Sunday, January 17, 2010

Prediction: Vikings euphoria (and a messy mix)

Weather Headlines

* Significant icing possible by midweek, highs in the 20s could mean very slippery secondary roads, while treated freeways, major highways stay mostly-wet.

* Potential for a rain-event Saturday into Sunday morning, possibly glaze ice for the northwestern half of the state.

* Changeover from rain/ice to mostly snow by Sunday PM, potential for a couple inches late Sunday into Monday.

* Outlook for Sunday in New Orleans: morning puddles/rain giving way to some sun, highs frmo 65-70 F.

Be honest: did you even notice the weather Sunday? I vaguely recall a little sunshine and blue sky filtering through, the sound of dripping icicles and gurgling drain-spouts. The National Weather Service insists the high on Sunday was 34 in the Twin Cities (a respectable 13 degrees above average). The NWS reported 51 in St. Cloud yesterday, which is an order of magnitude milder than anywhere else in the state. All I can think is a). milder air aloft was able to mix down to the surface, or b). the official airport thermometer received direct sunlight - which seems rather odd. Check out Sunday's official STC hourly observations (below) for a real meteorological head-scratcher. With sunshine, light winds, and an airmass of Pacific origin drifting overhead the mercury climbed above freezing statewide, with the exception of Rochester, where 14" of snow on the ground prevented temperatures from climbing any higher than 28 F. Even Grand Marais registered an impressive (for mid January) high of 41, nearly 25 degrees above average!

It never rains in southern California. It pours. A Doppler radar mosaic Sunday night showed a powerful storm hitting near L.A., where flooding rains and isolated mudslides are possible this week, at least 5 separate storm impulses hitting the west coast between now and Friday. These storms will weaken slightly after moving inland, but then re-intensify over the southern Plains, tapping moisture from the Gulf of Mexico before turning north, spreading a mix of wet snow, ice and rain into Minnesota as early as Wednesday-Thursday. The latest (high-res) national Doppler mosaic is here.

Potential for a very sloppy/icy week. The GFS models are consistent in predicting over 1" of liquid precipitation later this week. Much of that moisture may fall as rain or freezing rain, rain freezing (instantly) on surfaces colder than 32 F. With daytime highs stuck in the mid/upper 20s there is a potential for significant ice on highways & sidewalks the later half of the week, especially outside of the Twin Cities.

What the heck was going on in St. Cloud yesterday? Check out the temperature at 11:53 am Sunday. The official print-out said 47, with a high (in-between hours) of 51. Or was it 60. Impossible, right? This is a real head-scratcher. To get a blow-by-blow, hour-by-hour print-out of weather in the Twin Cities for the last 24 hours click here.

With rare 100% accuracy I can predict a severe & widespread outbreak of Vikings-mania this week. Weather will be something of an afterthought (as it should be). The big weather story: the atmosphere will probably be warm enough for mostly-rain later this week, in fact computer models are hinting at nearly 1" of liquid precipitation by Sunday, much of that falling as rain. The models are suggesting a few inches of wet, slushy snow for parts of central and northern Minnesota, but the bulk of the moisture (Thursday, another wave coming in next weekend) may be wet vs. white. Odd for mid January in Minnesota, but certainly not unprecedented. Here in Minnesota we've all come to expect the unexpected, the meteorological exception becomes the norm. Translation: weather at this latitude can be extraordinary, unusual, at times bizarre and downright freaky. Think about it: in just the last few months we've seen heavy, wet snow in mid October, 50s and 60s in November, an early outbreak of subzero weather, and now this: potentially significant rain falling during what his (historically) the coldest week of the entire year! What will this mean for the St. Paul Winter Carnival, which kicks off later this week? Not sure, but it's safe to say weather conditions will not be ideal for snow & ice preservation. Rain, coupled with highs in the low/mid 30s could mean rapid snow-melt by the weekend. I hope I'm wrong about this; but I have a pretty strong feeling we're going to experience a taste of mid March in mid January. Great.

There is a potential for significant icing Wednesday and Thursday, surface temperatures in the teens/twenties, while 3,000 to 5,000 feet above the ground temperatures are above freezing. The result may be sleet (ice pellets) and even a significant period of freezing rain (liquid rain freezing into glaze ice on contact with cold surfaces, powerlines, roads and sidewalks). The timing is tricky, I don't expect any huge headaches today or Tuesday, but by Wednesday a long fetch of moisture direct from the Gulf of Mexico may spark freezing drizzle/rain, with some icing expected Wednesday and Thursday (mixed with wet snow, especially north of St. Cloud and Lake Mille Lacs, where a couple inches of slush may accumulate). Models are still hinting at a brief break in the action Friday into early Saturday, before the next sloppy, southern storm pushes a shield of moisture back into Minnesota late Saturday into Monday. Once again the atmosphere may be (just) warm enough for rain, or freezing rain, much of Saturday into Sunday morning, followed by a gradual changeover to wet snow (from west to east) on Sunday. A few inches of snow may still pile up at the tail-end of the storm Sunday PM into Monday, but at this point that's just hand-waving speculation (as my favorite college professor used to say). He was not fond of "hand-waving arguments."

Photo courtesy of the Star Tribune.

The vacation from snow/ice was nice while it lasted. Prepare for a more challenging week on Minnesota's highways. But the Vikes are going to the NFC Championship. Forgive me for saying this (out loud) but I'm not alone in believing that this is our year. The planets have aligned. I hope to have the opportunity of updating you on Miami weather in the weeks ahead. Wouldn't that be something.

Monthly climate update for the Twin Cities. Looking for a convenient web site to track Twin Cities weather, day by day? Click here to use the National Weather Service's handy climate site. Click on "Minneapolis" and "daily data for a month", then "go" to see the latest.

Risk of a mixed-bag of wintry weather. The latest GFS model is hinting at mostly rain south of I-94, but temperatures aloft may be just cold enough for a couple inches of wet, heavy, slushy snow north/east of St. Cloud and Mille Lacs by Wednesday and Thursday. I'm more concerned about the potential for a significant icing event across central and portions of southern Minnesota, with surface temperatures ranging from 20-25, and rain freezing (instantly) on cold surfaces. Stay tuned.

Paul's Outlook for the Twin Cities

Today: Partly sunny, cooler than yesterday. Winds: W 3-8. High: near 30

Tonight: Patchy clouds, colder again. Low: 14

Tuesday: A mix of clouds and sun, still dry. High: 28

Wednesday: Cloudy with a chance of freezing rain (ice), possibly mixed with wet snow north of the metro area. High: 27

Thursday: Freezing rain and drizzle possible, significant icing possible outside the downtowns. High: 28

Friday: Mostly cloudy - better travel conditions. High: 29

Saturday: Overcast with a cold rain, freezing on contact with many surfaces - potential for significant ice, especially north/west of the Twin Cities. High: 32

Sunday: Rain/ice changes over to wet snow, potential for a couple inches of slush. High: 30

Monday (Jan. 25). Light snow gradually tapers to flurries. High: 29

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