Coding used in the Preliminary Surface Analysis

The Atlantic preliminary surface chart is a product prepared by the Weather Prediction Center (WPC).


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Coding for Fronts
front type intensity character
0 stationary no spec no specification
1 stationary above surface weak, decreasing frontal decreasing
2 warm weak, little change activity little change
3 warm above surface weak, increasing area increasing
4 cold moderate, decreasing intertropical
5 cold above surface moderate forming or existance suspected
6 occlusion moderate, increasing quasi-stationary
7 instability line strong, decreasing with waves
8 intertropical line strong diffuse
9 convergence line strong, increasing position doubtful

Coding for Pressure Features
pressure type character movement indicator
0 Complex low no specification no specification
1 low weakening stationary
2 secondary low little change little change
3 trough intensifying becoming stationary
4 wave complex retarding
5 high forming or existance suspected curving to left
6 area of uniform pressure weakening, but not disappearing recurving
7 ridge general rise of pressure accelerating
8 col general fall of pressure curving to right
9 tropical system position doubtful expected to recurve