Saturday, February 20, 2010

Pothole season comes early...

Praying for a gradual thaw. The latest flood forecast has been released by NOAA. There is a better than 50/50 chance of "major flooding" from St. Paul to Hastings and Red Wing. The odds of major flooding in Fargo? 98% Hopefully our eventual spring thaw will be gradual (not accompanied by heavy rain). For the very latest details from NOAA hydrologists (river forecasters) - literally a science within a science - click here.

Good news for commuters. Bad news for snow-loving kids of all ages. The latest storm sliding off to our south will drop a "plowable" snow on much of the Midwest and Great Lakes. Models are hinting at a whopping half inch of snow Tuesday as colder air arrives - no breaking weather news anytime soon.

The last week or so has been unusually pleasant across Minnesota, temperatures running 5-10 degrees above average. Nice to be serenaded by dripping icicles and gurgling drain spouts, although all that melting snow has the unpleasant tendency to re-freeze at night, resulting in glare ice every morning. Water is one of the few elements that EXPANDS when it freezes at night, so all those little cracks in the pavement that fill up with water fill up with water by day, freeze (and expand outward) at night, literally pulverizing highways over time. Yes, we're heading into pothole season in Minnesota, the result of the freeze-thaw cycle. Like gravity (and taxes) it can't be avoided, I fear. Between the ice - and the potholes - and the wet patches throwing up a dirty spray on your windshield - driving can be hazardous - even with nothing falling from the heavens.

Saturday Highs. Click on the graphic to bring it full-screen. Highs were in the low to mid 30s from St. Cloud to the Twin Cities - cooler just south and west (where there is more snow on the ground).

That sloppy caveat aside, there has been precious little to complain about in the weather department in recent days. Saturday's high in the Twin Cities was a relatively balmy 35 (5 degrees above average, 9 degrees warmer than last year on this date). That makes 4 days above freezing since last Tuesday, February temperatures now +1 F. in the metro area - in spite of 13" of snow on the ground. While parts of America wrestle with snow and ice we experienced an odd "Air Pollution Advisory". We've seen at least 5-6 days in the last few weeks with unusually light winds and an "inversion" overhead, temperatures warming with altitude, trapping man-made pollutants near the ground. Mid-winter smog? I know. It's a little strange. Unusual, but not unprecedented. As I wrote last week, rain/ice is becoming more frequent during January and February - according to Professor Mark Seeley at the U. of MN the frequency of ice in Jan/Feb has quadrupled since 2003. We also seem to be seeing more air pollution events during the winter. A smoking gun? Not sure we can chalk this up to climate change (or even El Nino for that matter).

Prediction: frustrated Minnesota snow-lovers. Close but no-go. The models are printing out an inch of liquid water from central Missouri into western Illinois (which may translate into 10-12" of snow). Chicago: potential for 6-8" or more. The forecast is valid from 7 am Sunday through 7 am Monday.

Blame (or thank) El Nino. Unusually warm water in the equatorial Pacific Ocean may be causing the storm track to become temporarily "locked", bringing more heavy snow from the central Plains to Chicago and Detroit. Click here to see the latest NOAA watches and warnings.

Back to reality. Here are Wednesday's predicted highs: close to 20 in the Twin Cities, holding in the teens across much of central and northern Minnesota. With a sun angle as high in the sky as it was during the third week of October it's getting increasingly difficult for temperatures to fall below zero. Difficult but not impossible. I'll be shocked if we don't experience at least a couple more subzero lows before spring arrives in earnest. Where the heck is Earnest, anyway?

I still don't see any real storms looking out 10-14 days. The models consistently keep any real "weather" passing off a couple hundred miles to our south. Another major snow/ice/rain storm may be shaping up for the east coast by the first week of March. Minnesota temperatures run 5-10 degrees below average this week, cooler than average weather probably hanging on through the first week of March. I do expect a warming trend the second week of March, more 30s likely. No dramatic warm-ups (good news for people living in flood-prone areas of the state). At some point that active storm track will probably shift northward - expect a stormier, more active weather pattern the middle and end of March. No, we haven't seen the last of the snow. Statistically we should pick up at least another 10-20" before the first daffodils of spring appear. Count on it.

Paul's Conservation Minnesota Outlook for the Twin Cities and all of Minnesota:

Today: Intervals of sun, still milder than average. Winds: N 5-10. High: 32

Tonight: Patchy clouds. Low: 18

Monday: Mostly cloudy, feeling a cooler breeze. High: 29

Tuesday: Potential for a little light snow/flurries. Coating - 1/2" possible. High: 21

Wednesday: Cold sun, feels like February again. High: 19

Thursday: Blue sky - brisk. High: 18 (after waking up to 3 F).

Friday: Mostly cloudy, temperatures trending upward. High: 21

Saturday: Mostly gray, closer to average again. High: 27

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