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					A Reanalysis of Hurricane Hazel
            (1954)

  Scott Weese, Ron McTaggart-Cowan
         and John R. Gyakum

  Department of Atmospheric and Oceanic Sciences
                 McGill University
            Montreal, Quebec, Canada

                  June 4th, 2003
                 Talk Outline
1   .   Background
2   .   Synoptic Overview
3   .   MC2 Simulation Results
4   .   Conclusions
Purpose: to study the thermodynamic and
dynamic properties of one of the most deadly and
costly weather disasters to strike southern Ontario

• Hazel struck Ontario on 15-16 October 1954
• rains led to flooding in Humber, Credit and
  Don River valleys situated near Toronto, and
  in the Holland Marsh north of Toronto
• over 80 fatalities, and $175 million damage
  was done by Hurricane Hazel in Ontario
          Track of Hurricane Hazel




Reference: Mason, A.H., M.K. Thomas and D.W. Boyd. 1955.
The October 15-16, 1954 Storm, “Hurricane Hazel” in Ontario.
          Synoptic Overview
• Considering the time between October 15th
  at 00z to October 16th at 12z as this is the
  period of the most intense rainfall in
  southern Ontario
• Using the NCEP reanalysis data (Kalnay et
  al. 1996) to generate fields of interest
Figs. (a)-(d): SLP (hPa) and Thickness (dam)
      00 UTC 15 to 12 UTC 16 October
    Dynamic Tropopause Maps
• The dynamic tropopause is defined as the
  1.5 PVU surface
• 1 PVU = 10-6m2s-1K kg-1
• Ertel’s Potential Vorticity (PV)
  (Ertel 1942):
           1
     EPV      
           
Figs. (a)-(d): DT Winds and , and 850 hPa 
      00 UTC 15 to 12 UTC 16 October
    Coupling Index, Equivalent Potential
    Temperature and Precipitable Water
• Coupling Index (CI) is a measure of bulk
  atmospheric stability (Bosart and Lackmann
  1995)
              CI  (  DT   e max sfc )

• Values of CI < 10 suggest convective instability
• Precipitable water is the column integrated water
  vapour                    1 p
              PWTR            
                                   2
                                       w dp
                           g   p1
Figs. (a)-(d): Coupling Index and Precip. Water (mm)
      00 UTC 15 October to 12 UTC 16 October
           MC2 Simulation
• Using MC2 (Mesoscale Compressible
  Community Model) to simulate Hazel
• NCEP Reanalysis data utilized for the initial
  and boundary conditions
• following the work of Palmen (1958) and
  Anthes (1990)
• test sensitivity of Hazel to improved vortex
  structure using model by Kurihara (1993),
  and increased spatial resolution (36 km)
                    Tracks of Hurricane Hazel
                    Sea Level Pressure for Hurricane Hazel

                  1010
                  1000
                                                                                                                     Anthes
SLP (mb)




                  990                                                                                                NCEP
                  980                                                                                                Bogus
                                                                                                                     Knox
                  970
                  960
                          15/00z


                                          15/06z


                                                          15/12z


                                                                       15/18z


                                                                                         16/00z




                                           October 1954 Date


                         Average Depth of Precipitation

                  20
    Amount (mm)




                  15
                  10
                   5
                   0
                                                                                                           21.-24.
                         0-3

                                   3.-6

                                                   6.-9

                                                             9.-12

                                                                     12.-15

                                                                                15.-18

                                                                                                  18.-21



                                                                                                                       24.-27




                                                     Time Period (hours)
   SLP       top: Palmen’s analysis
Comparison   lower left: MC2
             lower right: Anthes
15 UTC 15
 October
    SLP      top: Palmen’s analysis
Comparison   lower left: MC2
             lower right: Anthes
 3 UTC 16
  October
              Knox’s Jump




SLP for 21 UTC 15 October to 03 UTC 16 October
Precipitation Comparison, 15 October
              Conclusions
• Successfully reproduced transformation of
  Hazel with accompanying frontogenesis and
  heavy precipitation over U.S.
• Improved vortex structure and increased
  spatial resolution necessary for successful
  mesoscale modeling of Hazel

				
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