Temperatures warmed nicely on Monday with highs in the 40s for those without significant snow cover. Do warm surface temperatures translate to warm temperatures aloft? The featured chart presents December temperature percentiles for mandatory sounding pressure levels from the Omaha site on Monday night. Values of 100 would indicate the warmest on record for the site. Please recall that pressure decreases with height, so the first value shown at 925 mb is the closest to the surface. So indeed the levels nearest to the ground are warm as well, which makes sense as this is the air that mixes to the ground during the day. But as you go up higher in the atmosphere, temperature percentiles go down until rapidly increasing again above the tropopause. The explanation is a bit complex, but likely involves the 400 to 50 mb levels being anonymously high due to the warmer lower atmosphere and thus colder temperatures near the tropopause.

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