Thursday, August 2, 2012

What To Look For In The CFS

Looking at long range forecasts can be difficult. Let's look at what the CFS v2 is showing this winter and see what we can decipher.
This is the CFS v2 forecast for 850mb anomalies in January 2013. Here we see warmer than normal temperature anomalies over the Northwest and extreme Southeast portions of the nation. Warmer than normal anomalies also exist over the Caribbean. So what does this have to do with anything?

Warmer than normal temperatures exist over the Northwest, which is usually a strong signal of a high pressure ridge in place over the region. The same ridge of high pressure rule may also apply over the Southeast and Caribbean. These two ridges could have very profound impacts on storm tracks for this winter. If one was to superimpose an estimated track for storm systems, this is what I would put:

I would estimate that the jet stream would be displaced north over the Northwest before sharply dropping down to the southern Plains. Following this drop, a turn northeast would be expected thanks to the ridge in the Southeast. Another storm track could follow along the Southwest, with systems ejecting into the Southern Plains before being picked up and shifted back across the main track through the Northeast.
If this were to happen, I would anticipate the Midwest and Ohio Valley getting in on the snowy weather. The question is, do precipitation forecasts for January match up with what I am projecting here? The answer would be yes, as seen below.

One can trace the storm track below the arm of above normal precipitation that extends into the Ohio Valley and Midwest, as well as above normal precipitation anomalies on the US/Canada border in the Northwestern portion of the nation. This is also reflected in the extreme Southwest US.

There are a number of things that can also be deciphered among other long range models, but this is all I have at the moment.


1 comment:

ERN WX said...

This looks more like a Nina than a Nino. The CFS has an error with the Pac NW being wet. Ninos are not going to make the Pac NW wet. I do think the Midwest WILL get good snow. Weak Ninos tend to be good. The upper MW and NW will be mild.