Final Wyoming Spring Snowmelt Flood Outlook--updated May 13 2008

…Little Snake, Upper North Platte, Middle Powder River, and headwater locations along the Snake River Basin have the greatest potential for spring snowmelt flooding… 

 …Above average temperatures are expected Saturday through Monday (May 17 to 19) across Wyoming will cause significant rises in streams and rivers Monday through Thursday of next week…

 …Near normal temperatures to below normal temperatures are expected for the rest of May…

 …Near normal to precipitation expected for the rest of May…


The Little Snake River, the Upper North Platte River, the Middle Fork of the Powder River, and headwater streams over the Snake River Basin have the greatest potential for snowmelt flooding during the rest of the Spring. Snow water equivalents (SWEs) in the snowpack (as of May 10th) over these basins continue to be above 125 percent of normal.

In the short-term, significant snowmelt across Wyoming will begin Saturday through Monday (May 17 to May 19) as above normal temperatures are expected across Wyoming. Significant rises in area rivers and streams will begin early Monday and last into early Thursday.  Rain showers are expected across the state by late Wednesday into Thursday. Statewide temperatures are also expected to cool down to near normal by Wednesday which will slowdown the snowmelt runoff.

Remember, if only higher than normal temperatures are generating the snowmelt runoff,  minor isolated and sporadic stream and river flooding can be expected along low lying areas, secondary river/road crossings, pasturelands/rangelands,  and other flood-prone areas.  However, if there is an extended period of significant rainfall (at least 2 days) over a melting snowpack, then more wide spread river flooding can occur which will more directly affect lives and property.

Also remember that during an active snowmelt runoff period, the rivers and streams will be at their highest levels during the early morning hours--to compensate for the stream flow travel lag after the active snowmelt in the late afternoon hours.

For the rest of May, near normal to below normal temperatures are expected as well as near normal precipitation. 






























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