The Intermountain Precipitation Experiment

Intensive Observation Period 3

Intensive Observation Period 3 for the IPEX field program was held on Saturday February 12. All field resources were deployed to study the storm that brought storm-total snowfalls of more than 2 feet to some locations of the Wasatch Mountains of northern Utah. A complete summary of the storm is pending and research on this storm will continue for years to come to fully understand its structure and dynamics. This page includes a few snapshots of this remarkable storm.

P-3 tail radar reflectivity

In these images, you are looking at roughly east-west cross sections from the tail radar on the NOAA P-3 research aircraft. The center of the grid is the plane's location and the high reflectivity trace underneath the plane is the ground surface. Range rings are at 5 km intervals.

Doppler-on-Wheels Data

Jeff Trapp collected the following RHI scan at 1640 MST. On the left is the velocity away from the radar and on the right is the reflectivity, showing the strong jet moving towards the mountains (to the east) below 3 km in elevation.

WSR-88D Data

Steve Vasiloff generated these images that coincided with the last image above from the P-3 flight (0040 UTC). The range rings are every 10 km. The three-letter IDs correspond to U of U MESOWEST IDs. Note that SNI (Snowbasin) in in a blocked area where the vertically-pointing Doppler radar is.

Observations of Convection

Mike Seaman noted 2 CG strikes in West Valley around 5:45 pm or so Saturday evening, along with graupel. David Yorty noted lightning associated with a heavy graupel shower near the mouth of Big Cottonwood Canyon from 6:15-6:30 pm. This was associated with a convective line that passed from the West Desert through Salt Lake City Airport around 6 pm when the winds shifted from variable to 300 at 13 knots, gusting to 33. The NOAA P-3 was trying to land after a nine-hour mission around this time, requiring an aborted landing attempt because the pilot reported a classic downburst signature to the right of the plane upon approach. Several planes ahead of us, a business jet was struck by lightning, reported smoke in the cabin, and required emergency landing procedures.

For More Information

Shafer, J. C., 2002: Synoptic and Mesoscale Analysis of Wasatch Mountain Snow Storm. M.S. thesis, Department of Meteorology, University of Utah, 70 pp. [PDF]

Cox, J. A. W., 2002: Kinematic structure of a Wasatch Mountain snowstorm. M.S. thesis, Department of Meteorology, University of Utah, 60 pp. [PDF]

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Last revised: 8 January 2003 DMS