Brief Overview
                 A severe thunderstorm outbreak occurred on April 2  1956.   Several tornadoes or tornado families occurred
                and 2 of these were killers in Oklahoma and southern Kansas. Tornadoes also occured further west in northwest
                Oklahoma and southwest Kansas. These moved over fairly rural territory with some scattered damage. This
                study will attempt to show that storms developed when a cold front(charging east at 45 mph) met a dryline
                that was retreating westward. All the tornadoes on this evening occurred along or immediately ahead of
                the cold front.

                At 15 UTC, a 991 mb surface low was located over western Colorado with another low over northern, NM. A warm front
                stretched from south Texas northwestward to south of Amarillo to southern Colorado.

                 At 21 UTC a strong "pacific" cold front was moving east into central NM. A 986mb surface low was located over central
                Colorado.  Two drylines were apparent. The westernmost dryline stretched from near east of Amarillo to east of Lubbock to
                near Midland. But the really rich low level moisture was quite a bit further east and confined to the east of a line from east of
                Del Rio to near Abilene.  A front that was mainly stationary or moving very slowly northward stretched from south of Houston
                to north of Abilene to east of Amarillo, then north into western Kansas. However, persistent rain into a dry, cool airmass had
                resulted in a cooler airmass over far northern Texas into much of Oklahoma and Kansas. The leading edge of this airmass was
                charging westward through western Kansas. I chose  not to label this boundary as a front but as a dashed pink line.

                By 00 UTC the warm/stationary front stretched from near Houston to just south of Waco to southwest of Childress. The
                cold front was still charging east into eastern NM. A surface low was over central CO with another low along the front
                in New Mexico.           

           
                The  03 UTC 500mb  showed a powerful shortwave trough ejecting into the plains. The 500mb winds were very strong--
                probably at least 90 kts over central Oklahoma.

a longwave trough over the western US.  Shortwave troughs were rotating around the main
                trough and one of these was approaching the southern plains. The 700mb chart  showed a fairly strong temperature gradient
                over New Mexico behind the pacific front.  500mb temps were very cool--around -18C in the Texas panhandle. Thus
                surface based CAPES were around 3000 j/jg even in the nearly saturated surface air just north of the warm front.

                The 12 UTC 500mb and 700mb charts can be found here.