
I can see 3 seconds update in the Tempest website but not sure if its related with the "Tempest app setup", I have to double check that since I'm not sure where that setting is (I'm new to WeatherFlow).
If I enabled rapid fire in WeeWx, I see WU getting the RapidFire interval but with the missing Gust value.
Dec 2 14:03:27 weewx-vm weewx[9466] INFO weewx.restx: Wunderground-RF: Published record 2020-12-02 14:03:26 EST (1606935806)
Dec 2 14:03:28 weewx-vm weewx[9466] DEBUG weewx.restx: Ambient: url: https://rtupdate.wunderground.com/weatherstation/updateweatherstation.php?action=updateraw&ID=KMDMILLE9&PASSWORD=XXX&softwaretype=weewx-4.2.0&tempf=47.9&humidity=040&dateutc=2020-12-02%2019%3A03%3A27&realtime=1&solarradiation=219.00&rtfreq=2.5&baromin=30.123&dewptf=24.7&rainin=0.00&UV=1.35&dailyrainin=0.00&winddir=321&windspeedmph=3.3
Dec 2 14:03:28 weewx-vm weewx[9466] INFO weewx.restx: Wunderground-RF: Published record 2020-12-02 14:03:27 EST (1606935807)
Dec 2 14:03:30 weewx-vm weewx[9466] DEBUG weewx.restx: Ambient: url: https://rtupdate.wunderground.com/weatherstation/updateweatherstation.php?action=updateraw&ID=KMDMILLE9&PASSWORD=XXX&softwaretype=weewx-4.2.0&tempf=47.9&humidity=040&dateutc=2020-12-02%2019%3A03%3A29&realtime=1&solarradiation=219.00&rtfreq=2.5&baromin=30.123&dewptf=24.7&rainin=0.00&UV=1.35&dailyrainin=0.00&winddir=317&windspeedmph=4.1
Dec 2 14:03:30 weewx-vm weewx[9466] INFO weewx.restx: Wunderground-RF: Published record 2020-12-02 14:03:29 EST (1606935809)
Dec 2 14:03:33 weewx-vm weewx[9466] DEBUG weewx.restx: Ambient: url: https://rtupdate.wunderground.com/weatherstation/updateweatherstation.php?action=updateraw&ID=KMDMILLE9&PASSWORD=XXX&softwaretype=weewx-4.2.0&tempf=47.9&humidity=040&dateutc=2020-12-02%2019%3A03%3A32&realtime=1&solarradiation=219.00&rtfreq=2.5&baromin=30.123&dewptf=24.7&rainin=0.00&UV=1.35&dailyrainin=0.00&winddir=022&windspeedmph=8.9
Dec 2 14:03:33 weewx-vm weewx[9466] INFO weewx.restx: Wunderground-RF: Published record 2020-12-02 14:03:32 EST (1606935812)
Dec 2 14:03:36 weewx-vm weewx[9466] DEBUG weewx.restx: Ambient: url: https://rtupdate.wunderground.com/weatherstation/updateweatherstation.php?action=updateraw&ID=KMDMILLE9&PASSWORD=XXX&softwaretype=weewx-4.2.0&tempf=47.9&humidity=040&dateutc=2020-12-02%2019%3A03%3A36&realtime=1&solarradiation=219.00&rtfreq=2.5&baromin=30.123&dewptf=24.7&rainin=0.00&UV=1.35&dailyrainin=0.00&winddir=005&windspeedmph=5.1
Dec 2 14:03:36 weewx-vm weewx[9466] INFO weewx.restx: Wunderground-RF: Published record 2020-12-02 14:03:36 EST (1606935816)
Dec 2 14:03:39 weewx-vm weewx[9466] DEBUG weewx.restx: Ambient: url: https://rtupdate.wunderground.com/weatherstation/updateweatherstation.php?action=updateraw&ID=KMDMILLE9&PASSWORD=XXX&softwaretype=weewx-4.2.0&tempf=47.9&humidity=040&dateutc=2020-12-02%2019%3A03%3A39&realtime=1&solarradiation=219.00&rtfreq=2.5&baromin=30.123&dewptf=24.7&rainin=0.00&UV=1.35&dailyrainin=0.00&winddir=298&windspeedmph=1.1
Dec 2 14:03:39 weewx-vm weewx[9466] INFO weewx.restx: Wunderground-RF: Published record 2020-12-02 14:03:39 EST (1606935819)
