Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 202322
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
522 PM CST Sat Jan 20 2018

.SHORT TERM...(This evening through Sunday)
Issued at 335 PM CST Sat Jan 20 2018

A weak frontal boundary to our north lingers and trepidatiously
makes its way east while a Hudson Bay high pushes the boundary
south across Lake Superior on Sunday. This will give the slightest
potential for precip mainly near the big lake, but have concerns
that even a hundredth will be hard to come by, so have minimal
PoPs.

The bigger story will likely be the potential for fog as an
approaching weather system surges warm, moist air poleward. The
WAA will ride up and over the cool snowpack and thus am concerned
about fog with likely dense patches tonight and Sunday. Fog should
begin to mix out Sunday afternoon as the larger winter storm
system approaches.

Today was the last warm day before a cool down.

.LONG TERM...(Sunday night through Saturday)
Issued at 335 PM CST Sat Jan 20 2018

The main focus of the extended continues to be on the winter
storm impacting the Northland Monday morning into early Tuesday
morning. Late Sunday night into early Monday a trough will dig
into the Central Plains, while an area of low pressure develops
across the eastern Central Plains/Mid Mississippi River Valley.
The low will deepen on Monday and Monday night, while moving
northeastward into the central Great Lakes by Tuesday morning.
Ahead of the incoming system, there is a period where freezing
drizzle/rain is possible especially along the south shore of Lake
Superior due to ice loss aloft between 00Z and 12Z Monday. The
layer where ice loss is occurring will gradually moisten on Monday
as the low lifts northeastward, this will change any freezing
drizzle/rain to all snow. In general, guidance is in excellent
agreement for this system, however the latest ECMWF/GFS/NAM and
GEM move the low pressure center a bit further to the south and
slower in comparison to the previous runs. So, have delayed the
onset time of precipitation another 6 hours and pushed the winter
storm watch back from midnight to 6 AM. Confidence is still high
that 6 to 12 inches of snowfall will fall across portions of
northwest Wisconsin. Have lowered totals along the I-35 corridor
and into western portions of northwest Wisconsin as the tight
precipitation/snowfall gradient has shifted further southeast due
to the low moving a bit further south. If the system continues to
track southward then precipitation/snowfall totals will need to be
lowered further along the northwest side of the system. Gusty
winds will develop on Monday as the pressure gradient tightens due
to the deepening low. This combined with the snow, will bring
blowing and drifting snow especially along the south shore of Lake
Superior. The low will lift out of the region on Tuesday, but
lake effect snow showers will continue along the south shore of
Lake Superior during the morning hours before drier air moves in
during the afternoon. In wake of low, colder air will advect into
the region. Expect highs on Tuesday in the mid teens and low 20s.

The extended quiets down after this system exits with high pressure
in control for much of the upcoming week. After a cool start to the
week temperatures will be on the rebound. By Friday highs will be in
the mid 30s and low 40s. Precipitation chances return on Friday into
Saturday as a trough digs into the Central and Northern Plains. At
the moment precipitation looks to be a mixture of rain/snow before
becoming all snow on Saturday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 522 PM CST Sat Jan 20 2018

VFR at the outset of the forecast with high pressure in the
neighborhood. However, with the snowmelt that occurred today and
light winds expected tonight, will see BR and FG develop and
affect all terminals up to 18Z Sunday before dissipating. Some
locations may have the BR/FG erode earlier. Regardless, a decline
in cigs and vsbys into the MVFR/IFR/LIFR, and possibly VLIFR, is
anticipated. After 18Z, improvement to VFR is expected at all
sites but BRD which may linger the MVFR cigs through the end of
the forecast.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  22  31  22  26 /   0  10  20  50
INL  18  27  11  23 /   0   0   0   0
BRD  22  31  23  29 /   0  10  10  20
HYR  25  37  26  31 /   0  10  40  80
ASX  26  33  25  28 /   0  20  40  80

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Winter Storm Watch from Monday morning through Monday evening
     for WIZ002>004-006>009.

MN...None.
LS...None.
&&

$$

SHORT TERM...Wolfe
LONG TERM...WL
AVIATION...GSF


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