Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 200954
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
354 AM CST Tue Feb 20 2018

.SHORT TERM...(Today through Wednesday)
Issued at 339 AM CST Tue Feb 20 2018

The short-term forecast period continues to feature light to
sometimes heavy snowfall across the Northland through the morning
hours today, diminishing from southwest to northeast by this
afternoon. Current radar imagery indicates a band of lake effect
snow from Sand Island, WI west towards the Twin Ports and towards
Cloquet, Sawyer, and Cromwell in Carlton county. Moreover, a swath
of moderate to perhaps heavy snow at times continues from
southern Cass and Crow Wing counties north-northeast towards
Itasca and Koochiching counties due to a mid-level impulse lifting
northeast. The lake effect band is due to a northeasterly fetch
over Lake Superior, as indicated by the 20.00z guidance. The
1000-850 mb layer winds are progged to shift more easterly as the
morning wears on, which appears reasonable given the current band
of lake effect snow is shifting slightly to the north as of this
AFD issuance. Because the band is lifting north, decided to
remove Douglas county from the Winter Storm Warning, replacing
with a Winter Weather Advisory, but keeping the Carlton
county/southern St. Louis county zone in the Warning due to more
lake effect snow expected. No other changes to the winter weather
headlines have been made. Generally, the swath of heavier snow
across our northwestern counties could bring another 1 to 4
inches of snow across our northern half of our northeast Minnesota
counties through this afternoon. Also, the threat for icing
remains over northwest Wisconsin this morning, with up to 0.10"
of icing possible due to freezing rain. Price county continues to
remain in the most favorable area for icing. The models are in
pretty good agreement with diminishing the precipitation as the
surface low that`s driving this activity eventually moves off to
the northeast over the central Great Lakes. Drier air moves into
the region and winds turn more westerly, diminishing the threat
for significant lake effect snow, although some lingering light
snow will be possible over the Bayfield Peninsula region this
evening.

Overall, much drier conditions will develop overnight through
Wednesday as surface high pressure builds into the region. The
main area of focus for this time frame will be temperatures
tonight, as radiational cooling is expected as skies clear out
and winds weaken. Overnight lows should drop into the single
digits below zero over northwest Wisconsin, with negative teens
over the northwestern one-third of the forecast area. Wind chill
values could drop into Wind Chill Advisory criteria for a time
Wednesday morning, but held off on issuing headlines as the
duration of the wind chill values are a bit more marginal than in
past cases for advisories, so will let the day shift have another
look at these wind chill values.

.LONG TERM...(Wednesday night through Monday)
Issued at 339 AM CST Tue Feb 20 2018

High pressure will bring quiet weather to the Northland for the
start of the long term period, with dry weather expected Wednesday
night. With mostly clear skies, temperatures are expected to fall
into the single digits below zero across the region. Would not be
surprised to see some teens below zero across northeast
Minnesota. The dry weather will be short-lived, though, as another
low pressure system moves into the region in southwest flow.
Clouds will increase on Thursday, with some light snow, or a
wintry mix moving in Thursday afternoon. The best chance of
precipitation will be on Thursday night, where several inches of
snow will be possible. Northwest Wisconsin has the best chance of
seeing some freezing rain. At this point, it appears this system
has the potential to bring advisory-type precipitation to the
region, although we will need to keep an eye on it. The ECMWF and
GFS are actually in decent agreement in terms of sensible weather.
High pressure will then build back into the region for Friday and
Friday night. The next system should move in on Saturday and
Saturday night. The GFS has a much stronger system moving across
the Great Lakes region, while the ECMWF has a much weaker low. The
best chance of precipitation with this system will be in the
eastern portion of the CWA. The forecast becomes more difficult to
pin down over the weekend and into early next week. The models
are indicating some dramatic differences, and as a result,
confidence is low in any particular solution. Highs throughout the
period will generally be in the upper 20s to middle 30s, with
some mid 20s possible at times across northeast Minnesota.
Overnight lows will largely be in the single digits and teens,
with the exception of Wednesday night.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1144 PM CST Mon Feb 19 2018

MVFR and some IFR ceilings were becoming more numerous this
evening as an area of low pressure and a shortwave affect the
region. Much of the precipitation has diminished late this evening
and the lake effect band over far western Lake Superior was
showing signs of become less organized. Drying aloft has led to
diminished ice in the clouds and freezing drizzle or freezing rain
over parts of northwest Wisconsin. Saturation should again
increase later tonight for most areas as forcing again increases
with and light to moderate snow should become more widespread,
especially over northern Minnesota.

As the forcing decreases during the day Tuesday, the chance for
snow will diminish and ceilings will increase. Conditions will
improve to VFR late afternoon or during the evening.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  18  -4  19  -2 / 100   0   0   0
INL  11 -12  18  -8 / 100  10   0   0
BRD  17  -9  19  -4 /  80   0   0   0
HYR  24  -3  20  -4 /  80  10   0   0
ASX  24   3  22   1 / 100  10   0   0

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory until noon CST today for WIZ001>004-
     006>009.

MN...Winter Weather Advisory until noon CST today for MNZ010>012-
     018>021-025-026-033>036-038.

     Winter Storm Warning until noon CST today for MNZ037.

LS...None.
&&

$$

SHORT TERM...JTS
LONG TERM...DAP
AVIATION...Melde



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