Enroute Icing

### Produced by The COMET® Program

### Step 3: Use NWP Guidance to Make Adjustments, If Needed » Introduction

After you complete the first forecast, you use NWP forecast data to determine if it needs to be adjusted. However, another activity should be done before doing this step.

#### Question

What should you do before comparing the NWP model forecast data against the first forecast?

a) Validate the model initial conditions against the observed initial conditions
b) Determine if the PIREPs have been quality controlled
c) Find areas where cloud top temperatures are less than -22°C

The correct answer is a.

We need to validate the NWP model initial conditions before we can be confident in using its forecast guidance.

If you used the NWP analysis to diagnose areas of icing, you needed to determine the quality of NWP model initial conditions. We determined this in Step 1, and saw that the the NWP analysis was in good agreement with the observations used for icing diagnosis. Therefore, we can go directly to the next step - using the Forecast Icing Product (FIP) data to modify your first forecast, if necessary.

Options B and C are incorrect because they are performed as part of the icing analysis done in Step 2.

Please make a selection.