Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 180011

Area Forecast Discussion
National Weather Service Duluth MN
611 PM CST Fri Nov 17 2017

.SHORT TERM...(This evening through Saturday)
Issued at 242 PM CST Fri Nov 17 2017

Hazardous travel conditions continue across the Northland this
afternoon as a band of light to moderate snow due to 700-500 mb
frontogenetical forcing progresses eastward. Ahead of the FGEN
band of snow was a plethora of p-types, including snow, drizzle,
freezing drizzle, sleet, rain, and freezing rain in some isolated
spots. This precipitation will eventually diminish this evening as
a cold front associated with a sfc low pressure system, centered
over northeast Manitoba Canada, will scour out the moisture. RAP
and NAM model soundings indicate that some drier air will
infiltrate the 900-600 mb layer, which should inhibit any ice
production aloft as the cold front exits northwest Wisconsin. Due
to the lack of ice growth aloft, and the dry layer underneath the
ice producing layer, and some shallow moisture in the boundary
layer still existing in the soundings, decided to go more
drizzle/freezing drizzle over northwest Wisconsin. Cold air
advection behind the cold front will once again bring some chilly
air over the region, especially over north-central Minnesota, with
lows tonight ranging from the middle teens north to the middle to
upper 20s over northwest Wisconsin where the warmer air will
linger the longest.

Saturday will be much drier compared to today as sfc high
pressure will build into the region behind the cold front. Despite
the high pressure in place, skies should be partly to mostly
cloudy as we remain underneath a mid-level trough, which should
also keep our temperatures on the cold side, with highs Saturday
in the lower 20s along the International Border to the upper 20s
and lower 30s over the south. There may be some small chances of
snow showers along the International Border as a lobe of positive
vorticity advection embedded within the trough will translate over
our north. The better chances of snow could be on the South Shore
of Lake Superior as some lake effect snow showers could develop
by the afternoon. These chances shouldn`t be too high either, as
there are some questions regarding the amount of moisture
available, as well as more favorable delta-Ts holding off until
the evening. I still put in some slight chance/chance PoPs over
Iron and Ashland counties for Saturday afternoon, but didn`t want
to go any higher due to the uncertainty.

.LONG TERM...(Saturday night through Friday)
Issued at 234 PM CST Fri Nov 17 2017

The extended period will feature mainly northwest flow aloft with
several shortwaves moving through bringing chances for light
precipitation. No strong low pressure systems are forecast into next
week by either the GFS or ECMWF.

Colder air will continue to move south and east across the region
Saturday night. The low level winds will be northwest and should be
less than ideal for lake effect snow along the South Shore despite
favorable lapse rates. We have a chance for snow showers across
portions of Ashland and Iron Counties Saturday night with
accumulation of a dusting to around an inch. There may also be some
light snow or flurries along the International Border.

A low level ridge will move across the region Saturday night into
Sunday. Dry weather is expected for most areas Sunday through
Monday. Southerly low level winds Sunday night into Monday will
advect in warmer temperatures and highs Monday will be in the mid
thirties in the Arrowhead, to the lower to middle forties from the
Brainerd Lakes into northern Wisconsin.

A shortwave will bring a return to cooler air Monday night into
Tuesday with 850MB temperatures dropping from the single digits
above zero to teens below zero by 00Z Wednesday. Light snow showers
will be possible as the colder air moves in. There may also be lake
effect snow along the South Shore, especially Tuesday afternoon and
Tuesday night. The wind is northwest which isn`t supportive of heavy
lake effect snow accumulation. Highs Tuesday into Wednesday will
drop to the upper teens to upper twenties.

There will be a couple opportunities for light snow through the rest
of the week but significant snow looks unlikely.


.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 605 PM CST Fri Nov 17 2017

A front crosses tonight, but plenty of low level moisture will
lead to a variety of sub-VFR conditions. A few breaks here and
there may temporarily improve conditions to VFR, but largely
expecting low crud to linger. Moisture begins to erode as stronger
winds arrive Saturday and mixes the BL at least raising ceilings,
but will also have gusty winds at terminals to contend with.


DLH  22  27  10  26 /  10   0   0   0
INL  15  23   6  24 /  10  30  10  10
BRD  24  28  12  34 /  10   0   0   0
HYR  27  31  13  28 /  30   0   0   0
ASX  29  32  17  29 /  30  20  20  10




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