WES WEEK TWO: 17-21 September 2001

THE AUTUMNAL EQUINOX -- The Autumnal Equinox will occur on the afternoon of Saturday, 22 September 2001 (at 2305Z, or 5:05 PM EDT, 4:04 PM CDT, etc.). At that time the noontime sun will appear directly above the equator, representing one of the two times during the year for such an occurrence, with the other being at the vernal equinox in March. Within the next several days the length of daylight will become noticeably shorter than that of nighttime.

Concept of the Week: Water Chill

The epic movie Titanic dramatically portrayed how immersion in cold water can be deadly. After abandoning ship, passengers and crew left floating in relatively calm seas perished within a short time. Residents of cold climates are warned of the dangers posed by a combination of low air temperature and strong winds (the wind-chill). Because of the special thermal properties of water, immersion in cold water can be even more hazardous. A boating accident or a plunge through thin ice on a lake can have deadly consequences.

One of the principal hazards of cold water immersion is a lowering of body temperature due to excess heat loss. (Perhaps half of all drowning victims actually die from this effect of cold water rather than water-filled lungs.) Heat is energy that is transferred between two objects at different temperatures, always flowing from the warmer to the colder object. Since the human body can regulate its core temperature so that it normally varies by no more than about 2 Celsius degrees (3.6 Fahrenheit degrees) above or below 37 ^oC (98.6 ^oF), heat usually flows from the human body to its cooler surroundings. Core temperature refers to the temperature of vital organs such as the heart, lungs, and kidneys.

When immersed in cold water, a body may lose heat at such a high rate that thermoregulatory processes cannot prevent a steady drop in core temperature and the victim may exhibit symptoms of hypothermia. These symptoms set in when a person’s core temperature falls below 36 ^oC (96.8 ^oF). Shivering (a natural thermoregulatory process) becomes violent and uncontrollable and the victim has difficulty speaking and becomes lethargic. If the core temperature drops below 32 ^oC (90 ^oF), shivering ceases, muscles become rigid, and coordination deteriorates. At a core temperature of 30 ^oC (86 ^oF), a person may drift into unconsciousness and death may ensue at a core temperature below 24 ^oC (75 ^oF).

A person runs a greater risk of developing hypothermia when immersed in water than air at the same temperature. Water conducts heat at a rate that is more than 20 times greater than still air and water’s specific heat is almost 6 times that of dry air. Whereas the risk of hypothermia due to low air temperature primarily occurs in winter, cold water immersion is possible anytime of year in many locations. Ocean or lake temperatures may remain relatively low throughout the summer months because of water's relatively great thermal inertia.

The Naval Atlantic Meteorology and Oceanography Center maintains a web site that gives expected maximum human survival times in the waters along the Atlantic coast. Go to: http://www.nlmoc.navy.mil/newpage/oceans/ Then, under "Analysis," click on "VACAPES Water Survival graphic." Note, for example, the longer survival time in the warm Gulf Stream. (Actual survival time also depends on such factors as age, physical activity, and protective clothing.) For a Water Survival Table giving survival times as a function of water temperature for a person without an anti-exposure suit, go to: http://nlmoc1.nlmoc.navy.mil/prods/oceans/specwar/tables/water.html

1. Water is a [(much better)(poorer)] conductor of heat than still air.
2. Hypothermia is a potentially lethal [(rise)(fall)] in the temperature of the human body’s vital organs.

• 17 September 1963...Nearly two and a half inches of rain fell at Yuma, AZ in 24 hours. This rain, from Tropical Storm Katherina, was the most intense rain for Yuma during the period between 1909 and 1977. (The Weather Channel)

