Wind Guidance added to the MRF MOS Messages

Effective on or about September 18, 2002, guidance for maximum sustained surface wind speed (WND) during a 12-h period will be added to the MRF MOS alphanumeric and BUFR messages produced from the 0000 UTC run of the NWS Global Forecast System (GFS). Guidance for the wind speed will be available in the alphanumeric message for forecast projections valid every 12 hours ending 24 to 192 hours after 0000 UTC. The forecasts are valid for the 1200-0000 and 0000-1200 UTC periods. In the development of the equations used to produce this guidance, the record observations at all hours between 1200 and 0000 UTC (or between 0000 and 1200 UTC) were examined, and the maximum sustained wind speed was extracted. The equations were derived for individual stations. Since the wind speed is continuous, a full range of forecast values is possible and will be displayed in the message in units of knots. Likewise, because equations were developed for individual stations, missing forecasts are possible if the station was not open full-time during the period of record used for development. A missing forecast is denoted by 999. Finally, please note that the wind speed forecasts are inflated before dissemination to the users, as is done with MOS wind speed forecasts valid at specific hours. In AWIPS, the MRF MOS alphanumeric messages are available as the MEXxxx product where xxx denotes the station identifier (3 characters). See Technical Procedures Bulletin No. 460 at TPB 460 for further details about the MEX product. Note, however, that the description of the WND guidance is incorrect in the TPB. A modified TPB will be forthcoming soon..

In addition to the guidance for sustained wind speed, the BUFR messages contain probabilistic forecasts of four categories of wind speed, namely, speeds less than 13 knots, 13 to 21 knots, 22 to 33 knots, and 34 knots or greater. Guidance is valid for projections every 12 hours from 24 to 192 hours after 0000 UTC. Please see MOS Guidance in BUFR Format for additional details. For a complete summary of the MRF MOS products, including graphical displays of the probabilities, please view the: MOS Forecast Products Page

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Page created September 16, 2002