Lower Mississippi RFC
River Forecast Center
Important Disclaimer
The following table is experimental and not an official forecast product. The table was created to display the Z-R (radar reflectivity to rain rate) relationships being used by individual NEXRAD sites throughout the LMRFC area. Bias correction values and selected ZR relationships are valid for the entire NEXRAD coverage area and are not necessarily valid for individual spot locations.
Experimental products may not always update in a timely manner and may be discontinued at a future date. Experimental products may not always reflect accurate, quality controlled information and should be used with caution.
Official rainfall estimates and observations remain available from the main LMRFC "Observed/Past Precipitation" page.
| { "timestamp":"Wed Jun 12 07:30:02 CST 2024", "zrData":[ { "bgstyle":"row-even", "id":"BMX", "cellbg":"", "update":"7am CST 12-Jun-2024", "zrCoef":"300", "zrExp":"1.4", "icon":"Deep Convective ZR.png", "iconAlt":"Summer Deep Convection Z/R icon", "rate":"0.48", "formulaName":"Summer Deep Convection Z/R", "bcfTitle":"390 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 0.75", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#CC0000", "bcf":"0.75", "bcfNumPairs":"390", "bcfDesc":"over-estimation" }, { "bgstyle":"row-odd", "id":"DGX", "cellbg":"", "update":"7am CST 12-Jun-2024", "zrCoef":"300", "zrExp":"1.4", "icon":"Deep Convective ZR.png", "iconAlt":"Summer Deep Convection Z/R icon", "rate":"0.48", "formulaName":"Summer Deep Convection Z/R", "bcfTitle":"538 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 0.65", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#CC0000", "bcf":"0.65", "bcfNumPairs":"538", "bcfDesc":"over-estimation" }, { "bgstyle":"row-even", "id":"FCX", "cellbg":"", "update":"7am CST 12-Jun-2024", "zrCoef":"300", "zrExp":"1.4", "icon":"Deep Convective ZR.png", "iconAlt":"Summer Deep Convection Z/R icon", "rate":"0.48", "formulaName":"Summer Deep Convection Z/R", "bcfTitle":"132 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.19", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#CC0000", "bcf":"1.19", "bcfNumPairs":"132", "bcfDesc":"under-estimation" }, { "bgstyle":"row-odd", "id":"FFC", "cellbg":"", "update":"7am CST 12-Jun-2024", "zrCoef":"300", "zrExp":"1.4", "icon":"Deep Convective ZR.png", "iconAlt":"Summer Deep Convection Z/R icon", "rate":"0.48", "formulaName":"Summer Deep Convection Z/R", "bcfTitle":"356 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 0.89", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#00CC00", "bcf":"0.89", "bcfNumPairs":"356", "bcfDesc":"over-estimation" }, { "bgstyle":"row-even", "id":"FWS", "cellbg":"", "update":"7am CST 12-Jun-2024", "zrCoef":"300", "zrExp":"1.4", "icon":"Deep Convective ZR.png", "iconAlt":"Summer Deep Convection Z/R icon", "rate":"0.48", "formulaName":"Summer Deep Convection Z/R", "bcfTitle":"237 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 0.84", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#CC0000", "bcf":"0.84", "bcfNumPairs":"237", "bcfDesc":"over-estimation" }, { "bgstyle":"row-odd", "id":"GSP", "cellbg":"", "update":"6am CST 12-Jun-2024", "zrCoef":"300", "zrExp":"1.4", "icon":"Deep Convective ZR.png", "iconAlt":"Summer Deep Convection Z/R icon", "rate":"0.48", "formulaName":"Summer Deep Convection Z/R", "bcfTitle":"704 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.33", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#CC0000", "bcf":"1.33", "bcfNumPairs":"704", "bcfDesc":"under-estimation" }, { "bgstyle":"row-even", "id":"HDC", "cellbg":"", "update":"7am CST 12-Jun-2024", "zrCoef":"300", "zrExp":"1.4", "icon":"Deep Convective ZR.png", "iconAlt":"Summer Deep Convection Z/R icon", "rate":"0.48", "formulaName":"Summer Deep Convection Z/R", "bcfTitle":"591 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 0.80", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#CC0000", "bcf":"0.80", "bcfNumPairs":"591", "bcfDesc":"over-estimation" }, { "bgstyle":"row-odd", "id":"HGX", "cellbg":"", "update":"7am CST 12-Jun-2024", "zrCoef":"300", "zrExp":"1.4", "icon":"Deep Convective ZR.png", "iconAlt":"Summer Deep Convection Z/R icon", "rate":"0.48", "formulaName":"Summer Deep Convection Z/R", "bcfTitle":"12 positive gage-radar pairings found over the past 5 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.16", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"5-hr", "bcfColor":"#00CC00", "bcf":"1.16", "bcfNumPairs":"12", "bcfDesc":"under-estimation" }, { "bgstyle":"row-even", "id":"HPX", "cellbg":"", "update":"7am