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This is what the ‘dirty side’ of a storm means

Storm’s right, front quadrant the most dangerous

The forecast from the EURO forecast model, is closer to the official track from the National Hurricane Center, but still west of the official track.
The forecast from the EURO forecast model, is closer to the official track from the National Hurricane Center, but still west of the official track.

ORLANDO, Fla. – Meteorologists often refer to the east (right) side of a tropical system or hurricane as the dirty side of the storm.

Every part of a tropical storm or hurricane can cause severe weather, but one section is even more intense, thus “dirty.”

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The storm’s right, front quadrant is relative to the motion of the storm. If the storm is moving north, the “dirty side” would be on the upper-right side if you drew a cross down the center. If the storm is moving west into land, it would be on the upper-left side of that cross.

An easier way to think about this is that the worst weather will be to the right of the eye of the storm.

The direction of the storm matters because as wind moves counter clockwise around the center of the storm, wind shear is amplified as it encounters land. This is the region where the tornado threat with land-falling storms is the highest. This region also promotes onshore flow, which creates deadly storm surge as it pushes water inland from the ocean.

On the “dirty side,” these weather conditions are more likely to occur:

  • Higher tornado threat
  • Storm surge along the coast
  • Strongest wind gusts

Remember, all parts of the storm are bad, the “dirty side” is just worse.

Keep a close eye on the tropics by downloading our free Hurricane Tracker App.


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