A serious structural icing threat, but no official advisories?

[scottd]

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[poadeleted20]

Wild guess -- it's all above FL180 in that region.

 

[Dave Siciliano]

I look forward to your comments. We flew out of there Monday and were -7C in the mid teens and got rain that wasn't freezing. Lots of wind out of the west and a lot of convective activity, but no ice. It was very interesting.
Farther west, there was a constant cloud deck around 6,000 feet for hundreds of miles. When we finally descended in the Dallas area, it was 70F just above the clouds and the temp quickly dropped down to the upper 40s in the clouds with bottoms about 1,400 feet. Interesting stuff!

Best,

Dave

 

[Lance F]

PIREPS in southeast so far are either negative or light.

 

[Dave Siciliano]

In the Southeast? What specific location? 15,000 feet? What kind of aircraft?

We departed Tampa just after 10:00 on Monday; maneuvered east a bit to circumnavigate storms, then, turned north and climbed to FL200 in a Baron 58P. We were still in clouds at FL200 until we got up in the Florida panhandle just before entering Tyndall airspace. In the climb, we encountered light rain at 15,000 with the OAT showing -5 to -7 C. That gauge has been pretty accurate in the past. Had all icing systems on but didn't pick anything up.

Dave

 

[Ted]

I look forward to your comments. We flew out of there Monday and were -7C in the mid teens and got rain that wasn't freezing. Lots of wind out of the west and a lot of convective activity, but no ice. It was very interesting.
Farther west, there was a constant cloud deck around 6,000 feet for hundreds of miles. When we finally descended in the Dallas area, it was 70F just above the clouds and the temp quickly dropped down to the upper 40s in the clouds with bottoms about 1,400 feet. Interesting stuff!

I've had similar things happen. In one memorable case, I was getting mixed ice in the climb until I got on top of the layer around 13,500 ft. Some miles later the layer went up to about FL230. Big jets reporting ice up at the top, at 15,000 ft I wasn't getting anything, even when I was going through rain.

While I've never had temps go from 70s on top of the clouds to 40s in the clouds, I have seen 10-15 degree drops entering cloud tops. And then I start building ice, varying from benign rime to having it start to streak back and form on the wings aft of the boots. Less fun.

As to this, hard to say. But then again, I'd just be trying to avoid the thunderstorms, and otherwise I'd be above freezing at the altitudes I fly.

 

[Ted]

Here's a case last year where I was flying with an instrument student up in the Bismarck area. The temperature at 6,400 feet was 72°F (22°C). As we descended on the approach into the clouds, the temperature dropped to 47°F (8°C) at the cloud tops. That's a drop of nearly 29°F in a little over 1,000 feet. Of course, we had spent a fair amount of time looking at the weather prior to departing, so this wasn't a shock and the temps in the clouds were well above 0°C. Still pretty amazing to see such a drastic drop in temperature in just 1,000 feet.

Definitely. What I find is much more common is for something about 35-40F above the clouds to turn into 25-30F in the cloud tops. Nice and inconvenient for ice.

So, what's the answer to your question yesterday?

 

[Ted]

See if this answers the question.

Pretty much tells me what I knew - come to your own conclusions off the raw data before trusting the products.

Good info, Scott!