Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 232054

Area Forecast Discussion
National Weather Service Duluth MN
354 PM CDT Mon Oct 23 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 354 PM CDT Mon Oct 23 2017

The main forecast concerns during the short term include strong
north to northwest winds and shower chances this afternoon through

An area of low pressure was located over northwest Ontario with a
cool front extending south across northeast Minnesota and
northwest Wisconsin. Another low pressure system was over southern
Lower Michigan and advancing northward. The Michigan system will
rapidly intensify overnight and the pressure gradient will tighten
over the Northland. Cold air advection will keep the boundary
layer mixed overnight, so the wind speeds will not diminish much,
if at all, overnight. Wind speeds and gusts will increase Tuesday
early morning affecting areas along the North Shore, including the
Minnesota Highway 61 corridor from Grand Portage to the Twin
Ports. Wind speeds from central Minnesota across northwest
Wisconsin will follow suit later in the morning. Have hoisted a
Wind Advisory for the areas where the strongest winds are
forecast. Rain showers will continue along and west of the front
this evening. Cool air advection over the lake will support lake-
enhanced rain showers over portions of northwest Wisconsin
overnight. A few snowflakes may mix into the precipitation late
overnight, especially in the high terrain along the North Shore,
the Bayfield Peninsula, and the Gogebic Range. The storm system is
forecast to lift northward into eastern Upper Michigan and then
wobble westward through mid-morning. Rain showers will spread
westward into our northwest Wisconsin zones during the morning
before shifting eastward once again as the low departs.
Temperatures will trend cooler tonight and Tuesday with lows near
30 degrees over much of north-central and northeast Minnesota and
the upper 30s in northwest Wisconsin. Highs on Tuesday will reach
the upper 30s in northeast Minnesota and the upper 40s in the St.
Croix River Valley.

.LONG TERM...(Tuesday night through Monday)
Issued at 354 PM CDT Mon Oct 23 2017

A more active pattern will develop over the Northland for the
upcoming week, with the potential for our first widespread
snowfall of the season.

A longwave upper-level trough is progged to be situated over the
Great Lakes Tuesday night and Wednesday, which will eventually
translate eastward. A deep area of low pressure should be settled
over the eastern U.P. of Michigan, which will linger gusty
northwest winds before moving eastward. We will be on the very
western fringe of the tighter sfc pressure gradient, so winds will
be stronger the further east you go. Still, wind gusts between 15
to 20 kts will be possible over much of the Northland in the
early evening Tuesday. There is a chance for a rain/snow mix from
the Arrowhead south to NW WI as a channel of sheared vorticity
dives southeastward from Manitoba, Canada. Generally, QPF appears
to be light, and the deeper lift looks to be relatively weak, so
not expecting much impact from this vorticity.

The primary focus for the upcoming week will be the potential for
accumulating snowfall Thursday evening through Friday morning.
The culprit for this system will be a mid-level shortwave trough
that will dive southeastward from British Columbia/Alberta,
Canada. At the sfc, an area of low pressure will develop due to
lee cyclogenesis and deepen over the Upper Midwest, along with a
deformation zone over the northern fringe of the low. There is
still a good bit of uncertainty among the synoptic models for
snowfall potential due to differing sfc low tracks. The NAM wants
to keep the sfc low center over southwest Ontario, while the
GFS/ECMWF/CMC wants to bring the low center across our south.
Given the track from the NAM, it appears to be more of an outlier
compared to the other three models. Snowfall amounts will depend
on the low track, but considering that the GFS progs the low a bit
further south with the 23.12z run compared to the 23.06z run, the
potential for snowfall has shifted south. The current GEFS
ensembles continues to mention between 1 to 3" of total snowfall
accumulation across the Northland. However, the consensus blends
are indicating between 2 to 5" over northwest Wisconsin due to the
shift in the GFS. I would take this with a grain of salt until
the models come into better agreement, especially considering the
waffling of the models with the latest handful of runs.

Conditions will improve Friday afternoon in terms of snowfall,
but once the system departs, much colder air will settle into the
region. Low temperatures Saturday morning may drop into the middle
to upper teens for much of northeast Minnesota, with lower 20s
over northwest Wisconsin. Winds will remain from the northwest, so
some lake effect precipitation will be possible from the Bayfield
Peninsula southeast to the Gogebic range Friday through Saturday.
Temperatures will remain cool into next week.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1221 PM CDT Mon Oct 23 2017

VFR to high-end IFR conditions were observed across the Northland
this early afternoon as a cold front boundary makes its way
through the region. Behind the front, cigs will decrease from west
to east into the MVFR categories, with heights between 1.5 to 3.0
kft. Some light rain showers will be possible this afternoon and
evening as cold air advection becomes enhanced behind the front.
Also, north to northwesterly winds will be gusty this afternoon
through tonight as the surface pressure gradient tightens, so
winds will likely gust up to 30 knots in some locations. These
wind gusts will likely persist through the day Tuesday.


DLH  33  42  33  50 /  40  20  10  10
INL  28  42  31  48 /  40  10  20  10
BRD  35  46  35  55 /   0   0   0   0
HYR  36  43  31  53 /  70  60  10  10
ASX  38  44  32  50 /  80  70  30  20


WI...Wind Advisory from 7 AM to 6 PM CDT Tuesday for WIZ001>004-

MN...Wind Advisory from 4 AM to 6 PM CDT Tuesday for MNZ020-021-037.

     Wind Advisory from 7 AM to 6 PM CDT Tuesday for MNZ033-034-036-

LS...Gale Warning from 10 PM this evening to 10 PM CDT Tuesday for

     Gale Warning from 10 PM this evening to 10 AM CDT Tuesday for

     Small Craft Advisory until 4 PM CDT this afternoon for LSZ140.



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