After a January Cool-Down to More Normal Temperatures the Past Few Weeks; Back to More Battles for the Second Half of the Winter?

A few weeks ago; I talked about El Nino taking a few week holiday and more typical winter weather would overspread and takes over the region. During the past few weeks, the main competitor for El Nino, was the "dreaded" or, our more typical mid-winter companion - the Polar Vortex. After pushing 4 - 6 degrees above normal the first third /10 days/ of the month, we were able to erase just about all of the above normal departures at Detroit /25.8, +0.3/ through the 24th. At both Flint and Saginaw; climate data still reflects a 2 to around 3 degrees above normal departure - mainly due to lower normal's at both sites and thus, larger above normal departures (remember; Detroit's normals have been inflated due to mainly, the large urban-heat affect).

In any event; we are now in transition again from the colder, more typical Polar/Arctic air dominance (or "Polar Vortex aided") back to a more mixed pattern, at least thru the first week of February. This is mainly due to the "bi-polar" Polar Vortex spinning around in the northern hemisphere and creating a variable NAO/AO  patterns the next few weeks. Initially; the NAO/AO retreats north-northeast and allows El Nino/Pacific Polar enhanced air to overspread much of the country again. This will produce a normal to above normal temperature pattern for the end of January across the Great Lakes and Southeast Lower Michigan. After; it appears the NAO/AO is in a major flux but with a decided negative direction after some sort of storm developing over the Midwest and Lakes Region early February.

Milder temperatures early in the week will bring some rain showers, while colder readings mid-week bring back some colder temps and snow showers but nothing major. Toward weeks end, a more zonal flow will commence off of the Pacific; overspreading the region with milder air once again over the weekend. The map below is an estimate of the 250 MB/~34KFT wind flow over the Northern Hemisphere by Sunday morning, 01/31/16

I started the blog with stating a more mixed pattern is evolving the next few weeks; after our milder, end of month pattern; February into March looks to be somewhat more active at times which also gets a thumbs up by our Winter Outlook guidance. The problem comes in just as it has much of the winter; nearly all of the major activity has been out West, East and South - actually the way it should during a strong El Nino.

From my earlier Outlook:



Snowfall/Precipitation

With snowy winters (above normal snowfalls) dominating the past 10 - 15 years, the season snow outlook for snow lovers is rather dreary. In fact, like the warmer temperature dominance this analogue go-around, snowfall averaged on the lightest side of past analogue winter totals seen at Detroit. Snowfall deficit runs from around a foot at Detroit to just a inch or so at Saginaw. This also fits with thinking of the polar jet still affecting the Lakes enough to bring near normal snows in that region.

However, all is not lost snowfall lovers! Two winters contained normal snowfall at Detroit, one normal and two above normal at Flint and finally; two normal and three above normal at Saginaw. Therefore, the most obvious pattern seen in these winters is that the further north one goes in Southeast Michigan, the better chance for more snow. The same can be said for general precipitation across the region. The Winters of 1991-92 and 1972-73 saw the best snows across the entire region with normal to above normal. The Winter of 1940-41 saw the next best "snow showing" the entire region but still well below at Detroit /26.8/ to near 50 at Saginaw /49.7/. The actual snow pattern for this winter will be watched for updates.

The best snows in the analogues on average were more likely to occur very early in the season, November and then again later in the season. November did indeed see above normal snowfalls with snowfalls running mainly below normal across much of the region since. There still is at least two and a half months for potential snowfall into mid April.

We shall see what winter's second half, snow-wise brings....

Look for any potential major storm updates through the rest of the winter.

Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian