Area Forecast Discussion
Issued by NWS Duluth, MN

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335
FXUS63 KDLH 170538
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1138 PM CST Sat Dec 16 2017

.SHORT TERM...(This evening through Sunday)
Issued at 303 PM CST Sat Dec 16 2017

Radar has one linear band of heavier snow over the north shore
and extending out to the Apostles otherwise all is quiet.

High pressure to our northeast has been fighting a low to our
southwest. Short term model guidance has had a rough go today
without a single ensemble member picking up on the evolution of
precipitation today. Further run to run HRRR reliability is next to
zero with the model losing the current features by hour 1, so that
being said very low confidence in PoPs and precip placement tonight.
The overall trend should be drier, but there are indications that
there may be a shallow layer of fzdz with a "warm" -5 C isothermal
inversion with higher RH between 900 and 800 mb. That thin layer
narrows by morning with much drier air moving in aloft. The HRRR
does form an expansive layer of fog by 12Z Sunday over the western
portions of our CWA, so will have to watch for that as its only
covered with patchy wording for now. Hopefully subsequent runs
better capture the moisture profile. Winds should continue to be <
10 kt in most places.

Sunday should be dry and warmer as the area is between systems.

.LONG TERM...(Sunday night through Saturday)
Issued at 303 PM CST Sat Dec 16 2017

This upcoming week will likely have noteworthy weather, including
wind and accumulating snow. Also, the Northland could be heading
into cold snap late this week and into early next week,
potentially bringing the coldest air yet seen this season.

The Northland could flirt and get above freezing Monday. Those
looking forward to clearing our roads of some snow and ice though
may be disappointed. Cloud cover will probably make any melting very
limited. A mid-level trough and passing cold front will bring light
snow Monday afternoon and evening.

Enjoy Monday`s temperatures while they last. It`s downhill from
there. Even colder air begins to rush into the Northland Tuesday. It
looks quite windy. The GFS and NAM12 indicate deep mixing, with at
least 30 to 40 knots within the mixing layer, and potentially up to
50 knots! While it will be difficult to tap into the higher-end of
those wind speeds because of cloud cover limiting the effectiveness
of the mixing, widespread wind gusts of 25 to 35 mph are likely.
It`s safe to say though there could be stray gusts of 40 to 45 mph,
like in the higher terrain of Duluth and the North Shore.

The winds will quickly subside Tuesday night when high pressure
moves through the region. It will be another cold night of lows in
the single digits, if not lower if there is good clearing overnight.

Accumulating snow is likely for the Northland Wednesday and
Wednesday night. The GFS and European still indicate an area of low
pressure will develop in the northern High Plains Wednesday. It will
bring a period of moderate large-scale forcing for ascent over the
Northern Plains and western Great Lakes region later Wednesday into
early Thursday as it moves through the Plains. This low will likely
spread accumulating snow through the Northland Wednesday afternoon
through Wednesday night. Widespread snowfall of 2" to 4" is likely,
but there is potential for more. The greatest snowfall appears most
likely to fall from central Minnesota into northwest Wisconsin, but
it`s possible the band of greatest snowfall could fall farther south
or north. The GFS and European are in reasonable agreement, but the
Canadian has much less snow and much farther south. Placing my
confidence in the GFS and European scenario because of fairly good
consistency with its previous model runs. This system could have a
significant impact on the Wednesday afternoon and evening commute.

Temperatures will likely continue to drop into the weekend.
Temperatures may not get above the single digits Friday and
Saturday. The GFS and European suggest even colder air will be
setting up to move into the Northland early next week. This could
mean a stretch of subzero weather.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1138 PM CST Sat Dec 16 2017

An area of mainly MVFR stratus was draped across the area as of
issuance time, with a few locations having deteriorated to IFR.
Expect this trend to continue, with all sites IFR by 09z. MVFR/IFR
fog is also expected to develop, as low level moisture is very
high and falling temperatures should produce fog. Improving
conditions are expected to begin in the 15z-18z time range, with
most site returning to VFR in the 21z-00z time range. There may be
deteriorating conditions again after 02z, but timing and location
are uncertain and have left out for now.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  16  28  19  32 /   0   0   0  30
INL  13  29  19  32 /  20  10   0  50
BRD  17  31  20  35 /   0   0   0  10
HYR  17  29  17  33 /   0  10   0  20
ASX  16  31  19  34 /   0  10   0  20

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&

$$

SHORT TERM...Wolfe
LONG TERM...Grochocinski
AVIATION...LE



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