Updraft: March 6, 2011 Archive

1"+ PM &Tonight? Edge of major storm Wednesday?

Posted at 12:57 AM on March 6, 2011 by Paul Huttner
Filed under: Winter storms, Winter/spring 2011

Just back from 2 (great!) days at Wolf Ridge ELC in Finland above the North Shore presenting a talk on the extreme & record weather of the past year to the 2nd annual Minnesota Phenology & Weather Observers gathering.

Many thanks to Peter Harris & the entire Wolf Ridge ELC team for hosting the event. And thanks to the many MPR listeners who showed up to greet us. It was great meeting you!

Sunshine on Lake Superior Saturday at Lutsen. I was not lucky enough to have time to ski, but we did ride the gondola up for lunch. What a view!

Here's a quick update on the latest model runs and thinking on snow chances the next few days. I'll have a more detailed analysis Sunday PM.

Sunday & Sunday night:

A weak "open wave" will pass over Minnesota Sunday. This minor system should eek out a little light snow today into early Monday. Models are putting out maybe an inch or two, but there are some signs the system could weaken as it moves in Sunday. Right now it appears we will have little if any snow for most of Monday PM into Tuesday.

Bottom line? Expect the possibility for a minor nuisance snowfall from Sunday PM & night into early Monday AM.

On the edge of a major winter storm Tuesday night & Wednesday:

There have been several changes in the potential track of the major winter storm which is still expected in the Midwest this week. I'll give you some quick highlights rather than a lengthy description of each (contradictory) twist in the models.

-I still expect a major winter storm to hit the Upper Midwest Tuesday night into Wednesday. At this point It looks like there is a 80% chance of a plowable event from the Twin Cities south into southern Minnesota, northern Iowa, and much of central Wisconsin.

-Weekend model trends track the storm further south, but there is still some chance it may "recurve" to the north, meaning it is still too early to pinpoint the heavy snow bands, and therefore to place reliable* snowfall accumulations.

*It is often not accurate (or even responsible) to forecast snowfall totals more than 24 to 48 hours in advance of these systems, as the track can and usually does vary significantly in the days preceding the storm. (How many different snowfall forecasts do you want? And which one should you "plan" for?)

-The models are coming into "closer" agreement, and we should hopefully have a better handle on storm track and where the heavy snow bands will set up (and totals) by Sunday night's model runs.

NAM hinting Twin Cities on edge of major snow by Wednesday? Stay tuned as models sort things out.

***
Bottom line: There is a high chance of snow for southern Minnesota, northern Iowa and central Wisconsin Tuesday night & Wednesday. Heavy snow (6"+) is possible somewhere between the Twin Cities and La Crosse. Forecasts should gain clarity (and hopfully accuracy and reliability!) in the next 24 hours.

Stay tuned!

PH

1" to 2"+ by morning; Still on the edge Wednesday

Posted at 4:39 PM on March 6, 2011 by Paul Huttner (3 Comments)
Filed under: Winter storms, Winter/spring 2011

Snow totals update 11:15pm Sunday:

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1002 PM CST SUN MAR 06 2011

...PRELIMINARY SNOWFALL AMOUNTS FROM SUNDAY...

THE TOTALS BELOW ARE SEPARATED INTO SNOW...AND ICE AND SLEET
CATEGORIES...THEN BY AMOUNT...AND ARE NOT NECESSARILY THE
FINAL AMOUNT FOR EACH LOCATION.

SNOW REPORTS LISTED BY AMOUNT

INCHES LOCATION ST COUNTY TIME
------ ----------------------- -- -------------- -------
4.50 BRANDON MN DOUGLAS 0926 PM
4.00 SAUK RAPIDS MN BENTON 0833 PM
4.00 CARLOS MN DOUGLAS 0455 PM
3.40 LONG PRAIRIE MN TODD 0610 PM
3.20 ST CLOUD MN STEARNS 0600 PM
3.00 2 W FOLEY MN BENTON 0524 PM
2.50 LITCHFIELD MN MEEKER 0632 PM
2.00 GLENWOOD MN POPE 0759 PM
1.60 BLOOMINGTON MN HENNEPIN 0856 PM
1.50 WINTHROP MN SIBLEY 0825 PM
1.30 SHAKOPEE MN SCOTT 0845 PM
0.40 CHANHASSEN MN CARVER 0554 PM
0.20 MINNEAPOLIS AIRPORT MN HENNEPIN 0554 PM

Sunday PM & evening Update:

Through Sunday night:

Weak system is producing light snow in most areas as expected. Totals should range mostly between 1" and 2" through tonight, with some isolated higher totals (to 4"?) toward Alex & St.Cloud (& maybe far NW metro) where heavier snowfall bands are present. Remember even a little light snow can produce some slick spots so take it easy as you're out and about through tonight.

Bands of light snow will move through tonight.

Still on the edge of a storm Wednesday:

The forecast models are still showing considerable differences (big surprise!) in the track and intensity of Wednesday's storm system.

*The overall trend remains to steer the surface and upper lows further south than many models were suggesting last week.

Modles track the surface low. Note the wide range in (model) locations for the surface low by 6am Wednesday! (Click to enlarge for a better view)

That means the heavy snow band will likely set up (well?) southeast of the metro, and locations such as Mason City, Iowa, Rochester and La Crosse appear to have a much better chance of heavy snow (than the metro) Tuesday night and Wednesday.

Some models (including the NAM) track the surface low from south of Kansas City Tuesday at 6pm to south of the Quad Cities Wednesday morning at 6am, and then track the system to near Madison or Milwaukee by Wednesday evening. That is generally not a favorable storm track for heavy snow in the metro, and tends to lay out the storms "heavy snow band" in northern Iowa, far southeast Minnesota and central Wisconsin.

The European & very latest GFS model (Sunday PM) have the surface low as far south as Chicago by Wednesday evening. If that track pans out, it would drastically reduce snowfall totals near the metro. There is even a chance we could see very little snow in parts of the metro if the more southerly track verifies.

European model tracks the surface low to near Chicago by late Wednesday.

*The most reliable forecast at this point is to expect some potentially heavy snow Tuesday night & Wednesday in southeast Minnesota, northern Iowa and central Wisconsin.

*If the model trends pushing the system south continue, there is even a chance the storm could mostly miss the Twin Cities to the south.

*One thing that appears very likely? We're probably not going to get a foot of snow anywhere near the metro with this system. Now you know why we don't (publicly) forecast over a foot of snow a week in advance. As good as I'd like to think I am at forecasting snow...nobody is that good, especially with the error rate in the numerical weather forecast models a week out. Things could still change for the snowier, but at this point I'd say there is a better chance the system will miss the metro than there is for getting a foot of snow.

*I will post some model output with specific snowfall totals when I think it's more reliable, right now I don't think it's reliable enough to have much value. Hopefully things will come together with model runs tonight and Monday morning.

Bottom line: It's still too early to make a call on snowfall totals for the Twin Cities with the storm system passing to the south Tuesday night & Wednesday.

It looks like any snowfall that does hit the metro won't begin until late Tuesday night, and any effects would be during the Wednesday morning commute. We're still more than 48 hours away from this system in the metro.

Those of you in or planning travel to southern Minnesota (I-90 corridor from Worthington-Albert Lea-Rochester), northern Iowa (Spencer-Mason City-Decorah) and SW & central Wisconsin (La Crosse, Eau Claire & Tomah) should know there is a good chance of heavy snow Tuesday night & Wednesday with the latest forecast model trends.

Enjoy(?) the light snow through tonight & stay tuned!

PH

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