Winter storm update; Twin Cities rides northern edge of heavy snow

March is indeed a fickle month.

Some years we see highs in the 80s, and we occasionally have single digit highs in March.

We can have beautiful sunny days, some rainy days, sleet, snow and occasionally a severe thunderstorm.

Some Minnesotans will see several inches of snow from Friday afternoon into early Saturday.

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The snow potential

A rain/snow mix is expected to enter southwestern Minnesota Friday morning, then spread northeastward through the day. The mix could change to all snow in the west Friday evening, and during Friday night to the east.

The snow is expected to continue overnight Friday night and taper of Saturday morning.

The National Oceanic and Atmospheric Administration's North American Mesoscale forecast model shows the potential precipitation pattern from Friday through Saturday morning:

rt0322rad
NOAA NAM simulated radar from Friday through Saturday morning, via tropicaltidbits

The color chart to the right of the loop refers to the strength of the signal that returns to the radar, not to the amount of snow or rain.

The NAM snow totals are heaviest from west-central Minnesota into parts of southern Minnesota:

rt0322rad2
NOAA NAM snow accumulation from Friday through Saturday morning, via tropicaltidbits

The NAM indicates some double digit amounts are possible, but snow totals are tricky when dealing with the uncertain timing of the change from rain or a mix of rain and snow to all snow.

The National Weather Service snow forecast shows how tight the gradient from heavy snow to lighter snow will be:

rt322sno2
NWS Twin Cities

I wouldn't be surprised if the far northeastern part of the Twin Cities metro area only sees an inch or two of snow from the storm, while five to eight inches of snow accumulate in some parts of the far southwest metro from Friday night through early Saturday.

Any metro area snow should hold off until sometime Friday evening.

Watches and warnings

Winter storm warnings have been posted for portions of west-central and northwestern Minnesota:

rt0322wch3
NWS Twin Cities
rt0322wch4
NWS Grand Forks ND

The southwestern half of the Twin Cities metro area is in a winter storm watch that begins Friday evening:

MNZ049-058>060-066-068>070-076>078-085-230500-

/O.EXT.KMPX.WS.A.0005.180324T0000Z-180324T1500Z/

Stearns-Meeker-Wright-Hennepin-McLeod-Carver-Scott-Dakota-

Le Sueur-Rice-Goodhue-Steele-

Including the cities of St Cloud, Litchfield, Monticello,

Minneapolis, Hutchinson, Chaska, Shakopee, Hastings, Le Sueur,

Faribault, Red Wing, and Owatonna

355 PM CDT Thu Mar 22 2018

...WINTER STORM WATCH NOW IN EFFECT FROM FRIDAY EVENING THROUGH

SATURDAY MORNING...

* WHAT...Heavy snow and blowing snow possible. Total snow

accumulations of 4 to 9 inches are possible, with the lightest

amounts along I-94.

* WHERE...Portions of central, east central, south central and

southeast Minnesota.

* WHEN...From Friday evening through Saturday morning.

* ADDITIONAL DETAILS...Plan on difficult travel conditions.

Winds gusting as high as 35 mph could cause patchy blowing and

drifting snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is potential for significant

snow, sleet or ice accumulations that may impact travel. Continue

to monitor the latest forecasts.

Here are details of the winter storm warning in west-central Minnesota:

URGENT - WINTER WEATHER MESSAGE

National Weather Service Twin Cities/Chanhassen MN

355 PM CDT Thu Mar 22 2018

...WINTER STORM WATCH HAS BEEN UPGRADED TO A WARNING ACROSS WEST

CENTRAL MINNESOTA WITH ADDITIONAL COUNTIES LIKELY BEING ADDED THIS

EVENING...

...VERY SHARP SNOWFALL GRADIENT STILL EXPECTED TO SET UP NEAR

SAINT CLOUD...THE TWIN CITIES...AND RED WING...

.A Winter Storm Warning is now in effect across west central

Minnesota with a watch remaining elsewhere southwest of the

Mississippi River Friday afternoon into Saturday morning.

The main forecast concern remains where the sharp gradient of

snowfall totals sets up on the northeast side of this winter

storm. Little has changed in the last 24 hours with the best

potential of this setting up the Mississippi River, but enough

uncertainty remains so the Winter Storm Watch will continue until

we have a better idea of where this gradient sets up.

Snow will begin to develop across the Dakotas late tonight and

build eastward into west central Minnesota late Friday morning,

reaching east central Minnesota late Friday evening. There may be

a brief period of rain or sleet, but it is expected to turn to

heavy snow quickly as temperatures cool to near freezing.

Snowfall amounts will range from 6 to 10 inches across western

and southern Minnesota. As mentioned before, there will be a sharp

gradient in amounts near the Mississippi River, with possibly little

or no snow northeast of there. Any shift would lead to significant

forecast changes near this gradient, including in the Twin Cities

metro.

MNZ047-055-056-230500-

/O.UPG.KMPX.WS.A.0005.180323T1500Z-180324T1500Z/

/O.NEW.KMPX.WS.W.0005.180323T2100Z-180324T1500Z/

Stevens-Swift-Chippewa-

Including the cities of Morris, Benson, and Montevideo

355 PM CDT Thu Mar 22 2018

...WINTER STORM WARNING IN EFFECT FROM 4 PM FRIDAY TO 10 AM CDT

SATURDAY...

* WHAT...Heavy snow and blowing snow expected. Total snow

accumulations of 6 to 10 inches are expected.

* WHERE...Stevens, Swift and Chippewa Counties.

* WHEN...From 4 PM Friday to 10 AM CDT Saturday.

* ADDITIONAL DETAILS...Plan on difficult travel conditions.

Winds gusting as high as 40 mph will cause patchy blowing and

drifting snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning means significant amounts of snow, sleet

and ice will make travel very hazardous or impossible. The latest

road conditions for Minnesota can be found at 511mn.org and for

Wisconsin at 511wi.gov, or by calling 5 1 1 in either state.

Check forecast updates, especially if you will be traveling in Minnesota Friday afternoon into early Saturday.

Updated weather information can be heard on the Minnesota Public Radio Network, and you can also see weather updates on the MPR news live weather blog.

Programming note

You can hear my live weather updates on Minnesota Public Radio at 7:49 a.m. Thursdays and Fridays, and at 7:35 a.m., 9:35 a.m. and 4:35 p.m. each Saturday and Sunday.