National Weather Service United States Department of Commerce

Heavy Rain Threat Along Central Gulf Coast and in the Pacific Northwest

Locally heavy rainfall and flash flooding remains likely along the central Gulf Coast into the weekend from southeast Louisiana to the Florida Panhandle. A strong cold front will bring heavy rain and some high elevation snow with the arrival of cooler temperatures to the Northwest through the weekend. Widespread elevated fire threat possible from the Great Basin into the northern/central Plains. Read More >

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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":"Fri Sep 17 03:30:02 CST 2021", "zrData":[ { "bgstyle":"row-even", "id":"BMX", "cellbg":"", "update":"3am CST 17-Sep-2021", "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":"366 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.17", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#00CC00", "bcf":"1.17", "bcfNumPairs":"366", "bcfDesc":"under-estimation" }, { "bgstyle":"row-odd", "id":"DGX", "cellbg":"", "update":"3am CST 17-Sep-2021", "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":"11 positive gage-radar pairings found over the past 3 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 2.12", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"3-hr", "bcfColor":"#CC0000", "bcf":"2.12", "bcfNumPairs":"11", "bcfDesc":"under-estimation" }, { "bgstyle":"row-even", "id":"FCX", "cellbg":"", "update":"3am CST 17-Sep-2021", "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":"119 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.51", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#CC0000", "bcf":"1.51", "bcfNumPairs":"119", "bcfDesc":"under-estimation" }, { "bgstyle":"row-odd", "id":"FFC", "cellbg":"", "update":"3am CST 17-Sep-2021", "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 10 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.24", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"10-hr", "bcfColor":"#CC0000", "bcf":"1.24", "bcfNumPairs":"13", "bcfDesc":"under-estimation" }, { "bgstyle":"row-even", "id":"FWS", "cellbg":"", "update":"3am CST 17-Sep-2021", "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":"16 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 0.83", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#CC0000", "bcf":"0.83", "bcfNumPairs":"16", "bcfDesc":"over-estimation" }, { "bgstyle":"row-odd", "id":"GSP", "cellbg":"", "update":"3am CST 17-Sep-2021", "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":"11 positive gage-radar pairings found over the past 5 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 2.27", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"5-hr", "bcfColor":"#CC0000", "bcf":"2.27", "bcfNumPairs":"11", "bcfDesc":"under-estimation" }, { "bgstyle":"row-even", "id":"HGX", "cellbg":"", "update":"3am CST 17-Sep-2021", "zrCoef":"250", "zrExp":"1.2", "icon":"Tropical ZR.png", "iconAlt":"Rosenfeld Tropical Z/R icon", "rate":"0.85", "formulaName":"Rosenfeld Tropical Z/R", "bcfTitle":"1270 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.00", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#00CC00", "bcf":"1.00", "bcfNumPairs":"1270", "bcfDesc":"unbiased estimation" }, { "bgstyle":"row-odd", "id":"HPX", "cellbg":"", "update":"3am CST 17-Sep-2021", "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":"481 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.52", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#CC0000", "bcf":"1.52", "bcfNumPairs":"481", "bcfDesc":"under-estimation" }, { "bgstyle":"row-even", "id":"HTX", "cellbg":"", "update":"3am CST 17-Sep-2021", "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":"27 positive gage-radar pairings found over the past 10 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.41", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"10-hr", "bcfColor":"#CC0000", "bcf":"1.41", "bcfNumPairs":"27", "bcfDesc":"under-estimation" }, { "bgstyle":"row-odd", "id":"INX", "cellbg":"", "update":"3am CST 17-Sep-2021", "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":"74 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.15", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#00CC00", "bcf":"1.15", "bcfNumPairs":"74", "bcfDesc":"under-estimation" }, { "bgstyle":"row-even", "id":"LCH", "cellbg":"", "update":"3am CST 17-Sep-2021", "zrCoef":"250", "zrExp":"1.2", "icon":"Tropical ZR.png", "iconAlt":"Rosenfeld Tropical Z/R icon", "rate":"0.85", "formulaName":"Rosenfeld Tropical Z/R", "bcfTitle":"24 positive gage-radar pairings found over the past 10 