Terms such as "slight chance" of rain (10-20%), "chance" of rain (30-50%) or rain "likely" (60-70%) are used when there is uncertainty of receiving measurable precipitation anywhere in the forecast area (such as the Greater Phoenix Area). For instance, if there is only a 30-50 percent chance that rain will fall anywhere in the Phoenix Metro area, then the forecast will call for a "chance" of rain.:::
"Measurable rain" refers to a rainfall total of 0.01 inches or greater. When you hear the terms "isolated" showers or "few" showers (10-20%), "scattered" showers (30-50%), or "numerous" showers(60-70%), in the forecast, this refers to the percent of the forecast area covered by measurable rain. For instance, "scattered showers" means that the forecast area WILL receive rain, and approximately 30-50 percent of the area will experience showers.:::
Most of the severe weather is seen in Arizona, especially in the Phoenix Metro area, is caused by micro bursts--not tornadoes. A "micro burst" is a small area of rapidly descending air beneath a thunderstorm. When the descending air hits the ground, it quickly spreads out in all directions, causing very strong, straight-line winds. These winds are commonly as strong as 40-60 mph but can exceed 100 mph at times. Micro bursts occur over a rather small space-scale, typically the area affected is less than 2.5 miles in diameter.:::
Although Phoenix residents may feel that their city MUST be the hottest place around at times, top honors go to Lake Havasu City, where the mercury climbed to 128° on June 29, 1994. This bests the Phoenix mark of 122°, set on June 26, 1990.:::
A common misuse of the term "monsoon" is to refer to INDIVIDUAL thunderstorms as "monsoons" (example - "The east valley was pounded by monsoons this evening!"). The correct statement would be "The east valley was pounded by strong thunderstorms this evening!"<br/> <br/>
Seasonal wind shifts often bring a dramatic increase in moisture, and associated shower and thunderstorm activity, to the affected region. As the monsoon ends, and the winds shift again, the reverse occurs, with much drier air moving into the area.<br/> <br/>
The best example of a monsoon on Earth occurs over the Indian sub continent. During the months of April through October, a moist southwest wind brings heavy rains to this region...while a dry northeast wind is prevalent during the remainder of the year.<br/> <br/>
In North America, a similar situation occurs over much of Mexico. For example, in Acapulco, rainfall averages 51.8 inches during the months of June through October...while only 3.3 inches falls during the remainder of the year.<br/> <br/>
In the United States, Arizona and New Mexico are located on the northern fringe of the Mexican Monsoon. For most of the year, winds aloft over the southwest U.S. are west to northwest. During the summer, winds turn to a more south to southeast direction, importing moisture from the Pacific Ocean, the Gulf of California and the Gulf of Mexico.:::
A statement generally provides additional or follow up information to an existing weather condition. An <strong>advisory</strong> is for less serious conditions that cause significant inconvenience and, if caution is not exercised, could lead to situations that may threaten life and/or property.  A <strong>watch</strong> is used when the risk of a hazardous weather event has increased significantly, but its occurrence, locations, and/or timing is still uncertain. It is intended to provide advance notice of possible inclement weather.  A <strong>warning</strong> is used for conditions posing an immediate threat to life or property. Depending on the type of warning, you should take immediate, appropriate action.:::
The air that makes up our atmosphere exerts a pressure on the surface of the earth. This pressure is known as atmospheric pressure. Generally, the more air above an area, the higher the atmospheric pressure. Barometric pressure changes with local weather conditions, making barometric pressure an important and useful weather forecasting tool. High pressure zones are generally associated with fair weather, while low pressure zones are generally associated with poor weather. For forecasting purposes, the absolute barometric pressure value is generally less important than the change in barometric pressure. In general, rising pressure indicates improving weather conditions, while falling pressure indicates deteriorating weather conditions.:::
