Weekend warmth; winter storm watch Sunday evening through Monday evening

Our average high is only 24 degrees this time of year in the Twin Cities metro area.

We could flirt with 40 at some point this Saturday afternoon.

Highs in the 30s should be widespread in Minnesota Saturday afternoon, and some spots in the south could pop into the 40s.

Temperature trends

Highs Sunday will be in the 30s across most of Minnesota, with 20s northwest:

20s spread into central Minnesota on Monday:

Twin Cities metro area highs are expected to be in the 20s Tuesday and Wednesday, then rebound to the 30s for Thursday and Friday.

Winter storm watch

Parts of southern and east-central Minnesota, the Twin Cities metro area and western Wisconsin could see significant snow from late Sunday evening through Monday.

The National Weather Service has issued a winter storm watch, which begins Sunday evening or late Sunday night in those areas:

NWS Twin Cities

Here are details of the portion of the watch that includes the Twin Cities metro area and nearby counties, and runs from midnight Sunday night through Monday and Monday evening:

URGENT – WINTER WEATHER MESSAGE
National Weather Service Twin Cities/Chanhassen MN
344 AM CST Sat Jan 20 2018

…Winter Storm to affect Central and Southern Minnesota and
Western Wisconsin Sunday night into Monday…

.A strong storm system will bring an area of moderate to heavy
snow across a portion of southern through east central Minnesota
into western Wisconsin Sunday night, spreading east through
Monday. Snowfall totals of 6 to 10 inches are possible by the
time the storm exits the region Monday evening. At this point,
the heaviest snow will fall south of a line from Redwood Falls
through the Twin Cities toward St Croix Falls and Rice Lake.
Other areas that may see heavy snow include Fairmont, Mankato,
River Falls and Eau Claire.

A wintry mix with a period of freezing rain is possible in far
southern Minnesota near the Iowa border, then toward Eau Claire,
leading to slick roads. In addition, northeast winds between
20 to 35 mph will cause blowing and drifting snow and whiteout
conditions at times, especially in open country. Winds will begin
diminishing Monday night.

Remember, this is still a Winter Storm watch, and the track of
the heaviest snow may change. Be prepared for difficult driving
conditions if you have travel plans across central or southern
Minnesota and western and northern Wisconsin.

MNZ053-060>063-066-068>070-077-078-WIZ014>016-023>028-201745-
/O.CON.KMPX.WS.A.0002.180122T0600Z-180123T0600Z/
Chisago-Hennepin-Anoka-Ramsey-Washington-McLeod-Carver-Scott-
Dakota-Rice-Goodhue-Polk-Barron-Rusk-St. Croix-Pierce-Dunn-Pepin-
Chippewa-Eau Claire-
Including the cities of Center City, Minneapolis, Blaine,
St Paul, Stillwater, Hutchinson, Chaska, Shakopee, Hastings,
Faribault, Red Wing, Osceola, Rice Lake, Ladysmith, Hudson,
River Falls, Prescott, Menomonie, Durand, Chippewa Falls,
and Eau Claire
344 AM CST Sat Jan 20 2018

…WINTER STORM WATCH REMAINS IN EFFECT FROM LATE SUNDAY NIGHT
THROUGH MONDAY EVENING…

* WHAT…Heavy mixed precipitation possible. Plan on difficult
travel conditions, including during the evening commute on
Monday. Total snow accumulations of 6 to 10 inches and ice
accumulations of a light glaze are possible.

* WHERE…Portions of northwest and west central Wisconsin and
central, east central, south central and southeast Minnesota.

* WHEN…From late Sunday night through Monday evening.

* ADDITIONAL DETAILS…Winds gusting as high as 35 mph will
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.

And now, details of the southeastern Minnesota portion of the watch, which begins Sunday evening and runs through Monday evening:

URGENT – WINTER WEATHER MESSAGE
National Weather Service La Crosse WI
336 AM CST Sat Jan 20 2018

…Snow, Wintry Mix Likely Sunday Evening Through Monday…

.Motorists should anticipate impacts to travel Sunday evening
into Monday evening as snow or an icy wintry mix spreads across
the area. Snow accumulations of 6 inches or more are possible,
along with icing up to 2/10 of an inch.

The exact track of the storm is still in question. If the track
changes, where the band of heaviest snow falls and where the
threat for the greatest icing lies will change with it.

