What Is Weather Chart?

The Met Office Observation of the Cold Fronts

A cold front is near the edge of a cold air mass. A cold front appears as a blue line with triangles on a synoptic chart. The direction in which the triangles point is the direction in which the front is moving.

A warm front marks the edge of a warm air mass. A warm front appears as a red line on a synoptic chart. The front is moving in one direction and the semi-circles point is in another.

When the cold front catches up with the warm front, the warm air between the fronts is lifted into a narrow wedge above the surface. An occluded front appears as a purple line with a combination of triangles and semi-circles on a synoptic chart. The direction in which the front is moving is the direction in which the symbols point.

The current weather is recorded by the Met Office with 100 codes. The weather symbols used to represent different types of weather can be found below. If the gust is greater than 25 knots, it is recorded as whole knots and the letter G is used to calculate the speed.

Fronts and Semi-circles in the Isometries of a Land Map

The isobars are similar to the lines on a land map and join areas of equal barometric pressure. The air will move from high to low pressure when the pressure is greater. Stronger winds can be seen if the isobars are close together.

Lighter winds are indicated by the further apart of the isobars. The wind scale in the top left of the chart helps you to forecast wind speed. The lines with triangles and semi-circles are fronts.

The weather map shows warm fronts with semi-circles and cold fronts with triangles. The way in which the semi-circles and triangles point shows the direction in which the front is moving. The lines show where a cold front and warm front meet an occluded front.

Weather Maps and Sky Cover Symbol

If a weather map has already been analyzed, you won't find much use for the station plot data. Station plot data is the most important information you start with when analyzing a weather map. Having a map of all stations helps you decide where to draw in high- and low-pressure systems, fronts, and the like.

Sky cover symbols have been established by the National Oceanic and Atmospheric Administration. The percentage that the circle is filled is a good indicator of the amount of sky that's covered with clouds. The sky cover circle has a line that extends out.

The PIREP Weather Forecast Form

The data gathered from upper altitude observations form the basis of all weather forecasts. There are three types of weather observations. A pilot can usually contact an EFAS specialist from 6 a.m. to 10 p.m.

The EFAS is a common radio frequency used by pilots of aircraft flying between 5,000 feet AGL and 17,500 feet MSL. A shortened version of the standard briefing is called an abbreviated briefing. It should be requested when a departure is delayed or when specific weather information is needed to update the previous briefing.

The height of bases and tops of clouds, wind shear and turbulence, and the location of in-flight icing are all things pilots can confirm. If the ceiling is below 5,000 feet, or visibility is less than 5 miles, ATC facilities are required to ask pilots for PIREPs. When weather conditions are unexpected, pilots are encouraged to report it to the ATC.

The ATC facility or FSS will add the pilot weather report to the distribution system to brief other pilots. The elements of a PIREP form are shown in Figure 4. When making a report, item numbers one through five are required to provide information about at least one weather phenomenon.

The reports are usually transmitted as an individual report, but may be appended to a surface report. Most of the contractions used in the reports are self-explanatory. Areas of precipitation and storms are observed by radar.