Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 102359
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
559 PM CST Wed Jan 10 2018

.SHORT TERM...(This evening through Thursday)
Issued at 352 PM CST Wed Jan 10 2018

Short term forecast focus remains on a winter storm and how much
snow and mixed precipitation will fall across the Northland. We
have made some changes to the snowfall forecast, decreasing it in
spots and increasing some in others, see below for details.

A broad area of low pressure stretched from northern Ontario
through Minnesota into Colorado. A cold front was moving through
western Minnesota and temperatures have dropped into the single
digits to lower teens over northeast North Dakota into far
northwest Minnesota as of 3 pm. Much of the Northland had
temperatures in the lower to middle thirties as of 3 pm. A
shortwave will progress east tonight and the surface low will
continue east into Wisconsin by 09Z. An area of strong FGEN
forcing is expected to develop just west of the surface low and
move across the Northland. Although the models are in decent
agreement, significant differences remain in how much QPF will
fall with this storm. The high resolution models including the
ARW/NMM and NAM all are significantly higher than the
Canadian/ECMWF/GFS. We went with a blended approach of the models
to incorporate some higher QPF due to the expectation heavier
bands of snow will develop as the FGEN moves through. We still
expect some freezing drizzle to occur before deeper saturation and
cooling occurs. However, we don`t expect heavy icing and
generally a light glazing. We have snow amounts tonight through
Thursday of 3 to 6 inches over much of far northern Minnesota with
1 to 4 inches from the Brainerd Lakes into the I35 corridor and
up to Duluth. Higher amounts are expected over northern Wisconsin
as well with 3 to 6 inches expected with higher amounts through
portions of Sawyer, Price into Ashland and Iron Counties. Ashland
and Iron counties will get lake enhanced snow Thursday into
Thursday night and we have the highest snowfall of 6 to 9 inches
over Iron County. Much of the significant snow will be over by mid
Thursday afternoon with the exception of the snowbelt of Ashland
and Iron Counties. A portion of the Bayfield Peninsula into
Douglas County may also see moderate snow linger longer Thursday if
a gravity wave develops, although confidence is low at this time.

Temperatures will drop sharply overnight over much of the region.
Temperatures by 8 am will be around zero in north central
Minnesota to the teens along the Minnesota and Wisconsin border.
Temperatures will drop through the day and be around zero or in
the lower teens by 4 pm.

.LONG TERM...(Thursday night through Wednesday)
Issued at 352 PM CST Wed Jan 10 2018

Much colder air moving in Thursday night through early next week as
temperatures plunge back into subzero territory. A chance for light
snow Sunday into Sunday night from a passing weak clipper, but
otherwise little precipitation expected outside of the south shore
of Lake Superior where lake effect snow will linger through much of
the long-term forecast period.

On the synoptic scale colder air will move in aloft through the
weekend with 850mb temps approaching -25C. While this will lead to
colder temperatures, this is not as cold as the frigid arctic blast
that affected the region in late December into early January. THe
colder arctic air will be drier which should result in skies
becoming sunny towards the weekend. A broad area of high pressure
will build across the Upper Midwest on Saturday, but then a weak
clipper will approach from the northwest on Sunday leading to
increasing clouds and a chance for light snow. At low levels this
clipper will track along a warm frontal boundary moving eastward
across the Great Plains Saturday night into the Midwest on Sunday,
which will result in temperatures just a bit warmer on Sunday.
Colder air returns for the early part of the week but temperatures
will not be as bad...850mb temps approaching -20C. The large-scale
pattern becomes much more progressive next week with a warmer
airmass moving in by mid-week. This progressive pattern will favor
more frequent chances for light precipitation and generally
temperatures closer to normal values.

Lake effect snowfall is expected across the south shore through much
of the long term period due to the colder airmass in place and much
of Lake Superior ice-free. (The bitter late-Dec/early-Jan cold
formed a lot of ice, but the winds last weekend and warm temps early
this week caused it to get broken up and melt.) The best chance for
lake effect will be right after the arctic cold moves in late-week.
With drier air on Saturday the lake effect snow will taper off, but
the Sunday clipper will likely bring it back to life Sunday night
into Monday. The best chances for accumulating snowfall will be
Thursday night into Friday (perhaps 1-4") and then Monday (maybe
another 1-3").

The Sunday clipper will bring around 1-2" of snow to the Northland.
Confidence is fairly high that amounts will be within this range and
that the snow will fall during the Sunday into Sunday night period.

Temperatures will be below normal through the long term forecast
period. Highs in the single digits near to below zero Friday through
Tuesday, except for Sunday when most locations should climb into the
single digits above zero. Warmer Wednesday through at least the end
of the week with temps trending to near to above normal. (Normal
high temperature for this time of year in the upper teens near 20.)
Low temperatures will be below zero through the long term forecast,
coldest this weekend when lows will range from -15 to -25 or even
colder along the international border region. This is not as frigid
as some of the days with widespread lows in the -25 to -40 range
during the last arctic outbreak, but is still well below normal.
Wind Chill Advisories may be needed some nights.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 547 PM CST Wed Jan 10 2018

Not a good night to fly. Plenty of IFR and even VLIFR out there.
Not expecting much of an improvement until after the cold
front moves through Thursday afternoon and scours out the low
crud, but then wind will pick up and blow the snow that falls
around. Ceilings may improve to MVFR late, late in the TAF period
with improvements first at the northerly sites.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH   9  13 -13   3 /  80 100  10   0
INL  -2   3 -30  -3 / 100  90   0   0
BRD   4   6 -17   4 /  90  80   0   0
HYR  22  23  -9   8 /  80 100  20   0
ASX  23  26  -3   8 /  80 100  50  10

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory from midnight tonight to 3 PM CST
     Thursday for WIZ001-006-007.

     Winter Storm Warning from 3 AM to 6 PM CST Thursday for WIZ008-
     009.

     Winter Storm Warning from 4 AM Thursday to midnight CST Thursday
     night for WIZ003-004.

     Winter Weather Advisory from 3 AM to 6 PM CST Thursday for
     WIZ002.

MN...Winter Weather Advisory from midnight tonight to 3 PM CST
     Thursday for MNZ012-020-021-033>038.

     Winter Weather Advisory until noon CST Thursday for MNZ010-011-
     018-019-025-026.

LS...Small Craft Advisory from 4 AM Thursday to 4 AM CST Friday for
     LSZ121-146>148.

     Heavy Freezing Spray Warning from 4 AM to 10 PM CST Thursday for
     LSZ146>148.

     Small Craft Advisory from 4 AM to 10 PM CST Thursday for
     LSZ143>145.

     Gale Warning from 4 AM to 6 PM CST Thursday for LSZ140>142.

&&

$$

SHORT TERM...Melde
LONG TERM...JJM
AVIATION...Wolfe



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