CST 12-Jun-2024", "zrCoef":"200", "zrExp":"1.6", "icon":"Gen Stratiform ZR.png", "iconAlt":"Marshall/Palmer Stratiform Z/R icon", "rate":"0.45", "formulaName":"Marshall/Palmer Stratiform Z/R", "bcfTitle":"977 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.08", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#00CC00", "bcf":"1.08", "bcfNumPairs":"977", "bcfDesc":"under-estimation" }, { "bgstyle":"row-odd", "id":"HTX", "cellbg":"", "update":"7am CST 12-Jun-2024", "zrCoef":"300", "zrExp":"1.4", "icon":"Deep Convective ZR.png", "iconAlt":"Summer Deep Convection Z/R icon", "rate":"0.48", "formulaName":"Summer Deep Convection Z/R", "bcfTitle":"1211 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.04", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#00CC00", "bcf":"1.04", "bcfNumPairs":"1211", "bcfDesc":"unbiased estimation" }, { "bgstyle":"row-even", "id":"INX", "cellbg":"", "update":"7am CST 12-Jun-2024", "zrCoef":"300", "zrExp":"1.4", "icon":"Deep Convective ZR.png", "iconAlt":"Summer Deep Convection Z/R icon", "rate":"0.48", "formulaName":"Summer Deep Convection Z/R", "bcfTitle":"178 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 0.67", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#CC0000", "bcf":"0.67", "bcfNumPairs":"178", "bcfDesc":"over-estimation" }, { "bgstyle":"row-odd", "id":"LCH", "cellbg":"", "update":"7am CST 12-Jun-2024", "zrCoef":"300", "zrExp":"1.4", "icon":"Deep Convective ZR.png", "iconAlt":"Summer Deep Convection Z/R icon", "rate":"0.48", "formulaName":"Summer Deep Convection Z/R", "bcfTitle":"13 positive gage-radar pairings found over the past 5 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.54", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"5-hr", "bcfColor":"#CC0000", "bcf":"1.54", "bcfNumPairs":"13", "bcfDesc":"under-estimation" }, { "bgstyle":"row-even", "id":"LSX", "cellbg":"", "update":"7am CST 12-Jun-2024", "zrCoef":"300", "zrExp":"1.4", "icon":"Deep Convective ZR.png", "iconAlt":"Summer Deep Convection Z/R icon", "rate":"0.48", "formulaName":"Summer Deep Convection Z/R", "bcfTitle":"472 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 0.65", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#CC0000", "bcf":"0.65", "bcfNumPairs":"472", "bcfDesc":"over-estimation" }, { "bgstyle":"row-odd", "id":"LZK", "cellbg":"", "update":"7am CST 12-Jun-2024", "zrCoef":"300", "zrExp":"1.4", "icon":"Deep Convective ZR.png", "iconAlt":"Summer Deep Convection Z/R icon", "rate":"0.48", "formulaName":"Summer Deep Convection Z/R", "bcfTitle":"821 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 0.82", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#CC0000", "bcf":"0.82", "bcfNumPairs":"821", "bcfDesc":"over-estimation" }, { "bgstyle":"row-even", "id":"MOB", "cellbg":"", "update":"7am CST 12-Jun-2024", "zrCoef":"300", "zrExp":"1.4", "icon":"Deep Convective ZR.png", "iconAlt":"Summer Deep Convection Z/R icon", "rate":"0.48", "formulaName":"Summer Deep Convection Z/R", "bcfTitle":"258 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.12", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#00CC00", "bcf":"1.12", "bcfNumPairs":"258", "bcfDesc":"under-estimation" }, { "bgstyle":"row-odd", "id":"MRX", "cellbg":"", "update":"7am CST 12-Jun-2024", "zrCoef":"200", "zrExp":"1.6", "icon":"Gen Stratiform ZR.png", "iconAlt":"Marshall/Palmer Stratiform Z/R icon", "rate":"0.45", "formulaName":"Marshall/Palmer Stratiform Z/R", "bcfTitle":"1179 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.10", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#00CC00", "bcf":"1.10", "bcfNumPairs":"1179", "bcfDesc":"under-estimation" }, { "bgstyle":"row-even", "id":"NQA", "cellbg":"", "update":"7am CST 12-Jun-2024", "zrCoef":"300", "zrExp":"1.4", "icon":"Deep Convective ZR.png", "iconAlt":"Summer Deep Convection Z/R icon", "rate":"0.48", "formulaName":"Summer Deep Convection Z/R", "bcfTitle":"903 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 0.85", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#CC0000", "bcf":"0.85", "bcfNumPairs":"903", "bcfDesc":"over-estimation" }, { "bgstyle":"row-odd", "id":"OHX", "cellbg":"", "update":"7am CST 12-Jun-2024", "zrCoef":"300", "zrExp":"1.4", "icon":"Deep Convective ZR.png", "iconAlt":"Summer Deep Convection Z/R icon", "rate":"0.48", "formulaName":"Summer Deep Convection Z/R", "bcfTitle":"1047 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 