Enroute Icing

### Produced by The COMET® Program

### Step 1: Diagnosing Locations of Icing » NWP Analyses » Current Icing Potential (CIP) - Description

The CIP combines model analysis (RUC2 in 2011, RAP in 2015) and observations into one group of products to show the current icing picture over the CONUS airspace. Five CIP products are available:

- Icing severity and supercooled large droplets (SLD) potential
- Icing severity by flight level
- Icing severity where icing probability is greater than 25%
- Icing severity where icing probability is greater than 50%
- Probability of icing

Plots are available every 2000 feet from 1000 feet above mean seal level (MSL) through FL290. Maximum value plots through this range of elevations can also be viewed. When available, icing PIREPs and AIREPs are plotted, indicating icing severity or both severity and type to help validate the analysis. For FL plots, icing reports within 1000 vertical feet of the plotted flight level are included. For maximum value plots, all icing reports are shown.

Plots of CIPs can be obtained from the aviation weather website.

The following observations are used in the CIP: lightning, PIREPs, METARs, radar, and satellite radiances. The model analysis data used in the CIP include temperature (T), relative humidity (RH), negative pressure vertical velocity (‒VVEL), and supercooled liquid water (SLW) if available.

When using the CIP, consider the quality and limitations of the observations and model analyses. Ask yourself:

- How well does the NWP model analysis validate?
- How good are the data supplementing satellite LW IR data beneath the cloud top?
- Are bad PIREPs included in the observational data, potentially affecting the CIP?
- Are PIREPs available in areas of significant icing?