Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 222138
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
338 PM CST Wed Nov 22 2017

.SHORT TERM...(This evening through Thursday)
Issued at 336 PM CST Wed Nov 22 2017

A fast moving clipper is moving across the area this afternoon and
evening. The surface low is currently over northeast North Dakota
southeast of Minot, and will move east-southeast this evening across
Minnesota and weaken before moving into central Wisconsin by
Thursday morning.  This system is somewhat moisture starved and is
not particularly vigorous and weakens as it moves across the area,
so do not expect much out of it- in fact, the lowest visibility I
have seen is an hour or two or no worse than a half mile, with a few
more hours of 1-2sm.  This is unlikely to produce much more than an
inch of snow, so have maintained the forecast fairly close to what
we had before, as a high probability, low QPF forecast.  This system
moves through the area fairly quickly this evening, with clearing
skies expected later this evening and overnight.  This will allow
temperatures to drop into the 10-20 degree range once again, with
some colder spots possible once again.  Thursday to be fairly quiet
with a surface ridge moving across during the morning, and another
warm air advection wing moving in during the afternoon.  It has a
farther north track, and is even weaker and more moisture starved
than the current feature, so am only carrying some flurries along
the Canadian border during the afternoon. Warm air advection to
push temperatures into the upper 20s north with some mid 30s
across the south.

.LONG TERM...(Thursday night through Wednesday)
Issued at 336 PM CST Wed Nov 22 2017

A trough will dig across central Canada Thursday evening into
Ontario on Friday. At the surface, low pressure will track from
northern Saskatchewan southeastward into Ontario. Initially the warm
front associated with the low will lift across northern Minnesota.
The warm air will overrun cold moist air over the Minnesota
Arrowhead, which will lead to a period of freezing drizzle and
potentially freezing rain. Bumped precipitation chances toward the
NAM guidance, but these chances will need to be increased if things
continue to trend toward the current ARW/NMM. The NAM seemed like a
good compromise as the GFS/ECWMF/CMC keep the precip shield further
north. A Winter Weather Advisory may be needed across parts of the
Minnesota Arrowhead if confidence increases in the freezing
rain/drizzle threat. The cold front associated with the low will
move through the CWA throughout the day Friday. Temperatures will be
warm enough for precipitation to be all rain. Highs on Friday range
from the low 40s along the International Border, to the upper 40s
across southern portions of the CWA.

Cold northwesterly air will advect into the region as the low exits,
and high pressure builds in from the west. This will bring clearing
skies to much of the region with much cooler temperatures in
comparison to Friday. Highs range from the low to mid 20s along the
International Border, to the mid 30s in southern locations. Flow
will be favorable for lake effect snow across portions of the South
Shore of Lake Superior.

High pressure will build eastward into the central Great Lakes on
Sunday. This will advect warm 850 hPa air into the region as flow
becomes southwesterly. Skies will be partly to mostly sunny. Highs
range from the low 30s to the low 40s. Temperatures will continue to
warm on Monday as the next system tracks across central Canada and
its warm front lifts into Ontario. Highs range from the upper 30s to
the mid 40s.

After Monday, the forecast becomes uncertain as the latest set of
guidance has deviated considerably from previous runs. The previous
set of guidance suggested some sort of phasing going on between the
trough digging into Intermountain West and a shortwave moving across
central Canada. This would bring potentially significant snowfall
accumulations to the CWA. Whereas, the current set of guidance
depicts these two features remaining separate (minus the CMC), and
less in the way of snowfall. Due to the large discrepancy kept
chances of snowfall, but not confident in the forecast past Monday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1120 AM CST Wed Nov 22 2017

Snow will spread in from northwest to southeast this afternoon
into the evening hours as a shortwave quickly moves through. This
will bring lowering ceilings to MVFR levels, generally between
1200-2500 feet. In addition, snow will reduce visibility to
MVFR/IFR conditions. Confident on the ceilings as the latest
guidance is in good agreement with current observations. Less
confident on visibilities, but utilized upstream observations to
get an idea on how low visibilities will drop at times.

Snow will end at all terminals between 01-06Z. Afterwards VFR
conditions are expected as high pressure builds in.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  16  31  28  44 /  70   0  10  40
INL  12  29  27  42 /  30  10  10  50
BRD  18  34  33  46 /  30   0   0  40
HYR  17  34  30  47 /  70   0   0  40
ASX  20  34  30  48 /  60   0   0  50

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Small Craft Advisory until 4 AM CST Thursday for LSZ140-141.

&&

$$

SHORT TERM...LE
LONG TERM...WL
AVIATION...WL



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