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, SDABRABR06 Nov 2009 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:0.77 #392
Over-estimation
Bethune, SKXBEWWG06 Nov 2009 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
720-hr:1.44 #54
Under-estimation
Bismarck, NDBISBIS06 Nov 2009 21:00Z=200R1.67.87Marshall/Palmer
Stratiform Z/R
168-hr:1.36 #54
Under-estimation
Chicago, ILLOTLOT06 Nov 2009 21:00Z=200R1.63.44Marshall/Palmer
Stratiform Z/R
168-hr:1.12 #1090
Under-estimation
Des Moines, IADMXDMX06 Nov 2009 21:00Z=250R1.25.91Rosenfeld
Tropical Z/R
168-hr:1.24 #1429
Under-estimation
Detroit, MIDTXDTX06 Nov 2009 21:00Z=200R1.64.53Marshall/Palmer
Stratiform Z/R
168-hr:0.97 #279
No Bias
Dryden, ONXDRWTO06 Nov 2009 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:5.23 #67
Under-estimation
Duluth, MNDLHDLH06 Nov 2009 21:00Z=130R24.09Cool Season (East)
Stratiform Z/R
168-hr:0.98 #878
No Bias
Exeter, ONWSOWTO06 Nov 2009 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.32 #74
Under-estimation
Foxwarren, MBXFWWWG06 Nov 2009 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
720-hr:1.57 #59
Under-estimation
Gaylord/NC Lwr MIAPXAPX06 Nov 2009 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.03 #295
No Bias
Grand Rapids, MIGRRGRR06 Nov 2009 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.00 #694
No Bias
Green Bay, WIGRBGRB06 Nov 2009 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.12 #576
Under-estimation
Indianapolis, ININDIND06 Nov 2009 21:00Z=200R1.64.92Marshall/Palmer
Stratiform Z/R
168-hr:0.98 #417
No Bias
La Crosse, WIARXARX06 Nov 2009 21:00Z=200R1.63.00Marshall/Palmer
Stratiform Z/R
168-hr:0.94 #1044
Over-estimation
Lasseteer Lake, ONXNIWTO06 Nov 2009 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:2.98 #63
Under-estimation
Lincoln/Ctl IllinoisILXILX06 Nov 2009 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.09 #1725
Under-estimation
Marquette, MIMQTMQT06 Nov 2009 21:00Z=130R24.09Cool Season (East)
Stratiform Z/R
168-hr:1.02 #292
No Bias
Mayville/Grand ForksMVXFGF06 Nov 2009 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.26 #350
Under-estimation
Milwaukee, WIMKXMKX06 Nov 2009 21:00Z=200R1.61.97Marshall/Palmer
Stratiform Z/R
168-hr:1.29 #1042
Under-estimation
Minneapolis, MNMPXMPX06 Nov 2009 21:00Z=130R22.78Cool Season (East)
Stratiform Z/R
168-hr:0.95 #943
No Bias
Minot AFB, NDMBXBIS06 Nov 2009 21:00Z=200R1.67.87Marshall/Palmer
Stratiform Z/R
168-hr:0.98 #52
No Bias
Montreal River, ONWGJWTO06 Nov 2009 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:2.13 #145
Under-estimation
North Webster/Nrn INIWXIWX06 Nov 2009 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:0.87 #708
Over-estimation
Omaha/Valley, NEOAXOAX06 Nov 2009 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.70 #439
Under-estimation
Owensville, INVWXPAH06 Nov 2009 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.11 #734
Under-estimation
Paducah, KYPAHPAH06 Nov 2009 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:0.99 #796
No Bias
Pleasant Hill, MOEAXEAX06 Nov 2009 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:0.96 #349
No Bias
Quad Cities, IA/ILDVNDVN06 Nov 2009 21:00Z=130R24.09Cool Season (East)
Stratiform Z/R
168-hr:0.93 #1665
Over-estimation
Sioux Falls, SDFSDFSD06 Nov 2009 21:00Z=130R24.09Cool Season (East)
Stratiform Z/R
168-hr:1.19 #569
Under-estimation
Springfield, MOSGFSGF06 Nov 2009 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:1.54 #345
Under-estimation
St. Louis, MOLSXLSX06 Nov 2009 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:0.97 #1776
No Bias
Woodlands, MBXWLWWG06 Nov 2009 21:00Z=200R1.64.09Marshall/Palmer
Stratiform Z/R
168-hr:3.42 #51
Under-estimation


Generated by get_ZR script Fri 11/06/2009 21:55 UTC