Radars light up – December rain; Brutal winter predictions a bust so far

.23" rainfall for MSP Airport - latest NAM model output

.49" rainfall at MSP - latest GFS output

2" to 4" snowfall likely from Alexandria to Brainerd to Duluth and the Iron Range Cities by Thursday

December Rain!

-Latest Twin Cities radar loop

Radars are lighting up around Minnesota with rain. Expect the showers to increase overnight and peak into early Wednesday.

Overall rain totals look like .25" to .50" for most areas in southern Minnesota.

NAM model precipitation output

A band of snow will form from near Alex to Brainerd, The Iron Range and Duluth and the North Shore. Snowfall totals generally look to be between 2" and 4" by Thursday morning.

NAM model snowfall output

A Different December

What a difference a year makes. Last year we had 17" of snow on the ground on this date. Today? Good luck finding enough to make a snowball in much of Minnesota.

Not that I'm complaining after last year's 86.6" snow blitz. No matter what kind of weather you like, Minnesota weather is what it is.

We talk a lot about "average" and what winter "should be like" in Minnesota. The fact is, averages are made up of extremes. We have an "ideal" of what any one month should be like. The reality often doesn't match our weather perceptions. Weather in the Upper Midwest exhibits a high degree of "variability." We're used to the wild swings, but they seem to be getting even more dramatic from month to month and year to year.

Is La Nina turning into El Nino?

Yesterday I observed on MPR that the jet stream pattern on the weather maps looks more like an El Nino "Split Flow" signature that a La Nina induced arctic winter pattern.

There may be a discernable reason why this December is so different from last year.

NOAA's CPC and others we're calling for another, albeit weaker. La Nina winter. The latest ENSO Diagnostic Discussion indicates that tropical Pacific Ocean temps are on the rise. Most of the models return to "ENSO neutral" by spring. Three of the models even push into a weak El Nino phase by early next year.

In the past two months there were dire predictions from everyone from our local newsrag to NOAA to "Accu" weather blaring headlines about a brutally cold winter starting in December.

In my October Winter Outlook, I was (and still am) hesitant about forecasting two back to back cold & snowy winters in a row, and I leaned toward average while mentioning the possibility of a milder winter with less than average snow.

I may be wrong here, but I looked at this again today and still come back to decadal trends as the most probable outcome for this winter in Minnesota.

From my October post:

"Decadal Trends: Our changing winter climate?

Juxtaposed over the technical and dynamic factors that may control winter weather are so called decadal trends, which lean strongly in favor of milder winters with less snowfall for Minnesota.

Some facts from the past decade include:

-7 of the past 10 winters have featured significantly below average snowfall in the metro, (70% bias toward less than average snow in the past 10 years)

-In those years the average winter snowfall has been 33.6"

(Roughly 22" below the 30 year average of 55.9"!)

-6 of the past 10 winters have featured above average temperatures

(60% bias toward milder than average winters the past 10 years)

-Minnesota winter nights got a lot milder in the past 30 years! (1981-2010 data set) Overnight low (minimum) temperatures in January average a full 2 to 4 degrees F warmer than the previous 30 year (1971-2000) data set.

The bottom line is, winters are trending milder in Minnesota, and while averages are made up of extremes on both ends, you can't ignore the background trend when looking at the potential for two colder and snowier than average winters in a row.

Variable: Decadal trends in winter temps and snowfall in Minnesota

Potential effect on Minnesota winter: Milder winters temps (especially at night) and a apparent bias toward lower winter snowfall totals.

Trend for 2011-'12: Increased odds for a milder winter with less snow than 2010-'11"

Winter may still rear up with teeth and claws in January and February, but so far there is no sign of any huge storms or epic arctic outbreaks on the horizon.

I'm sure we'll get our share of arctic cold and some more snow this winter, but with each passing week the odds for a cold snowy winter overall drop some.

As we say in the weather biz...stay tuned!

PH