What does this red hatched area mean on the icing severity analysis?

[Scott Dennstaedt, PhD]

Below is an icing severity analysis (CIP severity) as shown in the WeatherSpork app.  You can also get this from the Aviation Weather Center website under the "Severity + SLD" and by selecting the 0 hr forecast (analysis).  Notice the red-hatched area around Chicago from the satellite thread I started.  That is the Supercooled LARGE Drop (SLD) threat valid at the top of the most recent hour.  What does this tell you or not tell you about the icing threat in this area?  The devil is in the details, so be specific.

[gsengle]

None shall pass.


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[M016576]

It Doesnt tell you probability, just potential severity.  

 

But... like I mentioned in the other thread... you’re talking about Detroit in the winter time.  100% icing risk is the going in assumption.... you should pick an area that’s a little more ambiguous- like Salt Lake City, or Portland, Or... makes for more of a “mind twister.”

[Danb]

Looks like moderate to severe icing with super cooled drops, acts like water drops on the plane except when it hits the planes it spreads and freezes on contact, clear ice threat, TKS system can’t keep up with bad ass stuff stay away I can’t be more specific STAY AWAY

[Cruiser]

IF you encounter icing FIKI equipment probably won't be enough.

[NeedSpeed]

 

[Scott Dennstaedt, PhD]

52 minutes ago, M016576 said:

It doesn't tell you probability, just potential severity.  

That's correct.  Unlike the CIP or FIP, the SLD is a potential field, not a calibrated probability.  Any likelihood of SLD that's greater than 5% will show up on the Aviation Weather Center severity charts.  In WeatherSpork, we show the actual scale...so in this case, it's a high likelihood given the red color.  This was prompted by the rather warm, subfreezing cloud tops and the freezing drizzle potential at the surface.  All of this means a good signature that there's an altitude or two that you want to avoid (below 5K MSL).  

 

There were a bunch of reports of moderate ice and one report of severe ice between 3.5 and 5K MSL.