0.93", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#00CC00", "bcf":"0.93", "bcfNumPairs":"1047", "bcfDesc":"over-estimation" }, { "bgstyle":"row-even", "id":"PAH", "cellbg":"", "update":"7am CST 12-Jun-2024", "zrCoef":"200", "zrExp":"1.6", "icon":"Gen Stratiform ZR.png", "iconAlt":"Marshall/Palmer Stratiform Z/R icon", "rate":"0.45", "formulaName":"Marshall/Palmer Stratiform Z/R", "bcfTitle":"1201 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 0.74", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#CC0000", "bcf":"0.74", "bcfNumPairs":"1201", "bcfDesc":"over-estimation" }, { "bgstyle":"row-odd", "id":"POE", "cellbg":"", "update":"7am CST 12-Jun-2024", "zrCoef":"300", "zrExp":"1.4", "icon":"Deep Convective ZR.png", "iconAlt":"Summer Deep Convection Z/R icon", "rate":"0.48", "formulaName":"Summer Deep Convection Z/R", "bcfTitle":"13 positive gage-radar pairings found over the past 5 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.27", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"5-hr", "bcfColor":"#CC0000", "bcf":"1.27", "bcfNumPairs":"13", "bcfDesc":"under-estimation" }, { "bgstyle":"row-even", "id":"RLX", "cellbg":"", "update":"7am CST 12-Jun-2024", "zrCoef":"300", "zrExp":"1.4", "icon":"Deep Convective ZR.png", "iconAlt":"Summer Deep Convection Z/R icon", "rate":"0.48", "formulaName":"Summer Deep Convection Z/R", "bcfTitle":"45 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.12", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#00CC00", "bcf":"1.12", "bcfNumPairs":"45", "bcfDesc":"under-estimation" }, { "bgstyle":"row-odd", "id":"SGF", "cellbg":"yellow", "update":"6am CST 11-Jun-2024", "zrCoef":"300", "zrExp":"1.4", "icon":"Deep Convective ZR.png", "iconAlt":"Summer Deep Convection Z/R icon", "rate":"0.48", "formulaName":"Summer Deep Convection Z/R", "bcfTitle":"756 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 0.70", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#CC0000", "bcf":"0.70", "bcfNumPairs":"756", "bcfDesc":"over-estimation" }, { "bgstyle":"row-even", "id":"SHV", "cellbg":"", "update":"6am CST 12-Jun-2024", "zrCoef":"300", "zrExp":"1.4", "icon":"Deep Convective ZR.png", "iconAlt":"Summer Deep Convection Z/R icon", "rate":"0.48", "formulaName":"Summer Deep Convection Z/R", "bcfTitle":"63 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 0.84", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#CC0000", "bcf":"0.84", "bcfNumPairs":"63", "bcfDesc":"over-estimation" }, { "bgstyle":"row-odd", "id":"SRX", "cellbg":"", "update":"7am CST 12-Jun-2024", "zrCoef":"300", "zrExp":"1.4", "icon":"Deep Convective ZR.png", "iconAlt":"Summer Deep Convection Z/R icon", "rate":"0.48", "formulaName":"Summer Deep Convection Z/R", "bcfTitle":"730 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 0.90", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#00CC00", "bcf":"0.90", "bcfNumPairs":"730", "bcfDesc":"over-estimation" }] } |
The table above shows WSR-88D Z/R relationships for radar sites within the LMRFC area. A Z/R relationship is a empirical formula that is used to estimate rainfall rates from reflectivity signal strength. Parameters that can be varied at each radar site are those shown in red.
Often times stratiform rain events have a reflectivity signal strength of 20-40dBZ. Convective rain events can often range from 40-55dBZ. For more information and recommendations regarding Z/R relationships, see the Radar Operations Center's Handbook. Refer to Section 7.7.2 Z-R Coefficients. (This handbook is for agency use only, and requires a NOAA LDAP login.)
The bias correction factor can only be computed if there are at least 10 gage-radar pairs with both values 0.03 inches or more. Sometimes, data has to be searched back several hours to find at least 10 such pairs. (The actual number of pairs used in computing this bias factor is shown following the # sign.) The number of hours searched is shown preceding the bias factor. Bias factors are color-coded green if the radar estimates are within 15% tolerance of what the gages verify, or red otherwise. Values over 1.0 mean the radar is under-estimating. Values under 1.0 means the radar is over-estimating. This may seem counter-intuitive. To get the radar estimates to verify well with the gage values, the radar estimates would have to be multiplied by this bias factor shown for each radar.
Any cells with a yellow background under the "Last Reported" column indicate that the latest report is not up-to-date (perhaps the radar is down for maintenance).
