No worries about a brown Christmas this year. Santa will not need to ditch the sleigh and squeeze into the cherry-red Escalade. There will be PLENTY of fresh snow this year, in fact, we're on target to set a few records for the most snow observed in a 24 hour period, especially on Christmas Eve. Yes, Snowmageddon Central is open for business, lot's of excitement, angst, and a fair amount of outright confusion. The timing is fortuitous - fresh snow for Christmas brings out the inner child in all of us; and unfortunate: last-minute travel to see friends/relatives will be more of a hassle than usual, by an order of magnitude. A few meteorological observations:
1). No widespread travel headaches today before 10 pm. Get your errands done TODAY!
2). A surge of wet snow approaching from the south arrives tonight, after midnight snow may accumulate at the rate of 1"/hour.
3). Still sticking with a forecast for a "snow sandwich." Expect 4-5" by 7 am Christmas Eve, perhaps as much as 8-10" by Thursday night, just in time for Christmas Eve church services. From the Twin Cities on south/east there may be enough warm air aloft for a period of ice on Christmas Day, sleet and freezing rain, which will keep amounts down a bit, and possible compress the snow that does fall on Christmas Eve. The storm stalls (temporarily) over Iowa, before pushing off to the northeast late Friday and Saturday, winds swing back around to the north, meaning a changeover back to mostly (light) snow late Friday into midday Saturday, with a potential for another 1-3", maybe more.
4). How much? Definitely plowable for the metro area, where I expect a cool 8-12" before snow mixes with an icy concoction on Friday. Temperatures will be close to freezing from MSP south to Rochester and east to Eau Claire and Tomah, WI, meaning most interstates will probably be wet/slushy, but secondary roads will be snow covered.
5). Just 50-150 miles north and west of MSP precipitation should fall as MOSTLY SNOW. There may not be a changeover to an icy mix. Models still print out close to 2" of liquid precipitation, which translates into 18-22" of snow. I could see a potentially crippling snowstorm from Windom and Willmar to St. Cloud, Brainerd to Duluth, some 15-20" amounts are very plausible. The farther north/west you travel, away from MSP, the more snow you'll see. The farther south/east you drive, toward Wisconsin and Iowa, the faster you'll run into an icy mix, even some rain by Christmas Day as warmer air wraps into the storm circulation.
6). Snow gradually tapers off Saturday PM hours - Sunday should be MUCH BETTER to get to the store (to return those handsome sweaters) or make the drive back home. Saturday may still be rough on the highways, especially if you're driving west on I-94 or I-90 west of Albert Lea. Sunday looks like the safer travel bet.
The Right Idea. I still think the projected amounts are a bit high for the western metro of the Twin Cities, but the overall outlook is valid. Expect lesser amounts of snow over eastern Iowa, southeastern MN and much of Wisconsin, where a changeover to sleet and freezing rain is likely by Christmas Day. Still leaning toward an 8-12" range for much of the metro, less far eastern metro, but as much as 15" for the far western suburbs, like Delano, Monticello and St. Micheal. The St. Cloud area could easily pick up some 15-20" amounts from this storm - there any changeover to ice is iffy at best.
Snowmageddon! Scenario # 2, less likely, but still possible. If (and it's a huge if) the snow does not change over to an icy mix, this forecast could verify. Look at the massive area forecast to see more than 18-20" of snow, stretching from Nebraska and eastern South Dakota into most of Minnesota. This scenario is still possible, but I'd put the odds at 1 in 3. Snow lovers: don't give up on this best-case-scenario just yet!
Hey, this is exciting! A real storm! Something to point to on my magic green chroma key at WeatherNation! I have to admit to simple, petty jealousy last Saturday when the Mid Atlantic states were getting blasted with heavy snow. I know that's bordering on pathetic, but Washington D.C. with more snow than the Twin Cities? That's just so wrong on so many levels. With this storm we have a chance to right the wrong, to catch up in the snow department, to regain our weather-boasting-rights for North America.
