Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 171730

Area Forecast Discussion
National Weather Service Duluth MN
1130 AM CST Tue Jan 17 2017

Issued at 1130 AM CST Tue Jan 17 2017

Updated for the latest 18Z Aviation Discussion below.

UPDATE Issued at 618 AM CST Tue Jan 17 2017

Precipitation is rapidly diminishing across northwest Wisconsin as
expected. Per spotter reports this morning it sounds like most of
the precipitation fell as light freezing rain/drizzle with
occasional snow/sleet mixed in. Made some small changes to the
forecast to add more freezing drizzle and snow mix wording and small
timing adjustments. While some stratus may stick around in parts
of northern Wisconsin, clearing trend should prevail through the


.SHORT TERM...(Today through Wednesday)
Issued at 300 AM CST Tue Jan 17 2017

A brief wintry mix for parts of northwest Wisconsin this morning,
but otherwise the quiet weather pattern and gradual warming trend
continues through mid-week.

On the synoptic scale a weak low is moving east across the mid-
Mississippi River Valley while a mid-level shortwave trough drops
out of northwest Ontario into the upper Midwest today. While this
mid-level shortwave trough may contribute to large-scale lift across
northern Wisconsin this morning, impacts will otherwise be fairly
benign with clear skies in the wake of it today. Some stratus will
likely stick around in northern Wisconsin after the precipitation
ends, but as broad ridging develops at mid and upper levels across
the Great Plains into the upper Mississippi River Valley clearing
should mainly prevail. Under clear skies temperatures will fall and
areas of fog will again develop tonight - most likely in northern
Wisconsin but possible anywhere across the Northland. Warm air
advection due to westerly winds through the column tonight into
Wednesday and sunny skies will result in warmer temperatures on

Highs in the low to mid 30s today, with lows falling to the teens
overnight tonight - possibly as cold as the mid-single digits in a
few spots under the clear skies, though a light south-southwest wind
should prevent temps from falling below zero. Warmer Wednesday with
highs in the mid to upper 30s - about 15 degrees above normal.

.LONG TERM...(Wednesday night through Monday)
Issued at 300 AM CST Tue Jan 17 2017

Surface high pressure wil be over the Ohio Valley Wednesday night
through Thursday night. This will leave a ridge axis over the
forecast area with no precipitation. A southwesterly flow aloft will
cover the region. However, temps will start warm with 850mb temps
near 10C Wednesday night, but cooling to around 6C Thursday night.
On Friday, model differences become quite large. The ECMWF has a
horizontal long wave trof from the Northern Plains to the East Coast
by 00Z Saturday, and a surface trof lifting northward through
Minnesota and Wisconsin and across much of the forecast area. The
GFS has a closed mid level low over northern Illinois and surface
ridging still over the region. The GEM is leaning toward the ECMWF,
but is further south and weaker with the upper trof, and further
south with the surface trof over southern Minnesota. Will follow a
blend which leans on the GFS/GEM more than the ECMWF, which is a dry
forecast. The models come together a bit Friday night through Sunday
aloft. However, their locations for the closed upper low/trofs at
about 250 miles apart, with the ECMWF the furthest west. The GEM is
too far to the east and will be discounted. Using a blend of the
GFS/ECMWF gives opportunities for light precipitation through
Monday. Surface temps will be warm enough for light rain during the
day, and a mix of rain and snow in the evening before changing to
all snow overnight. There is a small window for freezing rain late
Friday night, but with the model differences in the thermal profile,
have removed the freezing rain. None of the model soundings support
sleet and have removed. Precipitation amounts will be hard to
discern at this time due to the aforementioned model differences.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1130 AM CST Tue Jan 17 2017

Expect widespread VFR conditions across northwest Wisconsin and
northeast Minnesota through this afternoon, with the exception of
lingering fog and LIFR/IFR ceilings near KDLH through early this
afternoon. The lack of wind flow could make the fog linger longer
than forecast, but the hope is the rising sun will soon make
quicker work on the lifting the fog.

Light southwest flow will develop by later this afternoon.
Thinking there will be enough wind going into the evening to stave
off any fog, except for maybe the KHYR area since it is so prone
to such light wind flow with the trees. There is a period of IFR
visibility for KHYR this evening through the wee hours of the
morning, but may need to lower the visibility and ceiling forecast
even more if there is higher confidence in the fog development.
Most other areas should remain VFR.

A strong 30 to 40 knot west-southwesterly low-level jet will
develop tonight, spreading south and east across northern
Minnesota towards Superior and northwest Wisconsin overnight into
Wednesday morning. Added periods of low-level wind shear to KINL,
KHIB, and KHYR. Did not add LLWS for KDLH, but might add it with
subsequent forecasts.


DLH  30  19  34  23 /   0   0   0   0
INL  28  20  35  19 /   0   0   0   0
BRD  30  14  36  22 /   0   0   0   0
HYR  34  17  36  24 /  10   0   0   0
ASX  36  21  38  26 /   0   0   0   0


MN...Dense Fog Advisory until 1 PM CST this afternoon for MNZ020-037.



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