LINES:

For this class of graphics, thin black lines represent isobars which are defined as lines of constant pressure. In this case the pressure shown is the pressure at 5000 ft. The isobars are labeled in two hecta Pascal (hPa) increments. There are very few isobars shown on these types of maps because horizontal pressure changes usually take place over larger regions than are contained in this map which is a close-up of western Washington.

COLORS:

Background color represents the wind magnitude in knots (kt) at 5000 ft. The color-bar located at the right side identifies the wind strength for each shading of color. Regions in white represent where the topography is higher than the level requested.

WIND BARBS

Evenly spaced on the map are wind barbs that indicate the strength and direction of the wind at the 5000 ft level.

1 kt ~ 1.15 mph ~ 1.85 km/hr

WHY IS THIS IMPORTANT?

Constant height maps give forecasters the ability to see current and future wind patterns that have a dramatic impact in our daily lives at the surface. Each map is a horizontal slice of our local lower atmosphere. Providing graphics of many different levels helps forecasters see changes in the winds at different levels. Very small changes to the wind direction or intensity at these elevations are very important for air quality forecasting. Wind events that can potentially have dangerous or damaging impact on the region can also be located here. Strong winds pushing down the Strait of Juan de Fuca, windstorm events and even the Puget Sound Convergence Zone can be forecast by examining the winds at different levels in the boundary level.