SYNOPSIS FOR 04/27/94 - VORTEX-94

Another of several days that seem to fit the trend of '94 - the year of the 
warm-frontal convection. We had another front that was inactive as far as 
convection along or ahead of it, but widespread severe convection behind it.

Cold front led the way for quasi-arctic air to overspread all but southeast 
OK and central/eastern TX. Front sagged SE during the day , aided by 
outflow from post-frontal t-storms and unseasonably cold air that led to 
thunder-snow and patchy sleet/ZR across parts of western KS and 
northwest OK into the TX panhandle.  Despite intense thermal gradient 
across front (50s to 80s ) and strong convective instability and high helicity 
in the warm sector, convection failed to develop along or ahead of the 
boundary in TX. Timing of shortwaves likely inhibited development in the 
unstable surface air, as an initial weak wave lifted into AR by evening 
which placed subsidence over northeast TX during peak heating.  
Meanwhile, the second major trof to lift out of the southwestern US 
longwave postion did so after dark, sparking another round of post-frontal 
convection across western OK and TX during the evening and again after 
midnight.  The ejecting shortwave, coupled with the overnight convection, 
pushed the cold air well south into TX by Thu morning (4/28).

Number 3 dropped into southern CA and is progged to swing into NM by 
late Fri. More action appears likely then, but warm air now relegated to far 
southern/eastern TX may have a hard time coming back N into the 
VORTEX area.  Widespread  activity likely n of front, but tornadic potential 
may be too far S.

Branick 4/28/94