Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 052326
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
526 PM CST Mon Dec 5 2016

.UPDATE...
Issued at 526 PM CST Mon Dec 5 2016

Updated to include 00Z aviation discussion below.

&&

.SHORT TERM...(This evening through Tuesday)
Issued at 325 PM CST Mon Dec 5 2016

An arc of rain and snow along the warm front stretching from near
Morris to St. Cloud and New Richmond will lift north late this
afternoon. Temperatures have been rising into the 40s south of
this precip and am expecting some milder air to lift across the
entire area early this evening. Meanwhile, the arctic cold front
will reach MN and eastern Nebraska around 00Z this evening. A band
of rain will develop in advance of it about the same time (near
the 21Z enhanced cloud tops on IR stretching from Sioux Falls to
MSP). This band will then head east with the cold front slowly
through the overnight hours. Max wet bulb temps aloft are above
0 deg C across eastern MN this evening, but the warmer air
retreats late this evening before reaching WI. So, p-type will
depend more on surface temperatures there. QPF of 0.10-0.15 inches
could mean about an inch of snow (more if forcing along the front
can spike up rates), but think rain will mix in until later
tonight. This kept forecast snow amounts below an inch except in
Barron and Rusk counties where elevation may help p-type stay more
snow. There, an inch or two will be possible through early Tuesday
morning.

Following the frontal passage, west southwest winds gusting to 35 to
45 mph are expected in a strong cold air advection regime.
Steepening low level lapse rates with the temperature profile
falling into the DGZ will facilitate scattered to numerous snow
shower development from mid morning through late afternoon. Snow
accumulations are likely in the region with the deepest DGZ and
moisture aloft, namely across central MN (north of a line from
Morris to St Cloud and Cambridge). An inch or two will likely fall
there. There will be some blowing snow if such accumulations
materialize. These snow showers could bring brief visibility
reductions to 1/2 mile. Snow shower coverage will diminish
heading south toward the IA border, closer to the system`s dry
slot.

.LONG TERM...(Tuesday night through Monday)
Issued at 325 PM CST Mon Dec 5 2016

The long wait of a "true" Minnesota winter will envelop the
region and will continue through the end of the extended period.
The long wave pattern will become controlled by a long wave trough
across northern North America with the center of the cold air mass
in central Canada. This type of flow regime will keep the Upper
Midwest cool, with bouts of colder than normal conditions for the
next two weeks in December. A strong west to east "zonal" flow
will commence across the CONUS which will lead to several short
waves moving across the region. This progressive pattern will make
it difficult for timing of precipitation events, especially due to
the warm air advection regime and how it becomes oriented along
the thermodynamic boundary.

Tonight`s and Tuesday weather system will slowly weaken, but
affect a large part of the Upper Midwest as it translates to the
east across the Great Lakes through Thursday. As it moves over the
Great Lakes, a surface trough will move southward across Minnesota
and western Wisconsin. As the moisture depth increases in the
dendrite zone and coincides with weak lift, expect scattered snow
showers late Wednesday night and into Thursday. This will be the
best chance of snow showers with only minor accumulations
expected. However, snow ratios will be much higher, roughly 15 to
25-1, which means any chance of measurable precipitation
associated with the snow showers could measure an inch or two of
light fluffy snow.

As mentioned before with the fast west to east flow, the next
system will likely affect the Upper Midwest Friday night/Saturday,
and possibly another late Saturday, and into Sunday. Current
models are fairly certain of accumulating snowfall this weekend,
but timing and moist depth remains in question. Chance percentages
will likely be altered based on location of the warm air advection
regime and moisture depth.

Temperatures during the extended period will range from lows in
the single digits to the teens, and highs in the teens and 20s.
This is good weather for snow making and for ice to form on area
lakes.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 526 PM CST Mon Dec 5 2016

No significant changes to the previous forecast, with things
generally looking on track. Cold front will move across this
evening, with some light precipitation, initially rain, later
possibly snow for eastern locations, accompanying it. Winds will
shift westerly behind the front, and become gusty, especially
later tonight through the day on Tuesday. We`ll see ceilings lower
behind the front as cold air stratocumulus develops, and should
see some snow shower on Tuesday as lapse rates increase and we
take advantage of some of the low-mid level instability. Overall,
appears to be mainly MVFR conditions, although some IFR can`t be
ruled out, especially during any periods of snowfall.

KMSP...Main uncertainties are with timing of the intial arrival of
lower ceilings and with any visibility restrictions owing to
snowfall on Tuesday.

/OUTLOOK FOR KMSP/
Tuesday overnight through Wednesday...MVFR expected at times with
a chance of snow showers/flurries. West to west-northwest wind 15
to 25 kt.
Wednesday night through Thursday...MVFR expected at times with
scattered snow showers. Northwest wind 15 to 25 kt.
Thursday night...MVFR possible early with a chance of snow
showers/flurries. Northwest wind 10 to 20 kt becoming west around
10 kt.
Friday...VFR. West wind less than 10 kt becoming south.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&

$$

UPDATE...
SHORT TERM...BORGHOFF
LONG TERM...JLT
AVIATION...


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