20th Conference on Weather Analysis and Forecasting/16th Conference on Numerical Weather Prediction


Case studies of warm season cutoff cyclone precipitation distribution

Jessica S. Najuch, University at Albany/SUNY, Albany, NY; and L. F. Bosart, D. Keyser, T. Wasula, and K. LaPenta

Forecasting heavy precipitation associated with warm-season cutoff cyclones presents a particularly challenging forecast problem in the northeastern US. These challenges arise in part from physiographic features that modulate the distribution of precipitation and severe weather, and the rapid changes in the character of precipitation due to the evolution and motion of the cutoff cyclones.

Four case studies of cutoff cyclones, which produced significant damage from severe weather and flooding across the Northeast, are being analyzed using the 40 km ETA initialized dataset from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR). Precipitation plots were also made for each day of each case using the NCEP Unified Precipitation Dataset (UPD).

In this presentation emphasis will be placed on the case of 30 June to 1 July 1998 featuring a cutoff low that tracked through the Great Lakes, producing significant severe weather in many parts of the Northeast. Severe weather included flash floods in Vermont, New York, and Rhode Island, and three tornadoes on Long Island, New York. This cutoff featured a strong upper-level jet on its equatorward side and a strong low-level jet on its eastern side. The heaviest rain fell along the New York and Pennsylvania border and in isolated pockets in the vicinity of significant orographic features (e.g., Adirondacks). Synoptic and mesoscale analyses will be used to relate the severe weather and heavy precipitation to orographic features, lower- and upper-level jet interactions, and to the structure, shape, and track of the evolving cutoff.

extended abstract  Extended Abstract (620K)

Poster Session 1, Monday Posters
Monday, 12 January 2004, 2:30 PM-4:00 PM, Room 4AB

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