"WADING TO PEMBINA": 1849 SPRING AND SUMMER WEATHER IN THE VALLEY OF THE RED RIVER OF THE NORTH AND SOME CLIMATIC IMPLICATIONS

The weather of 1849 in the central Great Plains and western interior of the United States has been reconstructed in numerous analyses of diaries from the mass migration to the California goldfields, military post records, and other archival materials. These studies have demonstrated that the spring and summer periods of 1849 were unusually cold and wet, particularly in the eastern region of the Oregon Trail (near Kansas City). Historical sources from the valley of the Red River of the North of Norht Dakota, Minnesota, and Manitoba support this contention and extend the climatic reconstruction 1,000 km northward. Spring breakup of the Red River was exceptionally late, snow fell in the Red River Settlement on several days in late May, and widespread, heavy rainfall from June to August caused unusual and protracted flooding of the Red River and its tributaries. Instrumental records from Fort Snelling and Norway House confirm the anecdotal accounts. Similarly abnormal weather was produced by the July, 1958 synoptic pattern and it is suggested that this pattern may provide a suitable large-scale analog than others which have been suggested. As unusual as these observations appear to be when compared with the modern record, they may have been more typical of conditions on the Great Plains in the first half of the nineteenth century.