Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 201736
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1136 AM CST Mon Nov 20 2017

.UPDATE...
Issued at 1126 AM CST Mon Nov 20 2017

Updated for the 18z Aviation Discussion below.

&&

.SHORT TERM...(Today through Tuesday)
Issued at 356 AM CST Mon Nov 20 2017

At 330 AM, it was fairly quiet across the Northland. Abundant high
clouds had spread across the region, allowing for some moderation
in temperatures. The cold spot at 3 AM appeared to be Crane Lake,
with 9 degrees. The rest of the CWA was generally in the teens to
lower 20s.

The focus for today through Tuesday will continue to be the big
warm up today, followed by the dramatic cool down tonight and
Tuesday. Low pressure over southeast Saskatchewan will move into
the Manitoba Lakes region by 18Z today. This will allow a warm
front across the Northland to push northeast into the northern
Lake Superior region. Southwest winds will become a bit gusty
today, as WAA helps to boost temperatures into the lower 40s
across much of the region. The exception will be in the Arrowhead,
which will see highs in the 30s. Today should generally be
precipitation-free, with the exception of the border region, which
could see some light precipitation this afternoon.

Low pressure will move into northwest Ontario by 00Z Tuesday, and
then reach just north of Lake Superior by 06Z Tuesday. A cold
front will then push rapidly southward across the Northland,
ushering in arctic air on strong northwest winds. Strong CAA and
efficient momentum transfer will cause winds to increase to 15 to
25 mph, with gusts of up to 35 mph or higher tonight and Tuesday.
Some precipitation is expected to drop southward behind the front,
with a mix of rain and snow showers giving way to all snow showers
overnight and on Tuesday. Overnight lows will range from the teens
to lower 20s, with highs on Tuesday ranging from the teens in the
north to the 20s south.

.LONG TERM...(Tuesday night through Sunday)
Issued at 356 AM CST Mon Nov 20 2017

Another brief period of arctic cold mid-week before temperatures
trend milder towards the end of the week. A low chance for a brief
snow shower or drizzle Wednesday from a passing clipper, then a
better chance of precipitation Friday with a mix of rain and snow
possible. Arctic air returns for the weekend causing temperatures
to fall as low as the single digits Saturday night, then back to
more seasonable temperatures for the beginning of the work week.

Tuesday night through Thursday...Skies clear out as arctic air
builds in Tuesday night leading to lows falling to the single digits
across much of the Northland, which is below normal but far from any
record values. A warm front builds from the Dakotas east into the
Upper Midwest Wednesday, with the frontal zone stalling out along a
line from far southern Manitoba to north-central MN to northern WI
late Wed through Thursday. A weak clipper moves along the frontal
zone Wednesday afternoon into Wednesday evening which could result
in some light snow (or freezing drizzle given the clipper`s
relatively mild and dry origin of in the northern high plains), but
in general little to no measurable precipitation is expected. Clouds
from the clipper diminish Wednesday night leading to a mainly sunny
Thursday. Highs in the 20s Wednesday, warming up into low 30s for
areas along and south of Highway 2 for the Thanksgiving holiday on
Thursday.

Thursday night through Friday night...On the synoptic scale a mid-
level shortwave trough will cross the Canadian Rockies and track
east towards Ontario Thursday into Friday. Guidance has gradually
come into better agreement with the track of this system, with the
GFS, GEFS mean, and ECMWF all in generally good agreement. As the
mid-level trough and associated surface low track east across
southern Canada, the Upper Midwest will be well within the warm
sector. Southerly flow at low levels Thursday night into Friday will
lead to 850mb temps around +10C Friday, which is well above the 90th
percentile relative to climatology and will lead to highs in the 40s
across much of the region. As the cold front associated with the low
pressure system approaches Friday, a period of light rain/snow is
expected Friday, with most precipitation falling as rain given the
warm surface temperatures. A brief period of no precipitation
following the frontal passage Friday evening, then light snow
spreads across northern Minnesota with lake effect developing along
the south shore late Friday night into Saturday as 850mb temps fall
to around -10C to -15C Saturday morning. Overall snowfall amounts
are expected to be light for northern MN, but along the south
shore north-northwest winds could lead to a few inches of snow
before drier air moves in.

Saturday and Sunday...High pressure builds in leading to clearing
skies and below normal temperatures through the weekend, with
lows in the single digits to low teens Saturday night. Warmer air
builds in Sunday night into Monday causing temperatures to rebound
to closer to normal values on Monday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1136 AM CST Mon Nov 20 2017

VFR conditions should continue through the afternoon over the
Northland TAF terminals before becoming MVFR/IFR overnight. An
area of low pressure will advance eastward across southern
Manitoba and southern Ontario Canada this afternoon, which will
bring a strong cold front this evening. Some snow showers, which
could reduce vsbys to MVFR, are possible, especially for KINL and
KHIB. Northwest winds will also strengthen as we mix down some
stronger winds from aloft. Low-level jet should strengthen
overnight to the 35 to 45 knot range along the front, so there
should be a small window for LLWS for most of the TAF sites before
these winds mix down to the surface.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  40  19  23  11 /   0  10  10   0
INL  38  15  20   7 /  20  50  20  10
BRD  45  20  25  10 /   0  10   0   0
HYR  44  22  26  10 /   0  10  10   0
ASX  45  25  27  16 /   0  20  30  10

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Gale Warning from 10 PM this evening to 4 PM CST Tuesday for
     LSZ121-140>148.

&&

$$

UPDATE...JTS
SHORT TERM...DAP
LONG TERM...JJM
AVIATION...JTS


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