NWS forecasts use such categorical terms as occasional, intermittent, or periods of to describe a precipitation event that has a high probability of occurrence (80%+), but is expected to be of an "on and off" nature. Unless specified otherwise, the time period is normally 12 hours. Measurable precipitation is equal to or greater than 0.01 inches. The probability of precipitation (POP), is defined as the likelihood of occurrence (expressed as a percent) of a measurable amount of liquid precipitation (or the water equivalent of frozen precipitation) during a specified period of time at any given point in the forecast area. Strong, dangerous, high, damaging (High Wind Warning Criteria) New precipitation amounts of less than a tenth of an inch possible. The wind forecast is included in the first three periods of the zone forecast.Ä«reezy (mild weather) Brisk or Blustery (cold weather) Windy, with a southwest wind 16 to 21 mph increasing to 25 to 30 mph in the afternoon. The wind describes the prevailing direction from which the wind is blowing with speeds in miles per hour. The temperature in a forecast is used to describe the forecast maximum and minimum temperature, or in some cases, the temperature at a specific time. If a high probability of precipitation (60% or greater) is expected, then the sky condition may be omitted since it is inferred from the precipitation forecast. The sky condition describes the predominant/average sky cover based on percent of the sky covered by opaque (not transparent) clouds. Environment Canada reports a chance of precipitation (COP) that is defined as 'The chance that measurable precipitation (0.2 mm of rain or 0.2 cm of snow) will fall on any random point of the forecast region during the forecast period.' 6 The values are rounded to 10 increments, but are never rounded to 50. Listed below are descriptors of regularly used weather terms and their meanings to help give a better understanding of each forecast. The terminology used in these forecasts is quite variable. The National Weather Service issued forecasts for sky condition, temperature, wind and precipitation on a routine basis.
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