Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 181141

Area Forecast Discussion
National Weather Service Duluth MN
641 AM CDT Sun Mar 18 2018

.SHORT TERM...(Today through Monday)
Issued at 301 AM CDT Sun Mar 18 2018

After several days of abundant sunshine across the Northland, the
weather pattern will begin to shift, starting today, as clouds
will increase from the west, along with some small chances of
precipitation. The area of high pressure that has kept conditions
sunny and dry for the last several days has shifted to the south
over central Illinois, and will continue to the southeast away
from the region. Most areas this morning will see some sun before
clouds increase from the west later this morning and afternoon as
southerly return flow enhances moisture advection into the
region. At 08z this morning, current GOES-East satellite imagery
shows an overcast low-level stratus deck sneaking into the
Brainerd Lakes region. This stratus deck will only continue to
move eastward today. A subtle mid-level shortwave will ride the
ridge over the northern portions of our region, which will support
some small chances of precipitation near the International Falls
area today through tonight. RAP/GFS/NAM model soundings all
indicate a fairly shallow saturated layer in the low-levels, with
a thermal profile that is slightly colder than 0 degrees C, so
precip types appear to be either some light snow or some
drizzle/freezing drizzle, depending on the surface temperatures.
Some slick spots may develop on untreated roadways in this area
due to the freezing drizzle. Surface low pressure over Upper
Michigan will generate some on-shore flow along the long fetch of
Lake Superior, so maintained mention of chances of lake effect
snow flurries at the head of the Lake, including the Twin Ports.
850 mb to lake delta-T values don`t appear particularly
impressive, with values between 8 to 12 degrees C, but due to the
persistent northeast flow, and some 1000-850 mb saturation
lingering over the Lake, I felt it was better to keep the chance
of flurries through the day Monday.

A negatively-tilted longwave trough over the Intermountain West
states will generate a Colorado Low that will translate across
northern Oklahoma/southern Kansas region tonight, and through the
day Monday. We will be on the northern fringe of the inverted
trough of this low, but ahead of a mid-level shortwave that will
translate eastward. A corridor of 850-700 mb Q-vector convergence
will linger over the Dakotas Monday morning as well, and slowly
translate eastward over north-central Minnesota with this
shortwave. Through Monday afternoon, only some slight chance PoPs
are in the forecast over Cass and Crow Wing counties. Little QPF
is anticipated over this area. However, skies will continue to be
partly to mostly cloudy for Monday. Temperatures will also be a
bit colder Monday, with highs falling back into the lower to
middle 30s, which are slightly colder than seasonal average for
mid March.

.LONG TERM...(Monday night through Saturday)
Issued at 242 AM CDT Sun Mar 18 2018

An inverted trough will extend into the eastern Dakotas or
western Minnesota Monday evening with an upper level shortwave
moving through the Northern Plains. These features will move east
Monday night into Tuesday with the inverted trough weakening as it
does. Low level flow will be easterly through most of the period and
there will be several opportunities for mainly light lake effect
snow. A chance for light snow will occur over portions of northern
Minnesota and far northwest Wisconsin Monday night and Tuesday as
the upper wave and inverted trough move in but at this time, any
accumulation looks to be light. As the inverted trough weakens,
surface high pressure will reestablish itself and the upper level
trough will exit the Northland Wednesday. There will be chances for
lake effect snow Tuesday through Wednesday around Lake Superior,
including parts of the North Shore, Twin Ports, and parts of the
South Shore. Despite 850MB temperatures over eastern Lake Superior
as low as -14C at times, the lake effect snow is expected to be
light as plenty of upstream dry air is in place.

Most areas will be dry Tuesday night through Thursday night due to
high pressure. An area of low pressure will strengthen Thursday
night in the Colorado/Wyoming region, then track east well south of
the Northland through late week/weekend. Although the GEM/ECMWF/GFS
all show this low in some form, there are major differences in the
timing and some differences in the track. Portions of the Northland,
mainly the southern half, will have a chance for snow and rain late
week into the weekend. There is far too much uncertainty at this
time to speculate on the accumulating snow potential.

Tuesday will be the coolest day of the period with highs in the mid
twenties to lower thirties, but temperatures will moderate with
highs in the mid thirties to lower forties Thursday and Friday.


.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 641 AM CDT Sun Mar 18 2018

The run of widespread VFR conditions will be coming to an end
across the Northland through the TAF period. A cold front will
move into northern Minnesota from Ontario today and a trough will
also move in from the west. These features along with an upper
level shortwave and lake processes will combine to cause VFR
ceilings then MVFR today into tonight. There may also be enough
forcing for some light precipitation, which will fall as rain or
snow today then light snow tonight with some patchy freezing
drizzle toward KINL.

The wind will be on the increase through the period, especially
around Lake Superior late this afternoon through tonight.


DLH  41  20  30  14 /  10  10  10  10
INL  40  16  33  11 /  30  30  10  10
BRD  43  23  36  16 /  10  10  10  30
HYR  47  22  35  12 /   0  10  10  10
ASX  42  19  30  13 /   0  10  10  10


LS...Small Craft Advisory from 3 PM this afternoon to 10 PM CDT
     Monday for LSZ141>147.



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