Urban storm drain design in Montana and throughout the 11 western states is frequently based on precipitation values determined from NOAA Atlas 2. A statistical analysis of 44 yrs of data for Billings, Montana indicates significant differences from NOAA Atlas 2 for durations between 5 mins and 30 mins. The values in NOAA Atlas 2 understate the magnitude of some return period values in Billings by as much as 69%. Peak runoff rates based on precipitation data at Billings are as much as 71% greater than rates based on precipitation from NOAA Atlas 2.
No takes yet. Share an insight, caveat, or question.
Mark M. Peterson (1986) studied this question.