North Central River Forecast Center



WSR-88D Z/R Relationship Table

This table shows WSR-88D Z/R relationships for sites used in the North Central River Forecast Center Multisensor Precipitation radar mosaic. A Z/R relationship is an empirical formula used to estimate rainfall rates from reflectivity signal strength. Parameters that can be varied at each radar site are shown in red. Max Precip Rate is an adjustable parameter which limits overestimation from hail contamination, ground clutter, etc. The Bias Correction Factor shows three elements: the duration (in hours) used to calculate the bias, the bias (in red), and the number of non-zero gage/radar pairs used to calculate the bias for that duration.

Most stratiform rain has a reflectivity signal strength of 20-40dBZ with peaks to 45dBZ, but rarely anything higher (that isn't "brightbanding"). For more information, authorization, instructions, and recommendations regarding Z/R relationships, see the Radar Operations Center's page.

Radar SiteRadar IdWFO IdTime Reported (UTC) Z/R FormulaMax Precip
Rate(in/hr)
Z/R TypeBias Correction Factor
Aberdeen, SDABRABR09 May 2008 14:00Z=300R1.44.09Summer Deep Convection Z/R10-hr:0.74 #51
Over-estimation
Bethune, SKXBEWWG09 May 2008 14:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
2160-hr:2.78 #40
Under-estimation
Bismarck, NDBISBIS09 May 2008 14:00Z=130R24.09Cool Season (East)
Stratiform Z/R
168-hr:1.33 #29
Under-estimation
Britt, ONWBIWTO09 May 2008 14:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
0-hr:1.00 #0
No Bias
Chicago, ILLOTLOT08 May 2008 13:00Z=300R1.43.44Summer Deep Convection Z/R2-hr:1.23 #30
Under-estimation
Des Moines, IADMXDMX09 May 2008 14:00Z=300R1.45.91Summer Deep Convection Z/R2-hr:0.81 #26
Over-estimation
Detroit, MIDTXDTX09 May 2008 14:00Z=200R1.64.53Marshall/Palmer
Stratiform Z/R
168-hr:1.28 #163
Under-estimation
Dryden, ONXDRWTO09 May 2008 14:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:2.29 #44
Under-estimation
Duluth, MNDLHDLH09 May 2008 14:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:1.34 #616
Under-estimation
Exeter, ONWSOWTO09 May 2008 14:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.80 #56
Under-estimation
Foxwarren, MBXFWWWG09 May 2008 14:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
2160-hr:1.76 #43
Under-estimation
Gaylord/NC Lwr MIAPXAPX09 May 2008 14:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:1.10 #162
Under-estimation
Grand Rapids, MIGRRGRR09 May 2008 14:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:1.23 #288
Under-estimation
Green Bay, WIGRBGRB09 May 2008 14:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:1.04 #486
No Bias
Indianapolis, ININDIND09 May 2008 14:00Z=200R1.64.92Marshall/Palmer
Stratiform Z/R
10-hr:1.05 #30
No Bias
La Crosse, WIARXARX09 May 2008 14:00Z=300R1.43.00Summer Deep Convection Z/R168-hr:0.72 #1167
Over-estimation
Lasseteer Lake, ONXNIWTO09 May 2008 14:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:3.58 #53
Under-estimation
Lincoln/Ctl IllinoisILXILX09 May 2008 14:00Z=300R1.44.09Summer Deep Convection Z/R10-hr:1.00 #54
No Bias
Marquette, MIMQTMQT09 May 2008 14:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.25 #305
Under-estimation
Mayville/Grand ForksMVXFGF09 May 2008 14:00Z=130R24.09Cool Season (East)
Stratiform Z/R
168-hr:0.73 #212
Over-estimation
Milwaukee, WIMKXMKX09 May 2008 14:00Z=300R1.43.94Summer Deep Convection Z/R168-hr:1.07 #573
Under-estimation
Minneapolis, MNMPXMPX09 May 2008 14:00Z=300R1.42.78Summer Deep Convection Z/R168-hr:1.08 #923
Under-estimation
Minot AFB, NDMBXBIS09 May 2008 14:00Z=130R24.09Cool Season (East)
Stratiform Z/R
168-hr:0.70 #47
Over-estimation
Montreal River, ONWGJWTO09 May 2008 14:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.82 #54
Under-estimation
North Webster/Nrn INIWXIWX09 May 2008 14:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.10 #474
Under-estimation
Omaha/Valley, NEOAXOAX09 May 2008 14:00Z=300R1.44.09Summer Deep Convection Z/R2-hr:0.99 #20
No Bias
Owensville, INVWXPAH09 May 2008 14:00Z=300R1.44.09Summer Deep Convection Z/R10-hr:1.23 #43
Under-estimation
Paducah, KYPAHPAH09 May 2008 14:00Z=300R1.44.09Summer Deep Convection Z/R10-hr:0.98 #37
No Bias
Pleasant Hill, MOEAXEAX09 May 2008 14:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
1-hr:0.78 #23
Over-estimation
Quad Cities, IA/ILDVNDVN09 May 2008 14:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:0.69 #1159
Over-estimation
Sioux Falls, SDFSDFSD09 May 2008 14:00Z=300R1.44.09Summer Deep Convection Z/R3-hr:0.92 #24
Over-estimation
Springfield, MOSGFSGF09 May 2008 14:00Z=300R1.44.09Summer Deep Convection Z/R5-hr:1.18 #27
Under-estimation
St. Louis, MOLSXLSX09 May 2008 14:00Z=300R1.44.09Summer Deep Convection Z/R5-hr:0.56 #26
Over-estimation
Woodlands, MBXWLWWG09 May 2008 14:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.47 #36
Under-estimation


Generated by get_ZR script Fri 05/09/2008 14:55 UTC