A Spring Dust Storm over Colorado and Kansas
Rudolf Husar, Apr.11, 1999 rhusar@mecf.wustl.edu
Introduction
On the late afternoon of April 8, 1999, an intense dust storm was observed over
Colorado and Kansas. The dust storm was brought to our attention by the NOAA
Operational Significant Event Imagery Office (OSEI).
The storm is described by NOAA OSEI as follows:
A powerful storm centered over eastern Nebraska on the evening of April 8 was
producing severe thunderstorms in Iowa and Missouri. The storm continued to the
east overnight spawning tornadoes in Illinois and Ohio. Notice the light brown
area than curves from western Colorado, over Kansas and into the storm's
circulation. This is airborne dust that has been carried off the High Plains by
strong winds flowing into the storm center. Winds flow counterclockwise and
around the low pressure system and spiral toward the center.
NOAA AVHRR Images
Fig 1. NOAA AVHRR satellite image of the brown dust cloud (click on the images
to view larger version)
Fig 2. NOAA AVHRR image of the dust enhanced by the 'split window method.
GOES image and animation
The dust storm was also clearly evident in the GOES 8 visible images.
.
Fig 3. GOES 8 image of the Colorado - Kansas dust storm
Fortunately, the storm was also recorded on candid camera as shown in the
following GIF animations:
Fig 4. Animation of the Colorado-Kansas Dust Cloud (April 8, 1998)
A lager (2 MB) an even larger 1KM resolution (6 MB) animation is also available.
Weather Model or Friction Velocity
Doug Westphal pointed out to us that the effective wind velocity near the surface
(friction velocity) is available from the Navy Weather Model. It is accessible
through the NRL Monterey Aerosol Page.
Fig. 5. Model-based friction velocity (near the earth surface).
Evidently, on the afternoon of April 8, 1999, there was a sudden burst of high
surface velocity in Colorado and Kansas. At the peak where the dust is observed,
the friction velocity exceeded 50 m/s. (red shaded area)
Questions and Issues

Is the dust raised from a small area and subsequently dispersed or picked up
over a large area

Is 50+ m/s friction velocity enough to lift the dust from any dry soil?

What was the surface moisture situation?

Where did the dust disperse?

How many states will request waivers for PM10 exceedances?
Interested to contribute or discuss? Send me a note.
rhusar@mecf.wustl.edu