Stay up-to-date on the latest forecasts as the details of snow
amounts and icing potential become clearer.

MNZ086-087-094-201745-
/O.CON.KARX.WS.A.0002.180122T0000Z-180123T0600Z/
Dodge-Olmsted-Mower-
Including the cities of Dodge Center, Rochester, and Austin
336 AM CST Sat Jan 20 2018

…WINTER STORM WATCH REMAINS IN EFFECT FROM SUNDAY EVENING
THROUGH MONDAY EVENING…

* WHAT…Heavy mixed precipitation possible. Plan on difficult
travel conditions, including during the morning commute on
Monday. Total snow and sleet accumulations of 6 inches or more,
and ice accumulations of up to two tenths of an inch are
possible.

* WHERE…Dodge, Olmsted and Mower County.

* WHEN…From Sunday evening through Monday evening.

* ADDITIONAL DETAILS…Significant reductions in visibility are
possible.

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.

And for southwestern and south-central Minnesota, from the NWS Twin Cities office:

MNZ064-065-067-073>076-082>085-091>093-201745-
/O.CON.KMPX.WS.A.0002.180122T0000Z-180123T0600Z/
Yellow Medicine-Renville-Sibley-Redwood-Brown-Nicollet-Le Sueur-
Watonwan-Blue Earth-Waseca-Steele-Martin-Faribault-Freeborn-
Including the cities of Granite Falls, Olivia, Gaylord,
Redwood Falls, New Ulm, St Peter, Le Sueur, St James, Mankato,
Waseca, Owatonna, Fairmont, Blue Earth, and Albert Lea
344 AM CST Sat Jan 20 2018

…WINTER STORM WATCH REMAINS IN EFFECT FROM SUNDAY EVENING
THROUGH MONDAY EVENING…

* WHAT…Heavy mixed precipitation possible. Plan on difficult
travel conditions, including during the morning commute on
Monday. Total snow accumulations of 7 to 10 inches, with
localized amounts up to 12 inches, and ice accumulations of
around one tenth are possible.

* WHERE…Portions of central, south central, southwest and west
central Minnesota.

* WHEN…From Sunday evening through Monday evening.

* ADDITIONAL DETAILS…Winds gusting as high as 35 mph will cause
patchy blowing and drifting snow, and whiteout conditions at
times.

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.

A summary of the storm potential:

NWS Twin Cities

The forecast models

Computer models continue to show a low pressure system over the Oklahoma panhandle Sunday morning.

From there it moves northeastward, arriving in southern Wisconsin Monday afternoon.

It will spread moisture over much of the upper Midwest late Sunday into Monday.

Here’s the National Oceanic and Atmospheric Administration’s Global Forecast System (GFS) model for Sunday through Monday night:

NOAA GFS precipitation rate (mm/hour) Sunday through Monday night, via tropicaltidbits

The color chart to the right of the loop refers to the precipitation rate (mm per hour), not to the amount of precipitation.

Here are the snowfall totals racked up in the GFS model:

NOAA GFS snow totals from Sunday through Monday night, via tropicaltidbits

Yes, there are some double digit totals in southern Minnesota and the southern part of the Twin Cities metro area.

It’s likely to be a wet snow, so the snow to water ratio could be closer to 7 or 8 to 1 than the 10 to 1 ratio used in the snow graphic above.

A lower snow to water ratio would lower the snow totals a bit.

Here’s the snowfall generated in the latest run of the Canadian forecast model:

Canadian GEM forecast model snow totals Sunday through Monday night, via tropicaltidbits

The latest run of the European Centre for Medium-Range Weather Forecasts (ECMWF) model gives the Twin Cities about seven-tenths of an inch of precipitation late Sunday through Monday night:

ECMWF forecast for Minneapolis, via Norwegian Met Institute

Here’s the conversion of those 18.4 millimeters of precipitation to inches:

With about seven-tenths of an inch of water in the snow, it would translate to about 7 inches of snow if you use a 10 to 1 snow to water ratio.

Don’t be alarmed by the temperatures in the European Centre forecast, they’re in degrees Celsius.

We’ll monitor changes in the forecast models and give you updates as we get closer to Sunday evening.

Updated weather information can be heard on the Minnesota Public Radio Network, and you can read about 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.