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23.9  sqmi Willow Creek nr Crooks, SD

Continuous Nexrad Radar Rainfall-Runoff Comparisons in Real-Time
With Radar Hourly Ratio Adjustments and Snowmelt Provided by GetRealtime
More Basin Snowmelt Comparisons Here

May 10, 2019 to ... now and then as needed for Nowcasts and Snowcasts.


source:  Wunderground/Intellicast


Current composite radar loop above.  Below is zoomed FSD N0Q hi-res radar at Sioux Falls, Wundergages, and adjusted N0Q at watersheds.  Note that the raw N0Q radar here almost always shows "ground clutter" because of being so close to the radar site. Ground clutter (0.05" to 0.1" a day) is just another simple matter that rain gage adjustment removes.  No rain at the rain gages for the hour then no radar rain.  The rain gages are not heated so MRSM-A2M radar product is being tested this winter.  The rain gages appear to match the A2M totals when they thaw out the next day or two.




The 23.9 sqmi Willow Creek basin was not subdivided and the USGS gage is 06481497 WILLOW CREEK NEAR CROOKS, SD.  The basin boundary was digitized using Google Earth Pro Add Polygon method and saved as a KML file.  My GoogleKML2Text.exe program then converts the kml to text for my LatLongPixelsFromFile.exe that creates the GetRealtime basin boundary pixels.  These programs are free on my Help web page from the top menu above.


The USGS does not provide flow values, just stage in cooperation with the City of Sioux Falls.  They have made a couple flow measurements a year since 2001 and are subject to heavy vegitation and ice.  I constructed a flow vs stage table for lookups of the USGS provided stage.


Annual peak FLOWS are also provided since 2001 and I created a Log Pearson III annual propability distribution of the peaks for use for reporting peak flow recurrence.  I also got the NOAA Atlas 14 partial probability rainfall depths for reporting the 5-min to 3-day recurrence of rain depth.


Last model run info from database as text each run (GetFromAccessNOW.exe):     




NWS Snowcast Model Point LYOS2  :


NWS Model Point LYOS2 Compared to GRT Using NWS Rain+Snow Precip: input:

Current NWS snowpack:



Current automated graphs and radar (updated often when runoff)


Summary of Snowmelt (Series 1=Blue, Series 2=Pink, Series 3=Orange):


Radar ratio adjusted rainfall and Wundergages (pink is second parameter referred to)  :

Stage from GRT, USGS gage, & HMS (3rd parameter HMS is orange):



Wundergages and radar ratio adjustment of N0Q.  A2M may use a constant adjustment during winter.  Yellow gages are not used:



Past runoff comparisons:


Sep 15, 2019:



Willow Creek nr Crooks, SD Point precipitation frequency estimates (inches) NOAA Atlas 14 Volume 8 Version 2 Data type: Precipitation depth Time series type: Partial duration Project area: Midwestern States Location name (ESRI Maps): Crooks South Dakota USA Station Name: - Latitude: 43.7030° Longitude: -96.8310° Elevation (USGS): 1604.08 ft


Annual Peak Flows since 2001:


Flow Rating:


Important Note:  Nothing on this page is intended as interpretation of any legal authority such as water rights and supply. This page is intended solely as a demonstration of techniques in flood potential monitoring. The reader assumes all risk for any damages whatsoever in connection with the access, use, quality, or performance of the supplied data just so you know.  




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Copyright 2019 Carson, Reproduction permitted with attribution.
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