Area Forecast Discussion
Issued by NWS Duluth, MN

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327
FXUS63 KDLH 090237
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
837 PM CST Fri Dec 8 2017

.UPDATE...
Issued at 837 PM CST Fri Dec 8 2017

The clipper was located in northwest Wisconsin at 8pm and
continuing on its trek southeast. The stronger snow bands have
subsided after leaving 1 to 2 inches behind. The clipper should
exit the area by 3am. Lake effect snow is still progged to get
organized behind the clipper when surface winds turns northwest
along the south shore of Lake Superior. Current headlines are on
track. Made some minor changes to forecast.

&&

.SHORT TERM...(This evening through Saturday)
Issued at 335 PM CST Fri Dec 8 2017

A clipper coming down from northwest Ontario will bring a brief
burst of snowfall to much of the Northland this afternoon evening,
with lake effect snow lingering into tonight for parts of the south
shore. Temperatures will fall to the single digits above zero
tonight, except for some areas north of the Iron Range and in the
higher terrain of the north shore where lows may fall below zero.
Following this clipper winds will increase as a colder airmass moves
in at low levels, with gusts to around 20-30 mph for a period this
evening, strongest in north-central MN. Drier and colder air moves
in behind the clipper resulting in at least partially clearing skies
for Saturday morning, then increasing clouds in the afternoon as yet
another weak clipper approaches from the north. Highs in the upper
single digits to near 20 across the Northland, which is around ten
degrees below normal for this time of year.

This afternoon...MRMS radar reflectivity, incorporating both NEXRAD
and Environment Canada radar, depicted an area of moderate to heavy
snowfall moving south towards northern Minnesota this afternoon,
with the (albeit limited) surface observations in northwest Ontario
supporting a period of moderate to heavy snow. For example, Dryden
Airport (CYHD) had a solid hour of visibility under one mile between
1pm and 2pm CST due to moderate/heavy snowfall, with brief periods
under a half mile visibility. These conditions are expected to occur
at many locations across northeast Minnesota and northwest Wisconsin
this evening, except for areas basically south of Highway 2 in MN
where little snow is expected. Total snowfall of around 1 to 3
inches is expected this afternoon/evening...though it will all fall
in a short period with snowfall rates on the order of an inch per
hour.

This evening into Saturday morning lake effect snow ramps up across
the south shore, where rounds of heavy snowfall possible. A total of
3-7"+ is expected between this evening`s clipper snow and the lake
effect snow overnight. There is a bit of low level directional wind
shear which will probably result in a few bands of heavy snowfall
wavering west and east - it won`t snow all night, but when it does
snow rates could be heavy resulting in low visibility. There is a
very real possibility for a narrow corridor to receive over ten
inches of snowfall if the band does not actually move too much,
while other areas see much less. Winter Weather Advisory continues
for Ashland and Iron counties.

Drier and colder air moving in after the clipper will result in at
least partially clearing skies, with strong confidence in the
northwest low level flow resulting in a gravity wave developing down-
wind of the north shore creating an area of clearing skies for a
time late tonight into tomorrow morning. Clouds then increase
Saturday afternoon ahead of yet another clipper - and so the endless
parade of clippers continues!

.LONG TERM...(Saturday night through Friday)
Issued at 335 PM CST Fri Dec 8 2017

The main focus for the long term will be a series of clipper
affecting the region.

The first clipper that will affect the region will be Saturday night
and will be weak.   It will only affect the Arrowhead and the
snowbelt region of NW WI with less than an inch accumulation
expected.  There will be a break in the precip before a stronger
clipper moves through the region Sunday night and Monday morning.
The GFS/ECMWF are reasonably close to each other with the low center
moving from West Central MN Sunday afternoon to near MKE by midday
Monday with the NAM further east with the location.  Will go with a
blend of the forecast leaning toward the GFS/ECMWF solution.  WPC
has a band of 2-4 inches extending from NW MN SE through the
Brainerd/Leech Lake regions and east to Highway 53 in NE MN and into
NW WI.  The rest of the area will see around an inch. Will lean
toward that solution for forecast.  There could a slight chance for
FZDZ Sunday night so will have it in the grids.  Later model runs
may indicate no freezing precip.

The snow will end Monday morning with some lake effect developing in
Ashland and Iron counties later Monday and extending into Tuesday
night due to the colder air and favorable wind direction.  The next
clipper wil affect the region Wednesday night into Thursday morning
and will bring another 1-3 inches.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 524 PM CST Fri Dec 8 2017

A clipper was over northeast Minnesota at the start of the
forecast. A band of moderate, at times heavy, snow was dropping
past the terminals with IFR, isold VLIFR conditions. The clipper
is expected to exit northwest Wisconsin by 09Z with the snow
ending from North to South as it passes. An improvement to VFR is
expected as the system departs. There will be periods of MVFR cigs
at HYR after 09Z due to its proximity to anticipated lake effect
snow showers that will be nearby, but mainly off to the East. The
cigs at HYR will improve to VFR by 20Z as drier air shuts off the
lake effect. Gusty surface winds will occur behind the departing
clipper as cold air rushes over the terminals.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH   7  15  13  26 /  40  10  10  10
INL  -1  14  11  21 /  10  10  20  10
BRD  11  20  17  29 /  20   0  10  10
HYR  10  17  10  27 / 100   0  10  10
ASX  11  17  13  27 / 100  30  10  20

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory until noon CST Saturday for WIZ003-004.

MN...None.
LS...Small Craft Advisory until 10 AM CST Saturday for LSZ121-146>148.

&&

$$

UPDATE...GSF
SHORT TERM...JJM
LONG TERM...Stewart
AVIATION...GSF



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