Enroute Icing

### Produced by The COMET® Program

### Step 3: Use NWP Guidance to Make Adjustments, If Needed » NWP Forecast Products Used for Icing Prediction

As with the initial analysis, we can use model forecast soundings and two-dimensional T/RH/-VVEL cross sections to find flight levels for moist sub-freezing layers in a potential high impact area. We can also use the layer mean T/RH/-VVEL maps to determine the areal extent of potential icing conditions.

Like CIPs, FIPs use algorithms to convert the NWP data. Once checked for consistency with the icing products above, FIPs are a more efficient way of checking the first forecast.

FIP data from the most recent RAP forecast cycle is found on the aviation weather web page, using the “Time” pull-down menu to choose 2, 3, 6, 9, 12, 15, or 18 hour forecasts.

Before we use the FIPs to determine if adjustments to the first forecast are necessary, we will do a spot check of one FIP product against the other NWP icing guidance at two valid times, 18 UTC 26 February and 00 UTC 27 February.