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<br />
<br />Figure 31. Continued. (c) 0025 GMT, 1 August 1976. (d) 0100 GMT, 1 August 1976.
<br />
<br />in conjunction with surflCe observations and
<br />the Table Mountain wind data, a sounding
<br />was constructed for Loveland, Colorado,
<br />valid at 0000 GMT. This sounding, shown in
<br />Fig. 32, is an estimate of the Big Thompson
<br />storm environment. The L.I. was -6, and
<br />the mean vapor mixing ratio below the
<br />temperature inversion was 14.8 g kg-I.
<br />The LCL was at 730 mb (= 1. I km AGL),
<br />which agrees with observed low cloud
<br />heights at Ft. Collins, An additional 80 mb
<br />of lift was necessary to bring this air to its
<br />LFC.
<br />
<br />3,2 Radar Coverage
<br />
<br />The NHRE 10 cm radar at Grover
<br />scanned the storm complex along the
<br />northern Colorado foothills until a few mi-
<br />nutes after 0100 GMT. During this period
<br />the storm's intensity peaked about 0045
<br />G.\lT and then weakened temporarily. Re-
<br />flectivity data from Limon and Grover
<br />
<br />radars were compared during the peak
<br />period.
<br />Limon (00 elevation angle) and Grover
<br />(1. 90 elevation angle) radar echoes at 0045
<br />GMT are superimposed on a map of the Big
<br />Thompson area in Fig. 33. Both radars
<br />scanned a section through the storms at
<br />elevations between 15,000 ft MSL (4.6 km)
<br />and 20,000 ft MSL (6.1 km). Limon radar
<br />showed only a VIP level 3 contour, which
<br />corresponds to reflectivities between 41
<br />and 46 dBZ. However, Grover radar ob-
<br />served a level 5 (55-65 dBZ) with a meas-
<br />ured peak reflectivity of 64,6 dBZ. The
<br />Grover data contained more detail than the
<br />Limon data. This is partially explained by
<br />the narrower beam width of the Grover
<br />radar (10 conical beam compared with Li-
<br />mon's 20 conical beam) and Grover's loca-
<br />tion closer to the storm area. Fig. 33
<br />suggests that Limon radar underestimated
<br />the true intensity in the core of the storms
<br />l;y about 15 dBi.
<br />
<br />37
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