Wednesday, March 7, 2012

Western Wyoming is in great condition with Weather and Water

After a brief return to snowy weather Tuesday when Star Valley saw a  couple inches of fresh snow, an extended period of dry and relatively mild weather is ahead. High pressure  will dominate into the weekend with plentiful sunshine and daytime temperatures well into the 40s. By Sunday a low pressure trough will move onshore across the Pacific Northwest likely spreading clouds and a chance of rain and/or snow across Star Valley.
500mb Forecast Sunday evening 3/11/12
However cold air is not likely to affect Star Valley with this pattern as the upper flow remains west to southwest off the Pacific.  This is reflected in the longer range outlook for next week by the Climate Prediction Center.

Temperature Forecast March 13-17 2012

Precipitation Forecast March 13-17 2012

Unseasonably warm weather is expected over most of the U.S. from the Rockies eastward.

The March 2012 Snow/Runoff for Wyoming was recently issued by the National Resources Conservation Service in Casper.

Much improved conditions were experienced statewide from the February report.  In particular here is the report for the Snake River Basin which includes Star Valley.

The Snake River Basin snow water equivalent (SWE) is 95% of average.  
SWE in the Snake River Basin above Jackson Lake is 101% of average.  
Pacific Creek Basin SWE is 117% of average.  Gros Ventre River Basin 
SWE is 88% of average.  SWE in the Hoback River drainage is 87% of 
average.  SWE in the Greys River drainage is 90% of average.   In 
the Salt River area SWE is 89% of average.  SWE in the Snake River 
Basin above Palisades is 95% of average.  See the  Basin Summary of 
Snow Course Data  at the beginning of this report for a detailed 
listing of snow course information.
Precipitation across the basin was about average last month.  
Monthly precipitation for the basin was 98% of average (129% of last 
year).  Last month's percentages range from 72-127% of average for 
the 16 reporting stations.  Water-year-to-date precipitation is 96% 
of average for the Snake River Basin (89% of last year).  Year-to-
date percentages range from 68-116% of average.
Current reservoir storage is 122% of average for the 3 storage 
reservoirs in the basin.  Grassy Lake storage is about 103% of 
average (12,300 ac-ft compared to 13,200 last year).  Jackson Lake 
storage is 130% of average (640,000 ac-ft compared to 656,600 ac-ft 
last year).  Palisades Reservoir storage is about 118% of average 
(1,223,500 ac-ft compared to 875,700 ac-ft last year).  Detailed 
reservoir data is shown on the following page and on the reservoir 
storage summary at the beginning of this report.
The 50% exceedance forecasts for April through September are below 
average for the basin. The Snake near Moran is 905,000 ac-ft (100% 
of average).  Snake River above reservoir near Alpine is 2,560,000 
ac-ft (94% of average).  The Snake near Irwin is 3,570,000 ac-ft 
(92% of average).  The Snake near Heise is 3,830,000 ac-ft (92% of 
average).  Pacific Creek near Moran is 200,000 ac-ft (112% of 
average).  Buffalo Fork above Lava near Moran is 360,000 ac-ft (105% 
of average).  Gros Ventre River at Kelly is 260,000 ac-ft (107% of 
average).  Greys River above Palisades Reservoir is 355,000 ac-ft 
(90% of average).  Salt River near Etna is 365,000 ac-ft (87% of 

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