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What the SLD potential analysis won't tell you

Updated: Mar 8, 2022

Supercooled LARGE drop (SLD) icing is a hazard for all aircraft.  But is all SLD created equally?  Not necessarily.  It also helps to understand what's triggering the SLD event in the first place.  A little sleuthing and some basic education goes a long way to understand the analyses and forecasts we use every day.


Below is the Current Icing Product (CIP) severity analysis for 7,000 feet MSL.  CIP is an analysis of the icing environment that is always valid in the recent past...so it isn't a forecast - it's an analysis.


The blue-shaded regions correspond to icing severity categories of trace, light, moderate and heavy icing (shown below) that are expected at the top of the previous hour, in this case 1700 UTC.  The SLD threat is overlaid on the severity analysis as a red-hatched region.