HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE SALT LAKE CITY UTAH
1125 AM MST FRI APR 4TH 2008
STATE OF UTAH HYDROLOGIC OUTLOOK
APRIL 1ST, 2008
IT IS THE RARE EXCEPTION IN UTAH WHERE A SIGNIFICANT SNOW
ACCUMULATING WEATHER PATTERN LASTS MORE THAN A COUPLE OF MONTHS AND
SO IT IS THIS YEAR. A DRY FALL GAVE WAY TO SIGNIFICANT SNOW
ACCUMULATIONS IN MID-DECEMBER...JANUARY...AND FEBRUARY WHICH IN TURN
GAVE WAY TO DRIER CONDITIONS IN MARCH.
WHILE MARCH PRECIPITATION LEVELS WERE NEAR 50% OF NORMAL...
TEMPERATURES ACROSS THE STATE WERE COLDER THAN NORMAL OVER THE
NORTHERN AND CENTRAL PARTS OF THE STATE. DAYTIME HIGH TEMPERATURES
RANGED FROM 1-5 DEGREES BELOW NORMAL IN THOSE AREAS...WHILE
SOUTHERNMOST UTAH EXPERIENCED DAYTIME HIGH TEMPERATURES AVERAGING
1-3 DEGREES ABOVE NORMAL. AS A RESULT...SNOWPACKS IN MOST OF THE
STATE HELD TOGETHER. THE VIRGIN RIVER BASIN WAS THE
EXCEPTION...REDUCING IT SNOWPACK SIGNIFICANTLY TO EARLY MELT
CONDITIONS.
AS A RESULT OF THE DRIER MARCH...AND AS OF EARLY APRIL...UTAH'S
SNOWPACK REMAINS AT NORMAL TO ABOVE NORMAL LEVELS. STATEWIDE...SNOW
ACCUMULATION WAS ONLY 63% OF NORMAL FOR THE PAST MONTH. SOME AREAS
SUCH AS THE SEVIER...HAD NO NET ACCUMULATION AND SOUTHWEST UTAH HAD
A 285% OF AVERAGE DECLINE. EVEN WITH THIS HUGE DECLINE IN
SNOW...SOUTHWEST UTAH IS STILL AT 94% OF NORMAL REFLECTING THE MUCH
ABOVE AVERAGE SNOWPACK EARLIER IN THE SEASON. SNOWPACKS NOW RANGE
FROM A LOW OF 94% OVER SOUTHWEST UTAH TO A HIGH OF 124% ON THE
WASATCH BACK AREA OF UTAH.
THIS IS AS CLOSE TO AN "AVERAGE" SNOWPACK YEAR ACROSS THE STATE AS
UTAH EVER GETS. THE CIRCUITOUS ROUTE TAKEN TO REACH THE AVERAGE
APRIL 1 SNOWPACK WAS ANYTHING BUT AVERAGE. IN NORTHERN UTAH...THERE
REMAINS A SUBSTANTIAL LOW ELEVATION (6000 FT. TO 7500 FT.)
SNOWPACK...130% - TO NEARLY 200% OF NORMAL. IN MANY AREAS ...THIS
SNOW IS CURRENTLY MELTING...GIVING THE POTENTIAL FOR GREATER
STREAMFLOW EARLY IN THE SEASON. WATER MANAGERS SHOULD BE AWARE OF
AND PLAN FOR THIS RUNOFF POTENTIAL.
THE AREAS HIGHLIGHTED LAST MONTH FOR MUCH ABOVE AVERAGE SNOWPACKS...
SOUTHERN AND SOUTHEAST UTAH...ARE NOTED THIS MONTH FOR DECLINING TO
NEAR AVERAGE CONDITIONS.
SOIL MOISTURE VALUES ARE: BEAR - 57%...WEBER - 59%...PROVO -
49%...UINTA BASIN - 37%...SOUTHEAST UTAH - 54%...SEVIER -
58%...SOUTHWEST UTAH - 59%...AND STATEWIDE - 53% OF SATURATION.
THESE VALUES ARE SIMILAR TO THOSE OF APRIL 1, 2006 AND DRIER THAN
THOSE OF LAST YEAR.
