StormTrack: Long Range- Alaskan Vortex (2/10/12)

Something I look to for support in forecasting is the Alaskan Vortex. It is a low pressure system that sits in the Gulf of Alaska and typically makes for warmer weather over the US. Recently, we have been seeing a ridge over that region. So here's the forecast for 108 hours out.

12z GFS Hour 108 500mb Height Anomalies

See the dark blue on the upper left hand corner of the image? That is a key player in the forecast. That is a form of the Alaska Vortex. Check out how there is a ridge (orange) stretched out into Alaska trying to make a move. This low pressure system will see the ridge and beat it down, and I expect this pattern to go on for a while, where a ridge tries to move north but the low pressure system beats it down. This ought to lead to some more active weather as the two opposing factors (ridge and low pressure system) fight each other and try to get to Alaska, which appears to be the place to be.

Here's 500mb height anomaly forecasts produced by the ESRL forecast agency. The ESRL is showing a strong ridge to be present in much of the Pacific for the 6-10 day timeframe, which is what this image is for. However, notice the darker blue colors in west Alaska. What this could easily do is manipulate the polar jet stream to throw some systems from the big vortex out east into the West US, which is likely why we are seeing the darker blue colors in west/central US. (For verification, blue colors are a general stormier pattern and red colors are a general quieter pattern.)

~Andrew