The National Weather Service hesitated in its issuance of a Flash Flood Warning, because forecasters could not get confirmation of what they suspected was occurring in the city.   FIRST OF ALL, none of the 163 spotters in the immediate vicinity had called in.   SECONDLY, Doppler-estimated rain rates were underestimating actual amounts by 40-50%, because the Fort Collins storms had almost no frozen processes taking place within them.   The ONLY clue to the anomalous character of the Fort Collins storm was that little or no lightning (which requires the freezing process) was occurring in the vicinity of Fort Collins during most of the activity, while copious lightning was detected out on the Plains to the east and southeast.   Nevertheless, a   Flash Flood Warning   was issued at 9:40 p.m., based mostly on reports of a few flooded basements in southwest Fort Collins, as well as forecaster instinct regarding the duration of the rainfall and saturation of soils.

      This map of northeastern Colorado shows GOES-IR imagery for 2130 MDT with 15-min lightning strikes superimposed.     Notice the warmer tops and minimal lightning in the Fort Collins area.

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