SYNOPTIC - - SURFACE AND STABILITY.
. . . . . The 1200 UTC surface analysis found a low pressure area over eastern South Dakota and Nebraska. A cold front dropped southward from the low into western portions of Oklahoma and Texas, while an east-west oriented warm front stretched across southern Iowa. Numerical guidance suggested that the warm front would remain quasi-stationary through midday, then begin moving northward and be well to the north of the region by late afternoon.
. . . . . Soundings taken at 1200 UTC revealed a very unstable air mass. The lapse rate was nearly dry adiabatic between 800 and 500 mb over western Missouri. With a forecast temperature/dewpoint of 85F/70F, the Convective Available Potential Energy (CAPE) was estimated at over 3,000 J/Kg. By 1800 UTC, special soundings released in conjunction with a GOES-8 system test showed that the morning inversion had nearly mixed out, and that the air mass was becoming even more unstable than earlier expected. Surface data found temperatures in eastern Kansas and southern Missouri in the middle 80s with dewpoints as high as 75F. CAPE values ranged over 3,500 J/Kg and helicity was in the 100 to 200 (m/s)**2.