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Sudden Stratospheric Warming For Dummies

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Sudden Stratospheric Warming For Dummies

Post by Toot on 2013-01-12, 4:59 pm

Im trying to explain the process in easy to understand terminology is why I labeled the title SSW for dummies..Im not calling anyone a dummy


Sudden Stratospheric Warming For Dummies

I bet you are wondering whats causing this southward displacement of the Polar Vortex?

Well..lets start here..there is a semi permanent low pressure system called the polar vortex that sets over top of the north pole region (Arctic circle) and during winter it gets interupted by rossby waves. These waves propagate upward into the stratosphere and disturb the flow of the polar vortex. When this happens it begins to warm and get weaker and may even break into 2-3 pieces. Sometimes it gets so disturbed that it totally reverses its flow from westerly to easterly and when that happens is when it is then declared a MAJOR SSW event. (Which is what we have currently..a major one!)

When this happens the warming is able to propagate downward into the troposphere via subsidence. This subsidence warming propagates down and sets up high pressure systems (-AO) where once the lower pressures of the polar vortex dominated the polar region.

This creates high latitude blocking in the jet stream (-NAO) and those low pressures (Polar Vortex) that was once confined to the polar/arctic regions have no place to go but southward into lower latitudes of the conus..these pieces of the tropospheric polar vortex carry and contain the very cold air that you will see next weekend.

This sudden stratospheric warming event is why you are now seeing models prog the Polar Vortex down in the Ohio valley. These events can last the rest of the winter depending on the strength of the "Mid-winter Major Stratospheric Warming" MMW..and so far this one is a strong one!

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