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FXUS63 KMPX 061736

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1136 AM CST Fri Dec 6 2019

Issued at 1127 AM CST Fri Dec 6 2019

Updated to include 18z aviation discussion below.


.SHORT TERM...(Today through Saturday)
Issued at 312 AM CST Fri Dec 6 2019

A large area of low clouds covered the Upper Midwest with pockets
of clear skies in central and southern Minnesota. A surface 
ridge was centered across South Dakota this morning. This ridge 
will move eastward today, shifting the winds from the northwest, 
to the west/southwest tonight. Although the atmosphere is quite 
dry above the boundary layer this morning. The question is whether
there is enough mixing in the boundary layer to erode the cloud 
cover this morning, or until winds shift to the southwest, and 
more cloud cover begins to spread across the Dakotas, and into 
western Minnesota this afternoon. The best area of mixing and 
clearing skies will occur in eastern Minnesota, and western 
Wisconsin. Farther to the west, less mixing and the added cloud 
cover across the Dakotas will lead to cloudy skies for most of 
today. Temperatures could be cooler if more cloud cover is 
expected over the west. Later tonight, the surface ridge will move
off to the east. Warmer air will start to move across the 
Dakotas, and into Minnesota by late tonight, and into Saturday. As
models have been too cool lately with highs, or roughly 5 degrees
off, so I am increasing temperatures slightly from guidance on 
Saturday afternoon. At this time, mid to upper 30s are going to be
widespread across the southern half of Minnesota, and western 
Wisconsin. Depending upon the amount of cloud cover initially 
Saturday morning, temperatures could reach the 40s, especially 
along the Buffalo Ridge.

.LONG TERM...(Saturday night through Thursday)
Issued at 312 AM CST Fri Dec 6 2019

There's little in the way of change this morning with the long 
term forecast, with mild weather continuing into Sunday, followed 
by an abrupt reminder of what the heart of winter feels like in 
Minnesota and Wisconsin. 

On Sunday night and Monday, the highly advertised Alberta Clipper 
system arrives. GFS and ECMWF models have been quite consistent 
and persistent with this feature, so confidence remains high in a 
measurable snowfall and a potentially messy commute to start the 
week. Progged QPF amounts remain around 0.25-0.35 inches, which 
doesn't sound like much, but given anticipated snow ratios of 20:1
we look to have the potential for a solid 3-5" snowfall across 
central MN/WI, with lesser amounts around 1-2" along the Iowa 
border. Given both GFS and ECMWF models are showing pressure 
tracks/moisture/forcing relatively consistent with our climatology
of the Alberta Clipper archetype that yields 6"+ at KMSP, would 
be surprised if we don't see at least Advisory amounts. Some 
blowing snow will be possible as well with strong cold air 
advection ensuing, mainly from west central into southern MN. 

Models are beginning to narrow in on the extent of Arctic air
following the clipper, with -22C to -25C 925-850mb temperatures
settling in for Tuesday and Wednesday. This will most likely
correspond with highs from -5F to +5F on those days. Several days
of sub-zero lows are expected as well (Tue-Thu), with Wednesday
most likely the coldest morning. Could get within a couple degrees 
of record lows if we can clear the clouds out.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1127 AM CST Fri Dec 6 2019

VFR to start with high clouds slowly filtering across MN/WI from
the Dakotas. Mid-level ceilings likely at all sites by late this
afternoon into this evening as the nose of a warmer punch of air
moves in from the west. Ceilings will likely remain through the
overnight hours into sunrise Saturday, with some ceilings in
west central MN hitting MVFR range. These would most likely impact
KAXN-KSTC Saturday morning through midday. The remaining TAF sites
are expected to remain VFR and even have clouds scatter out. No
precipitation expected. Light and variable winds through this
afternoon will swing around to southerly this evening and remain
as such through Saturday morning with speeds 10kt or less.

KMSP...Little tricky with the ceilings but all while within VFR
range. May be some variance between 5-9 kft. Winds will also
become breezy Saturday afternoon through Saturday evening.

Sun...VFR/MVFR. IFR/-SN Sun night. Wind SW 10kts bcmg N late. 
Mon...IFR/SN likely, mainly in the morning. Several inches 
possible. Wind NNE bcmg NNW 10-15G25 kts.
Tue...VFR but bitterly cold with wind chills in negative teens.
Wind NW 8-12 kts.




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