surface analysis chart

Cards (32)

  • surface analysis charts - are analysed charts of surface weather observations.
  • surface analysis charts depicts the distribution of several items, including sea-level pressure, position of highs, lows, ridges, and throughs, location and type of fronts, and boundaries like drylines
  • WPC issues surface analysis chart eight times daily, meaning, valid at 00, 03, 06, 09, 12, 15, 18, 21
  • components of surface analysis charts are isobars, fronts, high pressure and low-pressure system, and surface weather station plots
  • isobars are lines on a map that pass through an area with the same pressure
  • iso means same, bar means unit of measure for pressure
  • isobars has 4hPa difference between and can range from 870 hPa to 1080 hPa
  • fronts are weather system that is the boundary separating two different types of air mass
  • types of fronts includes cold front, warm front, stationary front, occluded front, through, ridge, squall line, dryline, and tropical wave
  • cold front - cold air mass replacing warmer air mass
  • warm front - warm air mass replacing colder air mass
  • stationary front - forms when a cold or warm front stops moving
  • occluded front - forms when warm air mass gets caught between two cold air masses
  • through - elongated area of relatively low pressure extending from the center of a region of low pressure
  • ridge -  elongated area of relatively high pressure extending from the center of a high-pressure region
  • squall line - group of storms arranged in a line
  • dryline - boundary between moist and dry air masses
  • tropical wave - areas of low pressure in the tropics, generally from east to west due to trade winds
  • the large letters (Blue H’s and Red L’s) on weather maps indicate centers, marks the highest and lowest relative to the surrounding air
  • high pressure and low-pressure system are often labeled with a three or four digit pressure reading in millibars
  • surface weather station plots describes the weather at a station location
  • surface weather station plots includes reports of a variety of weather data at that location
  • surface weather station plots shows information like wind speed and direction, temperature and dewpoint, current weather, pressure and pressure trend, sky cover, visibility
  • current weather symbols are established by NOAA for use in weather station plots
  • current weather tells what conditions are currently happening at that particular station location
  • current weather symbols are typically plotted if some type of precipitation is occurring or some weather event is causing reduced visibility at the time of observation
  • sea-level pressure is plotted in tenths of millibars (mb) with the first two digits (generally 10 or 9) omitted
  • pressure trend has two components and that is a number and a symbol
  • pressure trend indicates how sea-level pressure has changed during the past 3 hours
  • in pressure trend, the number provides the 3-hour change in tenths of millibars, while the symbol provides a graphic illustration of how this change occurred
  • approximate amount of sky cover can be determined by the circle at the center of the station plot
  • horizontal surface visibility is measure in statute miles