Type Tracking

Is the cold front on your doorstep a growing, storm-laden monster with 50-knot winds or is it a nonevent, a mere wind-shift in clear skies? Although little advertised, there is a way to decode a front's intensity and trend. It's hidden in the chapter on surface analysis charts in the FAA's Aviation Weather Services, or AC-00-45E. To see the code in action, visit the Web site (www.awc-kc.noaa.gov/awc/aviation_weather_center.html) and click on the "surface analysis chart" link. The code uses three numbers in sequence, and it's printed near the plotted front's surface position. Here's how to break the code:

The first number indicates the type of front:

1	Quasi-stationary at surface
2	Quasi-stationary above surface
3	Warm front at surface
4	Warm front above surface
5	Cold front at surface
6	Cold front above surface
7	Occlusion
8	Instability (squall) line
9	Intertropical front
10	Convergence line

The second number indicates the intensity of the front:

1	No specification
2	Weak, decreasing
3	Weak, little or no change
4	Weak, increasing
5	Moderate, decreasing
6	Moderate, little or no change
7	Moderate, increasing
8	Strong, decreasing
9	Strong, little or no change
10	Strong, increasing

The third number indicates what the National Weather Service calls the character of the front:

1	No specification
2	Frontal area activity, decreasing
3	Frontal area activity, little change
4	Frontal area activity, increasing
5	Intertropical
6	Forming or existence expected
7	Quasi-stationary
8	With waves
9	Diffuse
10	Position doubtful

AOPA Wx Watch - Winter Wise - More fronts, moving faster

BY THOMAS A. HORNE (From AOPA Pilot, December 2001.)