You may have noticed a bunch of gray dots on the EZWxBrief EZDeparture Advisor like those shown in the red rectangle below. Any gray dot you see means that EZWxBrief does NOT have forecast data for that time of departure and that particular personal weather minimum category. Normally, icing and turbulence forecasts are available for departure times for the first 18 hours as shown below in the white rectangle. It is normal, however, for the icing probability, icing intensity and turbulence intensity EZMinimums to be missing at departure times of 19 hours and beyond as shown below in the red rectangle. This is because icing and turbulence are very difficult to forecast beyond 18 hours with any certainty and this is reflected in the EZDeparture Advisor.
However, gray dots can occur for any personal weather minimum category and any departure time. While this doesn't occur often, it is mostly associated with a forecast for surface visibility. This can happen from time to time when the model data for visibility arrives late and is unavailable for EZWxBrief to use. This occurs when there's a delay getting the raw data from the NWS for one or more of the models that EZWxBrief relies on to determine the surface visibility.
Interested in learning more about the Skew-T? You can order your copy of The Skew-T log (p) and Me eBook today.
Most pilots are weatherwise, but some are otherwise™
Dr. Scott Dennstaedt
Weather Systems Engineer
CFI & former NWS meteorologist