Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 110530
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1130 PM CST Wed Jan 10 2018

.UPDATE...
Issued at 1108 PM CST Wed Jan 10 2018

Updated to include 06z aviation discussion below.

&&

.SHORT TERM...(This evening through Thursday)
Issued at 254 PM CST Wed Jan 10 2018

An active short term period ahead with incoming winter weather
into the region.

The main changes to the forecast include an additional movement
eastward of the band, although it was not a drastic change. The
snow band looks to setup from near Albert Lea through Menomonie
and Ladysmith. 4-7" of snowfall looks like a good bet in that
area. Farther west, much lower amounts are expected due to the
tight gradient of the snow band.

As the forecast has shown, two main areas of snow are expected
with this system. The first will be across northern MN beginning
this afternoon/evening, and the second will be across
southeastern MN through western WI. The hi-res ARW and NMM were
outliers today, bringing several inches of snow to the metro.
Discarded those solutions as the overwhelming majority continued
to show the snow band from SE MN through western WI. The highest
snow amounts within the band are still somewhat in question, but
at this time we feel that this band should produce a strip of 4-7"
of snowfall. When combined with windy conditions and timing with
the Thursday morning commute, collaborated with neighboring
offices to issue a Winter Storm Warning for this band of highest
impacts.

Farther west (including the metro), we simply will fall in between
two sources of forcing for precipitation. Have lowered snowfall
amounts accordingly in the metro as the band to our east will have
a tight gradient and confidence has increased that it will indeed
fall primarily east of the metro. However, those traveling along
I-35 through southern MN and I-90 across southern and southeast MN
will be met with difficult travel conditions. We decided to
continue the advisory for the metro and west central MN due to the
combination of mixed precip at the onset, strong winds with gusts
in the 30-40 MPH range and crashing temperatures late tonight
through Thursday. Snowfall amounts will be light, but impacts
could be seen on the roadways given the rapidly falling
temperatures and potential for flash-freeze on the roads.

Lastly, wind chills will fall through the day and tomorrow night.
The updated forecast calls for values in the -25 to -30 degree
range tomorrow into tomorrow night mainly across western and
central MN. Wind Chill headlines may be needed at that time.

.LONG TERM...(Thursday night through Wednesday)
Issued at 254 PM CST Wed Jan 10 2018

The majority of the latter portion of the forecast will see
troughing over the eastern half of the continent with ridging over
the west and northwest flow for us. Things do look to become more
zonal toward the very end of the period as the western ridge
flattens. In terms of weather, things will obviously be cold, with
the only precipitating system of any consequence looking to move
through Sunday into Sunday night as an Alberta Clipper drops by to
our southwest. There is a small window of warm advection
ahead/north of it, along with some upper divergence and an area of
DPVA. Precipitation totals look to be from around 0.05" to 0.15",
which could actually give some locations more snow (albeit not
much) than they get with the system tonight/tomorrow. Otherwise,
look for temperatures too continue to cool through Saturday,
briefly warm up some with the Sunday system, then cool again
Monday into Tuesday before we see better warming by Wednesday as
the upper flow becomes more zonal.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1108 PM CST Wed Jan 10 2018

Quite the complex forecast with multiple precip types changing to
-SN, possibly SN to +SN at times for southern MN into western WI,
 then with BLSN for much of the day on Thursday. Conditions this
 evening will start out as IFR or worse for much of central MN
 into western WI where -DZ/BR/FG with low stratus is prevailing
 while western MN, having already shifted to NW winds with
 plummeting temperatures, has improved to MVFR. The trend will be
 to have precip change over from DZ/BR/FG to -SN/BR, but there may
 be a brief period of -FZDZ in the 06z-12z period between the two
 other prevailing p-types and trying to capture that period will
 be quite problematic. But, once the p-type changes over to -SN,
 the visibility will be mainly derived from any falling snow while
 ceilings will slowly rise through the MVFR levels. Nevertheless,
 flight conditions will likely remain as IFR-or-worse for at least
 the first half of the day tomorrow. Conditions will slowly
 improve tomorrow evening to VFR and remain as such going into
 Thursday night.

KMSP...Expect IFR-or-worse conditions through at least the first
half of Thursday, starting out due to ceilings and -DZ/FG then
transitioning to falling and/or blowing snow. There may also be
some icing, not only due to falling precipitation, but simply due
to ground/pavement moisture freezing with temperatures expected to
fall so quickly. P-type will change over to -SN by or shortly
after with precipitation continuing until late afternoon. Snow
amounts have been decreased such that it may be a stretch to even
get an inch of snow accumulation.

/OUTLOOK FOR KMSP/
Sat...VFR. Wind NW 5 kts.
Sun...MVFR with -SN likely. Wind S 5-10 kts.
Mon...VFR. Wind NW 10 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory until 6 PM CST Thursday for WIZ014-023.

     Winter Storm Warning from 3 AM to 6 PM CST Thursday for WIZ015-
     016-024>028.

MN...Winter Weather Advisory until 6 PM CST Thursday for MNZ041>045-
     047>070-073>077-082>084-091-092.

     Winter Storm Warning from 3 AM to 6 PM CST Thursday for MNZ078-
     085-093.

&&

$$

UPDATE...JPC
SHORT TERM...SPD
LONG TERM...
AVIATION...JPC



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