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A post-tropical cyclone is a former tropical cyclone. It can take one of several different forms.
Classification[]
Two classes of post-tropical cyclones exist:
- Extratropical cyclone, which is frontal, sometimes still retains winds of hurricane or tropical storm force. Hurricane Dorian (2019) provides a recent example of an extratropical cyclone, in which it no longer has a warm core in higher latitudes when it was over Nova Scotia and all points north in its trajectory.
- Remnant low, which is non-frontal, has maximum sustained winds of less than 34.00 knots, and mainly consists of stable Stratocumulus with little to no convective activity. These shallow systems may meander for sometime before opening into a trough of low pressure, or being absorbed into an extratropical cyclone.
Not all systems fall into the above two classes. According to the guideline, a system without frontal characteristics but with maximum winds above 34 knots may not be designated as a remnant low. It should be merely described as post-tropical.