Hurricanes

Characteristics


Hurricanes, coastal storms and Nor’easter are all forms of cyclones. Hurricanes and coastal storms are a tropical cyclone that is a rotating, organized system of cloud and thunderstorms that originate in tropical or subtropical waters and have closed low-level circulation.

Hurricane seasons runs from June 1 until November 30th each year. The peak period for named storms runs from around mid-August until late October.
Hurricane

Tropical Cyclones


Tropical cyclones in the northern hemisphere rotate counterclockwise. Tropical cyclones are warm-core, low pressure systems that thrive on the warmer airs and warmer waters.  There are four primary types of tropical cyclones:
  • Hurricane – max sustained winds of 74 mph and higher
  • Major Hurricane – max sustained winds of 111 mph or higher (Category 3, 4 and 5)
  • Tropical Depression – max sustained winds of 38 mph or less
  • Tropical Storm – max sustained winds of 39-73 mph

Nor-easters


A Nor’easter is a form of a cyclone that forms, typically, along the upper East Coast of the United States and Canada. Nor’easters also rotate counterclockwise. Nor’easters differ from tropical cyclones in that nor’easters are cold-core, low pressure systems, meaning they thrive on colder temperatures and waters.

The primary damaging forces associated with these types of storms include:
  • Coastal erosion
  • Flooding
  • Heavy precipitation
  • High-level sustained winds
  • Storm surge
  • Tornadoes
Nor’easters may also include snow and blizzard conditions due to the colder air temps.

Storm Development


Tropical cyclones can develop in the Gulf of Mexico, the Caribbean Sea, the Pacific and Atlantic Oceans. They are born in moist tropical air. 

About every four to five days, a tropical wave of low pressure moves along with westerly winds. In developing tropical cyclones, strong thunderstorms occur. Air pressure drops at the surface of these storms. This low pressure attracts warm moist air from the ocean's surface. 

The Coriolis force causes the resulting low-level winds to spiral in a counterclockwise direction around the center of the low in the Northern Hemisphere. Sinking air at the center clears the tropical cyclone of clouds and forms the "eye”, but an eye is not necessary for a tropical cyclone to become a hurricane. Falling surface pressure can occur only if air mass is removed from the circulation center. This is accomplished by wind flowing away from the circulation in the upper atmosphere.

When maximum sustained winds reach or exceed 39 miles per hour, the system is designated a tropical storm, given a name and is closely monitored by the National Hurricane Center in Miami, Florida.  

When sustained winds reach or exceed 74 miles per hour the storm is deemed a hurricane.  Hurricane intensity is further classified by the Saffir-Simpson Hurricane Wind Scale which rates hurricane intensity on a scale of 1 to 5, with 5 being the most intense. More information on intensity rating can be found on the Hurricane Wind Scale page.

Hurricane Wind Scales



Hurricane intensity is classified by the Saffir-Simpson Hurricane Wind Scale which rates hurricane intensity on a scale of 1 to 5, with 5 being the most intense.
  1. CAT 1
  2. CAT 2
  3. CAT 3
  4. CAT 4
  5. CAT 5

MINIMAL

Very dangerous winds will produce some damage

: Well-constructed frame homes could have damage to roof, shingles, vinyl siding and gutters. Large branches of trees will snap and shallowly rooted trees may be toppled. Extensive damage to power lines and poles likely will result in power outages that could last a few to several days.

Winds


  • 74-95 mph
  • 64-82 kt
hurricane preparedness

Hurricane Season


Summer is the best time to prepare for whatever tropical weather may affect Onslow County, and Emergency Management is urging residents to update their emergency plans and kits before storms strike.

The Atlantic hurricane season runs June 1 through November 30, but most hurricanes strike the East and Gulf Coasts between mid-August and mid-October. Summer is the best time to prepare for whatever tropical weather may affect Onslow County, and Emergency Management is urging residents to update their emergency plans and kits before storms strike. 

Dangers


Tropical storms and hurricanes bring damaging winds, heavy rains, flooding and even tornadoes. In coastal areas, hurricanes can cause rip currents and storm surge. In the foothills and mountains, these tropical storms can spur dangerous landslides and mudslides. Since hurricanes have impacted every part of North Carolina, it's important for everyone to have a plan in place before a storm threatens Onslow County. 

Ready Your Emergency Kit


Onslow County Emergency Management urges residents to make a plan and put together an emergency supplies kit to provide the tools needed to survive the storm and recover from it. 

Families should have their emergency kit ready to go at all times with enough non-perishable food and bottled water (1 gallon per person per day) to last 3 -7 days. Kits also should include: 
  • Bedding
  • Cash or checkbook
  • Changes of clothes
  • Copies of insurance papers and identification sealed in a watertight plastic bag
  • First-aid kit
  • Hygiene items such as toothbrush, toothpaste, soap and deodorant
  • Pet supplies including food, water, leashes, bedding, muzzle and vaccination records
  • Supply of prescription medicines
  • Weather radio and batteries

Stay Informed


Stay informed during severe weather using a battery-powered radio for weather and evacuation information. Know evacuation routes in your community; heed the warnings of state and local officials and evacuate quickly when told to do so. 

Be sure to review and update your homeowners' or renters' insurance policies to make sure they include coverage for accidental damage, natural disasters and, if necessary, flood insurance. 

More information on hurricanes and overall emergency preparedness can be found at the Ready.gov website and ReadyNC. Onslow County emergency officials also urge residents to get the free ReadyNC mobile app which provides real-time weather and traffic conditions for all parts of North Carolina.

Hurricane Safety

  1. Before the storm
  2. During the storm
  3. After the storm



Before the Hurricane



  • Closely watch/listen to the weather reports. Listening every hour as the storm nears.
  • Put fuel in all vehicles and withdraw some cash from the bank. Gas stations and ATMs may be closed after a hurricane.
  • If authorities ask you to leave, do so quickly.
  • If you leave (evacuate), be alert to flooded or washed-out roads. Just a few inches of water can float a car. Think: Turn Around, Don't Drown.
  • Keep a photo I.D. that shows your home address. You will need it when asking police if it is okay for you to re-enter your area or home.
  • Secure your property.
  • Bring inside all outdoor furniture, decorations, garbage cans and anything else that is not tied down.
  • Cover windows with permanent storm shutters or board up windows with 5/8” plywood, cut and ready to install. Tape does not stop windows from breaking.
  • Put in straps or extra clips to securely fasten your roof to the frame structure. This will lower roof damage.
  • Trim trees and shrubs around your home, so they are more wind resistant.
  • Clear clogged rain gutters and downspouts.
  • Reinforce garage doors. If wind enters a garage it can cause dangerous and expensive structural damage.