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.49", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"10-hr", "bcfColor":"#CC0000", "bcf":"1.49", "bcfNumPairs":"24", "bcfDesc":"under-estimation" }, { "bgstyle":"row-odd", "id":"LIX", "cellbg":"", "update":"3am CST 17-Sep-2021", "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 3 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.66", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"3-hr", "bcfColor":"#CC0000", "bcf":"1.66", "bcfNumPairs":"12", "bcfDesc":"under-estimation" }, { "bgstyle":"row-even", "id":"LSX", "cellbg":"", "update":"3am CST 17-Sep-2021", "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":"152 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":"152", "bcfDesc":"over-estimation" }, { "bgstyle":"row-odd", "id":"LZK", "cellbg":"", "update":"3am CST 17-Sep-2021", "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":"248 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.29", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#CC0000", "bcf":"1.29", "bcfNumPairs":"248", "bcfDesc":"under-estimation" }, { "bgstyle":"row-even", "id":"MOB", "cellbg":"", "update":"3am CST 17-Sep-2021", "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":"23 positive gage-radar pairings found over the past 10 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.63", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"10-hr", "bcfColor":"#CC0000", "bcf":"1.63", "bcfNumPairs":"23", "bcfDesc":"under-estimation" }, { "bgstyle":"row-odd", "id":"MRX", "cellbg":"", "update":"3am CST 17-Sep-2021", "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":"35 positive gage-radar pairings found over the past 10 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.30", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"10-hr", "bcfColor":"#CC0000", "bcf":"1.30", "bcfNumPairs":"35", "bcfDesc":"under-estimation" }, { "bgstyle":"row-even", "id":"NQA", "cellbg":"", "update":"3am CST 17-Sep-2021", "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":"409 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.35", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#CC0000", "bcf":"1.35", "bcfNumPairs":"409", "bcfDesc":"under-estimation" }, { "bgstyle":"row-odd", "id":"OHX", "cellbg":"", "update":"3am CST 17-Sep-2021", "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":"651 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.25", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#CC0000", "bcf":"1.25", "bcfNumPairs":"651", "bcfDesc":"under-estimation" }, { "bgstyle":"row-even", "id":"PAH", "cellbg":"", "update":"3am CST 17-Sep-2021", "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":"537 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 0.95", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#00CC00", "bcf":"0.95", "bcfNumPairs":"537", "bcfDesc":"over-estimation" }, { "bgstyle":"row-odd", "id":"POE", "cellbg":"", "update":"3am CST 17-Sep-2021", "zrCoef":"250", "zrExp":"1.2", "icon":"Tropical ZR.png", "iconAlt":"Rosenfeld Tropical Z/R icon", "rate":"0.85", "formulaName":"Rosenfeld Tropical Z/R", "bcfTitle":"23 positive gage-radar pairings found over the past 10 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 0.97", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"10-hr", "bcfColor":"#00CC00", "bcf":"0.97", "bcfNumPairs":"23", "bcfDesc":"unbiased estimation" }, { "bgstyle":"row-even", "id":"RLX", "cellbg":"", "update":"3am CST 17-Sep-2021", "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":"46 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.36", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#CC0000", "bcf":"1.36", "bcfNumPairs":"46", "bcfDesc":"under-estimation" }, { "bgstyle":"row-odd", "id":"SGF", "cellbg":"", "update":"3am CST 17-Sep-2021", "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":"253 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":"253", "bcfDesc":"unbiased estimation" }, { "bgstyle":"row-even", "id":"SHV", "cellbg":"", "update":"3am CST 17-Sep-2021", "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":"311 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.17", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#00CC00", "bcf":"1.17", "bcfNumPairs":"311", "bcfDesc":"under-estimation" }, { "bgstyle":"row-odd", "id":"SRX", "cellbg":"", "update":"3am CST 17-Sep-2021", "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":"200 positive gage-radar pairings found over the past 168 hours", "bcfTitle2":" suggest that the radar estimates need to be multiplied by 1.25", "bcfTitle3":" to bring them in line with what the gages are reporting.", "bcfDur":"168-hr", "bcfColor":"#CC0000", "bcf":"1.25", "bcfNumPairs":"200", "bcfDesc":"under-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).