Introduction A. Purpose & Authority

Image 1: Image 2:

Flooded View of Highway 264 Bypass Flooded View of Pinecrest MHP

Hurricanes & Tropical Storms

• 
  Description
  

Hurricanes are cyclonic storms that originate in tropical ocean waters pole ward of about 50 degrees N. latitude. Basically, hurricanes are heat engines, fueled by the release of latent heat from the condensation of warm water. Their formation requires a low-pressure disturbance, sufficiently warm sea surface temperature, rotational force from the spinning of the Earth, and the absence of wind shear in the lowest 50,000 feet of the atmosphere.

Hurricanes that impact North Carolina form in the so-called Atlantic Basin, from the west coast of Africa westward into the Caribbean Sea and Gulf of Mexico. Hurricanes in this basin generally form between June 1 and November 30, with a peak around mid-September. As a hurricane develops, barometric pressure at its center falls and winds increase. Winds at or exceeding 39 mph result in the formation of a tropical storm, which is given a name and closely monitored by the NOAA National Hurricane Center in Miami, Florida. When winds are at or exceed 74 mph, the tropical storm is deemed a hurricane.
Because hurricanes derive their strength from warm ocean waters, they are generally subject to deterioration once they make landfall. The forward momentum of a hurricane can vary from just a few miles per hour to up to 40 mph. This forward motion combined with a counterclockwise surface flow makes the right front quadrant of the hurricane the location of the most potentially damaging winds.
Table 5:

Saffir-Simpson Scale

Category	Max. Sustained	Min. Surface	Storm Surge (feet)
	Wind Speeds (mph)	Pressure (millibars)
1	74-95	Greater than 980	3 to 5
2	96-110	979-965	6 to 8
3	111-130	964-945	9 to 12
4	131-155	944-920	13 to 18
5	155+	Less than 920	19+

Hurricane intensity is measured using the Saffir-Simpson Scale (Table 5 above), ranging from 1 (minimal) to 5 (catastrophic). This scale categorizes hurricane intensity linearly based upon maximum sustained winds, minimum barometric pressure and storm surge

potential, which are combined to estimate potential damage. Categories 3, 4 and 5 are classified as “major” hurricanes, and while hurricanes within this range comprise only 20% of total tropical cyclone landfalls, they account for over 70% of the damage in the United States. Table 6 describes the damage that could be expected for each type of hurricane.
Table 6:

Hurricane Damage Classification

Category		Damage Level		Description
1	MINIMAL		No real damage to building structures. Damage primarily
			to unanchored mobile homes, shrubbery, and trees. Also,
			some coastal flooding and minor pier damage
2	MODERATE		Some roofing material, door and window damage.
			Considerable damage to vegetation, mobile homes, etc.
			Flooding damages piers and small crafts in unprotected
3	EXTENSIVE		Some structural damage to small residences and utility
			buildings, with a minor amount of curtainwall failures.
			Mobile homes are destroyed. Flooding near the coast
			destroys smaller structures with larger structures damaged
			by floating debris. Terrain may be flooded well inland.
4	EXTREME		More extensive curtain wall failures with some complete
			roof structure failure on small residences. Major erosion of
			beach areas. Terrain may be flooded well inland.
5	CATASTROPHIC		Complete roof failure on many residences and industrial
			buildings. Some complete building failures with small
			utility buildings blown over or away. Flooding causes major
			damage to lower floors of all structures near the shoreline.
			Massive evacuation of residential areas may be required

Directory: div
div -> 9th May 1950 the schuman declaration
div -> Supplemental demographic information
div -> Executive summary 8 I. Introduction 26 II. State government capability 28
div -> This section includes changes made during the 2013 update
div -> General occupational safety and health rules subdivision z toxic and hazardous substances
div -> Computer Basics What is a computer
div -> Mobile county, alabama regular board meeting
div -> Privacy: Campus Living & Technology

Download 0.81 Mb.

Share with your friends: