Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 160203

Area Forecast Discussion
National Weather Service Duluth MN
803 PM CST Mon Jan 15 2018

Issued at 802 PM CST Mon Jan 15 2018

Lake effect snow continued along the South Shore but the coverage
of the heavier snow showers has diminished over Douglas County.
The combination of low level convergence over western Lake
Superior due in part to the departing low and the topography
around far western Lake Superior and cold temperatures aloft
contributed to moderate to heavy lake effect snow today into this
evening. Spotters report 6 to 14 inches has fallen overnight into
this evening from northern Douglas County into Bayfield County.
The low level convergence has weakened through the evening as seen
in the observed wind field between the south and north shores of
Lake Superior but winds from 925mb through at least 850mb remain
northeast and only slowly come around to northerly around 12Z.
However, as the low pressure system moves further away from the
region tonight, the larger scale lift will turn neutral or
downward with the flow becoming more anticyclonic. Drier air is
also expected to move in later tonight. These factors should cause
the snow showers to decrease in both coverage and intensity but
not end altogether until Tuesday afternoon. The Winter Storm
Warning for Douglas County ends at midnight and we will monitor
conditions over the next few hours but there may be a need to
extend. The rest of the advisories and warnings go through the
night and we will continue those as well.


.SHORT TERM...(This evening through Tuesday)
Issued at 319 PM CST Mon Jan 15 2018

The main stories for tonight through Tuesday will be the lake effect
snow along the south shore of Lake Superior, along with
persistent bitterly cold wind chills over our western forecast area.

For tonight, chances of lake effect snow will continue along the
south shore as northeasterly 1000-850 mb layer winds will slowly
back, becoming more northerly. This should maintain lake effect snow
bands, mainly from as far west as Superior, WI east to the Bayfield
Peninsula, and southeast towards the Gogebic Range of northern Iron
county later tonight. We had received a report south-southeast of
Oulu of 5.1" of new snow for today. With additional snowfall of 3 to
5" expected in these areas, decided to upgrade the Winter Weather
Advisory for Bayfield county to a Winter Storm Warning. Also decided
to expand the Winter Weather Advisory to Douglas county as a good
portion of the county along Lake Superior could get between 3 to 5"
of more snowfall through this evening.

Surface low pressure will slowly drift eastward across southern Lake
Michigan tonight, with high pressure progged to build across the
Dakotas, which will help northerly winds remain gusty tonight,
diminishing slowly from the west into Tuesday. There is some
uncertainty regarding how much we will clear out tonight as the high
pressure approaches. Most of the guidance is indicating that
northwest Wisconsin will remain overcast due to lake induced clouds.
Some of the cloud cover could break up, especially over Koochiching
and Itasca counties, which will have some impact on our temperatures
and wind chills. Speaking of wind chills...the Wind Chill Advisory
remains in effect over north-central Minnesota, and even eastward
into Duluth. Wind chill criteria is a bit more marginal to the east,
but considering that climatologically we have some very cold spots
over central and northern St. Louis county, decided to expand.

Tuesday looks to be partly to mostly sunny, with highs slightly
warmer than today, with highs in the middle teens over north-central
Wisconsin to the middle single digits over the west. The most
sunshine could be along the north shore of Lake Superior where some
drier air will filter in early. Some mid to high level clouds will
move in as a weak push of warm air advection dives southward from
western Ontario Canada. The chances of lake effect snow from tonight
will eventually taper off as the drier air moves in and winds turn
more westerly.

.LONG TERM...(Tuesday night through Monday)
Issued at 319 PM CST Mon Jan 15 2018

On Tuesday night, an upper level ridge will move into the region
from the Northern Plains. The ridge will allow heights to build and
bring warmer air into the region Tuesday night and Wednesday.
Overnight lows will generally be in the single digits below zero on
Tuesday night, but highs on Wednesday will top out in the 20s for
most of the area. Wednesday night and Thursday should feature an
upper level, compact shortwave, which will slide southeast across
northern portions of Minnesota and Wisconsin. Will have some small
POP`s for this feature, as the precipitation will be on the light
side, but it could bring a light dusting of new snow to much of the
area. The upper level ridge will flatten to become more zonal on
Friday, with southwest flow developing over the weekend. Highs will
warm into the 30s for daytime highs on Thursday and Friday, before
gradually cooling over the weekend and into early next week. The big
story for the long term period will be the potential for a more
substantial storm system from Sunday into Monday. The 00Z runs were
in good agreement in bringing a storm system into our region during
that time frame, but the 06Z and 12Z GFS runs have trended well to
the southeast, and essentially out of our CWA. This storm system
will need to be watched closely, but it is still 7 days out, and a
lot of things can happen with it at this point. WPC solutions are
more in line with the ECMWF at this point.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 547 PM CST Mon Jan 15 2018

An area of low pressure over southern Lake Michigan with an
inverted trough extending into western Lake Superior will slowly
move south and east tonight into Tuesday. Moderate to heavy lake
effect snow was occurring along the south shore of Lake Superior
and will continue through most of the night although it will
gradually shift east late tonight. IFR/LIFR conditions will occur
in the snow showers, as far west at KDLH with a mix of MVFR to VFR
conditions further west over northern Minnesota. VFR conditions
will become more prevalent late tonight into Tuesday across much
of the Northland.


DLH  -5   9  -3  21 /  80   0   0   0
INL -20   6  -7  25 /   0   0   0   0
BRD -16   6  -8  25 /  10   0   0   0
HYR   1  14  -8  20 /  60  10   0   0
ASX   4  16  -1  24 /  90  30   0   0


WI...Winter Weather Advisory until 9 AM CST Tuesday for WIZ004.

     Winter Storm Warning until midnight CST tonight for WIZ001.

     Winter Storm Warning until 6 AM CST Tuesday for WIZ002.

     Winter Weather Advisory until 6 AM CST Tuesday for WIZ003.

MN...Wind Chill Advisory until 9 AM CST Tuesday for MNZ010-011-018-

LS...Small Craft Advisory until 4 AM CST Tuesday for LSZ121-140>148.



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