• 17-23 September 1989...Hurricane Hugo hit the Virgin Islands on the 17th, producing wind gusts to 97 mph at Saint Croix. Hurricane Hugo passed directly over the island of Saint Croix causing complete devastation and essentially cutting off the island from communications. A storm surge of five to seven feet occurred at Saint Croix. The only rain gauge left operating, at Caneel Bay, indicated 9.40 inches in 24 hours. Hurricane Hugo claimed the lives of three persons at Saint Croix, and caused more than 500 million dollars damage. A ship, Nightcap, in the harbor of Culebra, measured wind gusts as high as 170 mph. On the 18th Hugo hit Puerto Rico, producing a storm surge of four to six feet, and northeastern sections of the island were deluged with more than ten inches of rain. Hugo claimed the lives of a dozen persons in Puerto Rico, and caused a billion dollars damage, including 100 million dollars damage to crops. On the 21st Hugo slammed into the South Carolina coast at about 11 PM, making landfall near Sullivans Island. Hurricane Hugo was directly responsible for thirteen deaths, and indirectly responsible for twenty-two others. A total of 420 persons were injured in the hurricane, and damage was estimated at eight billion dollars, including two billion dollars damage to crops. Sustained winds reached 85 mph at Folly Beach SC, with wind gusts as high was 138 mph. Wind gusts reached 98 mph at Charleston, and 109 mph at Shaw AFB. The biggest storm surge occurred in the McClellanville and Bulls Bay area of Charleston County, with a storm surge of 20.2 feet reported at Seewee Bay. Shrimp boats were found one half mile inland at McClellanville. On the 22nd Hugo quickly lost strength over South Carolina, but still was a tropical storm as it crossed into North Carolina, just west of Charlotte, at about 7 AM. Winds around Charlotte reached 69 mph, with gusts to 99 mph. Eighty percent of the power was knocked out to Charlotte and Mecklenburg County. Property damage in North Carolina was 210 million dollars, and damage to crops was 97 million dollars. The strongest storm surge occurred along the southern coast shortly after midnight, reaching nine feet above sea level at Ocean Isle and Sunset Beach. Hugo killed one person and injured fifteen others in North Carolina. (Storm Data) (The National Weather Summary)
• 18 September 1926...The great "Miami Hurricane" produced winds reaching 138 mph which drove ocean waters into the Biscayne Bay drowning 135 persons. The eye of the hurricane passed over Miami, at which time the barometric pressure reached 27.61 inches. Tides up to twelve feet high accompanied the hurricane, which claimed a total of 372 lives. (David Ludlum) (The Weather Channel)
• 19 September 1967...Hurricane Beulah deluged Brownsville, TX with 12.19 inches of rain in 24 hours, to establish a record for that location. Hurricane Beulah made landfall on the 20th near the mouth of the Rio Grande River, where a wind gust to 135 mph was reported by a ship in the port. (19th-20th) (The Weather Channel)
• 20 September 1845...A tornado, called the "Adirondack Tornado" traveled 275 miles across Lake Ontario, New York and Lake Champlain, after starting as a waterspout over Lake Ontario and then traveling as a tornado through New York State to exit as a waterspout again on Lake Champlain. The treefall in the forest is still discernible. (Sandra and TI Richard Sanders - 1987) (Intellicast)
• 20 September 1909...A strong hurricane made landfall in southeastern Louisiana. A 15 foot storm surge flooded the Timbalier Bay area. 350 people perished. (Intellicast)
• 21 September 1938...A great hurricane smashed into Long Island and bisected New England causing a massive forest blowdown and widespread flooding. Winds gusted to 186 mph at Blue Hill, MA, and a storm surge of nearly thirty feet caused extensive flooding along the coast of Rhode Island. The hurricane killed 600 persons and caused 500 million dollars damage. The hurricane, which lasted twelve days, destroyed 275 million trees. Hardest hit were Massachusetts, Connecticut, Rhode Island and Long Island NY. The "Long Island Express" produced gargantuan waves with its 150 mph winds, waves which smashed against the New England shore with such force that earthquake-recording machines on the Pacific coast clearly showed the shock of each wave. (David Ludlum) (The Weather Channel)
• 21-23 September 1992...The south of France was deluged by torrential rains. As much as 17 inches fell in a 12 hour spell on the 22nd. A wall of water 49 feet high swept through Vaison la Romaine. Whole trees penetrated houses and vehicles. At least 38 died. (Accord Weather Calendar)