Tracking: Metro icy mixed precip & rain; Possible Ice Storm?

Update 7:15pm:

Ice storm in progress. Only question now is how bad?

PRELIMINARY LOCAL STORM REPORT

NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN

637 PM CST TUE FEB 28 2012

0630 PM ICE STORM 3 NNW MINNEAPOLIS 45.00N 93.29W

02/28/2012 HENNEPIN MN COCORAHS

ICE ACCUMULATING ON TREES…POWER LINES AND CARS.

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Ice coated trees and power lines in Highland Park. (Photo by Bill Stein)

Update 6:30pm:

With temps hovering around 32 in metro I’m getting more concerned about a possible full blown “ice storm” tonight.

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Icy coating on trees and power lines in the west metro Tuesday evening.

Temps upstream in southern Minnesota are around 34 in some locations. If we squeak another degree or two tonight it’s no big deal. If it holds at 32, expect significant icing tonight.

There is the potential that some areas could see significant ice accumulation on trees and power lines causing power outages.

It will not surprise me to see ice storm warnings issued if temps do not budge.

Stay tuned…and watch for ice tonight!

PH

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Mixed rain/snow/ice on radar with temps hovering near freezing Tuesday evening.

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Rain drops make dents in leftover light AM snow coating at weather lab Tuesday PM.

***posted 5:13pm CST***

Waves of mixed precip tonight from metro south

(mix as far north as St. Cloud?)

-Latest Twin Cities radar loop

Mostly snow along and north of an Alex-Brainerd-Duluth line

Heavy wet snow of 7″ to 15″+ from Alex/Fergus Falls to Brainerd & Duluth

Ice accumulations in some areas tonight

Metro mix tonight changes back to all snow by 4am?

1″ to 3″ totals likely for most of metro early Wednesday morning

3″+ possible in the north metro Wednesday morning

Subtle changes (temp & track) may mean more Metro snow Wednesday

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Wet & rainy MNDOT Traffic Cam and freeways Tuesday afternoon. (I-394/494)

System Overview: Still on track, with subtle (but important?) forecast changes

Our well advertised weathermaker has arrived and is behaving mostly as expected so far. There are however a few subtle, but potentially important changes that are worth noting.

Let’s focus on the possible changes.

1) The warm air still looks to push north with the system well into the metro causing a change to a mix/sleet/ice to rain situation overnight. The 18Z model runs (and surface observations) suggest the push may not be quite as strong as earlier suggested.

-This could mean more icing from liquid precip tonight with locations that don’t climb above freezing vs. those that can achieve at least 33 degrees.

***I am now a bit more concerned about icing in southern Minnesota and the metro. If temps hover near freezing, rain may freeze on contact and cause significant ice storm conditions! There could be significant ice coating on trees and power lines tonight!***

2) The NAM & GFS 18Z tracks are ever so slightly south of the previous runs…but still a good 100 miles north of where it was 48 hours ago.

-This may mean a more rapid changeover to snow on the system’s colder “backside” around 4am for the metro, when sufficient moisture lingers to pump out a period of heavy wet snow before the system pulls out later Wednesday.

If that happens I expect a good shot of 1″ to 3″ of snowfall for the metro on the system’s back side early Wednesday morning.

There is also the potential that the northern metro could see more than 3″ Wednesday…with totals increasing rapidly to 5″ to 10″ as you move along I-94 toward St. Cloud.

The height of the storm!

The main body of precipitation is moving through tonight. The height of the storms ability to generate heavy precip through intense lift or “upward vertical velocity” (UVV) peaks between 6pm and 6am Wednesday.

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Radar shows main precip shield moving north late Tuesday PM.

This the period where snowfall and rainfall intensities will peak. Expect bursts of heavy snow/sleet/icing/rain depending on how far north you are overnight.

NWS trims advisories:

Reflecting the northward track shifts, Twin Cities NWS has trimmed back advisories to the north.

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Winter Storm Warnings have been cancelled for the central and southern Metro, replaced by winter weather advisories.

Bottom Line:

Stay tuned as the mix of ice/rain/snow evolves overnight. Expect winter travel conditions especially north & west of the Twin Cities metro!

PH

  • John Stewart

    Already about 1/8″ icing on trees in Worthington.