Hydrometeorological characteristics of ice jams on the pemigewasset river in central New Hampshire

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Student Showcase of Research & Engagement Spring 2019
Sanders, Matthew
Ice jams regularly occur across the Northeast U.S. during the winter and early spring and can result in significant localized flooding, such as those that occurred on the Pemigewasset River in Plymouth, NH on 26 February 2017 and 13 January 2018. The hydrometeorological characteristics of 20 ice jams that occurred on the Pemigewasset River in Plymouth, NH since 1981 are investigated. Composite analyses indicate a period of slightly below normal temperatures over the Northeast U.S. from 1-2 weeks before the ice jam date that transitioned into a period of highly anomalous temperatures >7˚C above normal from two days before through one day after the ice jam date. All 20 events were associated with a period of enhanced integrated vapor transport (IVT) >250 kg m-1s-1during the anomalously warm period. The composite synoptic-scale flow over eastern North America was characterized by a plume of integrated water vapor values >25 mm and IVT magnitudes >600 kg m-1s-1into New England resulting in average precipitation totals of 30-50 in the Pemigewasset watershed.