Precipitable Water - This takes into account all the water vapor that is found in the atmosphere from the surface to a specified height. Precipitable water is the amount of liquid precipitation that would occur if all the water vapor were condensed. The measurement is given in inches of rain. Precipitable water values are watched closely by meteorologists when diagnosing the potential for heavy rains during weather events.

Forecast - A prediction of coming events or conditions. Forecasts are commonly used in business and weather.

Occluded front - An occluded front forms when a mid-latitude cyclone's cold front catches up and merges with the warm front. This occurs due to the fact that cold fronts move faster than warm fronts. Once a low pressure system contains an occluded front, the low pressure system begins to weaken. The passage of an occluded front will feel like the passage of a cold front to an observer as cooler and drier air moves in behind an occluded front.

Smog - The first definition of smog was a mixture of smoke and fog in the atmosphere which reduces visibility. Over time smog has now changed its meaning to restricted visibility due to pollution emitted from human activities. A type of smog known as photochemical smog, common to heavily populated areas, forms when UV light from the sun reacts with low level pollutants such as nitrogen oxides. On hot days this reaction can create ozone gas at the surface which is dangerous to humans.

Severe Thunderstorm Watch - This is issued by the National Weather Service when conditions are favorable for the development of severe thunderstorms in and close to the watch area. A severe thunderstorm by definition is a thunderstorm that produces one or more of the following: 1 inch hail or larger in diameter, winds equal to or exceeding 58 miles an hour, isolated tornadoes. The size of the watch can vary depending on the weather situation. They are usually issued for a duration of 4 to 8 hours. A watch doesn't mean severe weather is occurring, but it does mean that severe thunderstorms are possible in the watch area.

Advection - The transfer of an atmospheric property by wind. The most common entities that meteorologists look at when diagnosing areas of advection are temperature and moisture.

Cap Cloud - A stationary stratiform cloud that forms directly above an isolated mountain peak. This type of cloud develops when moist air pushes against the mountain and is forced upward. As the air rises it eventually cools enough for the water vapor to condense and form a cloud.