Tuesday, March 2, 2010

Celebrating 40 (above!)

42 F. Tuesday in the Twin Cities, about 8 degrees warmer than average (whatever "average" is). Admit it: you had a little extra spring in your step, you felt just a little bit better about our waning winter season. We're going on three weeks in a row of high pressure stalled overhead, unusually light winds, unusually blue skies. Some towns in central Minnesota will have gone nearly a MONTH without measurable snow, which is highly unusual. Blame (or thank) El Nino for the dearth of weather close to home. More than any El Nino I can remember the warming of equatorial Pacific Ocean water has influenced America's storm track, consistently guiding Pacific storms into California, sweeping across Dixie, often re-intensifying as they steamroll up the east coast. Ask anyone in Washington D.C. or New York if they're enjoying their winter and odds are you'll get an earful. Feast or famine. 37" of snow in one month (New York) or virtually snow-free since Feb. 8-9 (St. Cloud). Des Moines has seen more snow than Denver, Baltimore far more snow than Buffalo. Buffalo, New York? I know, very odd. Hey, I'm just the messenger, and lately I've had some of the same issues that meteorologists in San Diego, Naples and Honolulu face on a consistent basis: how many different ways can you say "sunny and nice"? No complaints at all - because I realize full well that this intermission from crazy storms is an illusion. At some point the bubble will burst, the storm track will migrate north, and we'll be in Old Man Winter's crosshairs once again.

Weather Rock
. No, it's not something from a 70s hair band. I can't tell you how many weather rocks I got when I was working at 11 and 4. In 20/20 hindsight it may have been the best weather tool ever invented (I kept all of them, btw). Who needs 'stinking Doppler when you have access to a weather rock?

A Slight Chance of Nothing
. Yep, that pretty much sums it up. Computers and automation: great when they work, huh?

Surface temperatures at 6 pm Tuesday. Note the strong correlation between the warmest temperatures and those regions of Minnesota that have the least snow on the ground (parts of central MN have under 8-9", while many southwestern counties have 15-20" left). As a rough rule of thumb: the more snow on the ground, the less warming of temperatures at ground level. The reason? This time of year much of the sun's energy goes into melting snow, and not warming up the air above the snow. If had (zero) snow on the ground we probably would have seen a high close to 60 Tuesday afternoon. Soon...

* Almanac. Tuesday high in the Twin Cities: 42 (average high for March 2: 34 F.)

* Useless weather trivia: snow melts from the bottom up. Yes, as strange as it may sound, the sun's UV rays penetrate the snow pack and warm up the ground below, causing the snow in contact with the earth's surface to melt. You may notice a little surface melting too, but the majority of melting starts at ground-level.

* Tuesday morning the NWS reported 11" of snow on the ground at MSP. My hunch is that, by Saturday, that number will be down to 8", possibly less. Word to the wise: conditions won't get any better, at least in the short term (in spite of a small chance of accumulating snow Tuesday). Get out asap and play in the snow - most of it will be gone by the end of March.

Sleepless nights at the National Weather Service? Granted, it could be worse, much worse. The fact that we've been spared heavy snow (or rain) for the last 2-3 weeks may wind up saving much of the Red, Minnesota and Mississippi River valleys from major flooding in a few weeks. The lack of (additional) snow could not have come at a better time. NWS models show 4-6" of liquid water still trapped in the snow, mainly south/west of the Minnesota River, with 6-8" over far west central Minnesota. The wild card: how quickly we thaw out in the coming weeks, coupled with any heavy rain events (which would greatly accelerate snow melt and worsen the overall flood outlook). To check this out for yourself click here.

The models have been consistently underestimating the strength of the sun and the amount of warming we've had in recent days. Some of that may be a function of the unusually light winds overhead. A steady breeze sweeping over snow pack is chilled from below, like an endless refrigerator cooling the air from the bottom up. But not lately. Under the center of a stalled fair weather bubble winds almost every day have been averaging well under 10 mph. This lack of wind, lack of mixing, may not only be increasing the potential for smog, but allowing us to warm up a few degrees more than we would if there were (average) March winds blowing overhead. Just a hunch.

