Extended Abstract (36K)16.9
Interannual variability of snowfall events and snowfall-to-liquid water amounts in Southwest Missouri
Anthony R. Lupo, University of Missouri, Columbia, MO; and D. Albert, R. Hearst, C. Allmeyer, and P. S. Market
In this study, the interannual variability of snowfalls occurring in Southwest Missouri (SWMO) was examined over a 50-year period. The goal was to determine not only whether there is year-to-year variability in the number of snowfalls, but also whether the character of the snowfall events themselves varies as well. In order to characterize snowfall events, we stratify these by flow regime and snow-to-liquid ratio amounts. Using a dense cooperative weather station network, the data for this investigation was provided by the Missouri Climate Center and in cooperation with the Springfield, MO (SGF) Weather Forecast Office (WFO). In particular, long-term trends and interannual variability in snowfalls and liquid equivalents were correlated to sea surface temperature variations in the Pacific Ocean basin (e.g., the El Nino/La Nina cycle (ENSO), the Pacific Decadal Oscillation (PDO)). Initial results indicate that year-to-year variability in snowfall events were different for SWMO than they were for other regions of the state. In SWMO, there were more events during El Nino years than during La Nina or Neutral years. There were also more snowfalls during PDO years as well, which was reflected by a general increase in snowfall events, especially during the 1970's and 1980's in SWMO. These differences are primarily accounted for by what are classified as moderate snowfall events. Superimposing the ENSO and PDO variability demonstrates that ENSO related variability fundamentally changes with the change in phase of the PDO. In order to examine snowfall liquid equivalents, the data from the SGF WFO were only used since they were assumed to be the most reliable. Singling out SGF snowfall data demonstrated that climatic variability at this one station very closely mirrored that of the entire region, and thus, should be a reliable indicator of climatic variability in the liquid equivalent ratio in SWMO. In SGF, fall and winter snowfall events tended to have a liquid water equivalent of greater than 12 inches of snow to one inch of liquid (12:1), respectively. The liquid water equivalents were less than 12:1 for more than 75% of spring season events. During El Nino years, there was a slight tendency for smaller liquid water equivalent ratios than during La Nina or Neutral years, but this result was not statistically robust. However, as the PDO changes phase, there was a distinct change in the distribution of smaller versus larger liquid equivalent ratios. In order to examine this issue in more detail, the flow regime character of snowfall events will also be examined.
Session 16, Interannual Variability III: Observational Studies
Thursday, 17 January 2002, 10:30 AM-3:30 PM
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