Coding used in the Preliminary Surface Analysis

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

PYAC01.gif (78522 bytes)

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