Updraft: November 15, 2012 Archive

NOAA: Colder winter for MN? Thanksgiving model soap opera continues

Posted at 5:36 PM on November 15, 2012 by Paul Huttner
Filed under: Winter 2012-13

Cold bias NOAA's updated outlook for winter temps in the Upper Midwest

"Equal Chances" for a wet or dry winter

"PDO" Negative phase of Pacific Decadal Oscillation cited in NOAA's outlook

"El Nono" Lack of clear El Nino signal cited

Uncharted & Unfrozen Waters How will record Arctic Sea ice loss factor in?

Trump card? Will longer term trend of milder winters trump iffy CPC outlooks?

Model squirm GFS all over the map on Thanksgiving forecast

4th tornado confirmed from Saturday night's "outbreak"

NOAA updates winter outlook:

We've rounded the corner and we're heading into the home stretch for winter 2012-'13.

NOAA updated the winter outlook Thursday, and it's a fairly radical departure from previous forecasts issued within the past month.

The latest outlook favors colder than average temps for metrological winter (Dec-Feb) 2012-'13 for the Upper Midwest.

The precipitation outlook calls for equal chances for a wet or dry season.

What they say:

NOAA cites the lack of any clear ENSO signal, and the presence of a negative PDO phase as the reasons for a cold bias in the upper Miswest this winter.

AREAS HIGHLIGHTED FOR BELOW NORMAL TEMPERATURES ACROSS THE NORTH CENTRAL CONUS AND ALASKA ARE CONSISTENT WITH NEGATIVE PDO PHASE COMPOSITES. THE LACK OF A STRONG ENSO SIGNAL, ALWAYS-PRESENT UNCERTAINTY IN THE PHASE AND PERSISTENCE OF THE AO OVER THE ENTIRE WINTER SEASON, CONSIDERABLE DIFFERENCES IN DYNAMICAL CLIMATE MODEL OUTPUT MAKE EC OR EQUAL CHANCES FOR ABOVE-, NEAR- OR BELOW-NORMAL TEMPERATURES THE APPROPRIATE CHOICE FOR MUCH OF THE EASTERN U.S..

These guys are really good, but I'm not inclined to agree with NOAA's outlook.

Here's why.

El Nino "head fake:"

After El Nino's unprecedented head fake late this summer, we're in more uncharted territory when it comes to the possible effects on winter circulation patterns over North America.

Tropical Pacific SST's have actually warmed lately, and a bubble of slightly warmer than average water is still present in the tropical Pacific.

There is still a decent chance that a weak or moderate El Nino could brew up this winter. If that happens, the bias will be for a milder than average winter in the Upper Midwest.

-Longer term trends - background hum of climate change in Minnesota:

Minnesota is near the epicenter of observed warming in North America when it comes to longer term climate trends. This is especially true in winter. Winter temps in Minnesota show a consistent warming signal as much as 4 to 6 degrees F, especially at night.

It's going to take the mother of all negative phase PDO's to overcome that.

-Record Arctic Sea ice melt and recovery

Last summer's record Arctic ice melt is a total wildcard in this winte's forecast. Ice has reformed at an impressive rate this fall, but still lags behind the record low year of 2007.

The fact is, nobody really knows how the extra Arctic Ocean heat content this fall will affect jet stream patterns this winter.

These factors and just a gut feel look at the maps these days leads me to favor my previous forecast fo a milder than average winter in Minnesota, with temps running +1F to +3F for winter as a whole.

But in the dicey game that is seasonal outlooks, your guess may be as good as mine this winter.

Thanksgiving Forecast: Mild or wild?

The soap opera surrounding the weather pattern next weekend continues.

The latest GFS runs have flipped back to the milder solution for Thanksgiving Day and Black Friday, with rain ending as a few flakes and a colder shot for the second half of the weekend.

I still think we have a good shot at 60+ degrees leading up to Thanksgiving, with at least 50s on Turkey Day. Codler winds are likely for Saturday & Sunday.

Stay tuned....

PH