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fxus63 kdlh 191143 
afddlh

Area forecast discussion
National Weather Service Duluth Minnesota
643 am CDT Fri Oct 19 2018

Update...
issued at 627 am CDT Fri Oct 19 2018

Updated for the 12z aviation discussion below.

&&

Short term...(today through saturday)
issued at 348 am CDT Fri Oct 19 2018

A mild morning ahead of a strong cold front that will bring an
airmass more typical of winter than fall. The front will also
bring increasing clouds and a broad chance for light rain to snow
showers late today into tonight, with little in the way of total
rain/snow amounts outside the South Shore where lake enhancement
could lead to up to an inch of snow. Strong winds will also
accompany the cold front passage, with northwest winds gusting to
30- 40 mph on Saturday morning.

On the synoptic scale a broad mid/upper level ridge is building over
the West Coast while a broad mid/upper level trough exists across
central Canada. Early this morning a well defined mid/upper low is
tracking south-southeast in the eastern reaches of the northwest
territories north of Saskatchewan, with a defined mid-level wave
ahead of the low across central Saskatchewan. The initial vort Max
will move into the northern plains today then east across the upper
Great Lakes today causing the surface low over northwest Ontario to
deepen and an initial cold front to move from west to east across the
upper Midwest. However, today into tonight the upper low and
associated cold air will track south across Manitoba and arrive in
the upper Midwest tonight causing temperatures to plummet and winds
to increase as a low deepens to the east and a strong area of high
pressure builds to the west. While there will be a chance for
rain/snow showers as well as lake enhancement over the South Shore
associated with this front, the main sensible weather impacts will
be the temperature and wind.

Today skies will begin mostly sunny except for a band of clouds and
rain showers lingering across parts of northwest Wisconsin,
generally east of a line from Hayward to Ironwood. Southwest winds
will be gusty in the morning, then the initial surface cold front
will track from west to east across the Northland in the mid to late
morning hours causing a shift in wind direction and a period of
clouds. In the afternoon a second push of cooler air as well as some
low level moisture will result in increasing clouds across northeast
Minnesota and northwest Wisconsin as well as the developing of rain
showers from the stratocu that develops as the cooler air moves in
aloft. Despite the morning cold frontal passage, with a fairly mild
starting point in the morning (lows will likely bottom out in the
low 50s in most spots), highs will reach the mid to upper 50s this
morning before temperatures fall quickly in the mid afternoon to
evening hours. Northwest winds 15 to 20 mph with gusts around 30 to
40 mph this evening, strongest along the North Shore. Peak wind
gusts as strong as 50 mph cannot be ruled out for locations like
Grand Marais and Lutsen this afternoon/evening.

Tonight temperatures will fall fast into the mid 20s to low 30s with
strong northwest winds persisting through the overnight hours. A
chance for snow showers for much of the region, but amounts will be
very light, less than an inch.

On Saturday the coldest air aloft will be centered over the
Northland by mid-morning, with 850mb temps around -13c, which would
be more typical for late December into January per inl sounding
climatology and will be near the record for the 12z Oct 20 sounding
climo of -12.0. A strong area of high pressure will continue to
build eastward from the northern plains into the upper Midwest,
which should result in decreasing clouds and winds letting up on
Saturday. However, despite the sunshine highs are only expected to
be in the 30s, around 15 degrees below normal. Northwest winds gusty
in the morning, then diminishing in the afternoon.

Long term...(saturday night through thursday)
issued at 348 am CDT Fri Oct 19 2018

The extended forecast continues to be mainly dry across the
Northland, with the potential for a late week system to bring
chances of rain showers. Temperatures through next week will
generally be below seasonal average.

The overall synoptic pattern shows a large high pressure ridge over
the intermountain west states, with a longwave trough over the
northeastern United States, which will keep the bulk of the mid-
level shortwave energy away from the region. Very dry air will be in
place through much of next week, with 1000-500 mb layer relative
humidities remaining well below 50 percent per the 19.00z GFS model.
A couple of areas of surface high pressure will translate through
the region for the upcoming week. The only exception will be for
late Monday and early Tuesday as a mid-level trough moves through
the region, enhancing cold air advection. There are some small
chances of precipitation for this time frame, mainly over adjacent
areas of Lake Superior, but very little impacts are anticipated.
This trough will more than likely bring some additional cloud cover
to The Arrowhead region due to the cold air advection. Low
temperatures will generally be near to slightly below freezing
through mid-week, with highs in the 40s and lower 50s. Sunday could
be the warmest day due to southwest flow and increasing warm air
advection, with highs in the upper 40s to lower 50s, very close to
average.

The next appreciable chances of precipitation could return to the
Northland Friday as the western ridge breaks down and shifts
eastward, allowing a large mid-level shortwave to enter the region.
However, there are significant discrepancies between the GFS, ECMWF,
and Gem models regarding the areal coverage and timing of
precipitation, so a large amount of uncertainty exists in this
scenario.

&&

Aviation...(for the 12z tafs through 12z Saturday morning)
issued at 643 am CDT Fri Oct 19 2018

A very gusty day today as a cold front will move through the
Northland. Current GOES-16 satellite imagery shows a band of
broken to overcast stratus moving southeast towards the region along the
cold front. Winds along the front will shift from the southwest to
a northwesterly direction as the front passes through. Colder air
behind the front will allow some very strong winds from aloft to
mix down to the surface, causing the strong gusts. More saturated
air will bring chances of showers this afternoon and evening
after the cold front passes through. Rain showers will be possible
for this afternoon and early evening before transitioning to
mostly snow overnight. Confidence in the areal coverage of the
showers is low at this time, so used vcsh to indicate the most
likely timing of the showers. Some snow accumulation is possible
after midnight, but should remain below one inch total.

&&

Preliminary point temps/pops...
dlh 55 29 36 27 / 10 30 0 0
inl 51 28 35 26 / 20 30 0 0
brd 57 30 38 27 / 10 30 0 0
hyr 58 31 37 25 / 10 30 20 0
asx 58 32 38 27 / 10 40 30 10

&&

Dlh watches/warnings/advisories...
WI...none.
Minnesota...none.
Ls...Small Craft Advisory until 10 am CDT Saturday for lsz121-140>148.

&&

$$

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