The cloud height on this site is an estimate of <acronym title="Cumulus clouds are puffy clouds that sometimes look like pieces of floating cotton.">cumulus clouds</acronym> using a formula based on temperature and dew point. Actual measurements of cloud height are made with a Micropulse Lidar (MPL). This device fires a laser into the sky and measures the backscattered signal. Costs for such a device are beyond the scope of weather hobbyists.:::
Dew point is the temperature to which air must be cooled for saturation (100% relative humidity) to occur. The dew point is an important measurement used to predict the formation of dew, frost, and fog. If dew point and temperature are close together in the late afternoon when the air begins to turn colder, fog is likely during the night. Dew point is also a good indicator of the air&#39;s actual water vapor content, unlike relative humidity, which takes the air&#39;s temperature into account. High dew point indicates high vapor content; low dew point indicates low vapor content. In addition a high dew point indicates a better chance of rain and severe thunderstorms. You can even use dew point to predict the minimum overnight temperature. Provided no fronts or other weather pattern changes are expected overnight, the afternoon&#39;s dew point gives you an idea of what minimum temperature to expect overnight.:::
The Heat Index (HI) (or apparent temperature) is a measure of relative discomfort due to combined heat and high humidity. It was developed by R.G. Steadman (1979) and is based on physiological studies of evaporative skin cooling for various combinations of ambient temperature and humidity. As temperatures climb above 90 &deg;F and humidity goes above 40 percent, conditions are ripe for heat-related illnesses.:::
Humidity or relative humidity measures the amount of water vapor in the air relative to the temperature. It is important in weather because humidity affects how humans feel. A hot, humid day feels hotter because we cannot sweat as effectively. A cool, dry day feels colder because moisture evaporates more easily.:::
An Acroymn for METeorological Aerodrome Report. It is the primary observation code used in the United States to satisfy requirements for reporting surface meteorological data. Minimum reporting requirements includes wind, visibility, runway visual range, present weather, sky condition, temperature, dew point, and altimeter setting.:::
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		<title>WEATHER STATION</title>
		<desc><![CDATA[Weather Station - A weather station is a facility with instruments and equipment to make weather observations by monitoring atmospheric conditions to study the weather. This weather station has a thermometer for measuring temperature; barometer for measuring changes in air pressure; hygrometer for measuring humidity; anemometer for measuring wind speed and wind direction; and rain gauge for measuring precipitation.:::
Wind Chill - The wind chill temperature is what the temperature "feels like" to people and animals during cold weather. Wind chill is based on the rate of heat loss from exposed skin caused by wind and cold. As the wind increases, it draws heat from the body, driving down skin temperature and eventually the internal body temperature. Once temperatures drop below 10 &deg;F and the wind is gusting, conditions are ripe for cold-related illnesses. Below -5 &deg;F, any wind is a major factor in frostbite and hypothermia.:::
Definition Humidex - Over the years, several measures have been proposed to relate various combinations of temperature and humidity into a single number to approximate what hot, humid weather feels like to the average person. Of these, humidex is the one most familiar to Canadians. Humidex was introduced into Canada in 1965. The index is a summer analogue of the wind chill factor in that it is an equivalent air temperature. Air of a given temperature and humidity is equated in comfort to air of a higher temperature that has a negligible moisture content. Comfort is quite subjective and largely dependent on the age and health of the individual. Weather conditions causing prickly heat in an infant may result in heat cramps in a teenager, heat exhaustion in a middle-aged and heat stroke in a senior. Humidex is also limited as an overall hot-weather comfort index because it does not consider other factors such as pressure, wind speed, precipitation, sunshine or pollen.:::
Hurricane Facts:  1961 was the last time two Category 5 hurricanes formed in the same year.
