Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 141128
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
528 AM CST Sun Jan 14 2018

.SHORT TERM...(Today through Monday)
Issued at 407 AM CST Sun Jan 14 2018

A clipper will bring a round of 1-3 inches of snowfall across
much of the Northland today with locally higher values along the
north shore this afternoon then along the south shore as lake
effect snow lingers into Monday. While temperatures will warm up
slightly ahead of the clipper today, colder air moves in behind
this clipper bringing a return to subzero temperatures into early
next week.

On the synoptic scale a mid-level shortwave trough will dig into
the Upper Midwest today, slowing down considerably as it becomes a
closed low and transitions east from Minnesota into Wisconsin on
Monday. Colder air moves in behind this clipper with 850mb temps
approaching -25C. A strong area of high pressure will build in
from the west Monday, with a 1050+ mb high centered over the
northern Plains late Monday. (This is approaching three standard
deviations above normal compared to climatology.)

Today into this evening the primary concern is a brief period of
moderate to potentially heavy snowfall as the clipper arrives.
Large-scale forcing from the warm air advection ahead of the cold
front and the incoming mid-level vort max is producing lift on the
order of around 20mb/hr per QG large-scale analysis of guidance,
which signals decent large-scale lift. Thermodynamic profiles
depict a nearly isothermal layer from around 900mb through 700mb,
and while the best vertical lift will be centered above this snow
growth layer, the deep layer within the snow growth zone may lead
to large aggregates to develop causing lower visibility and
slightly higher snowfall rates. Guidance has also been trending a
bit higher over recent runs, with the SREF mean rising from 1.9"
to 3.0" over the past four runs. Both convection-allowing and
parameterized guidance are in good agreement on precip values,
with only minor timing differences apparent across the range of
guidance. In total around 1 to 3 inches of snowfall are expected
late today into tonight, with much of that falling within a 2 to 4
hour window.

Along the north shore lake enhancement from the low level
southerly winds will lead to locally higher snowfall amounts,
around 3 to 5 inches. A Winter Weather Advisory was issued
yesterday for the southern Cook county/north shore zone, and no
changes were made to the advisory.

As the upper low shifts from Minnesota into Wisconsin on Monday,
low level flow will become favorable for fairly long fetch lake
effect snow showers for the south shore. Around 3 to 6 inches of
snowfall with locally higher amounts are possible in addition to
the clipper snow for a total of 4 to 8 inches. Locally higher
amounts are possible depending on how lake effect snow bands set-
up. A Winter Weather Advisory has been issued for Bayfield, Iron,
and Ashland counties late today through Monday night, though the
advisory is mainly for the lake effect snow Monday into Monday
night.

Colder air moving in from the west combined with increasing
northwest winds will lead to very cold wind chills late tonight
through early this week. A Wind Chill Advisory has been issued for
north-central Minnesota for tonight, with additional advisories
possible for Monday night.

.LONG TERM...(Monday night through Saturday)
Issued at 407 AM CST Sun Jan 14 2018

Snow showers linger over the Gogebic Range through Tuesday. High
pressure builds for Wednesday with warm air advection bringing in
much warmer air where highs get back into the 20s to even the 30s by
late in the week.

Models begin to diverge on specifics after Thursday. A few short
waves are progged to pass near the area which could bring increased
chances for precip, but nothing significant. There is a signature
towards late in the weekend that appears on all models of a fairly
robust system moving through the Great Lakes region, but that is
still 7 days out.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 528 AM CST Sun Jan 14 2018

VFR conditions this morning will deteriorate to MVFR/IFR this
afternoon as a round of snow moves across northeast Minnesota and
northwest Wisconsin today into tonight. This snow will reduce
visibility to MVFR values, with a 1-2 period of IFR visibilities
possible. Ceilings will be reduced to MVFR levels most of the
time, but periods of IFR ceilings are possible. Winds will be out
of the south today during the snow, then shift to become west-
northwesterly late tonight as a cold front moves in from the west.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH   9  -4   6  -8 / 100  90  30  20
INL  10 -13  -1 -20 / 100  40  20   0
BRD  12 -11  -2 -16 / 100  40  10  10
HYR  11   1  12  -2 / 100 100  50  30
ASX  12   4  15   5 /  90  90  70  60

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory from 3 PM this afternoon to 6 AM CST
     Tuesday for WIZ002>004.

MN...Wind Chill Advisory from midnight tonight to noon CST Monday for
     MNZ010-018-025-026-033>036.

     Winter Weather Advisory from 10 AM this morning to midnight CST
     tonight for MNZ021.

LS...Small Craft Advisory until 8 PM CST this evening for LSZ140>143.

&&

$$

SHORT TERM...JJM
LONG TERM...Wolfe
AVIATION...JJM


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