NWS Twin Cities, MN wrote its last area forecast discussion before the first event at Dec 21, 5:55 AM CST, 5 hours 5 minutes earlier.
Area forecast discussion, Dec 21, 5:55 AM CST, 5 hours 5 minutes before
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
555 AM CST Wed Dec 21 2022
.UPDATED for 12Z Aviation Discussion...
Issued at 543 AM CST Wed Dec 21 2022
&&
.DISCUSSION...(Today through Tuesday)
Issued at 252 AM CST Wed Dec 21 2022
KEY MESSAGES: OVERALL SYSTEM REMAINS ON TRACK
- TODAY AND TONIGHT, part 1 of this system will bring 5 to 9 inches
of light fluffy snow across the region, with the highest amounts
just north and west of the Twin Cities, into western Wisconsin. A
Winter Storm Warning is in effect area wide.
- LATE TONIGHT AND EARLY THURSDAY, a break will follow, but then
part 2 of the system kicks in as northwest winds increase Thursday
afternoon through Friday night with widespread blowing snow.
- THURSDAY AFTERNOON THROUGH FRIDAY NIGHT, Confidence remains in
blizzard conditions for much of southern and western Minnesota
Thursday afternoon through Friday night. Wind strength in areas
along and north of I-94 remains a bit more uncertain and it ramps up
a little later Thursday, so continued wit the Winter Storm Watch.
- IMPORTANT CHANGES, The wind forecast has decreased a bit for
Thursday into Friday night. The reason is the rapid intensification
of the surface low across the Great Lakes is a bit slower and
farther east, so the pressure gradient is less over the Midwest. As
a result, the potential for gusts greater than 50 mph has decreased,
but we still expect a long duration with at least 40 mph wind gusts.
TODAY AND TONIGHT...Not much change from the previous
forecast. An upper level wave across the Dakotas will move east
today, and warm air advection will spread out ahead of it brining
increasing clouds and snow across the region. Forecast soundings
continue to show a deep dendritic growth zone, so this snow will be
light and fluffy, with snow ratios of 20 to 25:1 expected, possibly
higher. Overall snowfall amounts are similar to the previous
forecast, with 5 to 9 inches across central MN into west central
Wisconsin, tapering off to 3 to 5 down near I-90. Winds will be light
with this snow, generally starting out of the east, and switching to
the northwest toward evening as the snow ends. The Winter Storm
Warning is in effect for this snowfall.
THURSDAY THROUGH FRIDAY NIGHT...The one noteworthy change is a
slight decrease (5 to 10 mph) in the wind forecast. As mentioned
above, this is due to the delayed onset of rapid intensification of
the surface low, combined with a slightly weaker high pressure system
to the west, and also the fact the strongest cold air advection is
focused to the south of the forecast area. This last point is
probably why the forecast soundings are a bit jumpy with the wind
gusts, meaning there's a few hours where they don't mix down the
gusts, which lowers the potential for +50 mph winds. If this system
does intensify more quickly and farther east, then the wind forecast
will increase. For now, we expect a long duration, Thursday night
through Friday night, with gusts in that 30 to 40 mph range, with a
few windows for gusts to be 40 to 50 mph.
In summary, we still expect blizzard conditions. Especially
considering how much light and fluffy snow is already sitting out
their. For added context, earlier, it was looking like this event
could have similar impacts to February 23/24 2019, which closed I-94
for over two days. That was a historic blizzard, with a much deeper
snow pack, and higher snow banks. However, this system will have a
long duration of strong winds, just not as high as that event. This
system also has several inches of fluffy snow to blow around. Given
that, it is possible that the Winter Storm Watch that is still in
effect east of the Blizzard Warning could be converted to a Blizzard
Warning. We just wanted to wait and see what the 12Z guidance shows,
in case this trend of lower winds continues. But as things stand
right now, widespread 40 mph gusts, with areas of 40 to 50 mph, are
still forecast.
