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B767Driver · December 11th, 2007, 20:04

Was the temp OAT or TAT?

I looked at the upper air progs for the time of your flight and they all were forecasting a freezing level at the surface with a standard lapse rate up to the 700mb level.

The Ram air rise at each of those altitudes you had recorded is consistent with that of 210kts at 6000', 180kts at 4000' and 140kts at 2000'...and finally a freezing level at the surface.

The strangest icing phenomenon (and weather flying in general) that I've ever encountered has been flying below FL240 around the Great Lakes Region. I think those bodies of water influence upper air temperature, moisture content and icing significantly. It's possible that the upper air was warmer over the lake, influencing the precip type at the shore.

The semi-permanent High that sits over SW MI has a large affect of frontal activity...for years and years I've watched fronts charge over the plains only to fall apart on the east side of L. Michigan.

But I think that same pressure area affects local temperatures between the surface and 10,000 feet as well...possibly pumping some warmer air in the coastal regions of Lake.

I've seen more variations in icing throughout WI, MI and MN than Baskin-Robbins has flavors of ice cream.

December 11th, 2007, 20:04	#2
B767Driver Old Skool Join Date: Sep 2003 Posts: 1,955	Re: Freezing Rain and Ice Pellets Was the temp OAT or TAT? I looked at the upper air progs for the time of your flight and they all were forecasting a freezing level at the surface with a standard lapse rate up to the 700mb level. The Ram air rise at each of those altitudes you had recorded is consistent with that of 210kts at 6000', 180kts at 4000' and 140kts at 2000'...and finally a freezing level at the surface. The strangest icing phenomenon (and weather flying in general) that I've ever encountered has been flying below FL240 around the Great Lakes Region. I think those bodies of water influence upper air temperature, moisture content and icing significantly. It's possible that the upper air was warmer over the lake, influencing the precip type at the shore. The semi-permanent High that sits over SW MI has a large affect of frontal activity...for years and years I've watched fronts charge over the plains only to fall apart on the east side of L. Michigan. But I think that same pressure area affects local temperatures between the surface and 10,000 feet as well...possibly pumping some warmer air in the coastal regions of Lake. I've seen more variations in icing throughout WI, MI and MN than Baskin-Robbins has flavors of ice cream. __________________ A self described gym rat. "I got next."