WMOD00591

• Title: Investigations of Winter Storms over the Wasatch Plateau during the 1994 NOAA-Utah Field Research Program - Final Report
• Date: 7/1/1996
• State: UT
• Weather Modification - Doc Type: Report

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By 0500 on 11 February the 700 mb trough axis was ncarly o\/cr the research area, with the
wmd at Ely, Nevada already shifted to the northwest. Cold air \vas beginning to enter ''''estern Utah,
and the back edge of the moisture as.-',.ociated \..ith the trough was mOving out of south em Idaho. The
center of the surface low pressure an:a again tracked almost directly over thl: Utah research arca The
surface analysis for 0500 on the 11 February (Fig_ 14) positioned the cold front directly over the
Wasatch Plateau, With northerly 110\\' already occurring at Salt Lake City. A GOES image al 0600
(Fig. 15) also shows the cloud band associated \\lith the front By 1700 on 11 February Utah was In
the [X)st-trough environment, with cold dry northerly 110\\' over the state. The 700 mb temperature
had dropped from _80 to -160 since 0500. Conditions for good orographic cloud developmcnt on thc
western slopes of thc Wasatch Plateau ended shortly after trough passage.

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Figure 15. GOf...:S JR Imaxe taken ar 0600 j\'fSTon 1 I February /99./. Co/dfront positiun shown hae
IS Ilkely roo filr ro lhe southew,t. hased nllhe 0500 M5iT NWS surface ana(V.Hs (Fig. 1./).

The weather data from RRS arc shO\\TI in Figs. 16 and 17 for 10 and II February,
rcs~cti...ely. In Fig. 16 the beginning of the influx of moisture for storm period C is seen as a rise
in the water vapor trace beginning at 0900. Liquid water began to appear ahout two hours later al

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