National Weather Service United States Department of Commerce

Flooding of Wyoming rivers typically occurs in the late spring or early summer as mountain snowpack melts.  Several weather factors including snowpack level, temperature, duration of warm temperatures, and additional precipitation, all play a role in how the snowpack melts and filters to streams, creeks, and rivers.  The links below are provided as a way for you to monitor current and forecast trends for snowpack, snowmelt, and flood potential.

Also, the US Geological Survey, USGS, operates "WaterAlert."   The WaterAlert service sends e-mail or text (SMS) messages when certain parameters, as measured by a USGS real-time data-collection station, exceed user-definable thresholds.  The development and maintenance of the WaterAlert system is supported by the USGS and its partners, including numerous federal, state, and local agencies.  To read more or register online visit



Snowpack and Precipitation Data
NRCS Snow Precipitation Update
Interactive Precipitation Summary Graphics
Percent of Average SWE by Basin (Graph) Percent of Average SWE by Basin
Percent of Average SWE and Precipitation Graph
(By Individual Station)
Wyoming SNOTEL Data
SNOTEL Water Year Graph
(By Individual Station)
Monthly Precipitation Maps
NRCS Snow Survey NOHRSC Regional Snow Analyses--Central Rockies




Streamflow and Reservoir Data
NWS Riverton Hydrology Page NWS Cheyenne Hydrology Page
USBR Lakes and Reservoirs--Central and Eastern WY USBR Lakes and Reservoirs--Western WY
USGS Streamflow Conditions NRCS Wyoming Basin Outlook Reports
Wyoming BOR Canal and Stream Gaging Stations  
River & Flood Outlooks and Forecasts
Missouri River Basin Significant River Flood 5-day Outlook
(east of the Continental Divide)
NWS Riverton Snowmelt Flood Potential Outlook
Colorado River Basin Peak Streamflow Outlook
(Green River Basin)
Northwest River Basin Significant Flood Outlook
(Snake River Basin)


Climate Outlooks
Three Month Outlook Climate Prediction Center


Drought Monitors and Assessments
NOAA Wyoming Drought Monitor NOAA Drought Assessment - US
State Climatologist's Wyoming Drought Page State Climatologist's Wyoming Climate Data
Palmer Drought Severity Index (PDSI) Wyoming Drought Watch - USGS
About the PDSI National Drought Mitigation Center


Abbreviations used on this page:
AHPS - Advanced Hydrologic Prediction Services
NOAA - National Oceanic and Atmospheric Administration
NOHRSC - National Operational Hydrologic Remote Sensing Center
NWS - National Weather Service
NRCS - Natural Resource Conservation Service
PDSI - Palmer Drought Severity Index
SNOTEL - Snow Telemetry
SWE - Snow Water Equivalent
USGS - United States Geologic Survey