Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 252104

Area Forecast Discussion
National Weather Service Duluth MN
304 PM CST Sat Feb 25 2017

.SHORT TERM...(This evening through Sunday)
Issued at 302 PM CST Sat Feb 25 2017

Chances of light snow showers will increase during the evening and
overnight hours as a weak clipper system moves through the region.
Weak 1000-850 mb frontogenetical forcing looks to be associated
with this system. Latest RAP/NAM model soundings are showing good
low-level moistening, which should support dendritic snow growth
as a cold air mass stays put. Isentropic lift should be modest as
subtle 850 mb warm air advection moves through the region before
intensifying as a mid-level shortwave trough moves in Sunday
morning, providing more robust lift, with the best isentropic
lift values developing by mid-morning Sunday. The latest high-res
models, such as the NAMNest and WRF ARW/NMM models are progging
higher reflectivity values in a southwest to northeast orientation
across the forecast area, which corresponds to this enhanced
lift. There is some concern for the support of snow late Sunday
morning as the GFS/NAM model soundings are indicating a layer of
dry air near the sfc, which could hamper any snow that does
develop, sublimating before reaching the ground. Still thinking
that there will be some light snow, especially overnight and
Sunday morning before the drier low-level air develops by late
morning into the afternoon. By Sunday afternoon, the mid-level
shortwave will move off to the east, which will reduce the chances
of precipitation. There should be lingering chances of snowfall
across northwest Wisconsin Sunday afternoon as the shortwave exits
and should be off to the east by Sunday evening. Overall, total
snow accumulations between 1 and 3 inches are expected through the
day Sunday for much of the Northland, with the heaviest amounts
expected from the northern Pine/southern Carlton county area
northeast to the Bayfield Peninsula and southeast towards the
Gogebic Range. While the snow amounts look to be relatively
light, there could still be some slick spots and reduced
visibilities on the roadways in heavier snows, especially Sunday

.LONG TERM...(Sunday night through Saturday)
Issued at 216 PM CST Sat Feb 25 2017

Model solutions are different Sunday night through Tuesday night
with the handling of the next system due to bring some precipitation
to the forecast area. They include the strength and orientation of
the upper trof, the amount of QPF, and the track/depth of the
surface low. As a result, have used a blended approach and toned
down the QPF, leaning towards the WPC forecast. This results in
lower and reasonable snow amounts. Rain will mix in with the snow
Tuesday and Tuesday evening before enough cold air works into the
system to change back to all snow. As the system departs Tuesday
night and high pressure begins to build, there is an opportunity for
lake effect snow showers along the south shore. The cold air is not
very deep, and the amount of dry air that may work into the lake
effect processes will affect snow amounts. The lake effect snow
showers will wind down on Wednesday as the dry air prevails. An
upper level long wave trof is progged to move over the region
Wednesday and Wednesday night. With the dry air already in place, it
will be tougher to generate any amounts. On Thursday, the ECMWF
and GEM have high pressure building across the region, while the
GFS generates snow showers. Leaned toward the ECMWF/GEM blend.
More lake effect is possible Thursday afternoon and night, along
the south shore of Lake Superior, before diminishing. Again the
drier air will play a role in snow amounts. High pressure will be
over the area for Friday.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1140 AM CST Sat Feb 25 2017

Ahead of a cold front in northwest Minnesota, mainly VFR ceilings
were found across the terminals. Some spotty flurries were also in
the neighborhood. As the cold front passes, look for MVFR
ceilings and areas of light snow. Vsbys will vary from VFR to
MVFR in the vicinity of the light snow tonight through the end of
the forecast. The snow will diminish from northwest to southeast
Sunday morning.


DLH  15  28  13  36 /  60  60   0  10
INL   5  19   5  31 /  30  30  10  30
BRD  17  30  16  40 /  50  40   0   0
HYR  18  32  12  39 /  60  50   0   0
ASX  19  32  14  39 /  70  70  10  10




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