Strange Skew-T sounding

[Everskyward]

I was reading the thread about the inversion in Nebraska where Jesse posted the sounding. On a whim I got the local current sounding and it looks like this.

How does that happen, with the dew point to the right (greater than) the temperature? Or is this an error?

 

[Jim Logajan]

How does that happen, with the dew point to the right (greater than) the temperature? Or is this an error?

Supersaturated air. Check this link:

http://mrcc.isws.illinois.edu/resources_links/link_weatherfaq_other.htm#

Click on the "What is the difference between dew point ..." link.

 

[Jim Logajan]

My guess is that it would be this supersaturation relative to ice. I have known for a long time that this occurs but it never dawned on me what it would look like on one of these charts.

Why ice? I notice the graph shows a temperature of over 20 C at 20,000 ft. Also, there is quite a large jump in temperature at 15,000 ft. I'm not sure what to make of all that.

I wonder if the Colorado fires cause some unusual readings if the radiosonde passed through the smoke?

 

[Jim Logajan]

Where do you see a temperature of 20 C at 20,000 ft? It looks to me more like -10 C.

Also, the jump at 15,000 ft is in the dew point (temp = thick red curve, dp = thick blue curve).

Oops! I made two errors - reversed the lines and used the wrong axis for temperature. I obviously misremembered how to read skew-t charts!

 

[Jim Logajan]

Nope. This is something that can occur in the RUC analysis, and is specifically caused by the cloud analysis in the model. This can happen while trying to conserve a parameter in the model called theta-v. The temperature is reduced and can "overshoot" the dewpoint, resulting in what appears to be supersaturation.

Thank you for the correction and explanation.

The Skew-T presented by the OP is from a model analysis, not from a rawinsonde observation.

Is it a rawinsonde or radiosonde? I had learned the latter term decades ago, but have to admit first seeing rawinsonde only a few years ago. (First time I saw it I thought it was a typo.) I see the definition at Wikipedia seems to indicate the equipment on a balloon used for Skew-t observations probably makes them radiosondes rather than rawinsondes. However, I've come across incorrect information on Wikipedia technical articles a little more often than I think should be the case.