Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 071723

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1123 AM CST Wed Dec 7 2016

.SHORT TERM...(Today and tonight)
Issued at 415 AM CST Wed Dec 7 2016

We will remain under cyclonic flow owing to the large low pressure
system departing to our northeast through the next 24 hours.  This
means continued stratus with snow showers or flurries and a cold
west/northwest wind will persist through this period.

The edge of the stratus deck early this morning is across
southwestern MN so folks in far southern MN and southwest MN may see
some sun today, but generally we expect clouds to fill back in.
Otherwise, most can expect the clouds to stay and similarly to
yesterday, see bursts of flurries or light snow that does not
accumulate.  The best chance of any accumulation will be tonight
across mainly central MN through west central WI as a subtle
secondary trough works through the area immersed in the parent deep
cyclonic flow.

Temperatures won`t recover much today under the persistent northwest
flow setup and gusts of about 30 MPH are likely again today, higher
in western Minnesota.  Overnight lows tonight will be similar to
last night as we stay breezy and under overcast skies with snow
showers continuing.

.LONG TERM...(Thursday through Tuesday)
Issued at 415 AM CST Wed Dec 7 2016

There are two features of concern in the long term. The first is
accumulating snow Saturday into Sunday with the second being an
Arctic outbreak beginning next Tuesday.

A cold cyclonic flow will cover the area at the start of the
period with scattered snow showers and flurries common. This
should abate on Friday as a ridge of high pressure moves over
the Upper Mississippi Valley. The fair weather will not last long
as a low pressure system begins to organize over eastern Colorado
Friday night and then progress eastward into the Plains on
Saturday and then to the western Great Lakes by Sunday.

This feature will be accompanied by a coupled jet aloft with one
segment heading into NE/IA on Saturday with the other over the
Upper Great Lakes. This leads to fairly widespread differential
divergence over the area with a focus in far southern MN and IA.
In addition, there is strong low level WAA/isentropic lift
indicated. The GFS is the strongest with this system with closed
H85 and H7 lows. The Canadian is not far behind with the ECMWF
weaker with open waves. A trend noted in the DP/DT is that the GFS
and Canadian have drifted southward in the past 24 hours while the
ECMWF is showing a deepening to the wave.

A check of the CIPS analogs using the two windows that cover our
area yielded two analogs that have a similar upper air/H85 pattern.
Although they were both in the bottom five of the analogs, the
precipitation pattern more closely matches what the current
solutions are showing. The top analogs just either didn`t show
much snow or the orientation of the snow was wrong with the
pattern unfolding. The one analog was 12/09/2008 with the second
being 11/29/1988. This would suggest the heaviest snow across the
southern third of MN/northern IA and adjoining areas of west
central WI with amounts in the 4 to 8 inch range. The high end
amounts may end up near the I-90 corridor and a winter storm watch
may be needed if noted trends stabilize.

The snow will diminish early on Sunday in the wake of the wave.
However, an Arctic front is posed to push through Monday night and
early Tuesday ushering in the coldest air of the season so far.
Temperatures at H85 are progged to drop to -30 deg C by Tuesday
afternoon with the cold air holding over the area into Thursday.
We will likely experience highs only in the single digits above
zero with lows well below zero. This will only be exacerbated by
the amount of snow we receive over the weekend. The more
widespread and deeper the snow is, the colder it will turn next


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1120 AM CST Wed Dec 7 2016

There is high confidence that MVFR ceilings will continue across
central/southern Minnesota, and western Wisconsin through the
forecast period. Although a few breaks in the overcast and
afternoon mixing will allow for some low end VFR ceilings across
far southern Minnesota. Otherwise, light snow will continue with
visibilities lowering tonight, and Thursday morning. Winds will
veer to the northwest over the next 24 hours but remain gusty.


Similar forecast with high end MVFR/low end VFR ceilings through
the period with the best chance of light snow later tonight,
Thursday morning. A half inch to an inch is likely by noon
Thursday. Winds will veer from the west to the northwest by
Thursday morning and remain gusty.


Fri...VFR. WNW wind 5-10 kts.
Sat...MVFR with SN and IFR likely. SE wind 5-10 kts.
Sun...IFR/MVFR early with SN. VFR by Afternoon. NW wind 10 kts.




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