Coding used in the Preliminary Surface Analysis

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

 

  

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