Dec 2 14:03:42 weewx-vm weewx[9466] DEBUG weewx.restx: Ambient: url: https://rtupdate.wunderground.com/weatherstation/updateweatherstation.php?action=updateraw&ID=KMDMILLE9&PASSWORD=XXX&softwaretype=weewx-4.2.0&tempf=47.9&humidity=040&dateutc=2020-12-02%2019%3A03%3A41&realtime=1&solarradiation=219.00&rtfreq=2.5&baromin=30.123&dewptf=24.7&rainin=0.00&UV=1.35&dailyrainin=0.00&winddir=293&windspeedmph=4.7
Dec 2 14:03:42 weewx-vm weewx[9466] INFO weewx.restx: Wunderground-RF: Published record 2020-12-02 14:03:41 EST (1606935821)
Dec 2 14:03:45 weewx-vm weewx[9466] DEBUG weewx.restx: Ambient: url: https://rtupdate.wunderground.com/weatherstation/updateweatherstation.php?action=updateraw&ID=KMDMILLE9&PASSWORD=XXX&softwaretype=weewx-4.2.0&tempf=47.9&humidity=040&dateutc=2020-12-02%2019%3A03%3A44&realtime=1&solarradiation=219.00&rtfreq=2.5&baromin=30.123&dewptf=24.7&rainin=0.00&UV=1.35&dailyrainin=0.00&winddir=006&windspeedmph=6.0
Dec 2 14:03:45 weewx-vm weewx[9466] INFO weewx.restx: Wunderground-RF: Published record 2020-12-02 14:03:44 EST (1606935824)
Dec 2 14:03:48 weewx-vm weewx[9466] DEBUG weewx.restx: Ambient: url: https://rtupdate.wunderground.com/weatherstation/updateweatherstation.php?action=updateraw&ID=KMDMILLE9&PASSWORD=XXX&softwaretype=weewx-4.2.0&tempf=47.9&humidity=040&dateutc=2020-12-02%2019%3A03%3A47&realtime=1&solarradiation=219.00&rtfreq=2.5&baromin=30.123&dewptf=24.7&rainin=0.00&UV=1.35&dailyrainin=0.00&winddir=299&windspeedmph=5.6
Dec 2 14:03:48 weewx-vm weewx[9466] INFO weewx.restx: Wunderground-RF: Published record 2020-12-02 14:03:47 EST (1606935827)
Dec 2 14:03:51 weewx-vm weewx[9466] DEBUG weewx.restx: Ambient: url: https://rtupdate.wunderground.com/weatherstation/updateweatherstation.php?action=updateraw&ID=KMDMILLE9&PASSWORD=XXX&softwaretype=weewx-4.2.0&tempf=47.9&humidity=040&dateutc=2020-12-02%2019%3A03%3A50&realtime=1&solarradiation=219.00&rtfreq=2.5&baromin=30.123&dewptf=24.7&rainin=0.00&UV=1.35&dailyrainin=0.00&winddir=311&windspeedmph=5.5
Dec 2 14:03:51 weewx-vm weewx[9466] INFO weewx.restx: Wunderground-RF: Published record 2020-12-02 14:03:50 EST (1606935830)
Dec 2 14:10:18 weewx-vm weewx[9622] DEBUG weewx.restx: Ambient: url: https://weatherstation.wunderground.com/weatherstation/updateweatherstation.php?action=updateraw&ID=KMDMILLE9&PASSWORD=XXX&softwaretype=weewx-4.2.0&tempf=47.7&humidity=040&dateutc=2020-12-02%2019%3A10%3A00&solarradiation=234.00&baromin=30.122&dewptf=24.6&rainin=0.00&UV=1.45&dailyrainin=0.00&winddir=334&windspeedmph=5.0&windgustmph=14.3
Log with RapidFire enabled;
Dec 2 14:03:51 weewx-vm weewx[9466] DEBUG weewx.restx: Ambient: url: https://rtupdate.wunderground.com/weatherstation/updateweatherstation.php?action=updateraw&ID=KMDMILLE9&PASSWORD=XXX&softwaretype=weewx-4.2.0&tempf=47.9&humidity=040&dateutc=2020-12-02%2019%3A03%3A50&realtime=1&solarradiation=219.00&rtfreq=2.5&baromin=30.123&dewptf=24.7&rainin=0.00&UV=1.35&dailyrainin=0.00&winddir=311&windspeedmph=5.5
Definitely "windgust" data is missing from WeeWx stream when WU RapiFire option is enabled.
When you are receiving wind speed values (only) every three seconds what does windGust mean? The highest wind speed value seen in that three second period?