CONSEQUENCES OF EXTREME WINDS &
SEVERE STORMS
Extreme Wind Speeds in the U.S.
Severe Wind Types
Severe Wind Types
Non-tornadic: All at Mount Washington, N.H.
Mountain Lee Waves & Extratropical Cyclones
Downbursts
Highest
Peak gust
PNoted
first by Fujita (1975)
PVertical downward jet from
a thunderstorm
PFrequently mistaken for
tornados
PTypes:
Speed (m/s)
PMountain
103.6
5-min speed
24-hr speed
Monthly speed
84.2
57.2
31.1
Annual speed
15.6
Lee Waves
Chinook, Fohn Winds
Ground speeds to 30 m/s (eg.
Boulder)
Gust factors from 2 to 7
PExtratropical
Cyclones
Weather storms rising outside
L
tropical lattitudes
Typical storms and weather seen
over most of USA
Ground speeds to 40 m/s
Microburst:
Macroburst:
75 m/s
60 m/s
28T & F1
1
F1
3
7T & F1
Severe Wind Types
Severe Wind Types
Tornadoes
Cyclones, Hurricanes or Typhoons
WEAK TORNADO
10-7 to 10-3/yr
PLength:
150-150,000 m
PWidth:
15-1,200 m
PSpeed Tangential: 25-150 m/s
STRONG TORNADO
PSpeed Vertical:
< 80 m/s
PSpeed Radial:
< 50 m/s
PProbability:
P Large scale organized rotating
flow system over sea surface
P Created when sea surface
temperature is > 26.5O C
P Energized by latent heat
release
P Eye translates at 2 - 10 m/s
P Wind speeds range from 33
to > 69 m/s
Miami
Daytona Savanah
Beach
50
mi
6T & F1
4
5
5T & F1
Hurricane
Andrew
Hurricane Size
300
mi
Hurricane Andrew
Saffir/Simpson Damage Potential Scale Ranges
Category
Central Pressure
[mb (in Hg)]
Winds
[mph]
Surge
[ft]
Damage
1
2
> 980 (28.94)
965-979 (28.50-28.91)
74-95
96-110
4-5
6-8
Minimal
Moderate
3
4
945-964 (27.91-28.47)
920-944 (27.17-27.88)
111-130
131-155
9-12
13-18
Extensive
Extreme
5
< 920 (< 27.17)
> 155
> 18
Saffir-Simpson
Category 4 Hurricane
Catastrophic
6
F1
8
7
1T & F1
Hurricane
Mitch
Direct Impacts of Hurricane Andrew
Total Cost $30 Billion:
Hurricane Mitch
R.A. Pielke, Jr. (1997)
>20,000 dead and > 20,000 missing
Refugees cross
flood waters
Insured Property - $16.5 B
P
2000 people killed
in mudslide down
side of volcano
Orphan from mud
slide on volcano,
Nicaragua
Defense Dept - $1.4 B
Uninsured Property - $0.35 B
Federal Relief - $6.5 B
Red Cross - $0.07 B
Flood - $0.1 B
Aircraft - $0.02 B
Environment - $2.12 B
Agriculture - $1.52 B
Infrastructure - $1.4 B
Saffir-Simpson
Category 5 Hurricane
10
9
Current Potential for Catastrophic
Losses in the United States
Losses assumed proportional to wealth, inflation and population
then adjusted to 1995$
P Multibillion $ storms are norm not the exception
P Over 71 years the normalized losses were $339B:
 Average year $4.8 B/year
 Maximum year $74 B/year
 43% of time
< $1 B/year
 25% of time
> $5 B/year
 18% of time
>$10 B/year
P Thus US has 1:6 chance of experiencing a $10 B loss
P No evidence for any climatic change
11
1T & F1
1T & F1
Conclusions from Normalized Data
Approach
Children flee over
damaged bridge,
Guatemala City
Bob Sheets (former director National Hurricane Center), 1995
PIf Hurricane Andrew had tracked 20 miles further
north “total property damage would have
exceeded $100,000,000,000"
PHurricanes like we had in the 40's and 50's today
would cost:
$68,000,000,000 in Maryland and Virginia
$106,000,000,000 in south Florida
$104,000,000,000 in New England
13
9T
14
5T
Prepared by Robert N. Meroney, June 2000