temperature (F) upper left present weather symbol center left dewpoint (F) lower left pressure (mb-coded) upper right cloud cover center circle white fill indicates % cloud coverage winds wind barb

temperature (C) upper left dewpoint (C) lower left height (m) upper right winds wind barb

Color Intensity Description Blue Light Light rain or snow Cyan Moderate Green Heavy Light thunderstorms/moderate rain showers Yellow Very Heavy Moderate thunderstorms Red Intense Potential flooding rains/severe thunderstorms Magenta Extreme Flooding rains

Frontal Location Plot
Frontal locations are denoted by bold lines in the following colors:

High and Low pressure systems are plotted with H and L and the associated pressure in millibars is displayed below the letter.

NOTE: Frontal data are only available every 3 hours so fronts may not exactly match the weather conditions. A label at the bottom left denotes what time the fronts are valid.

Isobar Plot
The pressure contours (or isobars) are plotted every 4 millibars and indicate positioning and extent of various pressure systems. 500 mb Height Contour
This is a contour plot of 500 mb height in meters with a interval of 60 meters. The 500 mb level is often refered to as the steering level as most weather systems and precipitation follow the winds at this level. The winds follow the height contours and generally run from 30 to 100 knots. The speeds can be roughly estimated from the 300 mb winds as roughly 2/3rds their magnitude. This level averages around 18,000 feet above sea level and is roughly half-way up through the weather producing part of the atmosphere called the troposphere.