SEMINAR SERIES and COLLOQUIA

The expansion of the United States, the need for weather information at remote locations, and a general scientific interest in the weather combined to greatly increase the geographical extent of regular weather observations during the second quarter of the 19th Century. These weather observations, primarily by Army Surgeons at frontier forts, typically include thrice-daily measurements or estimates of temperature, wind speed and direction, cloud cover and motion, and present and past weather. From these observations, it is possible to reconstruct the synoptic conditions across the central and eastern United States. Using analog techniques, one may even infer the likely jet stream pattern.

The weather observations reveal remarkably anomalous conditions during the month of March 1843. This month included what might be considered the most unusual average temperatures in the history of United States weather records. At three sites, the mean temperatures were four standard deviations below the long-term climatology. These unusual temperatures were sustained by a storm track involving the repeated formation of extratropical cyclones in the Gulf of Mexico and their motion across the southeastern United States and over the northwest Atlantic Ocean. Analyses of particular winter storms will be provided, and the nature of the upper air pattern that led to these unusual events will be discussed. The stories of some those who experienced that month will be recounted through observer reports and personal diaries. The entire episode serves as a reminder of the extremes to which weather may subject us.

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