What's the most incorrect/inaccurate TAF you have seen compared to the METAR or trends? I've had forecasters do NOWcast TAFs in which they call VFR all day then wait til a squall line is right off the departure end to put out an amended TAF. It is as if they are waiting on the ASOS sensors to update then they literally copy paste that into the TAF main body (yes I have seen it happen!). On the other hand I've had TAFs where they were calling for IFR conditions only for the past 4 hours and 4 hours thereafter showing VFR in every METAR update. The cuts to NWS isnt helping matters either when it comes to accurate reliable forecasts. This makes the forecast discussion even more useful to see reasoning behind the forecasters thinking.
In terms of wind forecast accuracy DEN is notorious for giving up on wind direction determination usually due to microbursts and the extreme wind shifts DEN gets during anything but clear skies. But in that case may as well put FC in the TAF too. Example the PROB30 below.
TAF KDEN 211223Z 2112/2218 23010KT P6SM FEW220
FM211500 25007KT P6SM FEW220
FM211800 01010KT P6SM SCT120 BKN150
PROB30 2122/2201 VRB25G40KT -SHRA
FM220100 09010KT P6SM FEW080 SCT120
The Forecast Discussion does however provide an explanation for the VRB other than the forecaster going "IDK".
"Even if showers do not pass directly over the TAF sites, gusty outflows are expected to impact the TAF sites, bringing potential for multiple wind shifts through the afternoon, with gusts up to 30-40kts possible."
In terms of wind forecast accuracy DEN is notorious for giving up on wind direction determination usually due to microbursts and the extreme wind shifts DEN gets during anything but clear skies. But in that case may as well put FC in the TAF too. Example the PROB30 below.
TAF KDEN 211223Z 2112/2218 23010KT P6SM FEW220
FM211500 25007KT P6SM FEW220
FM211800 01010KT P6SM SCT120 BKN150
PROB30 2122/2201 VRB25G40KT -SHRA
FM220100 09010KT P6SM FEW080 SCT120
The Forecast Discussion does however provide an explanation for the VRB other than the forecaster going "IDK".
"Even if showers do not pass directly over the TAF sites, gusty outflows are expected to impact the TAF sites, bringing potential for multiple wind shifts through the afternoon, with gusts up to 30-40kts possible."