Severe Storms (Weaver, Combs, Dostalek, Grasso, Motta, Winston)

• Data from the 31 May 1996 severe weather event are being used in a variety of applications.  The case is unique in that it was the “first-ever” 30-second interval imagery data set.  Data from the case are now part of the training material for the Convective Initiation segment of COMET’s SatMet course.  The data were also used as the basis for an article on nighttime outflow identification (see publications below).  An electronic version of this article can be found on the web at http://www.cira.colostate.edu/ramm/jw/outflow1.htm

• Carol Vaughn and Karen Winston have successfully integrated mesonet data and satellite imagery using the McIDAS, MDWRITE program.  Oklahoma mesonetwork data can now be displayed on maps in image format and therefore overlaid on images.  A case study of tornadic storms which occurred on 25 May 1997 in Oklahoma will now be carried out using this new capability.

• The Fort Collins Flash flood of 28 July 1997 killed 5 people, destroyed 200 mobile homes, 19 frame houses, and severely damaged 2,000 other structures.  This past quarter J. Weaver presented numerous talks to various federal, state, and local officials on the meteorological aspects of the flood.   An abstract of a paper on the event was submitted to the 8th conference on mountain meteorology to be held in Flagstaff, Arizona in August of 1998.  (Note: a few photographs from the night of the flood and following few days are available on the Internet and can be viewed at http://www.ci.fort-collins.co.us/C_SAFETY/DISPATCH/pfa3.htm

• Idealized CSU/RAMS model simulations were run using 26 Apr 1991 sounding data from Oklahoma City.  The study tests the sensitivity of severe storms to vertical wind shear.  Several runs were made using various wind profiles.  A near-zero wind case, in which two storms were triggered with model-generated convergence, finds that subsequent outflow interactions are not effective in generating long-lived convection.  This is because the new storm growth occurs in an environment of storm-induced subsidence.

• Forecast Systems Laboratory has supplied RAMMT with code to allow RAMS to initialize a three-dimensional cloud field from the LAPS (Local Area Prediction System) data.  The cloud field information will be used to initialize mesoscale environments for severe weather simulations.