Saturday rain/snow mix? The computer models bring a weak trough of low pressure into Minnesota Friday night and Saturday, the "540 line", marking the approximate rain/snow line, draped right over central Minnesota. Light precipitation is likely, my hunch is that it will fall as mostly-rain. If your Saturday travels take you to Alexandria, Wadena, Detroit Lakes or even Brainerd the potential for a little slush (or glaze ice) can't be ruled out, especially Saturday morning.

Computer simulations bring a weak system into Minnesota Saturday, when temperatures aloft will be close to freezing throughout the lowest mile of the atmosphere: meaning precipitation could fall as a mix of rain and wet snow. With highs expected to top freezing across most of the state my hunch is that roads will be mainly wet. If it arrives early enough Saturday I could envision a period of freezing rain or freezing drizzle. Otherwise I expect mainly wet roads after 9 or 10 am Saturday. We get a break Sunday (clouds linger, temperatures once again near 40) before the next, stronger storm approaches early next week. Once again models are hinting at a mostly rain-event Monday, but the main surge of energy and moisture is still forecast to slide off just to our south. There's still a potential for a changeover to wet snow Monday night and Tuesday (from west to east across the state), but it's still much too early to even speculate about specific timing or accumulation. Right now I can't get very excited, but for snow lovers, starved for ANYTHING to look forward to, it's a start. My gut feel: we will see 3-6 more snow events, 1-3 strong enough to qualify as "storms" between now and mid April. In spite of the recent lull, our late winter swoon, I think we'd all be naive to believe that Old Man Winter has had enough. Hope for the best - plan for the worst, right?

We just can't buy a storm as of late. The latest (GFS) run keeps Monday/Tuesday's storm just south of Minnesota, a potential for a rain/snow mix into far southern Minnesota. It looks like a close call, and just a slight northward shift in the storm track could bring a sloppy mix of rain and snow into the Twin Cities, even St. Cloud. So the risk of wet/wintry precipitation early next week has diminished, but if you're doing any traveling early next week I'd make it a point to stay up on the latest forecast.

* The potential for a real cold front the third week of March has diminished. Daytime highs reach the 30s and 30s for the next 2 weeks, with few exceptions (that I can see). The GFS has highs in the mid/upper 40s by March 17-18. The worst of winter is (definitely) behind us - give yourself a firm pat on the back - you've earned it.

An Ode to Eagles. I came across a great little article from an Englishman, a UK resident who grew up in Minnesota. Recently he came and celebrated the growing, recovering eagle population in Minnesota. His visit to the National Eagle Center near Wabasha is a worthy read at Conservation Minnesota's web site.

An ocean-current-altering iceberg? The iceberg that recently calved off of Antarctica is 60 miles long, roughly the size of Luxembourg. Click here to see how it may alter ocean currents.

Why today may seem a little bit shorter? Precisely 1.26 microseconds shorter than it would be, otherwise, according to researchers. BTW, a microsecond is 1/millionth of a second. The massive earthquake in Chile may be responsible - click here for more details.

Finally, a friend, J Drake Hamilton, Chief Scientist at Fresh Energy in the Twin Cities passed along a video, which lays out the empirical evidence for human-caused global warming. Bulletproof? No. Science never is - that's the nature of science: it evolves as new data arrives, new theories are tested, new consensus is reached. Will this consensus hold? Time will tell. Click here to watch the 9:48 video segment - it's worthy of your time.

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

Today: (what else?) Generous sunshine, still milder than average. Winds: W 5-10. High: 40

Tonight: Mostly clear, a touch of (ice) fog. Low: 22

Thursday: A blend of clouds and sunshine, still pleasant. High: 39

Friday: Sunny start, clouds increase during the day. High: near 40

Saturday: Cloudy with periods of light rain (possibly mixed with wet snow far northern/western MN). High: 39

Sunday: Mostly cloudy, better travel day statewide. High: 42

Monday: Chance of a light rain/snow mix (especially far southern Minnesota). High: 41

Tuesday: Chance of rain/snow (mainly south of the Twin Cities). High: 38

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