Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 201311

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
711 AM CST Sun Jan 20 2019

.Updated for 12Z Aviation Discussion...
Issued at 707 AM CST Sun Jan 20 2019


.SHORT TERM...(Today through Monday)
Issued at 357 AM CST Sun Jan 20 2019

Main change to the forecast was to tighten up the snow gradient
across southwest Minnesota today. Also went a little bit cooler on
temperatures tonight, especially in eastern Minnesota and western
Wisconsin where skies are expected to remain mostly clear
overnight. Winds will still be light, so wind chills will be in
the teens below zero, so not anticipating any wind chill
advisories for Sunday night into Monday morning.

Early this morning a narrow band of light to moderate snow was
ongoing across southwest Minnesota, and clipping the far western
part of the forecast area in Yellow Medicine county. HiRes models
have this snow sliding quickly southeast along the H850 warm
advection gradient, so for that reason removed precip chances for
areas east of I-35 and also along much of the Minnesota River

As this system departs, another one will develop with an upper
level wave that is forecast to transpire another area of warm air
advection, isentropic lift, saturation, and snow across western
Minnesota. Forecast models are in very good agreement with snow
northwest of the Twin Cities, so have increased the chances to
80-85 percent on Monday. This will be the beginning of a very
drawn out period of light snow that will last through Tuesday.

.LONG TERM...(Monday night through Saturday)
Issued at 357 AM CST Sun Jan 20 2019

Quite a bit of things to consider in the extended. A few inches of
snow are expected Monday through Tuesday. On Thursday an arctic
front will blast through the region and bring blowing snow, and
possibly a ground blizzard. This will be followed by the coldest
air of the season with wind chill values of 25 to 40 below
Thursday night.

First of all, snow will be ongoing Monday night, and should
become more widespread as a system organizes on Tuesday. The two
areas of enhanced lift and heavier snow will set up northwest of
the Twin Cities, and also southeast of the Twin Cities. Most
locations will see at least a couple of inches by the time the
snow ends, but the heavier snow bands in the aforementioned
locations could see around 4 to 6. This will be a drawn out light
snow event that will last 24 to 36 hours.

Secondly, the arctic front and potential blizzard event Thursday
does have some run-to-run consistency with the GFS, and also shows
up in the ECMWF and GEM. This front will push through early
Thursday morning and destabilize the boundary layer in its wake.
Forecast soundings off the GFS show several hours of 40kts of wind
at the top of the channel, which could easily translate to wind
gusts of 40 mph. Meanwhile, several snowfall events will results
in a light, fresh snowpack that should blow around and could
create blizzard conditions in the open areas of western and
southern Minnesota. For that reason added blowing snow to the
forecast on Thursday, and this is certainly something to monitor
going forward.

This arctic front will also bring frigid air. Expect falling
temperatures on Thursday with overnight lows in the teens below
zero for most locations, and likely colder in northern Minnesota.
Meanwhile northwest winds will continue overnight, so could see
wind chill values of 25 to 40 below zero. Little warm up is
expected on Friday, with another cold night Friday night. Beyond
that there is considerable spread in the forecast models, so did
not make any changes to the upcoming weekend.


.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 707 AM CST Sun Jan 20 2019

VFR conditions as the snow is expected to stay southwest of the
TAF sites. Today easterly winds will become more southeasterly
later tonight. Another band of snow will develop in the Dakotas
and could affect KRWF and KAXN before 12Z Monday morning.

VFR conditions throughout with northeast winds becoming easterly
and eventually southeasterly Monday morning. Mid level clouds will
increase Monday morning, and then could see snow showers toward
the end of Taf time Monday afternoon.

TUE...IFR with SN, bcmg MVFR with -SN in aftn. About 3 inches
Wind NW at 15G25 kts.
WED...VFR with MVFR possible. Wind S at 10 kts.
THU...MVFR with IFR/BLSN possible. Wind NW at 20G25kt.


WI...Wind Chill Advisory until 8 AM CST this morning for WIZ014-015.

MN...Wind Chill Advisory until 8 AM CST this morning for MNZ041>045-



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