Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 192351

Area Forecast Discussion
National Weather Service Duluth MN
551 PM CST Tue Feb 19 2019

Issued at 544 PM CST Tue Feb 19 2019

Updating Aviation section below for the 00Z TAF update.


.SHORT TERM...(This evening through Wednesday)
Issued at 327 PM CST Tue Feb 19 2019

Clear skies early tonight should allow for a very quick drop in
temps for a few hours after sunset, but clouds will rapidly
increase and thicken as the night wears on, with steady or rising
temps after midnight in most areas after evening lows in the
single digits above and below zero.

A fast-moving winter storm will rapidly spread snow across almost
the entire Duluth CWA from south to north early Wednesday morning.
Most model guidance seems to have converged on a solution of
taking the path of max forcing for ascent parallel to, and just
east of the I-35 corridor, which will spread moderate to heavy
snow across all of eastern/northeast Minnesota and northwest
Wisconsin. This system will be moving along pretty rapidly, with a
majority of the snow accumulations in a 6 to 9 hour period from
mid morning through early evening in most locations. However, the
dynamics with this wave are very strong with 180-200 meter/12-hour
height falls at 500 mb, and thus, forcing and snowfall rates are
expected to be quite strong, and perhaps in excess of an inch per
hour for a while.

Based on the strength of the forcing, and the augmentation that
off-lake northeast winds will bring around Lake Superior, we`ve
upped snowfall totals in most locations. Some locales close to the
big lake in ideal upsloping locations could push 1-foot totals.
Snow should rapidly end from southwest to northeast Wednesday
night, but significant snowfall should persist until after
midnight over portions of the MN Arrowhead and the south shore of
Lake Superior from Bayfield and Washburn to the Gogebic Range.

We have upgraded most of the watch to a winter storm warning
through midnight tomorrow night, and we`ve also expanded the
winter weather advisory to include Cass, Itasca, central St. Louis
and the interior Arrowhead portions of Lake/Cook Counties.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 327 PM CST Tue Feb 19 2019

The upper level wave departs on Thursday allowing surface ridging to
take hold, and linger through Thursday night. On Friday, models are
in good agreement with a positively tilted long wave trof moving
through the Rockies. Good warm air advection takes place over the
forecast area ahead of the trof in the afternoon with light snow
developing/spreading into the area from southwest to northeast. Best
opportunity for accumulating snow will be in the afternoon when
upward vertical motion is maximized. The trof begins to move out of
the Rockies and into the Northern Plains Friday night. The warm air
advection continues to pump moisture in the region with pieces of
vorticity shooting through the area keeping the light snow going.
The upper wave becomes negatively tilted Saturday, while a surface
low gets organized in northern Missouri. Additional pieces of
vorticity will move over the region with more opportunities for light
snow. The surface temps will be warm enough in the afternoon and
early evening, in northwest Wisconsin, to warrant introducing a
light rain/snow mix. The precipitation will change back to all snow
in northwest Wisconsin, late in the evening as colder air arrives.
All snow elsewhere. Large model differences are revealed Saturday
night and Sunday with respect to a closed low and its associated
deepening surface low and its track. The ECMWF is deeper and closer
to the area, the GFS is weaker and farther east, the GEM is deeper
than both models, with the same track as the ECMWF. With these
differences, using a blend is the right approach through Sunday,
which affects amounts. The strength and track of this low is likely
to change as we get closer to Sunday. The system departs Sunday
night allowing high pressure to build across the region. Some light
lake effect snow is possible through Monday morning with a northwest
wind over Lake Superior.


.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 551 PM CST Tue Feb 19 2019

Initial VFR conditions are expected to continue through at least
09z, with light southwest to south winds less than 10kts. A
snowstorm moving into the area from the south will bring snow and
deteriorating flying conditions after 09z, with KDLH, KHYR, KHIB,
and KBRD dropping to IFR by 15z, and KDLH, KHIB and KHYR
deteriorating still further to LIFR by 18z. KINL to get no lower
than IFR, but not until 18z. The poor conditions to remain low
through the end of the TAF period for most locations, with
improvement not expected until after 00z. Winds to remain less
than 10kts through the period.


DLH   4  21  12  26 /  40 100  80  10
INL   0  23  11  27 /  10 100  90  20
BRD   2  23   8  25 /  70 100  40   0
HYR   7  27  14  28 /  50 100  80  10
ASX   6  25  15  29 /  30 100  90  10


WI...Winter Storm Warning from 6 AM Wednesday to midnight CST
     Wednesday night for WIZ001>004-006>008.

     Winter Weather Advisory from 6 AM Wednesday to midnight CST
     Wednesday night for WIZ009.

MN...Winter Storm Warning from 6 AM Wednesday to midnight CST
     Wednesday night for MNZ020-021-036>038.

     Winter Weather Advisory from 6 AM Wednesday to midnight CST
     Wednesday night for MNZ012-018-019-025-026-033>035.



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