1960 was the last time two Category 5 hurricanes formed and eventually made U.S. land fall.  2005 has now matched that with
Katrina and now Rita.:::
"The most common incorrect reason given for the cause of the Moon's phases is that we are seeing the shadow of the Earth on the Moon! But this cannot be correct: when the Moon passes through the shadow of the Earth, we get a lunar eclipse. Anyone who has seen a lunar eclipse, though, might remember that the Moon actually passes through the Earth's shadow only rarely, so that can't be why the Moon has phases. The real reason for the Moon's phases depends on two things: the Moon is round, and the angle it makes with the Earth and Sun changes over its orbit."<br/>- As Quoted From Bad Astronomy:::
On February 12, 2010,  49 of the 50 U.S. States had snow on the ground, with the lone exception being Hawaii. Due to El Nino and a combination of unusual
patterns, over two-thirds of the country had snow on the ground. Warmer locations such as the Florida Panhandle, Dallas and Atlanta all received a rare dose of snow. From February, 6 - February 12, 2010, 1,180 new snowfall records were set across the country.:::
On the morning of February 10, 2011, Oklahoma broke its all-time record low temperature. Calm winds and clear skies caused the city of Nowata in northeastern Oklahoma to drop to an amazingly low temperature of 31 degrees below zero. The average low temperature for Nowata was 27 degrees, making this record low temperature 58 degrees below the normal low for the date. In contrast, the low temperature at the South Pole on the same date was only 23 degrees below zero.:::
Through August 2007, the United States experienced its hottest year ever. During the month of August, more than 8,000 new heat maximum and minimum records were set or tied across the country.:::  
In Hawaii, where surface temperatures are always above 50F, there is snow. Between 1 and 2 feet of snow falls each year in the mountains above 5,000 feet.:::
Clear skies, summer humidity as low as 4% and higher elevations in New Mexico produce a surprisingly low mean annual state temperature. Delaware (55.27 F), Maryland (54.22 F) and Virginia (55.11F) all possess a warmer average annual temperature than  New Mexico (53.44F).::: 
The coldest football game ever played was the NFL Championship Game on December 31, 1967 in Green Bay, Wisconsin between the Green Bay Packers and Dallas Cowboys when the temperature fell to -13F degrees. The 2007 NFC Championship game in Green Bay between the New York Giants and Green Bay Packers was the third coldest game in history with a temperature of -1F and wind chill of -23F.::: 
The temperature in Tampa Bay and Miami, Florida has never exceeded 100 degrees, while in Bismarck, North Dakota the record temperature for each of the 5 summer months of May through September is 102 degrees or higher.  Although North Dakota is the 2nd coldest state, Bismarck's all-time high is an amazing 114 degrees, set in July, 1936.::: 
The greatest United States cold wave of the 20th century occurred during January, 1977. Snow was reported in Miami, Florida and temperatures across the northern U.S. from Iowa to Pennsylvania didn't rise above freezing for the entire month.:::
Although Hawaii is  the wettest state in the U.S., the city of Honolulu does not receive a high amount of rainfall, receiving only 18.29" annually. Cities thought of as "Dry cities" actually receive more rainfall than Honolulu - Flagstaff, Arizona (22.91"), Amarillo, Texas (19.71") and Fargo, North Dakota (21.19").:::  
The longest rain-free period in the United States was 767 days (2 years, 37 days), from October 3, 1912 to November 8, 1914 at Bagdad, California.:::
A world record rainfall occurred at Holt, Missouri on June 22, 1947 when it rained 12 inches in just 42 minutes. This averages to over 1/4 of an inch of rainfall per minute. On July 4th, 1956 In Unionville, Maryland 1.23 inches of rain fell in 1 minute.:::
Phoenix, Arizona is one of the hottest U.S. summertime cities with an average July high temperature of 104 degrees. In contrast, Flagstaff, Arizona, located only 145 miles away, is the eighth snowiest city in the United States with an average annual snowfall of 99.9 inches.:::
The average annual temperatures of New York, St. Louis and San Francisco differ by only 1.8F degrees.:::
