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FXUS63 KMPX 111724

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1124 AM CST Wed Dec 11 2019

.SHORT TERM...(Today through Thursday)
Issued at 404 AM CST Wed Dec 11 2019

The shortwave to the south over Iowa continues to head southeast 
early this morning. Extensive cloud cover did make its way across 
southern Minnesota for much of the night, which impacted 
temperatures greatly. The cloud cover not only halted radiational 
cooling, but the increased surface temperatures weakened the 
inversion, differential cooling between clear skies and cloudy skies 
induced an ageostrophic flow, and a surface cold front is 
progressing southeast. All three of these processes increased wind 
speeds and resulted in even milder temperatures. For example, St. 
Cloud warmed from -16 to -7 in less than an hour. Even after the 
clouds cleared from portions of central MN, temperatures remain 
fairly steady between zero and 5 below with the wind persisting. 
Therefore, it is doubtful we'll make a run for teens below zero 
across the southern half of the CWA this morning. Further north, 
decoupled wind and being far removed from the stratus allowed 
temperatures to plummet into the lower -20s from Little Falls 
eastward to Mora, MN and Cumberland, WI for a time overnight.

The CAA behind the cold front and another approaching surface high 
should keep temperatures from warming significantly today, despite 
the warmer start. By late afternoon and early evening, quickly 
increasing clouds and winds turning more southerly behind the high 
will bring continuously rising temperatures through Thursday 

The next shot of snow will come tonight and Thursday morning, mostly 
along and north of I-94. There will still be some accumulating snow 
south of I-94, but the duration will be much shorter as a fairly 
narrow N-S oriented band swings east. This will occur in time for 
the morning commute, similar to Monday, and is expected to bring 
significant impacts. A mid level vort will track east across 
southern MN into central WI Thursday. A band of snow to the north of 
this vort will bring 3 to 4 inches along and north of Little Falls 
to Eau Claire, where a Winter Weather Advisory is in effect from 10 
pm tonight to 10 am tomorrow.

.LONG TERM...(Thursday night through Tuesday)
Issued at 404 AM CST Wed Dec 11 2019

The main trend for the latter portion of the forecast period is for 
things to be a bit cooler as the zonal flow that briefly develops by 
Thursday night gives way to upper troughing over the central US by 
the weekend. We then look to keep an upper low anchored over north 
central and northeast Canada for the remainder of the period, which 
works to direct shortwave troughs and reinforcing shots of cold air 
into our area through the balance of the period. It doesn't appear 
we'll see an airmass as cold as what we're currently seeing, but 
below normal temperatures still look likely for a good part of the 
period. In terms of precipitation, we still appear to escape seeing 
any significant storms through the period, with the consensus being 
that the only strong system will pass well to our east during the 
first part of the week. Our main weather producer will be a shortwave 
trough and associated surface low that will move east in the zonal 
flow on Friday and bring a chance for some light snow from Friday 
into Saturday. There is some disagreement on the timing of this 
system, so consensus PoPs are still a bit low and spread out in 
time, but that should get refined over the next day or so.


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1120 AM CST Wed Dec 11 2019

No aviation concerns through the afternoon/early evening as the
lower cigs/vsbys will be across North Dakota. Between 00-06z,
conditions will deteriorate rapidly across central Minnesota with
IFR/MVFR vsbys in -SN, possibly cigs lowering to IFR at times.
Conditions will rapidly deteriorate in south central/east
central Mn/west central Wisconsin between 06-12z, with the bulk of
the -SN between 09-15z. The -SN will diminish from west to east
Thursday morning, but cigs will likely hold in the IFR/MVFR range.
Light southwest/south wind this afternoon will become 
east/southeast tonight and increase. By morning, winds will shift 
to the north/northeast at around 10 kts. 


The best time frame for IFR cigs/vsbys will occur between 10-14z,
with locally one to two inches of snow before it ends Thursday
morning. Some blowing snow is possible, but winds will remain AOB
15 kts. MVFR cigs will likely continue through Thursday afternoon
as winds become northerly. 


Thu evening...MVFR, bcmg VFR. Wind N bcmg SE 5 kts. 
Fri...MVFR cigs, with -SN possible aftn. Wind SE 5-10 kts bcmg W.
Sat...MVFR/VFR cigs with -SN possible. Wind NW 10G20 kts.


WI...Winter Weather Advisory from 10 PM this evening to 10 AM CST 
     Thursday for WIZ014>016-023-025-027-028.

MN...Winter Weather Advisory from 10 PM this evening to 10 AM CST 
     Thursday for MNZ043>045-050-052-053.


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