Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 151721
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1121 AM CST Mon Jan 15 2018

.UPDATED for 18z taf discussion below...

&&

.SHORT TERM...(Today and tonight)
Issued at 419 CST Mon Jan 15 2018

Snow will continue to be possible today as the mid/upper low
pivots over the Upper Midwest. Accumulating snow is expected
along/east of the Interstate 35 corridor, with flurries to the
west. Given the thermal profile, snow ratios around 25 to 1 will
make for efficient snow production, even though anticipated QPF is
under one tenth of an inch. In general, expect amounts to range
from around one half inch along the I-35 corridor to around 3
inches in to the eastern-most part of the forecast area (Eau
Claire to Ladysmith). Given the persistent brisk northwest winds,
patchy blowing snow will remain a possibility.

Temperatures today will remain nearly steady in the west today,
with a nearly 25 degree temp spread from east to west across the
area at times. Anticipate highs in the mid/upper teens over west
central WI, with single digits below zero from west into south
central MN. Given continued brisk northwest winds, said areas from
west into south central MN will likely endure wind chills in the
-25 to -35 range through much of the daylight hours. Tonight
 despite lingering cloud cover we still expect temps to range from
 the low/mid teens below zero in west central MN to the single
 digits above zero in west central WI. The "warmer" WI temps will
 preclude the need for wind chill headlines there. Regarding our
 MN counties and current wind chill headlines, the updates to
 forecast cloud cover and temps we made overnight have improved
 (warmed) anticipated wind chills by around 5 degrees for tonight
 into Tuesday morning. This especially makes the wind chill
 advisory look more borderline, particularly along the I-35
 corridor from Cambridge across the Twin Cities metro.
 Western/southern outskirts of the metro look to have a bit better
 chance of hitting the -25 advisory criteria, but refinement to
 the advisory may be needed when today`s model runs come in and
 attendant trends are more certain.

.LONG TERM...(Tuesday through Sunday)
Issued at 419 AM CST Mon Jan 15 2018

Main theme for the extended is the expected pattern shift this
week that will have two impacts. One, the arctic air is out of
here after Tuesday. The other is a longwave weather pattern will
be in place by next weekend that will leave the door open for more
active weather locally.

The reason our arctic air will get out of here so quickly is tied to
the energy we are seeing this morning out over the north Pacific.
The broad trough out there will continue to work toward western
North America over the next couple of days, which will finally break
down the western ridge. The western ridge that has been the source
of our northwest flow and arctic air. As the ridge breaks down, we
will see it flatten out and slide east. This will result in the
compressional warming of an airmass that will be heading our way
from the Canadian Rockies. For Wednesday thru Saturday, our highs
and lows could be as much 5 degrees warmer than what we currently
have. The ECMWF continues to be the warmest guidance these days, and
the last time we got into a Pacific airmass back between the 7th and
11th, it was the ECMWF that performed best in that pattern. The one
difference tough between then and now is back on the 7th-11th, we
had a rather beige snowpack that had lots of bare ground showing.
Thanks to yesterdays clipper, we have a more complete snowpack in
place, so kept the more tempered SuperBlend numbers in place. Still,
on Friday, as a cold front moves into MN, we could very well see
lots of 40s show up from west central into south central MN.

As that front is moving into MN Friday, we`ll see a trough dig into
the 4-corners region and it is this trough that the 15.00
deterministic models eject out into the Plains over the weekend,
with a classic Colorado low/Panhandle hooker type system tracking
across the central CONUS. Though we see some rather impressive
winter storms from the ECMWF, GFS, and Canadian, there are plenty of
reasons to not starting planning for 18" of snow.  First, when
looking at the large scale pattern, we have what has been our
nemesis this winter, split flow. So far this winter, when in split
flow we have seen storm systems pass well south and east of us,
while we sat pretty much high and dry. Also when looking at the
15.00 GEFS QPF plumes for MSP next weekend, there is exactly one
GEFS member (of the 20) that has a QPF anywhere near what we saw
from the operational runs of the GFS/ECMWF. So although there is
relatively good agreement from deterministic models for a system
that is 6/7 days out, it`s much to early to start getting hung up
potential snow totals, this is definitely something to file in the
keep an eye on category.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1115 AM CST Mon Jan 15 2018

MVFR cigs with light snow with periods of IFR this afternoon
across west central WI. In MN, areas of BLSN over western MN will
affect KRWF/KMKT and possibly KAXN through the afternoon with NW
winds 30-35kts for a time. Flurries and possibly a few -shsn
developing this afternoon as the upper trough swings southeast
across eastern MN affecting mainly KSTC/KMSP. Should see overall
improvement to VFR during the evening from west to east with some
lower clouds remaining mainly to the far east. Should see VFR even
here after 06z. The gusty NW winds will diminish across MN during
the evening.

KMSP...Mainly MVFR with periods of lower CIGS/SHSN possible this
afternoon. Should remain VFR overnight into Tuesday. Dont expect
any significant accumulation.

/OUTLOOK FOR KMSP/
Tue...VFR. Wind NW at 5-10 kts.
Wed-Thu...VFR. Wind SW at 5-10 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory until 6 PM CST this evening for
     WIZ014>016-023>028.

MN...Wind Chill Advisory until 9 AM CST Tuesday for MNZ043-044-050-
     051-058-059-066>069-075>077-083>085-092-093.

     Wind Chill Warning until 9 AM CST Tuesday for MNZ041-042-047>049-
     054>057-064-065-073-074-082-091.

     Wind Chill Advisory until 9 AM CST Tuesday for MNZ045-052-053-
     060>063-070-078.

&&

$$

SHORT TERM...LS
LONG TERM...MPG
AVIATION...DWE



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