Wednesday, November 4, 2009

Long Long Range Outlook: Warmer Winter?

I feel guilty showing you this - I hate to build up expectations, especially among Minnesotans hoping, praying for a "moderate" winter, one with a little less snow and a lot less arctic air swirling around. Predicting weather for January of '10 is roughly equivalent to forecasting what the Dow Jones or Nasdaq will be doing early next year - billions of potential variables, a handful (like interest rates, the strength of the dollar, etc) critical.

El Nino is strengthening, now in the "moderate" range, and growing even stronger with time. As a rule, the stronger the El Nino, the warmer the equatorial waters off the coast of Ecuador and Peru, the greater the odds of a (somewhat) milder winter from the Pacific Northwest into the Upper Midwest, including Minnesota and Wisconsin. It's not a perfect correlation (ie. there are exceptions to the rule) but it seems to work most winters. The atmosphere is an incredibly complex feedback system, next week's weather still taking shape over Siberia, but there's no question that the atmosphere often takes its cues from the ocean water it passes over. Most of Earth's surface is water, right? It just makes sense (intuitively and otherwise) that the air takes on some of the characteristics it passes over. El Nino tends to set up an unusually strong and active subtropical jet stream, guiding big, sloppy Pacific storms farther south, buffeting California before sloshing east, toward Dallas and Atlanta. Heavy rain is far more likely for the far southern states, along with more severe weather outbreaks, including rare mid-winter tornadoes from Houston to Orlando. Most El Nino winters the coldest, subzero air is bottled up a few hundred miles north of Minnesota - our prevailing jet stream winds blowing from British Columbia rather than the frozen wastelands of the Yukon. There are exceptions, of course, but the sheer volume of bitter air tends to be less during El Nino years. The problem: every El Nino is different, with their own bizarre idiosyncrasies and oddities. With the atmosphere there are no hard/fast "rules". So even with a strong El Nino in place NOAA's confidence of a milder winter for the Pacific Northwest, northern Rockies and Upper Midwest is roughly 60% Not great odds, right? On paper we should have a (somewhat) milder winter. On paper. In reality I'm still not convinced, in spite of El Nino's signals. My semi-educated hunch: November will be considerably milder than average, as much as 3-4 degrees warmer than usual, with less snow than average. During a typical November we pick up 8-9" of snow, making this the third snowiest month of the year! This is also the second cloudiest month, second only to December. Gloom Alert. Hey, before you know it Thanksgiving will be here, then the blur of Christmas and Hanukkah, and before you know it we'll be opening up those credit card statements - in the dark - while shivering through a bleak, subzero, January evening....


NOAA Winter Outlook for November, December and January
. Cooler weather is expected for much of the south, with a 60% probability of warmer than average weather across the Rockies, Plains and Upper Midwest. Is it a sure thing? Not quite, but if you're hoping for a milder winter you should be somewhat encouraged. I'm not convinced we're going to escape the wrath of a typical Minnesota winter though - more details/reasoning below.
A Growing El Nino. NOAA graphics show unusually warm water spreading across the Pacific, accumulating off the coast of Central America, water temperatures running about 2-4 degrees F. warmer than average.

Sorry about that - didn't really think that through in advance.

All the available data is shouting "milder winter" but I'm going on the record with a prediction of a more "average" winter, temperatures closer to average. Don't get too excited (or bummed) by all the El Nino babble - not even a stain of warm Pacific water is going to save us this winter, I fear.


Wednesday Evening Surface Map. Note the lack of significant rain (or snow). This is about as quiet and dry as I can recall dating back to mid September. Mother Nature will continue to catch her breath - no mega-storms brewing through the end of next week.



24 Hour Rainfall. This graphic from the National Weather Service shows the last day's worth of rainfall, for Minnesota (or the nation). The key on the right shows amounts (about .10" fell at St. Cloud and the Twin Cities). To see this bookmark-worthy site for yourself, click here.

The rumors are true: a nice warm-up is scheduled for the weekend, 50s likely, a few thermometers over southern Minnesota may flirt with 60 by mid afternoon Saturday. We chill down early next week before another warming trend sets in the latter half of next week, more 50s seem likely, a good 5-10 degrees above average. Light jacket weather instead of heavy coat weather. I can live with that.

Deer Hunting Update. Not much has changed with the forecast. If you're heading north plan on ample sun Saturday, more clouds streaming in Sunday, dry weather likely both days. Expect early morning temperatures close to freezing, afternoon highs anywhere from 48-53 degrees, almost 10-15 degrees warmer than average. Stating the obvious: no snow for tracking. Not this year.

Heavy Freezing Spray Warning. Just when you think you've seen everything! Rest assured, this is for the arctic region, north of Fairbanks. 13 foot seas, winds of 30-40 mph, a steady spray of mist that freezes (instantly) on all objects. Sounds delightful. Sign me up.

Paul's Outlook for the Twin Cities

Today: (much nicer than yesterday). Plenty of sun, breezy, not bad for early November. Winds: SE 10-15. High: 48

Tonight: Partly cloudy and chilly. Low: 39

Friday: Patchy clouds, windy and milder. High: 56

Saturday: Ample sunshine, a hint of Indian Summer in the air. High: near 60

Sunday: Sunny start, increasing PM clouds. High: 55

Monday: Lot's of clouds, a few light rain showers. High: near 50

Tuesday: Windy, cooler and drier - intervals of sun. High: 48

Wednesday: Mix of clouds and sun - cooler than average. High: 46

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