surface analysis chart

• 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