Wyoming snowpack 97% of average
Current drought conditions persist
May 21, 2008
According to Jim Fahey, Wyoming NOAA hydrologist, Wyoming snowpack is 97 percent of average as of May 20th. Water supply forecast numbers still are showing near average to above average snowmelt streamflow volumes for 2008.
All major river basins across Wyoming had below to much below normal precipitation totals for April 2008. Severe hydrologic drought conditions continue over the Upper and Lower Green River Basins.
Synopsis
The drought situation across Wyoming has two major factors:
1) the amount of water in the mountain snowpack and corresponding runoff and/or water supply as the snow melts.
2) the amount rainfall across the lower elevations to include most of the range lands, pasture lands and other agricultural centers across Wyoming.
SWE NEAR NORMAL DURING APRIL
Water (or snow water equivalents--SWEs) in the Wyoming snowpack continued to be near normal to above normal during April and right into the middle of May. Snowpack averages across Wyoming were still near normal (97% of the 30-yr normal) as late as May 20th. One year ago the SWE averages across Wyoming were only 59 percent of normal.
WYOMING WATER SUPPLY OUTLOOK
Wyoming’s water supply still looks like it will be solid for the rest of the spring runoff and into early summer. The latest water supply forecast indicates the most of the state will see normal to above normal steamflow volumes during the spring runoff. Inflows to almost all of the major reservoirs this spring and summer are expected to be near normal.
The long-range temperature outlook still indicates that there is a 30-40 percent chance of a warmer than normal summer for most of central and western Wyoming. This is may initially help fill the most of the state’s reservoirs; but a warmer than average summer may not carry the state’s irrigation water supply deep into summer and into early fall.
DRY SPRING AT LOWER ELEVATIONS
Many low elevation areas in Wyoming are still experiencing a rather dry spring. Several locations east of the Continental Divide have only received 30 to 60 percent of average precipitation for January through April 2008.
The next 4 weeks are crucial for precipitation accumulation across these dry areas east of the Continental Divide. The latest long-range predictions for precipitation across Wyoming indicate that there is a developing trend (at least a 30 to 40 percent chance) for below normal precipitation across the state during June through August.
GREEN RIVER BASIN UNDER SEVERE HYDROLOGIC CONDITIONS
The Upper and Lower Green River basins continue to be under severe hydrologic conditions.
The latest drought outlook through August 2008 indicates that most of Wyoming will continue to see current drought conditions persist.
Source: Jim Fahey, Wyoming NOAA hydrologist, 307-857-3898 ext 493
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