WHAT YOU NEED TO KNOW ABOUT HURRICANES & TROPICAL CYCLONES. AUG 19, 2009. TROPICAL CYCLONES Marvin Bennett and Ken Tobin (CEES/TAMIU). OVERVIEW. DEFINITIONS, CLIMATOLOGY, & HISTORY HURRICANE HAZARDS FORECAST PROCESS HURRICANE PREPAREDNESS & RESPONSE. Tropical Cyclone Definitions.
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Marvin Bennett and Ken Tobin
Tropical Cyclone is a generic term for a warm-core low pressure system that forms in the tropics or subtropics.
Tropical Cyclones are further categorized by the difference in their wind speeds.
To become a tropical cyclone several ingredients are needed:
BIRTH : Nearly all tropical storms/hurricanes start out as a tropical disturbance - an area of unsettled weather in the tropics.
The conditions on the previous slide only occur close to the tropics (generally within 25o latitude) & during specific times of year!
Hence hurricane season in the Atlantic Basin is defined between June 1 and November 30.
The peak in hurricane season is around September 10th, which corresponds to the time when ocean water in the tropics reaches its maximum temperature.
Once a distributed area becomes organized this system becomes a Tropical Cyclone.
Remember that Tropical Cyclones are categorized by differences in their wind speeds:
Tropical Depression = < 39 mph
Tropical Storm = 39 mph - 74 mph
Hurricane Isabel’spower initially focused attention on the storm, but its size, not power, ensured it would be destructive. Surfers loved the big waves rolling into Ocean City, N.J., on Monday, but when Isabel hit on Thursday, much larger waves were hitting much of the East Coast.
Tropical Cyclone Evolution
Hurricane = > 74 mph
INFRARED SATELLITE PHOTOGRAPH … AUGUST 28, 1996
Points of Origin -- June
Points of Origin -- July
Points of Origin -- August
Points of Origin -- September
Points of Origin --October
Points of Origin -- November
Points of Origin -- September
Heavy rains create inland flooding that results in fatalities and/or loss of property. An example is Hurricane Carla where in Jefferson County, 180 miles from the land falling storm, $17.5 million in damage occurred, with $14 million of it water damage. Rain totaled 19" at Votan. Three to four feet of water flooded Port Arthur. Total damages from Carla estimated near $400 million.
100 Year FEMA
NWS Internet Site www.srh.noaa.gov
Note that the
“average” of the
Storm can end
up any where in
the cone & affect
areas outside of
The size of the cone
increases as the
• While official watches and warnings are issued on a time frame of 24 or 36 hrs EM professional need much more lead time to prepare.
• H Hour: The time in hours before Tropical Storm Force winds touch the coast.
• For Atlantic storms the countdown starts at H-120
• Storms that form off the coast of Texas can have as little as 24 hours from the formation to landfall.
The timeframe on Atlantic formed storms when the County Judge will make the decision to implement the Special Need Evacuation process. Bus loading will start at H-60 closest to 6 a.m.
• H-48 to H-36
Mandatory Evacuation orders for All Coastal Zip Zones in for a Catastrophic Hurricane Approaching the coast