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, SDABRABR31 Jul 2014 04:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:0.53 #99
Over-estimation
Bethune 10S, SKXBEWWG31 Jul 2014 04:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.35 #68
Under-estimation
Bismarck, NDBISBIS31 Jul 2014 04:00Z=300R1.47.87Summer Deep Convection Z/R168-hr:0.61 #28
Over-estimation
Chicago, ILLOTLOT31 Jul 2014 04:00Z=300R1.43.44Summer Deep Convection Z/R168-hr:0.68 #272
Over-estimation
Des Moines, IADMXDMX31 Jul 2014 04:00Z=300R1.45.91Summer Deep Convection Z/R168-hr:0.55 #374
Over-estimation
Detroit, MIDTXDTX31 Jul 2014 04:00Z=300R1.44.53Summer Deep Convection Z/R168-hr:1.16 #237
Under-estimation
Dryden 6NNE, ONXDRWTO31 Jul 2014 04:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.91 #121
Under-estimation
Duluth, MNDLHDLH31 Jul 2014 04:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:0.80 #382
Over-estimation
Exeter 5NNE, ONWSOWTO31 Jul 2014 04:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.40 #71
Under-estimation
Foxwarren 4NE, MBXFWWWG31 Jul 2014 04:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:0.82 #176
Over-estimation
Gaylord/NC Lwr MIAPXAPX31 Jul 2014 04:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:0.84 #204
Over-estimation
Grand Rapids, MIGRRGRR31 Jul 2014 04:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:0.76 #318
Over-estimation
Green Bay, WIGRBGRB31 Jul 2014 04:00Z=300R1.44.09Summer Deep Convection Z/R3-hr:1.25 #10
Under-estimation
Indianapolis, ININDIND31 Jul 2014 04:00Z=200R1.64.92Marshall/Palmer
Stratiform Z/R
168-hr:0.69 #116
Over-estimation
La Crosse, WIARXARX31 Jul 2014 04:00Z=300R1.43.00Summer Deep Convection Z/R10-hr:1.04 #18
No Bias
Lasseteer Lake, ONXNIWTO31 Jul 2014 04:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:2.03 #128
Under-estimation
Lincoln/Ctl IllinoisILXILX31 Jul 2014 04:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:0.81 #348
Over-estimation
Marquette, MIMQTMQT31 Jul 2014 04:00Z=300R1.44.09Summer Deep Convection Z/R10-hr:1.28 #14
Under-estimation
Mayville/Grand ForksMVXFGF31 Jul 2014 04:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:0.95 #143
No Bias
Milwaukee, WIMKXMKX31 Jul 2014 04:00Z=300R1.43.94Summer Deep Convection Z/R168-hr:0.69 #270
Over-estimation
Minneapolis, MNMPXMPX31 Jul 2014 04:00Z=300R1.43.25Summer Deep Convection Z/R168-hr:0.74 #385
Over-estimation
Minot AFB, NDMBXBIS31 Jul 2014 04:00Z=300R1.47.87Summer Deep Convection Z/R168-hr:0.84 #117
Over-estimation
Montreal River, ONWGJWTO31 Jul 2014 04:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:0.99 #53
No Bias
North Webster/Nrn INIWXIWX31 Jul 2014 04:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:0.92 #241
Over-estimation
Omaha/Valley, NEOAXOAX31 Jul 2014 04:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:0.46 #75
Over-estimation
Owensville, INVWXPAH31 Jul 2014 04:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:0.63 #86
Over-estimation
Paducah, KYPAHPAH31 Jul 2014 04:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:0.64 #68
Over-estimation
Pleasant Hill, MOEAXEAX31 Jul 2014 04:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:0.68 #61
Over-estimation
Quad Cities, IA/ILDVNDVN31 Jul 2014 04:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:0.80 #442
Over-estimation
Sioux Falls, SDFSDFSD31 Jul 2014 04:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:0.61 #230
Over-estimation
Springfield, MOSGFSGF31 Jul 2014 04:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:0.83 #42
Over-estimation
St. Louis, MOLSXLSX31 Jul 2014 04:00Z=300R1.44.09Summer Deep Convection Z/R168-hr:0.67 #245
Over-estimation
Woodlands 6SW, MBXWLWWG31 Jul 2014 04:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.02 #135
No Bias


Generated by get_ZR script Thu 07/31/2014 04:35 UTC