Transcript Tracks of Hurricane Hazel - University at Albany, SUNY

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
2
3
4
.
.
.
.
Background
Synoptic Overview
MC2 Simulation Results
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 
g

2
p1
w dp
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
SLP (mb)
1010
1000
Anthes
NCEP
Bogus
Knox
990
980
970
16/00z
15/18z
15/12z
15/06z
15/00z
960
October 1954 Date
Time Period (hours)
24.-27
21.-24.
18.-21
15.-18
12.-15
9.-12
6.-9
3.-6
20
15
10
5
0
0-3
Amount (mm)
Average Depth of Precipitation
SLP
Comparison
15 UTC 15
October
top: Palmen’s analysis
lower left: MC2
lower right: Anthes
SLP
Comparison
3 UTC 16
October
top: Palmen’s analysis
lower left: MC2
lower right: Anthes
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