMBERS CONTINUE TO BE EXPECTED FOR THE REST OF JUNE AND
INTO JULY FOR THE MAJORITY OF THE LARGE WATERSHEDS IN WYOMING.

RECORD AND/OR NEAR RECORD MAY PRECIPITATION ACROSS THE STATE HAS
MAINTAINED AND EVEN INCREASED THE FORECASTED SNOWMELT STREAMFLOW
VOLUMES FOR THE NEXT TWO MONTHS ACROSS THE MAJORITY OF BASINS IN
WYOMING.

COOLER THAN NORMAL TEMPERATURES ACROSS WYOMING IN MAY AND EARLY
JUNE HAS MAINTAINED AND/OR INCREASED THE ALREADY ABOVE NORMAL SNOW
WATER EQUIVALENTS (SWE) OR "WATER" MEASUREMENTS IN THE SNOWPACK ABOVE
9000 FEET.

BASIN-WIDE AVERAGE PRECIPITATION FOR MAY WAS 110 TO 210 PERCENT OF
NORMAL. FOR THE WATER YEAR 2008...MANY BASINS IN WYOMING WERE
REGISTERING 85 TO 120 PERCENT OF NORMAL PRECIPITATION. THE NORMAL
TO ABOVE NORMAL PRECIPITATION NUMBERS ACROSS THE STATE HAS GREATLY
HELPED INCREASE THE FORECASTED STREAMFLOW VOLUMES IN WYOMING.

STREAMFLOW VOLUMES FOR JUNE AND JULY ALONG THE WIND AND BIG HORN
RIVER DRAINAGES ARE EXPECTED TO INCREASE TO 105 TO 120 PERCENT OF
NORMAL. THE INFLOWS INTO BOYSEN RESERVOIR ARE FORECASTED TO BE 105
PERCENT OF NORMAL WITH AN ADDITIONAL 540,000 ACRE-FEET OF WATER
EXPECTED TO FLOW INTO BOYSEN RESERVOIR DURING THE REST OF JUNE AND
INTO JULY.

THE UPPER GREEN AND LOWER GREEN WATERSHED SUPPLY FORECASTS CONTINUE
TO POINT TO BELOW AVERAGE SNOWMELT STREAMFLOW VOLUMES WITH ONLY 70
TO 85 PERCENT OF NORMAL STREAMFLOWS EXPECTED THROUGH JULY.

NEXT ISSUANCE DATE...

THIS PRODUCT WILL BE UPDATED ON TUESDAY JULY 15, 2008 OR
SOONER IF NECESSARY IN RESPONSE TO SIGNIFICANT CHANGES IN CONDITIONS.

RELATED WEB SITES...

LOCAL DROUGHT INFORMATION.
www.crh.noaa.gov/riw/hydro/drought.php

WYOMING DROUGHT STATEMENT WITH GRAPHICS.
www.crh.noaa.gov/riw/hydro/drought_info.pdf

NATIONAL RESOURCES CONSERVATION SERVICE SNOW SURVEY
www.wrds.uwyo.edu/wrds/nrcs/nrcs.html

NATIONAL INTEGRATED DROUGHT INFORMATION CENTER.
www.drought.gov

NOAA DROUGHT INFORMATION CENTER.
www.drought.noaa.gov

CLIMATE PREDICTION CENTER
www.cpc.noaa.gov

ACKNOWLEDGEMENTS...
THE DROUGHT MONITOR IS A MULTI-AGENCY EFFORT INVOLVING THE NATIONAL
WEATHER SERVICE AND THE NATIONAL CLIMATIC DATA CENTER...THE
USDA...STATE AND REGIONAL CENTER CLIMATOLOGISTS AND THE NATIONAL
DROUGHT MITIGATION CENTER. INFORMATION FOR THIS STATEMENT HAS BEEN
GATHERED FROM NWS AND FAA OBSERVATION SITES...STATE COOPERATIVE
EXTENSION SERVICES...USDA...COE AND USGS.

QUESTION AND COMMENTS...

IF YOU HAVE ANY QUESTIONS OR COMMENTS ABOUT THIS DROUGHT INFORMATION
STATEMENT...PLEASE CONTACT...

ARTHUR MEUNIER
CLIMATE/DROUGHT FOCAL POINT
NATIONAL WEATHER SERVICE
RIVERTON, WY 82501
TELEPHONE 307-857-3898
EMAIL: ARTHUR.MEUNIER@NOAA.GOV


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