Thursday, March 18, 2010

Major Flooding Expected at St. Paul

It feels like a Dickens moment. "The best of times - the worst of times." Temperatures are flirting with 60, thoughts are turning to spring, and yet this lukewarm goodness simply came on too fast. The earth underfoot is still mostly-frozen (a few inches below the surface). The metro area lost a cool foot of snow in under 10 days, there's STILL as much as 10" of heavy, wet, cement-like snow lurking south & west of the Minnesota River, and it's melting fast. All that run-off is being diverted directly into area rivers - the result: widespread flooding that will rival last year, probably worse in the immediate metro area. The big unknown and giant wild-card in all of this: ice jams. They are virtually impossible to predict in advance, but we know that ice is far more likely to collect in sharp bends of rivers, causing water levels to back up - almost instantly and dramatically - upstream. When the ice dam breaks, a sudden surge of water comes cascading downstream, resulting in almost instant inundation of lowland areas.

Minnesota Flood Monitor. For a wealth of information related to Minnesota's rivers and predicted flood crests click here. More specific (text) warning information for the entire state of Minnesota here.
48 Hour Flood Risk. The red dot-towns are expecting moderate flooding, including Mayer, Rockford, the Sauk River near St. Cloud, as well as New Ulm and Montevideo. Major flooding is now predicted for the Delano area with the Crow River well out of its banks. For the very latest outlook click here.

A "Major Flood" for St. Paul. Here is the latest NWS outlook, showing a crest near 18' by next Tuesday/Wednesday, still 8 feet below the historical crest of 26'.

You've seen some of the footage, witnessed a few daring rescues - there will be more to come, I'm afraid. The river isn't forecast to crest in St. Paul until Tuesday. Flood stage is 14'; based on the latest, greatest information the Mississippi River in St. Paul is forecast to crest at roughly 18', major flood territory, but still well shy of the record flood stage of 26'. Flooding may be more severe in places like Delano, and along the Minnesota River from near New Ulm upstream to Montevideo. Expect the unexpected. I know that sounds weak and cliche, but it's the truth: the computer models only go so far with river flooding, to some degree every flood season is a new beast - an entirely new scenario. As is always the case with flooding, the outlook has "high bust potential", which is meteorological slang for "there is an awful lot that can go wrong with this forecast."

An Atmospheric Breather? Dry weather should persist through the weekend as temperatures cool back down, closer to "average" for this time of year. The GFS model is hinting at a potentially significant rain/snow mix from next Tuesday through next Thursday morning. It's still too early to know if this will complicate (and possibly prolong) river flooding statewide.

One thing appears inevitable: our mild-weather honeymoon is drawing to a close. The good news: the next storm should slide by (harmlessly) to our south tomorrow, not dumping any more rain (or snow) on Minnesota, complicating the flood situation. Light jackets return for the weekend, the next chance of (light) rain and snow mixed by Tuesday of next week, possibly a heavier rain/snow event next Wednesday and Thursday morning. Too far out to tell with anything approaching confidence. Hopefully we'll get a nice, long break from Mother Nature (additional heavy rain would make a bad flood outlook much worse right now). Fingers crossed. Stay tuned...

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

Today: Plenty of sun, near-record warmth across much of MN (last day of Spring Fever for some time to come). Winds: W 10-15. High: 62 (average high: 41. Record high: 71 in 1921)

Tonight: Patchy clouds, turning cooler. Low: 37

Friday: Partly to mostly cloudy, noticeably cooler (rain/snow mix stays south over Iowa). High: 43

Saturday: A mix of clouds and sun, seasonably cool. High: 45

Sunday: Some sun, a bit milder. High: near 50

Monday: Sun gives way to increasing clouds. High: 49

Tuesday: Chance of a light rain/snow mix. High: 44

Wednesday: Steadier, heavier rain/snow possible. High: 45

Thursday: Wet (slushy?) start, then clearing and windy. High: 47

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