A Reanalysis of Hurricane Hazel (1954)

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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

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Talk Outline

• . Background
• . Synoptic Overview
• . MC2 Simulation Results
• . Conclusions

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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

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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.
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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

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Figs. (a)-(d) SLP (hPa) and Thickness (dam)00
UTC 15 to 12 UTC 16 October
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Dynamic Tropopause Maps

• The dynamic tropopause is defined as the 1.5 PVU
  surface
• 1 PVU 10-6m2s-1K kg-1
• Ertels Potential Vorticity (PV)
  (Ertel 1942)

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Figs. (a)-(d) DT Winds and q, and 850 hPa q00
UTC 15 to 12 UTC 16 October
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Coupling Index, Equivalent Potential Temperature
and Precipitable Water

• Coupling Index (CI) is a measure of bulk
  atmospheric stability (Bosart and Lackmann 1995)
• Values of CI lt 10 suggest convective instability
• Precipitable water is the column integrated water
  vapour

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Figs. (a)-(d) Coupling Index and Precip. Water
(mm)00 UTC 15 October to 12 UTC 16 October
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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)

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Tracks of Hurricane Hazel
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SLP Comparison 15 UTC 15October
top Palmens analysis lower left MC2 lower
right Anthes
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SLP Comparison3 UTC 16October
top Palmens analysis lower left MC2 lower
right Anthes
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Knoxs Jump
SLP for 21 UTC 15 October to 03 UTC 16 October
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Precipitation Comparison, 15 October
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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