21st Conf. on Severe Local Storms and 19th Conf. on Weather Analysis and Forecasting/15th Conf. on Numerical Weather Prediction

Monday, 12 August 2002: 2:00 PM
Life cycle differences between consecutive rapidly deepening continental cyclones
Steven G. Decker, University of Wisconsin, Madison, WI; and J. E. Martin
Poster PDF (2.3 MB)
In the second week of April 2001, two powerful cyclones developed over and traveled across central North America, one immediately following the other. The storms evolved out of quite similar large scale environments and both reached minimum sea-level pressures (SLPs) near or below 980 hPa. Both storms also qualified as explosively deepening cyclones, which are relatively rare events over the continent. Upon reaching its minimum SLP of 977 hPa, the first cyclone began to fill quickly as its SLP rose by more than 27 hPa in the subsequent 36 h. The second storm reached a SLP minimum of 981 hPa but then remained below 990 hPa for the next 54 h.

These life-cycle differences are examined from two complimentary perspectives. First, a local energetics analysis that centers on investigating the processes that contributed to the eddy kinetic energy changes characterizing these two storms during their life cycles will be presented. Second, using output from successful numerical simulations of these two events performed using the Penn State/NCAR MM5, piecewise potential vorticity (PV) inversion is performed in order to examine the role played by distinct pieces of the total PV distribution on the intensification changes experienced by these two storms. The results of these two analyses will provide insight into the physical mechanisms on the meso-, synoptic-, and large synoptic-scales that contributed to the vastly different post-mature phase behaviors of these two cyclones.

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