Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 251320 AAC
AFDDLH

Area Forecast Discussion...UPDATED
National Weather Service Duluth MN
720 AM CST Sat Feb 25 2017

.UPDATE...
Issued at 720 AM CST Sat Feb 25 2017

Wind speeds at Grand Marais Harbor remain strong. The 7 AM
observation featured a wind gust to 48 kts (55 mph). Some high
resolution ARW core models (HRRR and DLHWRF) feature this ribbon
of very strong katabatic winds. The DLHWRF keeps speed max close
to shore, whereas the HRRR pushes the strongest winds onto the
lake in the next hour or so. Given the uptick in wind speeds in
the past hour, which supports the DLHWRF solution more than the
HRRR, elected to issue a Wind Advisory until noon for the southern
Cook zone. It`s worth noting, the DLHWRF keeps strong winds along
the shore as far south as Duluth through this morning.

Upstream radar echoes from KMVX and Environment Canada sites in
Manitoba continue to indicate a band of light snow moving toward
the Northland. Extended the POPs and snow showers northward to
include the entire western CWA. The band of light snow showers
will move eastward and gradually weaken with time. Taper off the
POPs by mid-afternoon.

UPDATE Issued at 627 AM CST Sat Feb 25 2017

Increased wind speeds and wind gusts for the next few hours along
the North Shore due to strong katabatic flow. Also added flurries
for central and southern St. Louis County and expanded the lake
effect snow showers in northwest Wisconsin. Light snow showers
were observed in the Red River Valley associated with an area of
weak DCVA. Added a mention of snow showers to my southwest and
southern zones as this feature moves through central Minnesota.

&&

.SHORT TERM...(Today through Sunday)
Issued at 502 AM CST Sat Feb 25 2017

At 330 AM light snow lingered over portions of Ashland, Iron, and
Price Counties in northwest Wisconsin. A narrow streamer of very
light snow drifted through the US Highway 53 corridor and passed
through over the office around 3 AM. Additional streamers of very
light snow were indicated by radar stretching from near Hibbing
and Virginia southeastward through Cotton, Alborn, and the Twin
Ports. The departing winter storm was centered over southern
Ontario with a closed 500 mb low over eastern Wisconsin. Quasi-
zonal flow was indicated from northwest Minnesota across the
Dakotas and Canadian Prairies and a weak clipper was found over
southern Manitoba with a cool front extending west into northern
Montana.

The winter storm will continue to pull away from the Northland
today. Low- and mid-level winds have veered northwesterly over
northern Minnesota and portions of northwest Wisconsin. The
northwesterly flow is favorable for lake effect snow over snowbelt
areas of northwest Wisconsin. In fact, a few light returns have
been noted on radar over northern Bayfield, extreme northeastern
Ashland, and northern Iron County. Expect the lake effect snow to
continue for the next several hours, until the upstream moisture
rotates east of our area. With the cold air advection aloft,
anthropogenic snow showers have intensified over central and
southern St. Louis County during the past hour. Think the very
light snow will continue past sunrise. Lake effect snow showers
should diminish later this morning or early afternoon as weak warm
advection in the 925-850 mb layer reduces instability. High
temperatures should tick a few degrees warmer today, especially
over the southwest portions of the CWA due to continued low-level
warm advection. The initial clipper will weaken as it moves into
northwest Ontario later this morning, opening to a surface trough.
An increase in cloud cover along the International Border and a
few flurries should be the only sensible weather change marking
the passage of the trough.

A more robust clipper will ride along the remnant front tonight
bringing a chance of light snow to the Northland. Confidence in
precipitation occurring remains high, but with very limited
moisture, the location of the snow remains somewhat uncertain.
Snow amounts around an inch or two are expected overnight, with
another inch possible on Sunday. Cloud cover with the transient
clipper should limit cooling overnight with lows from the middle
single digits north to the upper teens south. Highs on Sunday will
be a touch warmer in the south, but a few degrees cooler north.

.LONG TERM...(Sunday night through Friday)
Issued at 502 AM CST Sat Feb 25 2017

The period will start out with an upper level trough deepening
across the western CONUS with the flow west to southwest over the
Northland. The upper trough will move into the central CONUS
midweek then continue east with northwest flow developing over the
region as it passes in the Thursday/Friday time period.

An inverted surface trough will move over the Northland on Monday
with a chance for light snow or possibly a mix as temperatures
climb into the thirties for most areas. The chance for
precipitation will increase Monday night and Tuesday as a stronger
shortwave moves toward the area in southwest flow aloft. A
surface low will develop and track through the Upper Midwest or
toward the eastern Great Lakes depending on the model. The GFS is
further north with the track compared to the ECMWF/Canadian and
even the GFS ensemble mean. Temperatures do warm ahead of the low
and a wintry mix will be possible in spots. Some snow accumulation
will be possible Monday night into Tuesday night with this
system, but with the differences in track and possible mixed
precipitation types, it`s much too early to forecast amounts with
any certainty. Temperatures Tuesday will range from around 30 in
far northern Minnesota to the mid to upper thirties in northwest
Wisconsin.

The upper trough will still be over the region Wednesday which
may lead to some light snow in spots but significant precipitation
looks unlikely. The GFS then sends a stronger shortwave through
the Northland Wednesday night with a surface low tracking through
Minnesota. The ECMWF/Canadian have a much weaker shortwave and
only a weak surface reflection. At this time we have mainly low
POPs Wednesday night into Thursday. There may be some lake effect
snow showers that linger into Friday along portions of the south
shore of Lake Superior. Highs Thursday/Friday will cool a bit to
the lower to mid twenties along the International Border to 25 to
30 from the Brainerd Lakes region into northern Wisconsin.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 557 AM CST Sat Feb 25 2017

MVFR ceilings and light snow showers were occurring over far
northeast Minnesota and portions of northwest Wisconsin this
morning. These ceilings will gradually shift east through the day.
There were also some other localized affects going on with IFR
conditions reported at KEVM/KHIB which should last into mid
morning. Localized strong winds were also occurring along the
North Shore with KGNA gusting to 41KT in the 1156Z observation.
These strong winds will likely continue into mid morning.

A couple shortwaves will move through the area today and tonight.
The first shortwave will bring increasing clouds today, mainly
VFR ceilings from 3500-5000 feet. Some light snow showers will
also be possible. A stronger shortwave tonight along with a weak
surface low will bring a better chance for light snow and MVFR or
brief IFR conditions.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  27  15  28  13 /  20  60  60   0
INL  23   5  19   5 /  20  30  30  10
BRD  32  17  30  16 /  30  50  40   0
HYR  28  18  32  12 /  30  60  50   0
ASX  29  19  32  14 /  50  70  70  10

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...Wind Advisory until noon CST today for MNZ021.

LS...None.
&&

$$

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



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