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
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
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.
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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.
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