RESERVOIR STORAGE IS CURRENTLY AT 60% OF CAPACITY STATEWIDE COMPARED
TO 74% LAST YEAR. IF WE LOOK AT RESERVOIR STORAGE COMPARED TO WHAT
IS CONSIDERED NORMAL FOR THIS TIME OF YEAR...WE ARE CURRENTLY AT 89%
OF AVERAGE. LAST YEAR AT THIS TIME WE WERE AT 109% OF AVERAGE FOR
APRIL 1ST.
GENERAL WATER SUPPLY CONDITIONS ARE NEAR AVERAGE ACROSS THE STATE.
STREAMFLOW FORECASTS ARE VERY HEALTHY THIS YEAR WITH VOLUME
FORECASTS ACROSS THE STATE AT NORMAL TO SLIGHTLY ABOVE NORMAL
VOLUMES. AS WE RECEIVED ONLY 50% OF THE MARCH PRECIPITATION...
WATER SUPPLY NUMBERS DECLINED SOMEWHAT IN THE NORTH...AND
CONSIDERABLY IN THE SOUTH. WHILE THE SOUTHERN DECLINE WAS QUITE
LARGE...CURRENTLY VOLUME FORECASTS FOR THAT AREA REMAIN IN THE
AVERAGE RANGE.
SNOWPACK
APRIL 1ST SNOWPACKS AS MEASURED BY THE NRCS SNOTEL ARE AS FOLLOWS:
BEAR - 100%...WEBER - 108%...PROVO - 112%...UINTAS - 112%...
SOUTHEAST UTAH - 106%...SEVIER - 108%...SOUTHWEST UTAH - 94% AND THE
STATEWIDE FIGURE IS 108% OF AVERAGE. APRIL 1 IS THE NORMAL PEAK OF
SNOWPACKS WITH MELT BEGINNING IN THE LOWER ELEVATIONS...BUT MARCH
WEATHER WILL DICTATE THE PACE AND EFFICIENCY OF THE SPRING SNOWMELT
RUNOFF. COOL WET CONDITIONS WILL DELAY THE MELT AND LEAD TO GREATER
RUNOFF LATER IN THE SEASON...WHEREAS WARM DRY CONDITIONS WILL
ACCELERATE THE MELT LEADING TO A LESS EFFICIENT RUNOFF.
PRECIPITATION
MOUNTAIN PRECIPITATION DURING MARCH WAS MUCH BELOW TO NEAR NORMAL
RANGING FROM 32% OVER SOUTHWEST UTAH TO 92% OF AVERAGE ON THE
BEAR RIVER. THIS BRINGS THE SEASONAL ACCUMULATION (OCT-MAR) TO 105%
OF AVERAGE STATEWIDE AND RANGES FROM 98% ON THE BEAR TO 111% OVER
THE UINTAS.
RESERVOIRS
STORAGE IN 41 OF UTAH'S KEY IRRIGATION RESERVOIRS IS AT 60% OF
CAPACITY. AGAIN...IF WE LOOK AT THE VOLUME OF WATER IN OUR
RESERVOIRS AT THIS TIME AND COMPARE THAT VOLUME TO NORMAL FOR THIS
TIME OF YEAR...WE ARE AT 89% OF NORMAL...WHILE LAST YEAR WE WERE AT
109% OF NORMAL.
STREAMFLOW
SNOWMELT STREAMFLOWS ARE EXPECTED TO RUN AT NEAR NORMAL CONDITIONS
THIS SPRING. ESSENTIALLY...THIS IS THE BEST OF BOTH WORLDS...WHERE
WATER SUPPLY IS IN GOOD SHAPE...AND IT APPEARS AT THIS TIME WE WILL
AVOID ANY WIDESPREAD FLOODING.
WHILE THE THREAT OF MAINSTEM RIVER FLOODING IS REMOTE...ALL
WATERWAYS FED BY SPRING SNOWMELT RUNOFF WILL FLOW AT VERY DANGEROUS
LEVELS THIS SPRING. THESE FLOWS WILL BE SWIFT...VERY COLD...AND CAN
PRODUCE LIFE THREATENING CIRCUMSTANCES. PLEASE MONITOR ANY CHILDREN
NEAR THESE AREAS AND USE PRUDENT JUDGMENT WHEN VENTURING NEAR THESE
DANGEROUS WATERS.
BRIAN MCINERNEY RANDY JULANDER
HYDROLOGIST SNOW COLLECTION
SUPERVISOR
NATIONAL WEATHER SERVICE NRCS