Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 121150
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
550 AM CST Fri Jan 12 2018

.UPDATE...
Issued at 549 AM CST Fri Jan 12 2018

Have updated the winter weather advisory for Iron County,
Wisconsin to extend it until noon today. Lake effect snow showers
will linger in that area this morning, bringing another 1 to 3
inches of new snow.

UPDATE Issued at 531 AM CST Fri Jan 12 2018

Update for new 12Z Aviation Discussion below.

&&

.SHORT TERM...(Today through Saturday)
Issued at 325 AM CST Fri Jan 12 2018

At 330 this morning, it was bitterly cold across the Northland.
Temperatures ranged from 7 above at Ironwood, MI, to the 20s below
zero across much of northern Minnesota. Wind chill readings in the
25 to 40 below range were common across northeast Minnesota and
far northwest Wisconsin. Clouds lingered across most of northwest
Wisconsin, with snow showers downwind of Lake Superior.

The focus for today will be the potential for any additional snow
accumulation along the south shore of Lake Superior, as well as
wind chill readings across the rest of the region.

Today, we should see wind chill values improve somewhat by midday.
Will continue the current wind chill advisory through that time.
We will likely need additional wind chill headlines for tonight
and Saturday morning, as temperatures once again plummet across
the region. Snow showers will continue along the south shore of
Lake Superior, especially along the Gogebic Range. We could see
another inch or two, but the threat for significant additional
accumulation will decrease throughout the day as inversion heights
drop from about 1 km to 1/2 km by tonight.

Tonight, we will see lingering clouds and flurries/snow showers
across northwest Wisconsin, with mostly clear skies and bitterly
cold wind chills across the rest of the area. Overnight lows
should once again drop into the 20s to around 30 below zero in the
north.

On Saturday, we should see little change. The snow shower threat
should largely end along the south shore, with mostly sunny skies
area-wide. Highs will struggle to reach zero most areas.

.LONG TERM...(Saturday night through Thursday)
Issued at 325 AM CST Fri Jan 12 2018

The main challenges for the long term continue to be the
continued cold snap and potential for snow Sunday and Sunday
night.

Arctic high pressure will be centered in the Upper Mississippi
Valley Saturday evening and is expected to drift toward the Ohio
Valley by sunrise. A fast-moving clipper system will push out of
the Canadian Prairies and move through the western Great Lakes
Sunday and Sunday night. Light snow will accompany the passage of
the clipper system with 1 to 3 inches of accumulation expected
across the Northland. Confidence in precipitation is high. We
have increase POPs to likely or categorical, well above the
consensus blend. Nudged QPF a bit higher as well. Model profiles
suggest a deep dendritic growth zone of nearly 10kft. Think snow
ratios on the order of 20 or 22 to 1 will be likely. Another
Arctic cold front will move through the region with the clipper
bringing another round of strong northwest winds and reinforcing
the cold air over the Northland. In the wake of the clipper,
Monday through Tuesday night, northerly winds are expected over
Lake Superior which will support lake effect snow during that
time. Snow accumulations may exceed 6 inches in the snowbelt
areas of Bayfield, Ashland, and Iron Counties. The combination of
continued cold temperatures and winds will yield wind chills
colder than -25 for at least part of the Northland. Wind chill
headlines will likely be needed through Tuesday morning. Arctic
high pressure in the wake of the clipper will slowly slide
southward into the central Plains and eventually into the central
Mississippi Valley by Wednesday. As the ridge axis slides east
across Minnesota, winds will turn westerly and eventually
southwesterly ushering in warmer temperatures.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 531 AM CST Fri Jan 12 2018

High pressure ridging will move through the area during this
forecast cycle keeping conditions mainly VFR for Minnesota
terminals. Northerly winds over western Lake Superior keep lake
effect cloud cover and occasional snow showers over portions of
northwest Wisconsin, including HYR. We think the clouds will
linger through much of the day, gradually scattering out as winds
back northwesterly late this afternoon. Have also added a TEMPO
group to HIB to account for a brief window of anthropogenic clouds
and snow showers as winds aloft back through 320 degrees early
this afternoon.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH   2 -19   1 -13 /   0   0   0   0
INL  -4 -28  -2 -18 /   0   0   0   0
BRD   0 -23   1 -14 /   0   0   0   0
HYR   5 -18   2 -17 /   0   0   0   0
ASX   7 -12   4 -12 /  20  10  10   0

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Wind Chill Advisory until noon CST today for WIZ001-006.

     Winter Weather Advisory until noon CST today for WIZ004.

MN...Wind Chill Advisory until noon CST today for MNZ010>012-018>021-
     025-026-033>038.

LS...Small Craft Advisory until 10 AM CST this morning for LSZ121-
     144>148.

     Small Craft Advisory until 4 PM CST this afternoon for
     LSZ140>143.

&&

$$

UPDATE...DAP
SHORT TERM...DAP
LONG TERM...Huyck
AVIATION...Huyck



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