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, SDABRABR23 Nov 2009 10:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:0.78 #65
Over-estimation
Bethune, SKXBEWWG23 Nov 2009 10:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
720-hr:1.44 #31
Under-estimation
Bismarck, NDBISBIS23 Nov 2009 03:00Z=200R1.67.87Marshall/Palmer
Stratiform Z/R
720-hr:1.21 #239
Under-estimation
Chicago, ILLOTLOT23 Nov 2009 10:00Z=200R1.63.44Marshall/Palmer
Stratiform Z/R
168-hr:0.91 #704
Over-estimation
Des Moines, IADMXDMX23 Nov 2009 10:00Z=200R1.65.91Marshall/Palmer
Stratiform Z/R
2-hr:0.37 #32
Over-estimation
Detroit, MIDTXDTX23 Nov 2009 10:00Z=200R1.64.53Marshall/Palmer
Stratiform Z/R
168-hr:0.91 #125
Over-estimation
Duluth, MNDLHDLH23 Nov 2009 10:00Z=130R24.09Cool Season (East)
Stratiform Z/R
0-hr:0.72 #21
Over-estimation
Exeter, ONWSOWTO23 Nov 2009 10:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.34 #30
Under-estimation
Foxwarren, MBXFWWWG23 Nov 2009 10:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
720-hr:1.57 #34
Under-estimation
Gaylord/NC Lwr MIAPXAPX23 Nov 2009 10:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.05 #70
No Bias
Grand Rapids, MIGRRGRR23 Nov 2009 10:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:0.94 #295
Over-estimation
Green Bay, WIGRBGRB23 Nov 2009 10:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:0.92 #221
Over-estimation
Indianapolis, ININDIND23 Nov 2009 10:00Z=200R1.64.92Marshall/Palmer
Stratiform Z/R
168-hr:1.06 #362
Under-estimation
La Crosse, WIARXARX23 Nov 2009 10:00Z=200R1.63.00Marshall/Palmer
Stratiform Z/R
2-hr:0.45 #28
Over-estimation
Lasseteer Lake, ONXNIWTO23 Nov 2009 10:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:2.38 #47
Under-estimation
Lincoln/Ctl IllinoisILXILX23 Nov 2009 10:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.01 #1544
No Bias
Marquette, MIMQTMQT23 Nov 2009 10:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.17 #75
Under-estimation
Mayville/Grand ForksMVXFGF23 Nov 2009 10:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.11 #85
Under-estimation
Milwaukee, WIMKXMKX23 Nov 2009 10:00Z=200R1.61.97Marshall/Palmer
Stratiform Z/R
168-hr:1.16 #405
Under-estimation
Minneapolis, MNMPXMPX23 Nov 2009 10:00Z=130R22.78Cool Season (East)
Stratiform Z/R
2-hr:0.57 #23
Over-estimation
Minot AFB, NDMBXBIS23 Nov 2009 10:00Z=200R1.67.87Marshall/Palmer
Stratiform Z/R
720-hr:0.90 #232
Over-estimation
Montreal River, ONWGJWTO23 Nov 2009 10:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.90 #20
Under-estimation
North Webster/Nrn INIWXIWX23 Nov 2009 10:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:0.72 #426
Over-estimation
Omaha/Valley, NEOAXOAX23 Nov 2009 10:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.59 #104
Under-estimation
Owensville, INVWXPAH23 Nov 2009 10:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.31 #480
Under-estimation
Paducah, KYPAHPAH23 Nov 2009 10:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.12 #422
Under-estimation
Pleasant Hill, MOEAXEAX23 Nov 2009 10:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.02 #405
No Bias
Quad Cities, IA/ILDVNDVN23 Nov 2009 10:00Z=130R24.09Cool Season (East)
Stratiform Z/R
2-hr:0.41 #26
Over-estimation
Sioux Falls, SDFSDFSD23 Nov 2009 10:00Z=130R24.09Cool Season (East)
Stratiform Z/R
168-hr:1.11 #87
Under-estimation
Springfield, MOSGFSGF23 Nov 2009 10:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.57 #221
Under-estimation
St. Louis, MOLSXLSX23 Nov 2009 10:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:0.96 #1584
No Bias
Woodlands, MBXWLWWG23 Nov 2009 10:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
720-hr:1.76 #184
Under-estimation


Generated by get_ZR script Mon 11/23/2009 10:55 UTC