Chaos Theory. What I'd give for a black and white weather scenario. The forecast is almost always some nebulous, hard-to-fathom shade of gray. Keep in mind that every storm is different, unique, with its own characteristics and idiosyncrasies. The upcoming Christmas Storm may be similar to a storm years ago, but no two weather systems are ever identical. There is always some new wildcard in the data, something that may turn 20" of predicted snow into 6". Like the stock market: untold billions of variables and factors, a handful of which may be hyper-critical, far more important that the rest.
There are 2 reasons why I'm not (presently) predicting 18-20" snow for the Twin Cities metro:
1). Storm track too close to MSP. The farther west a storm tracks (or "hooks"), the greater the potential for a counterclockwise circulation to pull warmer air into Minnesota from the south and east. The "ideal storm track for snow" runs from Des Moines to about Eau Claire, a track that keeps most of the warm air well east of MSP. Check out the projected storm track below, and you'll see evidence of that northwestward hook, which may be just enough to pull a thin layer of air > 32F into southeastern and east central Minnesota Christmas Day. The models are hinting at a snowy/icy mix Friday - if this verifies it would keep amounts down, a bit. Instead of 20" we may have to be content with 8 or 10", still a very respectable pile.
Classic "Texas Hooker". Note how the storm appears to be tracking toward the northwest by Christmas Day? That zig to the west may be just enough to pull slightly warmer air into Minnesota, enough warm air aloft for a changeover to a snow/ice mix Christmas Day, keeping amounts down (a bit) from the Twin Cities into Wisconsin, southeastward to Rochester & Winona.
2). "Dreaded Dry Tongue." Big storms sweeping in from the south are not only laden with moisture from the Gulf of Mexico, but energized with dry air sweeping in from the desert southwest. This dry air has a tendency to wrap around a storm's circulation, approaching from the south or southwest, often cutting down on the most intense precipitation, turning moderate snow into moderate drizzle in the snap of a finger. Very frustrating for meteorologists, but this dry tongue (sounds like something from a bad deli) can make a huge difference in final snow totals. There is some evidence that dry air will wrap into our Christmas Storm, also serving to keep amounts down (a bit) from the cities on south and east.
That said: this is still going to be a very respectable pile. Just 50 miles west of MSP there may be some 15-18" amounts. This could be another scenario where the far northern/western suburbs see twice as much snow as Cottage Grove, Eagan and Stillwater. My favorite college professor would admonish us for trying to predict inch amounts more than 24 hours before the onset of snow. "Americans are preoccupied with inches!" he'd shout, literally getting red in the face. "Too often we don't have the technology to predict snow right down to the inch. Don't even try!" He was the one who dreamt up the "nuisance-plowable-crippling" scale for rating snowstorms. On this scale most of the metro area will see plowable amounts, but parts of central, western and northern MN could see a crippling snowfall, over 20" with some 3-5 foot drifts kicking in by Saturday.
Batten down the hatches. Here we go!
One Tough 'Vette. Looking forward to getting out and plowing some driveways later this week! If you see me, feel free to wave (preferably with all five fingers!)
Paul's Outlook for the Twin Cities
Today: Cloudy, chilly, damp (but dry). Last good travel day in sight. Winds: East 5-10. High: 25
Wednesday night: Winter Storm Warning. Snow developing (heaviest after midnight). 4" possible by Thursday morning. Low: 21
Christmas Eve: Winter Storm Warning. Snow, heavy at times. High: 27
Christmas Day: Winter Storm Warning. Snow mixes with sleet, possibly even a little freezing rain. Glaze ice possible on bridges and secondary roads. Hazardous travel. High: near 30
Saturday: Snow gradually tapers to flurries. Total snowfall amounts of 8-12" possible, less east of St. Paul, some 15" amounts possible far western suburbs of Minneapolis. Some blowing/drifting. High: 24 (falling)
Sunday: Much better travel day. Intervals of sun possible. High: 22
Monday: More clouds than sun, seasonably chilly. High: 23
Tuesday: Mix of clouds and sun, quiet. High: 25