Area Forecast Discussion
Issued by NWS Duluth, MN

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822
FXUS63 KDLH 161735
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1135 AM CST Thu Nov 16 2017

.UPDATE...
Issued at 1023 AM CST Thu Nov 16 2017

Updated the chances of precipitation over the head of Lake
Superior due to on-shore/northeasterly flow. There`s just enough
moisture to squeeze out some light snow showers/freezing drizzle.
Radar echoes are starting to show this light precipitation near
the Twin Ports, which is expected to ascend along the North Shore
through this afternoon as on-shore winds become more
southeasterly. Not expecting much impact from this precipitation
as it should remain light in nature, but some light icing on the
roadways and elevated surfaces cannot be ruled out, so some roads
may become slick.

&&

.SHORT TERM...(Today through Friday)
Issued at 316 AM CST Thu Nov 16 2017

Cloud continue over the region this morning, with moisture trapped
beneath a ridge axis producing a fairly consistent cloud cover, the
exception being over Lake Superior, where downsloping in the
northwest flow off the North Shore terrain ridge has torn a big hole
in the cloud cover over the lake.  Otherwise, the cloud cover
extends from Wisconsin west across Minnesota to affect much of North
Dakota.  The models have been persistent in clearing the cloud cover
out, but looking at the soundings I do not see any realistic hope in
clearing clouds out during the day today.  Thus, I have gone very
pessimistic with sky cover.  This will keep our temperatures on the
cool side today as well.  Tonight and Friday a shortwave and
trailing cold front will move across the area.  The initial warm air
advection wing tonight will bring a round of snow to the area, with
some light snowfall accumulations across the northern portions of
the area.  On Friday though, as the cold front and the shortwave
move across us things get more complicated.  We get warm and dry
enough aloft to lose ice formation in the 500-700 mb layer for parts
of the area, and with the lower layers remaining saturated, a
mixture of drizzle/freezing drizzle becomes a threat for the
southern portions of the forecast area, with mainly snow/rain
elsewhere.  It`s going to be kind of a wintry mix mess during the
day on Friday, with at least some potential to pick up a glaze of
ice during the morning hours. Thankfully we are not looking at a
full on freezing rain event and expect that this will be little more
than a nuisance to travel on Friday.

.LONG TERM...(Friday night through Wednesday)
Issued at 316 AM CST Thu Nov 16 2017

A trough axis will slide from the Intermountain West eastward
through the Northern Plains, and much of the Upper Mississippi River
Valley on Saturday. Cold air will advect into the region as low
pressure deepens as it moves into the central Great Lakes.
Precipitation will gradually taper off from northwest to southeast
Friday evening through Saturday morning, and change from a wintry
mix to all snow. Lake effect snow chances will linger across
portions of the south shore of Lake Superior on Saturday as flow
aloft becomes northwesterly. Expect breezy conditions on Saturday as
the pressure gradient tightens due to the deepening low. Increased
wind speeds and gusts through the day Saturday into the evening
hours.

High pressure will nudge into the region on Sunday. Lake effect snow
will continue across the south shore of Lake Superior, but gradually
taper off during the afternoon/evening as flow aloft shifts to a
westerly direction. In addition, the pressure gradient will relax,
which will bring lighter winds. High temperatures through the
weekend range from the upper teens to the low 30s. Expect a chilly
Sunday morning with lows ranging from the single digits above zero
to the middle teens.

High pressure will slide eastward on Monday, while a trough digs
into central Canada. Ahead of the low developing in central Canada,
warm 0 to 8 degree Celsius air will advect into the region from the
Plains. This will bring the warmest readings of the extended period
to the CWA on Monday. Increased temperatures a few degrees from the
previous forecast, highs range from the low 30s along the
International Border in Minnesota, to the low 40s across southern
parts of the CWA. The low will slide eastward along the
International Border on Tuesday into Ontario and western portions of
Quebec Province by Tuesday evening. This will bring chances of a
rain/snow mix along the Border before cooler air wraps around the
low and changes precipitation to all snow. Cooler temperatures are
expected for Tuesday and Wednesday as cold air advects in from the
northwest. Much of the CWA will dry on Tuesday and Wednesday, but
there will be chances of lake effect snow along the south shore of
Lake Superior. Highs on Tuesday and Wednesday will be in the 20s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1135 AM CST Thu Nov 16 2017

Widespread MVFR cigs at the start of the forecast, with the
exception of DLH with IFR cigs due to the flow off of Lake
Superior generating these cigs. As the surface ridge nearby slips
off to the east, expect the surface wind to become gusty ahead of
the system approaching the terminals for Friday. Expect the MVFR
cigs to prevail through the arrival of this system. Pcpn should
hold off until near 12Z as a front approaches from the southwest.
IFR cigs are possible at DLH and HIB near the onset of the pcpn.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  30  29  36  25 /  20  30  60  20
INL  28  28  36  19 /  10  40  30  10
BRD  32  31  39  24 /  10  20  30  20
HYR  33  31  36  28 /  10  40  70  50
ASX  33  31  38  29 /  40  40  70  40

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Small Craft Advisory from 9 PM this evening to 3 PM CST Friday
     for LSZ140>142.

&&

$$

UPDATE...JTS
SHORT TERM...LE
LONG TERM...WL
AVIATION...GSF



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