Now we will look at temperature, dew point and wind profiles with height at 8 a.m. E.D.T. from Flint, Michigan and Peoria, Illinois. This data is obtained by launching weather balloons at 8 a.m. from Flint and Peoria. The balloons are equipped with radiosondes that transmit the temperature, dew point and wind data to the weather forecast offices. Utilizing this data, meteorologists can assess the stability of the atmosphere, obtain a visual representation of how temperature and dew point profiles are changing with height, assess the potential for severe weather and analyze wind speed and directional shear profiles with height.
Observed Flint, Michigan Sounding 8 a.m. 5/13/80
A wealth of information can be derived from this upper air sounding. It is obvious that there is abundant low level moisture. The sounding is very nearly saturated from 700 millibars (roughly 10,000’) down to the surface. Instability was limited by all of the low clouds and fog. This Flint sounding is very representative of 8 a.m. conditions in Kalamazoo (although Kalamazoo’s surface temperature at 8 a.m. was a little milder… 56 degrees). Note the mid level dry punch, which is very clear between 500 and 700 millibars. Also, note the amount of speed shear. We could very easily deduce from this morning sounding that if the temperature in Kalamazoo reached the 60’s or 70’s, that some instability and CAPE would be generated. Please recall that the temperature in Kalamazoo reached 74 degrees before the tornado struck.
Zoomed in FNT 8 a.m. Observed Sounding
A close-up of the Flint 12 UTC sounding clearly shows deep low-level moisture and perturbed low-level wind fields north of the quasi-stationary boundary.
Observed Peoria, Illinois sounding 8 a.m. 5/13/80
The Peoria sounding indicates veering winds from the surface to around 5,000’ AGL and impressive speed shear (maximum observed winds are 110 knots at the 250 mb level). The cold front is already close to this area and note how quickly dry air is being advected in by brisk west southwest winds. The temperature profile also indicates very steep lapse rates quite close to the Dry Adiabatic Lapse Rate (9.8 degrees C/km).
Zoomed in PIA 8 a.m. Observed Sounding
A close-up of the Peoria observed 12 UTC sounding more clearly shows the veering low level wind profile and strong wind fields above 500 mb.