An excellent day for satellite-derived icing products

Yesterday was an excellent day for the Flight Icing Threat algorithm. The strong low pressure system that caused widespread grief for the aviation world yesterday pushed offshore, leaving only the back end of the deep trough in the eastern portion of the country (IR image below). With a 'cleaner' looking system (i.e. fewer high clouds), the FIT algorithm performed very well.

20160225 1515 UTC IR imagery with icing enhancement and PIREP reports

Two areas of immediate icing concern were 1) the region surrounding the New York area terminals and also 2) the Mississippi Valley.

20160225 1515 UTC FIT index with PIREPs and the experimentally issued CAWS over the eastern CONUS

CAWS forecasters used the FIT along with other icing tools to better narrow down areas in which a CAWS might be necessary. A widespread swath of higher FIT index values were noted over southern Illinois around 1500 UTC and generally wind patterns suggested that the clouds causing icing conditions would move ESE throughout the day. A separate area over eastern Tennessee was expected to move NE. This lead to the issuance of a CAWS for two separate areas in the Mississippi Valley.

The other area was in the Northeast, just north of the New York area airports. The FIT showed consistently high index values in the area. Along with model data guidance, forecasters issued a CAWS there. While still overdone in some places, there were many other areas in which the FIT did well yesterday (even though lack of time kept the forecaster focus on only two regions) as seen in the image above; the Ohio Valley, over Kansas City, and northward to Omaha and Sioux City. 

This year the AWT again collaborated with AWDE (Aviation Weather Demonstration and Evaluation) testbed at the FAA Tech Center in Atlantic City, NJ. Traffic flow management along with a number pilots participated in this collaboration, providing AWC forecasters with direct end user input. For yesterday's CAWS, AWDE participants noted that, while icing CAWS are not common practice now, they liked the idea of a product that fit between the broad scale G-AIRMETs and SIGMET issuance. They suggested that it would be useful over busy terminals. For example, if there were other conditions requiring aircraft into a holding pattern above an airport, air traffic managers would want to be informed of the possibility of icing. If an area of icing was expected it would be dangerous for aircraft to be holding in that cloud layer for too long. So, if a CAWS was issued, TFMs would use the information to 1) find another altitude in which aircraft could safely hold or 2) not allow holding and instead issue a ground delay or other program.

The FIT algorithm has potential to be a useful tool to this end. It provides an at a glance look at where icing conditions may be occurring. In this case, CAWS forecasters used it to better hone down the areas in which the CAWS were issued.