SATURDAY THROUGH TUESDAY...Winds will decrease on Saturday, but it
will still be very cold. Lows Saturday night will be -10 to -20
below as surface high pressure settles overhead. The lull in the
weather won't last long, as another clipper system brings snow
chances again on Sunday, with the highest probability across
southwest Minnesota, and lesser chances in western Wisconsin. This
too will be a colder, fluffy snow, but the northwest winds that
follow it are only around 10 to 20 mph. Looking ahead, there is a
glimmer of hope with above normal temperatures favored at the end of
December into the New Year.
&&
.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 543 AM CST Wed Dec 21 2022
Snow will move in from west to east today. Expect IFR/LIFR conditions
at times with visibility around a half to 2 miles. Snowfall rates
will be around a half inch per hour. Winds will be light, but become
northwest and increase overnight. Expect visibility to decrease on
Thursday as winds increase.
KMSP...
Snow will begin later this morning, but the lowest visbys may end up
just to the north of KMSP. Snow will continue through most of the
day, but become lighter this evening with a brief period of VFR
conditions possible overnight before winds increase on Thursday.
/OUTLOOK FOR KMSP/
Thu...MVFR/IFR and BLSN. Wind NW 15-20kts gusts 30-35 kts.
Fri...MVFR/IFR and BLSN. Wind NW 25G40 kts.
Sat...MVFR/IFR and BLSN. Wind NW 20G30 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...Winter Storm Warning until midnight CST tonight for Benton-Douglas-
Isanti-Kanabec-Mille Lacs-Morrison-Sherburne-Stearns-Todd-
Wright.
Wind Chill Warning from 6 AM Thursday to noon CST Saturday for
Brown-Chippewa-Douglas-Kandiyohi-Lac Qui Parle-Martin-Pope-
Redwood-Renville-Stevens-Swift-Watonwan-Yellow Medicine.
Winter Storm Watch from Thursday afternoon through late Friday
night for Anoka-Benton-Carver-Chisago-Dakota-Douglas-Goodhue-
Hennepin-Isanti-Kanabec-Mille Lacs-Morrison-Ramsey-Rice-Scott-
Sherburne-Stearns-Todd-Washington-Wright.
Wind Chill Watch from Thursday evening through Saturday morning for
Benton-Blue Earth-Carver-Faribault-Freeborn-Le Sueur-McLeod-
Meeker-Morrison-Nicollet-Rice-Scott-Sherburne-Sibley-Stearns-
Steele-Todd-Waseca-Wright.
Winter Storm Warning until noon CST Thursday for Brown-Chippewa-
Kandiyohi-Lac Qui Parle-McLeod-Meeker-Nicollet-Pope-Redwood-
Renville-Sibley-Stevens-Swift-Yellow Medicine.
Blizzard Warning from noon Thursday to 6 AM CST Saturday for Blue
Earth-Brown-Chippewa-Faribault-Freeborn-Kandiyohi-Lac Qui
Parle-Le Sueur-Martin-McLeod-Meeker-Nicollet-Pope-Redwood-
Renville-Sibley-Steele-Stevens-Swift-Waseca-Watonwan-Yellow
Medicine.
Winter Storm Warning from 9 AM this morning to 3 AM CST Thursday
for Anoka-Carver-Chisago-Dakota-Hennepin-Ramsey-Rice-Scott-
Washington.
Winter Storm Warning from 9 AM this morning to noon CST Thursday
for Blue Earth-Faribault-Freeborn-Le Sueur-Martin-Steele-
Waseca-Watonwan.
Winter Storm Warning from noon today to 6 AM CST Thursday for
Goodhue.
WI...Winter Storm Watch from Thursday afternoon through late Friday
night for Barron-Chippewa-Dunn-Eau Claire-Pepin-Pierce-Polk-
Rusk-St. Croix.
Winter Storm Warning from 9 AM this morning to 3 AM CST Thursday
for Barron-Polk-Rusk-St. Croix.
Winter Storm Warning from noon today to 6 AM CST Thursday for
Chippewa-Dunn-Eau Claire-Pepin-Pierce.
&&
DISCUSSION...CEO/JRB/PEM
AVIATION...JRB