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Area forecast discussion
National Weather Service Duluth Minnesota
613 am CST Wed Nov 20 2019

Short term...(today through thursday)
issued at 532 am CST Wed Nov 20 2019

Slick travel expected today through tomorrow through much of the
Northland due to a wintry mix of rain, snow and freezing rain.
Expect the most impacts along and north of the Iron Range to the
Minnesota arrowhead and Iron County in northwest Wisconsin due to
snowfall totals. Heaviest snowfall is expected Wednesday evening
into Thursday morning. Winter storm warnings and winter weather
advisories have been issued.

A positively tilted (northern stream) trough will dig from
Saskatchewan and Montana this morning into the northern plains by
late tonight. A negatively tilted shortwave trough will lift from
The Four Corners region into the High Plains. At the surface as
the northern stream approaches it will interact with a somewhat
stationary front that extends from North Dakota into Minnesota.
This will provide enough lift to spread a wintry mix of rain, snow
and freezing rain into northern Minnesota this morning. Later
this afternoon in response to both the northern and southern
stream waves a surface low will deepen over the High Plains and
mid Mississippi River valley. The surface low will deepen and lift
northeastward into Wisconsin overnight. Expect a frontogenetical
band of heavier snowfall to develop from northern Cass to the
Minnesota arrowhead as depicted by cams. This is supported by the
wpc super ensemble where members are clustering to higher quantitative precipitation forecast
values across northern Minnesota. Would not be surprised if a few
isolated spots where the Winter Storm Warning has been issued see
12+ inches of snow. The heaviest snowfall is expected across
northern Minnesota tonight into early Thursday morning. There is
some uncertainty in snowfall totals from the Brainerd lakes to the
twin ports. These locations are on the periphery of warm and cold
airmass. If the colder air moves in quicker then more snowfall
can be expected and a Winter Weather Advisory would be needed.
Northwest Wisconsin will remain where the warmer air is advecting
in which will keep precipitation all rain until early Thursday
morning when the colder air moves in. Iron County will be right on
the edge of the warmer and cooler air, so have kept a wintry mix
from roughly midnight until precipitation changes over to all snow
early on Thursday. Expect totals of 4 to 10 inches where the
Winter Storm Warning is in effect. Snowfall totals range from 3 to
7 inches where the advisories are in effect. Elsewhere totals
range from trace amounts to 3 inches. Bumped up low temperatures
due to the warmer air advecting in across northwest Wisconsin.
Highs today range from the mid 30s to the low 40s. Lows tonight
range from the upper teens to the mid 30s.

The surface low will lift into the central Great Lakes and
Ontario later on Thursday. This will bring snowfall to an end from
west to east as the day progresses. Eastern portions of northwest
Wisconsin may see some freezing drizzle as precipitation is
winding down due to loss of ice aloft. It will be colder in
comparison to today on Thursday as flow aloft is northwesterly.
Highs range from the low 20s to the mid 30s.

Long term...(thursday night through tuesday)
issued at 532 am CST Wed Nov 20 2019

Dry with near to above normal temperatures late-week and through the
weekend, then a low chance for light precip early week ahead of the
possibility for measurable snowfall mid to late week.

On the synoptic scale an area of high pressure builds across the
Great Plains east across the Midwest/Great Lakes late Thursday into
Friday. After a brief bout of cooler temps from the northerly low
level flow Thursday night, west to southwest flow that develops as
the area of high pressure builds east will lead to warmer air
advecting in across the region Saturday and Sunday, with highs in
the 30s, mostly above freezing, and lows in the low to mid 20s.
Skies should clear out on Friday, but some clouds return Saturday
and Sunday due to a few weak waves moving across the upper Great
Lakes in the northwest flow.

Early next week a surge of more seasonable air will approach from
the Canadian prairie as a mid-level shortwave trough deepens as it
tracks east across southern Canada, causing surface low to develop
in central Manitoba Sunday night into far northwest Ontario on
Monday. The surface cold front associated with this low may cause
some light snow to fall across far northern Minnesota on Monday,
with a reinforcing push of colder air approaching on Tuesday. Highs
in the low to mid 30s Mon/tues.

Mid to late week a more active weather pattern is expected to result
in accumulating snowfall across parts of the upper Midwest and Great
Lakes, but there are many possible solutions for how the pattern
will evolve. In general, cold Arctic air wil filter into the
Canadian prairie early to mid week with the possibility for a deep
longwave trough to develop across The Rockies and into the Great
Plains which could cause a surface low to deepen and lift towards
the Great Lakes. The timing and strength of such a wave remains
uncertain, to the point that there could be accumulating snowfall
before, during, or even after the Thanksgiving Holiday - but
regardless, snowfall could impact Holiday travel across the
Great Lakes region.

&&

Aviation...(for the 12z tafs through 12z Thursday morning)
issued at 613 am CST Wed Nov 20 2019

VFR to MVFR conditions will quickly fall to IFR conditions this
afternoon as low ceilings and a wintry mix of rain and snow
develops in northeast Minnesota today into northwest Wisconsin
tonight. IFR conditions are likely to persist through the taf
period with visibility less than a mile for much of tonight due to
rain/snow and fog. Winds will be out of the southeast to east
around 5 to 10 knots today, becoming northerly overnight.

&&

Marine...
issued at 532 am CST Wed Nov 20 2019

Light/variable winds today around 5 knots or less, becoming easterly
around 10 knots tonight. Winds back to become northeasterly to
northerly on Thursday at 10 to 20 knots, turning north-northwesterly
by late in the day. These stronger winds will likely cause dangerous
conditions for small craft across parts of Western Lake Superior,
especially on northern parts of the North Shore and along parts of
the South Shore where wave heights will increase in response to the
winds. Northwest winds weaken to around 10 knots on Thursday night,
becoming west/southwesterly on Friday at 10 to 15 knots. Rain/snow
likely developing late today and heavy at times tonight, ending from
west to east on Thursday then dry through the weekend.

&&

Preliminary point temps/pops...
dlh 36 30 31 13 / 60 100 90 0
inl 34 22 22 10 / 100 100 10 0
brd 39 28 28 13 / 70 90 40 0
hyr 40 33 34 15 / 30 100 100 10
asx 40 33 35 18 / 30 100 100 20

&&

Dlh watches/warnings/advisories...
WI...Winter Weather Advisory from midnight tonight to 6 PM CST
Thursday for wiz004.

Minnesota...Winter Weather Advisory from 4 PM this afternoon to 6 am CST
Thursday for mnz018-025-026.

Winter Storm Warning from 4 PM this afternoon to noon CST
Thursday for mnz011-012-019>021.

Winter Weather Advisory from noon today to 6 am CST Thursday for
mnz010.

Ls...none.
&&

$$

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