Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 191724

Area Forecast Discussion
National Weather Service Duluth MN
1124 AM CST Sun Nov 19 2017

Issued at 1124 AM CST Sun Nov 19 2017

Updated for the new 18Z Aviation Discussion below.


.SHORT TERM...(Today through Monday)
Issued at 338 AM CST Sun Nov 19 2017

At 330 AM, skies continued to clear from west to east. The low
clouds were now confined to the Minnesota Arrowhead, as well as
eastern portions of our northwest Wisconsin area. Meanwhile, high
clouds associated with an incoming low pressure system were
already streaming into northwest Minnesota and southern Manitoba.
Temperatures ranged from the single digits in north central
Minnesota, to the teens across the east and south.

The focus for today will be cloud cover, and the chance of
flurries/ snow showers. A weak low pressure system will move in
from the Northern Plains and southern Canada during the day,
sliding east/southeast across the CWA. Model guidance indicates
the potential for some flurries across the area today, so will
mention that across much of the area. High temperatures will range
from the 20s in the northeast half of the CWA, to the lower to
mid 30s southwest. Skies will be partly sunny, but there will be
periods of considerable cloud cover as well.

Some clouds will persist across the Northland tonight, as a
frontal boundary will remain draped across the region, and warm
air advection will again begin ahead of the next system late
tonight and Monday. This system will move across south central
Canada, bringing our CWA into the warm sector for Monday. Gusty
south to southwest winds can also be expected, with any chance of
precipitation likely holding off until Monday evening. Highs on
Monday will range from the mid to upper 30s in the Arrowhead, to
the lower to middle 40s elsewhere.

.LONG TERM...(Monday night through Saturday)
Issued at 338 AM CST Sun Nov 19 2017

Another arctic airmass early to mid-week leading to strong winds as
well as a chance for light snowfall across much of the region and
a period of lake effect snow for the south shore. High pressure
builds across the Upper Mississippi River Valley for the
Thanksgiving holiday leading to mainly sunny skies and below
normal temperatures. Then warmer Friday as a warm front builds
into the region with an increasing chance for precipitation Friday
into Saturday.

Mon night through Wednesday...An Alberta Clipper will track across
southern Canada Monday night into Tuesday, centered north of MN
Monday night lifting east-northeast towards central Ontario on
Tuesday. This will result in a chance for light snowfall across far
northern Minnesota, but the main impact from this clipper will be
the cold arctic airmass that builds in behind it Tuesday into
Wednesday. A broad area of high pressure builds from the Canadian
Prairie towards the Mid-Mississippi River Valley bringing with it
around -15C air aloft at 850mb. As the high builds in skies will
clear out leading to a chilly night Tuesday night with lows falling
to the single digits in some places. The colder air and northerly
flow at low levels will also result in a period of lake effect snow
showers along the south shore, but both along the international
border Mon night and along the south shore Tuesday amounts are
expected to be less than an inch. As the high pressure builds in
behind the clipper, a strong pressure gradient will lead to very
strong winds Monday night into Tuesday with gusts approaching
30-40 mph due to deep mixing up to around 750mb or so, which is
unusually deep for the winter. Strongest winds will occur late
Monday night through Tuesday afternoon. On Wednesday a fast-moving
weak clipper may bring a round of light snow/flurries to parts of
the Northland, but otherwise expect mainly sunny skies. Highs in
the 20s Tuesday and Wednesday.

A warm front builds east into the Upper Midwest Thursday into Friday
leading to gradually warmer temperatures and increasing clouds.
Highs in the 20s to low 30s Thursday, then into the 30s/low 40s
Friday. Late-week into the weekend guidance diverges greatly as a
mid-level shortwave trough traverses east across southern Canada
towards the Great Lakes region, with different models having vastly
different locations and timing for the wave and associated sensible
weather. The 00z ECMWF has a wet and fairly warm solution Friday
afternoon into Friday night, while the Canadian deterministic is
weaker and further north with the wave and thus generally dry and
mild Friday/Friday night. There is potential for at least some
precipitation Friday into Saturday, but beyond that it is difficult
to predict what the pattern may hold. Most scenarios would lead to
low-impact weather - many models/ensembles have some combination of
light rain/snow/mix - with a better guidance agreement on a push of
colder air moving in Saturday into Sunday.


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1124 AM CST Sun Nov 19 2017

The VFR conditions across northeast MN and northwest WI will
likely continue through Monday morning. There may be some very
light snow this afternoon, which could bring down visibility into
the MVFR range, but the probability of this is low. Expect our
southwest flow to become southerly Monday morning.


DLH  26  20  40  19 /  10   0   0  10
INL  23  14  38  15 /  10   0  10  40
BRD  35  23  44  20 /   0   0   0  10
HYR  29  21  44  22 /  10   0   0  10
ASX  28  23  45  24 /  10   0   0  10




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