TAMDAR Discussion Board

Helpful data at Champaign, IL

Posted By: Lyle Alexander
Date: 30-October-04 2327Z

Between 22 and 23Z on Saturday October 30th, 2004: I brought up my TAMDAR map display to get information on mid level winds over IN/IL. I noticed a plane had landed in central Illinois. Zooming in on it, I determined that it had landed at CMI. As I was looking at it, new data started adding to the map and the same aircraft was ascending (about 25 minutes after it had landed. Today's synoptic situation has stong low pressure to the north with roughly a westerly flow at surface to 40K. Winds near the surface are 20-30 knots and winds at 25-35K are 120 knots (from ACARS). I wondered what kind of shear there was in between. The TAMDAR data helped to fill in the gap. I found winds of around 35 knots up to 5K and then a jump to 60 knots at 8K. An east-west stratocu deck was situated about 20 miles north of CMI when the aircraft descended from the north-northeast. Judging from its locations, I believe it just missed the cloud or possibly skimmed the tops. An inversion was noted in the data at about 5K. At 6400 feet, the temerature was 7.7C and the humidity was 53 percent. At 4700 feet, the temperature dropped to 5C and the RH went to 80 percent. Surface temperatures were around 16C in the area. When the plane ascended, it went northeast and was further south for the given altitudes. The inversion was not noticeable. Humidity levels were around 60 percent from the surface to 5K then dropped to around 45 percent just above that. The data looks real good. This would be potentially great information for icing forecasts in similar but colder situations. Lyle