Thursday, December 17, 2009

Mid Atlantic Snow Blitz

* Air pollution advisory posted: light winds and inversion trapping pollutants near the ground.
* Temperatures close to average through Sunday.
* Saturday storm may unload over a foot of snow on Baltimore, Washington D.C. & Richmond!
* Sunday clipper may drop a light "nuisance" accumulation, up to 1" possible.
* Pre-Christmas storm may dump heavy snow on Chicago, Indianapolis and Detroit by the middle of next week, most moisture/energy passes south of Minnesota.
* Subzero New Year's Day? 2010 will probably start on a very cold note.

Mid Atlantic Dumping
. The NMM/WRF model spins up an impressive storm off the Outer Banks of North Carolina by noon Saturday, pumping Atlantic moisture inland, temperatures cold enough for mostly-snow across the Carolinas and Virginias, a narrow band of ice/rain near the Atlantic coast. Computer models are printing out some 12-18" amounts near Washington D.C. and Baltimore on Saturday!

The ultimate indignity: Washington D. C. (where the mere mention of "flurries" can leave locals racing to grocery stores to stock up on bread and milk - I kid you not!) is forecast to pick up a cool foot or more of snow from tonight into Saturday night as a nor'easter spins up off the coast of Virginia. If you have a flight into the Carolinas, Virginias, Maryland or Delaware count on potentially huge weather-related delays by Saturday. That's right, by Sunday parts of Delaware and southern New Jersey may have picked up considerably more snow than most of Minnesota so far this winter season. That's just not right. Whatever snow does fall out east will (mostly) stick around, meaning a rare white Christmas for places like Richmond, Washington D.C. and Baltimore, where the statistical odds of 1"+ snow on December 25 are about 20-30%

Solution #1Solution #2

Dueling Computers. Two different model outputs, two different forecasts of how much snow will pile up. Sunday's clipper may kick out 1-3" of snow across Minnesota - it's still too early to pin down which MN counties will see the most snow, but it may be "plowable" over parts of the state.

Those same models are hinting at 1-2" of snow Sunday, another potential for a light accumulation by Tuesday-Wednesday of next week as another Pacific storm crosses the Rockies and strengthens over the southern Plains, spreading potentially heavy snow into the Ohio Valley, Great Lakes and New England, with mostly rain for the eastern seaboard. It's way too early to get specific about a pre-Christmas storm, but right now the models keep most of the moisture and energy south/east of Minnesota. It looks like a much bigger risk of significant snow for Chicago, Detroit and Indianapolis than St. Cloud or St. Paul. After a glancing blow of snow MUCH colder air surges southward after Christmas, we may endure a few days with single digit highs and lows in the -5 to -15 F range.

Snowfall so far this December. Far southeastern Minnesota has picked up the most snow, 13-16"+. That compares to 7-10" for the Twin Cities, 5-7" in the St. Cloud area, and less than 3-4" for Brainerd, Bemidji, Detroit Lakes and Wadena. Sort of a mixed up (inverted) snowcover map.

Christmas flakes for Minnesota. The GFS model is hinting at flurries and a cold wind for Minnesota and Wisconsin - heavier, steadier snow for the Great Lakes and the Ohio Valley, mostly rain for the east coast. Christmas travel WILL be impacted by next week's storm - if you're traveling you'll want to stay tuned for the very latest.

Christmas Day Outlook for the Twin Cities: Mostly cloudy, windy and cold with flurries - dusting possible. High: 22

Models are suggesting highs mostly in the teens (north) and 20s (southern MN) through December 28 or so, followed by MUCH colder weather around New Year's Eve, when daytime highs may not climb much above zero, nighttime lows -10 to -20 statewide. Something to look forward to.

Paul's Outlook for the Twin Cities

Today: Mostly cloudy, few flurries in the air - temperatures at or even above average. Winds: N 5-10. High: 27

Tonight: Patchy clouds. Low: 16

Saturday: More clouds than sun, few flakes in the air, nothing significant. High: 25

Sunday: Cloudy with a little light snow/flurries. Coating to an inch or so (isolated snow bands may drop up to 2-3", but that should be the exception, not the rule). High: 23

Monday: Intervals of sun, drier day. High: 22

Tuesday: Some sun, chilly. High: 19

Wednesday: Cloudy with a period of light snow possible. High: near 20

Christmas Eve: Lingering clouds, flurries, a chilly wind. High: near 23

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