USA and Canada Holiday Hints
|Electrical Storm||The name given in the USA and Canada to what is called a thunderstorm in Britain.|
|Funnel Cloud||A tornado which has not yet touched down.|
|Hurricane||A tropical cyclone which originates over an ocean, particularly in the West Indian region, including the Caribbean Sea and the Gulf of Mexico, and the eastern Pacific. Hurricanes only occur north of the equator. In a hurricane high velocity winds blow circularly around a low pressure centre called the eye of the storm. According to one source a hurricane is defined by having winds in excess of 70 miles per hour.
The area affected by destructive winds can be greater than 150 miles in diameter, with gale force winds covering up to 300 miles in diameter. The strength of a hurricane is rated from 1 to 5, 1 being the mildest and 5 the strongest. Hurricanes generally move in a parabolic curved path, usually first in a northwesterly direction at 5 to 20mph and then later northeast at up to 50mph. The National Hurricane Centre in Florida tracks and predicts the path of each storm. Damage is usually confined to coastal regions.
States which are most vulnerable are Alabama, Florida, Georgia, Maryland, North Carolina, and South Carolina. Hawaii is susceptible to hurricanes in the Pacific Ocean but these are rare.
The hurricane season for the Atlantic and Gulf of Mexico coasts of the USA is from June to November. Hardly any hurricanes occur outside this period. The peak period is September.
Hurricanes can occur during this period on the Pacific coast of the USA but they are extremely rare, the last one being in 1935.
|Tornado||A funnel-shaped cloud of violently whirling wind, extending down from a cumulonimbus cloud. Tornadoes are also called twisters. Tornadoes develop from thunderstorms.
The width of tornado damage paths can vary from a few yards to over a mile and paths can be as much as 50 miles long. Damage can often be extremely severe. On average, 800 tornadoes are reported in the USA each year.
The funnel of a tornado is visible due to the water drops and dust and debris sucked up. According to some sources wind speeds within the funnel have been estimated as being up to 500mph. However, in October 2007 Brian Daly of Mobile, Alabama commented:
Most meteorologists (I being one) do not accept that figure anymore. Ted Fujita's work over the last fifty or so years has shown that those speeds would not be seen considering the physics, although it used to be. The old F-Scale indicates F-5 speeds based on damage would be in the range of 265 to 318 mph... now even that has been reduced, using a lower and more sophisticated scale called the "Enhanced Fujita" Scale (EF), and EF-5 is 200-234 mph. The Storm Prediction Center Website http://www.spc.noaa.gov/faq/tornado/ef-scale.html is germane to this... and has a lot of other information on the subject.In the southern USA tornadoes tend to form most frequently in the early spring, while in the northern USA they are most common in summer. For example, in Iowa most tornadoes occur between April and September, with April and May being the most dangerous months.
Most tornadoes occur in the American Midwest, between the Appalachian Mountains and the Rockies. However, tornadoes can occur in all American states. In 1999 there was a hurricane in Salt Lake City, Utah, which was regarded as being a highly usual event.
Most tornadoes move from southwest to northeast.
Most tornadoes occur in the late afternoon or early evening.
|"Tornado Alley"||The American states most prone to tornadoes: Arkansas, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Mississippi, Missouri, Nebraska, Oklahoma, Tennessee and Texas.|
|Tornado Warning||A tornado warning means that a tornado has been spotted and you should observe the safety hints listed below.|
|Tornado Watch||A tornado watch means that weather conditions are right for the formation of tornadoes. You should listen to local radio and television stations for up to date weather information, if possible using a battery operated set.|
|Tropical Storm||Officially this refers to a hurricane or a typhoon. Unofficially it is a term used to refer to less violent storms. According to another source a tropical storm is any storm with winds of 40 to 60 miles per hour.|
|Tsunami||See separate article.
Tsunami are not weather conditions but are included in this list of definitions for convenience.
|Twister||Same as a tornado.|
|Typhoon||The name given to storms similar to hurricanes in the western Pacific Ocean. Typhoons occur both north and south of the equator.|
|Warning||A warning means that the stated danger is actually occurring and you should observe the appropriate safety hints.|
|Watch||A watch means that weather conditions are right for the formation of the stated danger. You should listen to local radio and television stations for up to date weather information, if possible using a battery operated set.|
Major Jim Collins of the USAF, based at Nellis Air Force Base near Las Vegas Nevada, offers the following very sensible advice:
Extreme heat is something we deal with frequently in Las Vegas :)
In the West humidity is fairly low, so perspiration evaporates quickly, which is a good thing. What is not such a good thing is that one may dehydrate very quickly especially if not acclimatised. I have personally seen tourists collapse from heat exhaustion downtown. It's easy to tell the locals from tourists: the locals carry water bottles, the tourists carry soda or beer.
