Monday, March 8, 2010

Smog, Fog, Slush & Mush

No Tournament Snowstorms to be found - so how 'bout a little Tournament Smog? I know - not quite the same thing. Hard to lead a newscast with "Breaking News! Smelly air stuck overhead until further notice. No heavy-duty exercising or deep-breathing exercises outside! That, and video editors on strike - Facebook photos at 10!" An air pollution alert remains in effect again today, the result of light winds and a stubborn inversion (warming temperatures with altitude trapping pollutants near the ground). That's a switch: there was a time, not all that long ago, when March was the "snowiest month of the year." Since about 2000 that distinction now belongs to January, with March coming in a close second. The big difference? January snows stick around (well, forever). March snow tends to be wet, slushy and transient - most of it gone within a few days. The sun is just too high in the sky, as direct and powerful as it was back in early October. That's why those nasty patches of ice are mostly-gone, and why the 12" of snow on the ground early last week is now down to about 5" - and going fast. At the rate we're going, with a string of 40s (50 on Thursday?) and as much as .30 to .50" of rain falling from later today through Friday, we'll be lucky to have a dirty 2" or so by the weekend.

Calendar is whispering March 9. Atmosphere is shouting April 9! The latest NAM model is hinting at some .75 to 1" rainfall amounts south and west of St. Cloud and the Twin Cities over the next 84 hours. Less than .20" is forecast north of Brainerd and Hinckley.

Umbrella Alert. Computer models are wildly divergent with amounts, but there's little doubt we're about to see significant rain. At the low end: .20", but a few of the models are hinting at closer to .50 to .70" of rain from later today through Friday. This will be a long-lasting rain event, increasing snow melt, ultimately increasing the potential for some flooding issues on area rivers a couple of weeks from now.

Outlook: a few piles of dirty snow by Saturday. As of Monday only 4" of (grungy) snow was left in the Twin Cities, 6" at St. Cloud, 10" at Grand Forks and 11" at Duluth. To see the latest USA snowcover - and a long list of other products at the Plymouth State Weather Center click here.

Snow Water Equivalent. According to NOAA there is 2" of liquid water tied up in the snow pack across much of central and east central MN, but as much as 6-8" over far southwestern Minnesota. That's the wild card, especially for the flood threat along the Red River and portions of the Minnesota River. To check out the data for yourself click here.

Locked & loaded? This is why hydrologists, river forecasters at the NWS in Chanhassen, may be working overtime in the days and weeks ahead. The QPF (quantitative precipitation forecast) calls for some .5 to .7" rainfall amounts over far southern Minnesota, but far less over the northern half of the state. The problem: southwestern MN has some of the most snow on the ground, about 10-16" left, but much of that snow has a water content of 6"+. If that water, currently suspended in the snow cover, rapidly melts because of falling rain (and highs consistently in the 40s) the flood threat could spike a couple of weeks from now. It's all happening in real-time, and the threat for residents living along Minnesota's rivers is significant. If you live in a flood-prone neighborhood stay alert and stay tuned for possible watches and warnings.

Snow Potential. Although the lowest mile of the atmosphere across Minnesota, Iowa and Wisconsin is warm enough for all-rain, a "plowable" snow is possible from Kansas and Nebraska northward into the western Dakotas. If you're driving more than 4-5 hours west of town you may run into a snowy, slushy mess in the days ahead.

So that's it for winter? Well, not quite. The GFS is suggesting a couple of 30-degree days (above zero) around March 20-22, right around the official kick-off of spring! How convenient. A subtle (yet blunt) reminder that Old Man Winter has a well-defined (and inappropriate) sense of humor. That said, temperatures average 5-15 degrees above average for the next 2 weeks, and after we muddle through a rainy, unusually mild week (more typical of LATE March) we should dry out next week, no more significant storms (rain, snow or ice) shaping up through about March 25. After that all bets are off. The old crystal ball gets very, very murky beyond 10-14 days, depending on the pattern. Come to think of it, anything more than 3 days from now is more of a "trend" than a "forecast." So much for a lame disclaimer, but you deserve the truth.

Trust me. I'm a weatherman.

Weather Videos.

Snowboarding bulldogs. O.K. It's the best I can do today, but you have to see it to believe it. This is from Mountain High Ski Resort outside Los Angeles. I know: shocking to think this came out of California. Click here.

Perils of glaze ice/freezing rain. This video clip from Brooklyn Heights, Ohio shows the danger of standing on a major highway that is covered in ice - these troopers survived their injuries, and my reason for showing this clip is simple: if you ever find yourself in a similar situation (stuck on the shoulder, a flat tire or out of gas). It's IMPERATIVE that you move your vehicle well off the highway, to avoid a scenario like the one you're about to see.

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

Today: Foggy, damp and gray. Rain arrives later in the day. Winds: E 10-15. High: 43

Tonight: Periods of rain, patchy dense fog. Low: 36

Wednesday: Still soggy, periods of rain likely. High: 45

Thursday: More rain, even milder. Low: 39. High: near 50

Friday: Rain tapers to showers. Low: 39. High: 49

Saturday: Mostly cloudy and damp. Low: 35. High: 47

Sunday: Intervals of sun - dry day. Low: 33. High: 45

Monday: Mostly cloudy, still warmer than average. Low: 31. High: 43

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