Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 230445
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1045 PM CST Sun Jan 22 2017

.SHORT TERM...(This evening through Monday)
Issued at 253 PM CST Sun Jan 22 2017

Quite the uneventful next 24 hours over this region as there`s
deep upper level troughs over each CONUS coast with weak ridging
over the central states along with weak high pressure moving in
from the west. With very weak advection both at the surface and
aloft, the deeply moist atmosphere will be slow to exit the
region. Thus, low stratus and fog will again be the prevailing
weather features overnight into tomorrow but not at the extent
seen last night with such prevalent dense fog. Visibilities will
commonly drop to between 1-4sm so, at this point, a Dense Fog
Advisory is not expected. After daybreak Monday, the rate of
clearing will improve as drier air will be advected in from the
west, aiding in visibility first then scouring out the low clouds.
Temperatures will run very similar to today with highs again in
the mid-upper 30s. With some clearing and drier air in western MN,
lows will be a bit cooler, dropping to the mid 20s to lower 30s.
The lack of drizzle and dense fog should prevent icing issues
tonight.

.LONG TERM...(Monday night through Sunday)
Issued at 253 PM CST Sun Jan 22 2017

A Winter Storm Watch has been issued for about the southern third
of Minnesota for the potential of 6"+ snow from Tuesday through
Wednesday, with the heaviest falling Tuesday night. In addition
there will be some patchy blowing and drifting snow on Wednesday.

While there is still plenty of model spread when looking at the
GEM and NAM solutions, the GFS and ECMWF continue to advertise
the potential of several inches of snowfall from the Tuesday-
Wednesday storm. The GEFS ensemble has increased probabilities for
two consecutive runs for QPF>0.50" liquid equivalent. Snow ratios
may not be all that impressive as the lower atmosphere is not
very cold. With that said, plenty of moisture will be available
with this system. We felt more confidence siding with the
GFS/ECMWF and GEFS members with a track north of the GEM and NAM.
Now, this track could still shift but we still felt confident
enough to hoist a Winter Storm Watch for southern MN. The forcing
is coming together with a decently strong jet streak nosing into
the midwest placing us in a very favorable divergence zone, along
with an impressive PV anomaly pushing through, and plenty of
theta-e advection to provide low level lift and moisture.

While the best threat area of 6"+ is in the watch, farther north
will also see accumulating snow including the Twin Cities. At this
time 2-4" with some pockets of 5" looks reasonable from across
south central MN including the metro, through much of western WI
including Menominee and Eau Claire. Shifts in the storm track
either north or south would either increase or decrease amounts
across the forecast area. Please stay tuned for the latest
forecast details as we gain more confidence with this storm.

After the storm goes through, wrap around snow showers could be
seen for a couple days to round out the week and temperatures
will be seasonable, below freezing every day and near the average
max T with highs in the 20s generally expected. We do not expect
any bitter cold through the next week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1045 PM CST Sun Jan 22 2017

Poor aviation conditions overnight and early Monday morning for
most of the TAF sites as patchy -DZ/-FZDZ occur along with IFR or
lower ceilings/visibilities. The one area early in pretty good
shape is KRWF where a little downslope from the Buffalo ridge is
helping to keep things mainly MFVR. An improving trend for the
area beginning late Monday morning as high pressure moves in
lifting ceilings to MVFR along with visibilities to VFR. Light WNW
winds overnight and Monday morning becoming light and variable in
the afternoon.

KMSP...-DZ for a few hours early this morning. Not expecting any
-FZDZ at the airfield as the precipitation ends before the
temperature dips to 32 degrees after daybreak. Otherwise,
conditions improving by Monday afternoon to MVFR ceilings along
with VFR visibilities. It will stay that way until Tuesday
morning.

/OUTLOOK FOR KMSP/
Tue...MVFR/Chance -SN in the mrng with IFR/SN in the aftn. Winds
      E less than 10 kts becoming NE 10-15 kts.
Tue night...IFR with SN. Winds NE 10-20 kts becoming NW.
Wed...MVFR with IFR possible. -SN likely early. Winds NW 15-25 kts.
Wed night and Thu...MVFR possible. Chance -SN. Winds NW 10-20 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...Winter Storm Watch from Tuesday afternoon through Wednesday
     afternoon for MNZ073>078-082>085-091>093.

&&

$$

SHORT TERM...JPC
LONG TERM...SPD
AVIATION...RAH


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