Which is the least rainy city - Seattle, New York City or Miami? Although on average Seattle is cloudy 227 days a year, it only receives 39 inches of rain per year, compared to New York City (42 inches) and Miami (60 inches):::
Is Chicago really "The Windy City?" Of the 262 major weather reporting stations in the United States, 27% or 72 stations average higher annual wind speeds than Chicago, which averages 10.3 mph. For example, New York City's annual wind speed is 12.2 mph. The humorous explanation of the city's previous politicians being long-winded may be a more appropriate reason for the nickname.::: 
Due to Florida's proximity to the equator, the state receives more than a hundred times the UV exposure that Maine does.:::  
Cheyenne, Wyoming averages the most hail storms in the United States per year with 10 and Tulsa, Oklahoma experiences the most severe hail storms annually.::: 
The United States leads the world with an average of over 1,000 reported tornadoes each year. A distant second is Canada with an average of approximately 100 reported tornadoes.::: 
Kansas has received the most F5 tornadoes since 1880. Oklahoma encounters the highest number of significant and violent tornadoes per square mile.:::
The lowest ever recorded world temperature was at Vostok Station, Antarctica on the 21 July 1983 at a bitter -89.6C.:::
Mawsynram in India is noted as being the wettest place on earth is with over 11 meters of rain falling every year.::: 
Antofagasta in Chile is the driest place on the planet getting less than 0.1mm per year, and with many years having no rainfall whatsoever.:::
Yuma in the state of Arizona has over 4,000 hours of sunshine per year - making it the sunniest place on the planet!::: 
The South Pole is the least sunny place - only 182 days a year get sunshine.:::
The windiest place on earth is Commonwealth Bay, Antarctica where winds of 200mph have been recorded.::: 
The strongest ever recorded wind was on Mt Washington, New Hampshire, USA at an amazing 231mph.:::
Nearly 2,000 thunderstorm cells are estimated over the planet at any given time.::: 
The U.S. has over 100,000 thunderstorms every year, with over 16 million taking place across the world in a year.:::
9 out of 10 lightning bolts strike land rather than oceans.
A storm named John was the Longest-lasting Pacific tropical storm continuing for 31 days. As it crossed the dateline twice, it changed status from a hurricane to a typhoon and back to a hurricane.:::
"Ginger", was the longest-lasting Atlantic tropical storm, which spun around the open ocean for 28 days in 1971.:::
The world's largest snowflake was recorded in the Guinness Book of Records, at 38 cm wide and 20 cm thick. The snow flake fell at Fort Keogh, Montana, USA on 28 January 1887.:::
The greatest snowfall recorded was on Mt Rainier, Washington State, USA - Over 30 metres (98 feet) fell during the winter of 1972.:::
On 14th April, 1986 Bangladesh was hit by the biggest hail stones ever recorded - weighing in at over 1kg each - killing 92 people.:::
Tornadoes cause an average of 70 fatalities and 1,500 injuries in the U.S. each year.:::
The strongest tornadoes have rotating winds of more than 250 mph.:::
Tornadoes can be one mile wide and stay on the ground over 50 miles.:::
Lightning occurs in all thunderstorms; each year lightning strikes the United States 25 million times.:::
The energy from one lightning flash could light a 100-watt light bulb for more than 3 months.:::
The air near a lightning strike is heated to 50,000F hotter than the surface of the sun!:::
Most flash flood fatalities occur at night and most victims are people who become trapped in automobiles.:::
Listening to the chirps of crickets can give you a rough estimate of what the temperature outdoors is on the Fahrenheit temperature scale. Count the amount of chirps you hear in fifteen seconds and add 37!:::
Death Valley, California's temperature has the U.S. temperature record: 134 degrees Fahrenheit recorded at Greenland Ranch.::: 
Hilo, Hawaii is the wettest city in the United States with an average annual precipitation of 128 inches! To put that into perspective, one inch of rain falling over one acre of land is over 27,000 gallons of water or over 226,000 pounds of water.:::