Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 191755 AAB
AFDDLH

Area Forecast Discussion...UPDATED
National Weather Service Duluth MN
1155 AM CST Mon Feb 19 2018

.UPDATE...
Issued at 1155 AM CST Mon Feb 19 2018

Update for the new 18Z Aviation Discussion below.

&&

.SHORT TERM...(Today through Tuesday)
Issued at 338 AM CST Mon Feb 19 2018

Our active weather pattern continues today through much of the
day Tuesday, although we aren`t expecting snowfall amounts as high
as were observed yesterday. The synoptic pattern doesn`t change a
whole lot as we remain under the right-entrance region of the
160+ kt upper level jet streak. An 850 mb baroclinic zone is
progged to remain draped over northwest Wisconsin through Tuesday
afternoon, with a surface low pressure system currently over
central Kansas at 09z this morning translating northeastward over
eastern Iowa/northern Illinois this afternoon and evening.
Current radar imagery shows a band of higher reflectivity
extending from western South Dakota towards central Minnesota and
northwest Wisconsin. This is associated with a band of 850-700 mb
frontogenetical forcing, which should bring light snow and
possibly freezing drizzle to portions of the Northland. The
expectation for p-types through Tuesday is for all snow over
northeast Minnesota, with a mix of snow, freezing drizzle, and
possibly freezing rain over northwest Wisconsin due to the
placement of the baroclinic zone. Some ice accretion is expected
over our eastern Wisconsin counties, including Washburn to Price
and into Ashland and Iron counties. Price county could be hit
particular hard with ice accretion, with up to 0.2" of ice
possible, which will occur mainly this afternoon through Tuesday
morning. Moreover, a few more inches of snow will be possible over
northwest Wisconsin as well through the evening.

Then, a stream of sheared positive vorticity advection will eject
out of a longwave trough, situated over the Intermountain West
states. This wave will ride along west of the 850 mb baroclinic
zone, which will bring more chances of snow to northeast
Minnesota, mainly tonight into Tuesday morning. The best chances
of snow will be between 9 PM tonight and 6 AM Tuesday morning,
with between 1 to 4" of more snow on top of what fell today. As
the surface low approaches, winds should be northeasterly over
Lake Superior, so there could be some lake enhancement along the
South Shore. Model soundings indicate that while the northeast
fetch is quite favorable for lake enhancement, the 850-surface
delta-T values are not as much, with values between 10 to 15
degrees C, so not ideal. In any case, there could be some seeding
of ice crystals over the South Shore, so increased the QPF over
this area to better account for higher snow totals. This on-shore
flow could also lead to gusty winds upstream of the flow, with
gusts between 20 to 25 mph over northwest Wisconsin this afternoon
and evening. This could also lead to some patchy blowing snow in
these areas. Due to the combination of ice and snow with this
system, decided to issue a Winter Weather Advisory for the entire
forecast area, including all of northwest Wisconsin and adjacent
areas of northeast Minnesota starting this morning, with the rest
of northeast Minnesota starting this evening when that second
trough arrives. Advisories go out through the afternoon Tuesday.

.LONG TERM...(Tuesday night through Sunday)
Issued at 338 AM CST Mon Feb 19 2018

Low pressure will move off to the east of the Northland on Tuesday
night, with little additional accumulation expected overnight. High
pressure will then push in from the southwest. It will likely take
some time to scour out the cloud cover in the wake of the departing
low pressure system, but we should see an increase in sunshine by
Wednesday. By 00Z Thursday, high pressure should be centered over
southern Minnesota. This area of high pressure will then move off to
the east of the Great Lakes on Wednesday night and Thursday. The
next system in southwest flow aloft will approach the region late
Thursday, with increasing clouds throughout the day. Some light snow
is expected to make it`s way into the region by late Thursday, with
light snow spreading across the area Thursday night. This system
will move northeast of the region on Friday, after bringing some
accumulating snow to the CWA. At this point, it doesn`t appear to
bring heavy snowfall, but widespread snowfall amounts of a couple
inches will be possible. High pressure will bring mainly dry weather
by Friday. The models start to show some dramatic differences by
Saturday and Sunday, with the European model indicating some snow
potential on Saturday afternoon and Saturday night. The GFS is much
farther south with this system, with little to no precipitation
across our CWA. Temperatures will be their coolest on Wednesday,
with highs ranging from the teens to lower 20s. By Thursday, we
should see highs in the 20s, and 20s to middle 30s by Friday,
Saturday and Sunday. Overnight lows in the single digits below
zero on Tuesday night will rise to the teens above zero by the
weekend.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1155 AM CST Mon Feb 19 2018

A band of light snow stretched from central Minnesota into
northern Wisconsin late this morning. The band will slowly lift
northward this afternoon and gradually decrease in intensity from
west to east. Visibility in the heavier snow band ranged from
around 1/4 mile to 1 1/2 miles. Think those visibilities will
continue before intensities decrease. Another round of snow is
expected tonight through Tuesday morning as an area of low
pressure moves from the Dakotas through the Upper Midwest. Wind
gusts will likely continue where the heaviest snow is located
through this TAF period.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  16   7  18  -1 /  90  80  70  10
INL  13  -3  13  -8 /  10  80  70  10
BRD  16   6  17  -5 /  80  90  60   0
HYR  20  10  22   0 /  90  80  60  10
ASX  18  11  21   5 /  90  80  70  20

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory until 6 PM CST Tuesday for WIZ001>004-
     006>009.

MN...Winter Weather Advisory from 6 PM this evening to 6 PM CST
     Tuesday for MNZ010>012-018-019-021-025-026-033.

     Winter Weather Advisory until 6 PM CST Tuesday for MNZ020-
     034>038.

LS...None.
&&

$$

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


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