Paul Douglas Update: Biggest Storm of Winter Brewing (Tue/Wed)
- Blog Post by: Paul Douglas
- February 25, 2012 - 8:32 PM
Breaking News: We Won't See This Much Snow. Deep breaths - we've been down this road before. Although I suspect the storm brewing for Tuesday-Wednesday will be the biggest of the winter (by far) we'll get through this. I suspect a "plowable" snowfall, and there's at least a 1 in 3 chance this will be a "crippling" snowfall for parts of central Minnesota, even the metro area. It's still too early to put inch amounts on a weather event still 3 days away, but yes, this could be a pretty big deal.
* Thanks to meteorologist Todd Nelson for doing the heavy lifting with the Star Tribune blog in recent days. With the impending snow (blitz?) I had to fire up the laptop and check out the very latest. This is a supplement to what Todd is providing - and I think we're on the same wavelength with this approaching storm.
A few thoughts:
1). It's still too early to put an inch amount on metro snow amounts. It's looking more likely that our midweek storm will take a more southerly track across Iowa, placing most of Minnesota on the cold, northern side of the storm, implying more snow than rain or ice. The NAM model is still hinting at a few hours of sleet, possily even a cold rain Tuesday afternoon and evening from the MSP metro on south. The GFS keeps precipitation all-snow, with mind-boggling amounts predicted (1 to 2 feet).
2). I feel reasonably confident that much of central Minnesota will pick up over a foot of snow from this storm. It's not inconceivable that the northern suburbs of the Twin Cities could pick up close to a foot IF the storm tracks across Iowa, a changeover to sleet/rain on Tuesday is brief, and no dry air gets wrapped into the circulation (no "dreaded dry tongue" to worry about).
3). The heaviest snow will probably come Tuesday night into Wednesday afternoon. A few inches may come at the beginning of the storm (midday Tuesday), but I have a hunch the heaviest amounts will come Tuesday night into the first half of Wednesday, gradually tapering to flurries late Wednesday.
4). This may be a "heart-attack snow" for parts of Minnesota: heavy, sloppy and wet, with 1-2" liquid water tied up in the snowpack. It probably won't be prone to blowing and drifting with surface temperatures in the upper 20s on Wednesday. Be very careful out there shoveling on Wednesday. We're just not acclimated to lifting heavy, wet snow - certainly not this winter. All or nothing right?
Dueling Models. A few models (GFS specifically) are suggesting nearly 20" snow for the metro. That's a worst case scenario (best case if you love snow). The NAM and ECMWF models are predicting less, but still very significant amounts, in the 6-12" range. I'm still discounting that amount, because of a changeover to sleet Tuesday PM hours and the possibility of a dry surge aloft. But there's little question this will be a plowable snow for the Twin Cities metro, maybe a crippling storm for portions of central Minnesota.
Analog Analysis. From the local National Weather Service. This caught my eye:
"Based on the current run there are two events in the past: March 1985 and January 1997, which corresponds to the best thermal boundary expected by Tue/Wed. Both of these events have total snowfall amounts by the end of the storm that produces 12 to 18 inches across a large area of southern/central MN. Again...these are only tools which helps out forecasters to determine the overall severity of events and play accordingly."
Worst-Case Scenario: Snowpocalypse! I'm not buying the GFS solution, at least not yet. This model has had a pretty horrible track record in recent months, and it assumes no changeover to rain/ice, no surge of dry air aloft. With the storm track trending south in recent runs, and only a brief changeover, this scenario is more likely than it was 24 hours ago. Over a foot for central Minnesota (and the metro area?) Not out of the question. I'd put the odds (with what we know and the latest trends) at 1 in 3.
A More Modest (Snow) Forecast. The NAM model isn't quite as heart-stopping, closer to 4-8" snow by Wednesday afternoon in the metro, with over 1 foot for Moorhead, Detroit Lakes and the Brainerd Lakes area. This assumes a changeover to sleet/rain Tuesday PM hours, and may be a little closer to the mark. It would still be a "plowable" snowfall, but not crippling.
Short Answer: No.
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