Friday, November 4, 2011

Storm Chasing Plans

A brigade of students is heading out over the next several hours to examine tonight's storm.  The effort will serve as the first joint intensive observing period (IOP) of the two major field projects we have underway this fall.  They are the Storm Chasing Utah Style Study (SCHUSS), which involves educational use of the famed Doppler on Wheels radar, and the Sounding Observations of Lake-effect Precipitation Experiment (SOLPEX), a National Science Foundation sponsored project designed to improve our understanding of lake-effect storms and their interactions with complex terrain.

We have mobile upper-air sounding teams deploying to the Kelton "ghost town" to observe the atmosphere upstream of the Great Salt Lake and to west of Syracuse to examine mountain and lake-induced flows near the east shoreline.  We also have a car-mounted mobile weather station heading out and the Doppler on Wheels, which we hope will arrive for use by 10 PM from its exhibition in San Francisco.  It's currently somewhere in central Nevada!  Curses to Cal-Trans for closing Donner Pass last night!!!

Being an occasional golfer, I'll describe this as a high risk–reward event.  The storm is complex, the models suggest it has low predictability, and lake-effect is always a crap shoot.  The models have struggled with it all week.  At the moment, the surface front is pushing into the Wasatch Front.

There is no organized precipitation along the surface front, but scattered precipitation is trying to develop over northern Utah.  The prefrontal airmass is quite dry, however.  At KSLC, the relative humidity at 1553 MDT (2153 UTC) was 16% with a temperature of 61F and dewpoint of 15F.  Things aren't much better behind the front.  At roughly the same time at milepost 29 on I-80 the relative humidity was 45% with a temperature of 46F and dewpoint of 26F.  As a result, we presently have "virga all quads."

Prefrontal conditions at 1520 MDT (top, looking west from
Ensign Peak Ridge) and 1530 (bottom, looking south
from above City Creek Canyon)
Strong dynamics and moister air from the north and west are needed to juice this thing up.  The models believe this will happen, producing a broad band of precipitation initially and then conditions that could produce lake-effect tonight.  We are keeping our fingers cross that Mother Nature brings the goods and that the DOW arrives safely.

Update at 640PM
 The DOW has just crossed the border!  If all goes well, we'll be positioned and operating by 9:30!

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