If you are flying in the flight levels this summer and especially the upper flight levels, we have some new static weather Imagery for you! We recently added to WeatherSpork version 4.3.4 new guidance that is going to be very popular with you jet jockeys out there. It’s from the High Resolution Ensemble Forecast (HREF) which is updated four times a day and provides two probabilistic forecasts for echo top heights at hourly intervals with a lead time of 36 hours.
Two probabilistic forecasts are available in WeatherSpork. You will find this in the Imagery view under the HREF Model. Choices include echo top heights greater than 30,000 feet MSL and echo top heights greater than 35,000 feet MSL. The height of the echo top is a forecast for the highest simulated radar echo top (top of the precipitation core) with an expected reflectivity not less than 18 dBZ. Remember, these are forecasts, not actual NEXRAD echo tops. And note, the cloud tops are often higher.
Notice the scale at the bottom of the chart. The echo top height forecast depicted on the chart is a calibrated probability. The highest probabilities are on the right side of the scale (red and purple) with lowest probabilities on the left (green and blue). So a forecast that’s depicted in red means there’s a 90 to 100% chance at the forecast valid time, there will be tops greater than 30,000 feet (or 35,000 feet depending on the forecast you are using). Therefore, flying through or near areas of red and purple will likely require flying at an altitude higher than 30,000 feet (or 35,000 ft). They may be areas you want to avoid.
A flight at 30,000 feet (or 35,000 feet) through areas without colors depicted will very likely be above the highest echo tops or in an area without precipitation forecast.
The valid time is posted at the top of the chart as shown above (underlined in red). It uses a YYYYMMDD HHMMZ format. For example, the chart abvove is a 33 hour forecast valid at May 9, 2018 at 03Z (20180509 0300Z). The time on the left side is the initialization time of the model or what is referred to as the “run time” or “cycle time” of the HREF forecast model.
“Most pilots are weatherwise, but some are otherwise.”
Weather Systems Engineer