Drink plenty of fluids, primarily water. Sugary fluids such as soda and electrolytic drinks such as Gatorade take longer for your body to break down and have extra calories. Alcohol and caffeine are diuretics, avoid them at least during the day. Always drink at least one litre of water in the morning before you do any walking or hiking and continue throughout the day. Thirst is no indicator, often times dehydration as already occurred before one becomes thirsty. The converse is true as well, finish off your litre(s) of water even if you've slaked your thirst. A technique used in the military is to weakly flavour the water, with a drink mix, lemon etc. Psychologically, humans will continue to consume the fluid looking for the "real taste" of the drink. Related to this is the water temperature: it should be cool, neither cold nor warm, the ideal is around 50-60F. Otherwise, your body rejects it, and shuts down the drinking desire. Typically, urination will tell you if you are properly hydrated: colourless to light yellow and slightly more frequently than usual is ideal. Lack of urination and an orange to dark orange colour when you do is an indication that you are dehydrating. Avoid salt tablets, you get sufficient salt from your food. In very hot weather you may wish to lightly salt your meals yourself. Again, that's more than sufficient.
Pace yourself, and programme most of your physical activity towards the early morning or after sunset. Typically temperatures drop twenty to thirty degrees Fahrenheit in the desert after the sun sets. In order to really acclimatise you should do at least two hours of sweat-inducing activity a day for ten to twelve days. For most healthy people though, after a couple days you can start doing more physical stuff during the daylight hours. Let your body be your guide, if you feel tired with a headache, etc stop. Get in some shade and rest.
Wear light coloured, loose fitting clothes. The desert in summer is no place to dress Gothic. Save those clothes for the bars and clubs at night. Wear sunscreen; you can burn in less than forty minutes if you aren't acclimatised. As your tan builds you'll find you can stay out longer of course, but still put on some sunscreen.
The sun is proportionally stronger at higher elevations. The air may feel cool, but the UV radiation is still powerful. Be careful.
Most importantly, take the symptoms of heat exhaustion seriously. It is an actual medical condition and as such demands treatment. Let no one try to talk you into going on. Stop, get into shade, consume as much water as you can hold and rest. If possible take a bath in warm, not cool, water as it lowers the skin temperature. Symptoms of heat exhaustion include excessive thirst, a sudden reduction in perspiration (your body is trying to conserve water), headache, nausea (in some people), dizziness. Any combination of these symptoms warrants concern.
NOAA Weather Radios can be purchased widely in the USA. Prices start at around $25. Some more expensive models have an alarm feature and some can be set to only receive warnings for a specific geographical area. NOAA transmissions are on 162.4MHz to 162.55MHz and therefore cannot be received on normal radios.
NOAA stands for National Oceanic and Atmospheric Administration, a division of the US Department of Commerce.
Thunderstorms (Electrical Storms)
Thunderstorms, called electrical storms in the USA, are very common in summer, especially in the Rocky Mountains. States most affected are Colorado, Montana, New Mexico and Wyoming. Thunderstorms usually occur in the afternoon or early evening and last only a short time, the weather quickly returning to being warm and sunny. Rainfall may be very heavy while the storm lasts, however.
Tornado Safety Hints
Phone books often contain information regarding actions to take before and during extreme weather conditions.
The Weather Channel on television is an excellent source of information regarding current weather conditions. However, it is not universally available on motel room televisions. (External link verified Sep-02)
If a tornado warning is issued, then you should pay attention to where the tornado was seen, its direction of travel and the time the warning lasts. In towns, there may be warning sirens sounded.
You should take cover at once if you are in the path of travel, in a storm cellar or in a reinforced building. Basements offer the greatest safety. Seek shelter under a stairway if possible. If you are in building without a basement then take cover in the centre part of the building on the lowest floor, in a small room or under sturdy furniture. Stay away from windows. Avoid the southwest corner of a basement or building.
In an office building go to a designated shelter or to an interior hallway on the lowest floor.
If possible take a torch (flashlight) and a battery operated radio or television with you and listen for updates on the storm's activities.
Curl up so that your head and eyes are protected.
In the country, move away from the tornado's path at right angles. If there is no time to escape, get out of your car and lie flat in the nearest ditch or ravine. Avoid being under large trees, branches or power lines.
Mobile homes are particularly vulnerable to overturning, so evacuate them.
Do not call the emergency services unless you have a genuine emergency.
External Links - Weather
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Most recently modified 26-Oct-07