Wednesday, November 23, 2011

Long Range ECMWF Projects Aleutian Low Breaking Down; May Lead To Cold Air in US

Aleutian Low Example
(The Low Pressure system in Alaska is the Aleutian Low)

12z ECMWF Hour 240
In the top image, you can see the strong low pressure system located just around Alaska. This is called the Aleutian Low. This low pressure system is semi-permanent, meaning it can stay in that area for long periods of time and comes back frequently. When this happens, a consequence is that a ridge (high pressure system) forms in the West US, usually leading to some warmer air over the country. However, if this Aleutian Low breaks and dissipates, a high pressure can form over Alaska and lead to a low pressure forming over the West US, which can lead into colder weather for the country.
Are we saying this will happen? No. Are we saying it could be an indicator that the weather pattern may be changing soon? Possibly. We will have to wait and see at this point.

Thanksgiving Looks to be Quiet Across US

This Thanksgiving looks to be a quiet one across the country. Sunny skies are widely expected across the Eastern US, while some more humid air may provoke some showers and clouds as moisture from Tropical Storm Kenneth enters the country. A system will be moving onshore the Northwest region, so it can be expected some showers will be present as the day goes on. The Central US will likely have sunny skies.
Temperatures are expected to be above normal for the country.

Have a happy Thanksgiving from The Weather Centre!

GFS Hints at Mississippi, Alabama Snow After Thanksgiving

Projected Snow Depth on November 29
The GFS is hinting that Mississippi, Alabama, Louisiana could be in for some snow going into the November 29th timeframe. This does have potential to play out, but it may be slim. For instance, check out the factor that will be inducing snow below
GFS 6z forecast (Anything inside red circle may be snow)
The GFS says a cold pool of air will swirl around a cutoff low (low pressure that has been cut off from the jet stream and sits nearly motionless) and provide snow for the Southern US. It is entirely possible that this does not happen, and I am not too optimistic about it. We will have more information soon.