Wednesday, February 22, 2012

This Winter vs Northern Ohio's Mildest Winters

Late last fall, many winter forecasts continuously highlighted the fact that this winter 2011-12 would mirror last winter's La Nina characteristics--more cold and snow. Yes, LA NINA returned. But the cold air didn't  Yet, as we all know, this winter has been anything but a mirror image of last winter. (the reasons why are here) Instead of enduring snow squalls off of Lake Erie with 70 days with snow on the ground, we've had saturated backyards and average temperatures resulting in the 3rd warmest winter since 1895!

Was this winter's MILD LA NINA similar to any of the other top ten mildest winters here in Northeastern Ohio?  Does the tropical Pacific Ocean behave similarly in these milder winters?

To review, the top 10 winters in northern Ohio through January (February is running 3 degrees above normal as of this writing) are below:

Each map below are the average sea surface temperatures from November through January in each of the top 10 years listed above. Sea Surface Temperatures prior to the early 1950s are reconstructions. Notice where the warmer water is distributed in each map. Warmer colors indicate warmer water; colder colors, colder water.  I circled the La Nina/El Nino area in red. The first is the winter of 1931-32 right down the list finishing up with the winter of 1952-53.

Aside from each of these winters showing some signs of El Nino (8 of 10), the tropical Pacific Ocean looks very different in each example with each resulting in very mild winters. The 1949-50 winter's weak La Nina was the only one close!

What can we learn from this winter's LA NINA pattern?  I believe we put too much emphasis on the effects of La Nina as the main driver of our patterns in the eastern US and Northern Ohio during the winter months. Judging by these temperature reconstructions, mainly El Ninos result in mild winters. But in some instances like this winter, the opposite is true. La Nina or El Nino signatures are a great first start but in many instances like this winter, we need to look elsewhere (the Arctic) for the reasons we see flowers popping up in February!  The 2011-12 La Nina winter was a fluke. Will it happen again next year?   Will Lake Erie freeze over next winter?