Wyoming Drought Information and Graphics---updated April 30, 2009


…Moderate hydrologic drought persists across a small portion of southwest Wyoming--Upper Bear and Lower Green Basins…

…Normal to above normal precipitation totals for rangelands/basins across most of Wyoming for current water year 2009 (October - April 2009)…

 …Near normal to above normal mountain snowpack averages across Wyoming…

…Reservoir storages across Wyoming continue to well above water year 2008 storages…


3 key ingredients define the overall drought picture for Wyoming:  Rangeland Precipitation---Water Supply---Mountain Snowpack

Rangeland Precipitation---
Precipitation across Wyoming’s pasturelands/rangelands during the current water year 2009 (October 2008 - April 2009) was near normal to above normal for almost all of Wyoming. Precipitation across the major river basins across Wyoming was also near normal to above normal across almost all of Wyoming.  35 to 50 percent of the water year’s total precipitation across the majority of Wyoming’s rangeland/pastureland areas occurs in the spring (April - June).   

Water Supply---

Reservoir storages across Wyoming were averaging 102 percent of average as of April 1st.  Storages at a majority of major reservoirs continue to be above water year 2008 averages.  Overall, reservoir storage continues to be 124 percent of last water year’s reservoir storage.

The current water supply forecast calls for near normal snowmelt runoff volumes across the majority of basins across Wyoming.   Snowmelt runoff volumes are expected to be below normal over the major basins across the southwest part of the state.

 Mountain Snowpack---

Snow water equivalents (SWEs) by the end of the April 2009 were near normal to above normal across the majority of the basins across the state.   

Overall Drought Picture---

Wyoming is doing very well with respect to water supply and mountain snowpack averages.  Rangeland/pastureland precipitation totals through April have increased to near normal (for water year 2009) in many areas due to a wet late March and April.   The Lower Green and Upper Bear River Basins continue to be the driest basins in Wyoming---as these basins continue to be under the moderate hydrologic drought category.  The next 2 months (May and June) are critical for precipitation across the rangelands/pasturelands. As stated before---many rangeland locations (especially across areas east of the continental divide) receive 35 to 50 percent of their water year/annual precipitation during April through June. 

 Bottom line is that current precipitation, water supply, and precipitation conditions are keeping the momentum going with respect to totally breaking the long-term drought that has been plaguing Wyoming for the past 10 years.

  For the complete drought report with graphics (in .PDF format)---Please go to:


for additional drought graphics and information---please refer to:


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