Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 211743
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1143 AM CST Wed Feb 21 2018

.UPDATE...
Issued at 1143 AM CST Wed Feb 21 2018

Update for new 18Z Aviation Discussion below.

&&

.SHORT TERM...(Today through Thursday)
Issued at 324 AM CST Wed Feb 21 2018

A strong high pressure at the surface was centered over Nebraska
early this morning, with a ridge extending northeast to over
northern Minnesota. Aloft, there is a trough axis out over the
Rockies with ridging east, and a strong upper level jet extending
from Texas to the western Great Lakes. This jet is accompanied by
a strong baroclinic zone just east of it. These features that were
responsible for our winter storm earlier this week have now
shifted far enough east that they will not have much of an effect
on the local weather, and the surface ridge will be more in
control. During the day today the surface ridge slowly shifts east
to near the Iowa/Minnesota border, which should keep the weather
relatively quiet across the area. Temperatures to remain below
normal today and tonight with the ridge overhead and fresh snow
cover, with the airmass offsetting the late February sunshine.
Tonight the ridge and clear skies is going to make for good
radiational cooling conditions. While I have gone on the cool end
of guidance, cloud cover ahead of the Thursday-Friday snow is the
main question mark. If the clouds move in later, the temperatures
need to be lowered from what I have, if they move in sooner, they
need to be raised.

.LONG TERM...(Thursday night through Tuesday)
Issued at 324 AM CST Wed Feb 21 2018

The active late winter pattern will continue across the Northland
throughout the long term period. High pressure will quickly move off
to the east on Thursday, as the next system in southwest upper level
flow moves toward the region. While we did not have the full suite
of long term models this morning, the remaining models are trending
toward a consensus solution. Light snow should move in from the
southwest later Thursday, with widespread snow on Thursday night.
Some freezing drizzle or perhaps some light freezing rain could mix
in for a time as well, especially in northwest Wisconsin. The latest
consensus indicates the potential for a widespread 2 to 4 inches of
snow from Thursday night into Friday. However, all of the models
have been trending higher with QPF over the past few runs, so we
would not be surprised to see those numbers go up a bit. No matter
what, we should eventually need winter weather headlines for the
Thursday night and Friday periods. The big question after this time
will be the potential for accumulating snow on the weekend. The GFS
and GFS Ensemble means indicate the potential for a strong low
pressure system that will move into Wisconsin by 06Z Sunday. The
latest ECMWF we have is from 00Z on the 20th, but at that time, it
was much weaker and had the heaviest precipitation across central
Wisconsin. The Canadian is further south than that, with low
pressure in central Illinois. At this point, the consensus solution
is across our south and east CWA, but this system will need to be
watched closely in subsequent runs. The upper level flow becomes
more westerly after the weekend, with a bit more of a quiet pattern
into early next week. Highs will generally range from the upper 20s
to middle 30s throughout the period. Lows will be in the teens to
lower 20s for the most part.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1143 AM CST Wed Feb 21 2018

High pressure will continue to be the main story during this
period. VFR conditions will continue this afternoon into tonight.
Visibility may drop into the MVFR range overnight at INL and HIB
as patchy fog develops. Look for conditions to return to VFR and
continue through 18Z Thursday. An area of low pressure will
approach later in the afternoon which will bring in lower ceilings
and light snow to BRD and HYR after 18Z.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  18   0  25  17 /   0   0  10  80
INL  15  -9  28  12 /   0   0   0  60
BRD  18  -2  25  16 /   0   0  30  80
HYR  21  -6  29  20 /   0   0  20  80
ASX  22  -1  31  21 /   0   0  10  80

&&

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

$$

UPDATE...Huyck
SHORT TERM...LE
LONG TERM...DAP
AVIATION...Huyck



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