Occluded front
Also called occlusion, occluded front symbol, purple front
Weather-map symbol. A chart convention, not a forecast icon.
Weather-map symbolsOccluded front meaning
An occluded front is drawn with triangles and half-moons alternating on the side it is moving. NOAA lessons often use purple. The mix of shapes is the mark.
At a glance
- System
- Synoptic chart convention
- Used for
- A front that has overtaken another
- Not the same as
- A stationary front
A front that has caught up. Alternating triangles and half-moons share one side of the line.
The name. Triangles and half-moons on the same side, the side the occlusion is moving.
Where it comes from
JetStream draws an occluded front as a purple line with alternating triangles and half-moons on the side of motion. The color names the combination in the classroom. The combination itself is a triangle and a half-moon taking turns. This drawing uses that alternation and not the purple. A stationary front puts the same ornaments on opposite sides instead.
The line drawing is original to this cabinet. It is not an agency logo, a vendor icon, or the emoji for the same idea.
Weather
What it means
A cold front has caught the warm front, and the warm air is being lifted off the ground. The symbol says that geometry is what the analyst drew. It does not choose between a warm occlusion and a cold occlusion unless the map says more. It is not a thunderstorm icon.
Questions
What does an occluded front look like?
Triangles and half-moons alternating on one side of the line. JetStream draws that line purple. The side they share is the direction of motion.
Is purple required?
It is the teaching color in that NOAA lesson. The readable mark in one ink is the paired triangle and half-moon.
Near this
- Cold frontA line with triangles in the direction of motion. Cold air is advancing. The color is a publisher’s aid.
- Warm frontA line with half-moons in the direction of motion. Warmer air is advancing.
- Stationary frontA front that is not moving. Ornaments sit on opposite sides of the line.
- Low pressureAn L for a low-pressure center. Not a rain icon, and not a cold front.
Sources
Named when the entry depends on a text, a date, or a standard. Catalog numbers are not invented.
Your margin
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symbol.wiki, edited as Sigilla. Last reviewed 18 October 2026. A reading of public tradition, not a ruling.