Enroute Icing

### Produced by The COMET® Program

### Step 1: Diagnosing Locations of Icing » NWP Analyses » Vertical X-C and Plan View Maps - Data

Below are the cross section, 925-850, and 850-700 hPa plan view maps for the RUC2 analysis of layer mean T, RH, and –VVEL for 13 UTC 26 February 2011. The location of the cross section is found on the mean layer map as a horizontal line at 42°N. We are assuming that 13 UTC data would be the most current available to the daytime shift for analysis. We’ll analyze the cross section followed by the plan view maps.

#### Question 1

Circle area(s) in the cross section where icing criteria for T, RH, and –VVEL are met. (Review the Icing Flowchart)

Use the pen to circle area(s) where icing criteria for T, RH, and –VVEL are met.

Tool: | Tool Size: | Color:
--- | --- | ---
Pen Eraser |  |

The answer follows the guidelines for T (0°C to -22°C), RH (>80%), and –VVEL (> 0) for the cross section. Much of the cross section has an icing risk between the surface and 700 hPa at 13 UTC 26 February 2015.

Now we'll look for areas in the 850-700 hPa and 925-850 hPa plan view maps where icing criteria for T, RH, and –VVEL are met.

#### Question 2

Use the pen to circle area(s) in the 850-700 hPa map where the icing criteria are met.

Tool: | Tool Size: | Color:
--- | --- | ---
Pen Eraser |  |

The answer follows the guidelines for T (0° to -22°C), RH (>80%), and –VVEL (> 0) for the layer mean. We can see that a significant portion of the service area has an icing risk in this layer at 13 UTC 26 February 2015.

#### Question 3

Use the pen to circle area(s) in the 925-850 hPa plan view map where icing criteria are met.

Tool: | Tool Size: | Color:
--- | --- | ---
Pen Eraser |  |

Even more of the service area has an icing risk in the 925 to 850 hPa layer at 13 UTC 26 February 2015, as shown by the red shading.