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, SDABRABR24 Jul 2014 21:00Z=300R1.44.09Summer Deep Convection Z/R1-hr:0.56 #16
Over-estimation
Bethune 10S, SKXBEWWG24 Jul 2014 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.19 #63
Under-estimation
Bismarck, NDBISBIS24 Jul 2014 21:00Z=300R1.47.87Summer Deep Convection Z/R168-hr:0.60 #57
Over-estimation
Chicago, ILLOTLOT24 Jul 2014 21:00Z=300R1.43.44Summer Deep Convection Z/R168-hr:0.87 #319
Over-estimation
Des Moines, IADMXDMX24 Jul 2014 21:00Z=300R1.45.91Summer Deep Convection Z/R1-hr:0.37 #11
Over-estimation
Detroit, MIDTXDTX24 Jul 2014 21:00Z=300R1.44.53Summer Deep Convection Z/R168-hr:1.22 #198
Under-estimation
Dryden 6NNE, ONXDRWTO24 Jul 2014 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:2.26 #147
Under-estimation
Duluth, MNDLHDLH24 Jul 2014 21:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:0.82 #322
Over-estimation
Exeter 5NNE, ONWSOWTO24 Jul 2014 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.59 #41
Under-estimation
Foxwarren 4NE, MBXFWWWG24 Jul 2014 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
10-hr:0.71 #14
Over-estimation
Gaylord/NC Lwr MIAPXAPX24 Jul 2014 21:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:1.00 #161
No Bias
Grand Rapids, MIGRRGRR24 Jul 2014 21:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:0.84 #319
Over-estimation
Green Bay, WIGRBGRB24 Jul 2014 21:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:1.06 #112
Under-estimation
Indianapolis, ININDIND24 Jul 2014 21:00Z=200R1.64.92Marshall/Palmer
Stratiform Z/R
168-hr:0.73 #124
Over-estimation
La Crosse, WIARXARX24 Jul 2014 21:00Z=300R1.43.00Summer Deep Convection Z/R168-hr:0.88 #214
Over-estimation
Lasseteer Lake, ONXNIWTO24 Jul 2014 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:2.69 #107
Under-estimation
Lincoln/Ctl IllinoisILXILX24 Jul 2014 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:0.94 #300
Over-estimation
Marquette, MIMQTMQT24 Jul 2014 21:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:1.04 #69
No Bias
Mayville/Grand ForksMVXFGF24 Jul 2014 21:00Z=300R1.44.09Summer Deep Convection Z/R2-hr:0.50 #10
Over-estimation
Milwaukee, WIMKXMKX24 Jul 2014 21:00Z=300R1.43.94Summer Deep Convection Z/R168-hr:0.73 #273
Over-estimation
Minneapolis, MNMPXMPX24 Jul 2014 21:00Z=300R1.43.25Summer Deep Convection Z/R0-hr:0.58 #13
Over-estimation
Minot AFB, NDMBXBIS24 Jul 2014 21:00Z=300R1.47.87Summer Deep Convection Z/R5-hr:0.73 #15
Over-estimation
Montreal River, ONWGJWTO24 Jul 2014 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.25 #41
Under-estimation
North Webster/Nrn INIWXIWX24 Jul 2014 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:0.92 #332
Over-estimation
Omaha/Valley, NEOAXOAX24 Jul 2014 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
5-hr:0.31 #10
Over-estimation
Owensville, INVWXPAH24 Jul 2014 21:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:0.75 #110
Over-estimation
Paducah, KYPAHPAH24 Jul 2014 21:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:0.70 #137
Over-estimation
Pleasant Hill, MOEAXEAX24 Jul 2014 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:0.72 #91
Over-estimation
Quad Cities, IA/ILDVNDVN24 Jul 2014 21:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:0.88 #312
Over-estimation
Sioux Falls, SDFSDFSD24 Jul 2014 21:00Z=300R1.44.09Summer Deep Convection Z/R0-hr:0.49 #11
Over-estimation
Springfield, MOSGFSGF24 Jul 2014 20:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:0.82 #71
Over-estimation
St. Louis, MOLSXLSX24 Jul 2014 21:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:0.81 #252
Over-estimation
Woodlands 6SW, MBXWLWWG24 Jul 2014 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:0.96 #211
No Bias


Generated by get_ZR script Thu 07/24/2014 21:35 UTC