Area Forecast Discussion
Issued by NWS Duluth, MN

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198
FXUS63 KDLH 231159 AAA
AFDDLH

Area Forecast Discussion...UPDATED
National Weather Service Duluth MN
559 AM CST Thu Feb 23 2017

.UPDATE...
Issued at 559 AM CST Thu Feb 23 2017

Update for the new 12Z Aviation Discussion below.

&&

.SHORT TERM...(Today through Friday night)
Issued at 308 AM CST Thu Feb 23 2017

A winter storm is still on track to affect portions of the
Northland, especially northwest Wisconsin. The models have come
into better agreement with this model suite and adjustments were
made to expected snowfall.

Water vapor imagery showed an upper trough over the western CONUS
with shortwave energy just coming onshore. Another shortwave was
exiting the region and the Northland will see a mostly dry day
today. There may be some early morning light snow over
Ashland/Iron Counties. Skies will be partly to mostly cloudy and
highs today will range from the 25 to 30 over far northern
Minnesota to the mid to upper thirties over much of northern
Wisconsin.

The western trough will move east today into tonight causing a
surface low to deepen and move toward the Iowa/Missouri/Illinois
border by 12Z Friday. Most of the models are in agreement on this.
An area of strong warm air advection and FGEN forcing will lift
north tonight into portions of northern Wisconsin bringing an
increasing chance for snow. The low will then move toward southern
Lake Michigan by 00Z Saturday with the Canadian a bit further
south. The last few runs of the NAM has been to shift the track
further south toward most of the other solutions. The low will
continue northeast Friday night to just north of Michigan by 12Z
Saturday. Snow will develop later tonight over northwest Wisconsin
then increase to the west and north Friday into Friday evening.
Heavy snow is still expected over portions of the Northland but we
did diminish snowfall amounts over far northeast Minnesota into
far northwest Wisconsin. Consensus is that the heaviest snow will
fall over Price/Iron/Ashland and portions of Sawyer Counties, then
diminish to the west/north of there. We did keep the Winter Storm
Watch area the same but did push it back to start at 06Z. We left
Douglas/Burnett/Bayfield/Pine Counties in the watch despite
cutting the snow amounts there the most. Although not likely, it
is possible the track of the low may shift further north bringing
higher snowfall there. There will likely be a lake contribution to
the snow over portions of the South Shore as well, especially
Friday into Friday night leading to heavy snow there. Continue to
monitor the latest forecast as this storm system is still
developing and some changes to expected snowfall is likely.

.LONG TERM...(Saturday through Wednesday)
Issued at 308 AM CST Thu Feb 23 2017

Summary: Lake effect snow showers continue Saturday for portions
of northwest Wisconsin, then another chance of light snow arrives
with a weak upper-level trough Sunday. A more potent storm system
appears on the horizon in the Monday night through Wednesday
morning timeframe.

The lingering affects of the departing storm system will continue
on Saturday and Saturday night. Cool cyclonic flow across western
Lake Superior will support lake effect snow showers for northern
Bayfield and northern Iron Counties. Temperatures across the
Northland will trend slightly cooler, near normal for Saturday and
Saturday night. Another upper-level trough will push southeast
out of the Canadian Prairies late Saturday night and across the
Northland on Sunday. This disturbance will bring a bit of Pacific
moisture with it and a chance of light snow. As of this morning
accumulations appear low, less than an inch. Lake effect snow
showers are possible once again over snowbelt areas of northwest
Wisconsin in the wake of the Sunday system. High temperatures
Sunday will trend a degree or two warmer.

A deeper trough of low pressure will move across the western
United States Monday afternoon and cross into the Plains on
Tuesday. Deterministic guidance features three distinct solutions
for handling this system, so confidence is low this morning, and
ensemble members feature a wide envelope of solutions. There is a
general trend toward developing a storm system in the Plains and
lifting it into the Mississippi River Valley by midweek. The
location, timing, and type of precipitation with this system is
quite uncertain. The GFS is slowest and driest with low pressure
taking shape in southern Montana and quickly scooting east into
the western Great Lakes. There are timing differences between the
ECMWF and GEM solutions, but both models bring some fashion of a
Colorado Low into the region. Meanwhile the GEFS mean is farther
south from the ECMWF solution. Each of these solutions brings
precipitation to the Northland, but amounts and types vary widely.
Maintained a consensus approach which yields chance POPs and a
rain/snow mix for the Northland beginning late Monday and winding
down Tuesday afternoon or early Wednesday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 559 AM CST Thu Feb 23 2017

Lingering stratus was found over much of the area this morning in
the wake of a quickly departing clipper. A cool front was
situated near the Minnesota/Ontario border as of 09Z and will
gradually progress southward and weaken this morning. A few holes
have developed in the stratus over northwest Ontario and will push
into the terminals later this morning. Orographic gravity wave
effects may bring a period of VFR conditions to HYR mid-morning
before the stratus clears by noon today. Attention then shifts to
the approaching storm system forecast to arrive late tonight. The
23.00Z and 23.06Z models have shifted the low track farther
southeast, postponing the onset of light snow at HYR and other
northwest Wisconsin terminals. Downshifted the light snow at HYR
to VCSH at 24.04Z with -SN at beginning at 24.10Z. Did not include
VCSH at any other sites this morning due to lower probability of
precipitation. Confidence in ceilings this morning is average with
confidence above average for all elements thereafter.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  32  18  24  11 /   0  30  40  40
INL  26  10  22   7 /   0   0  10  10
BRD  34  20  27  13 /   0  20  20  10
HYR  38  24  28  15 /  10  60  80  70
ASX  36  23  28  16 /  10  50  70  80

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Winter Storm Watch from late tonight through Saturday morning
     for WIZ001>004-006>009.

MN...Winter Storm Watch from late tonight through Saturday morning
     for MNZ038.

LS...None.
&&

$$

UPDATE...Huyck
SHORT TERM...Melde
LONG TERM...Huyck
AVIATION...Huyck



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