Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 182202

Area Forecast Discussion
National Weather Service Duluth MN
402 PM CST Thu Jan 18 2018

.SHORT TERM...(This evening through Friday)
Issued at 402 PM CST Thu Jan 18 2018

At 330 PM, there was a great deal of cloud cover across the
Northland. Low clouds were generally confined to north central
Minnesota and the Arrowhead, as well as far northern Wisconsin,
close to Lake Superior. Meanwhile, high clouds were spreading
across the rest of the region from the west. Temperatures this
afternoon ranged from the upper 20s across the north, to the mid
30s south.

The focus for tonight and Friday will be cloud cover, as well as
the potential for some very light precipitation. Low clouds lingered
behind a departing upper level shortwave from this morning, and a
lot of the model guidance indicates that the low clouds could
linger across the the Arrowhead into tonight. Meanwhile, high and
eventually mid clouds will spread into the region ahead of an area
of low pressure moving across southern Canada. Southerly winds
ahead of the low will bring mild temperatures and increasing
moisture to the region. A warm front will push northward across
the region tonight, followed by a cold front on Friday. Low level
moisture pushing across the region on Friday could bring some
light freezing drizzle or drizzle to northern areas.

.LONG TERM...(Friday night through Thursday)
Issued at 402 PM CST Thu Jan 18 2018

The main concern during the long term continues to be the winter
storm which will move through the region Sunday through Monday

The forecast remains largely on track Friday night through
Saturday night. The Northland will be under quasi-zonal flow as a
longwave trough digs into the western United States. Temperatures
will remain above normal, but will trend cooler compared to
Thursday night and Friday.

The longwave trough will begin to move out of the western United
States and into the Plains Saturday afternoon with lee
cyclogenesis forecast over southeast Colorado. Low and mid-level
winds will turn southerly in advance of the digging trough and
will bring Gulf moisture northward through the Middle Mississippi
Valley by Sunday morning. The surface low is forecast to lift
northeastward toward western Iowa by Sunday evening.
Precipitation is forecast to develop to the north and west of the
low. Light snow is expected to push into our southern zones
Sunday morning. A wintry mix of freezing drizzle may accompany
the snow as it begins. Snow, possibly mixed with drizzle or
freezing drizzle, will continue to spread across the remainder of
the Northland through Sunday night. The storm system is forecast
to lift out of the region by Tuesday morning with lingering lake
effect snow showers in northwest Wisconsin.

The 12Z deterministic GFS, ECMWF, and GEM have shifted farther
south with the storm track, which has pushed the axis of the
heaviest snow farther south as well. Based on the shift in the
storm track, a measured approach to snow totals continues to be
the best course of action. There is a potential for more than 6
inches of snow south of a line from the Brainerd area northwest
through Cotton and into the Arrowhead, including the Twin Ports.
Lower totals seem likely north of that line across the remainder
of the forecast area. With details remaining fluid, confidence is
average in the forecast for an event which won`t begin for
another 60 hours. Anyone with outdoor or travel plans this
weekend into early next week is encouraged to keep up with the
forecast and plan ahead for the potential of heavy snow.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1118 AM CST Thu Jan 18 2018

With the exception of some MVFR (marginal IFR) at the start of the
period, we should generally see improvement this afternoon as the
surface frontal boundary pushes east and we get into some
subsidence in the wake of the shortwave evident in water vapor
imagery over Lake Superior. Through the remainder of the period we
will see some increase in mid/high clouds which are spilling down
the east side of the upper ridge centered from Saskatchewan south
into the desert southwest. Some MVFR fog and perhaps scattered low
clouds can be expected at most locations tonight given the
increase in boundary layer moisture owing to the warmer
temperatures and melting that is occurring. Main uncertainty is
with how long current low clouds will linger this afternoon and
whether visibilities will be lower than expected overnight (and if
we`ll see any low ceilings develop).


DLH  22  36  24  34 /   0  10   0   0
INL  19  38  22  32 /   0  20  10  10
BRD  21  38  23  36 /   0  10   0   0
HYR  21  39  24  38 /   0  10   0   0
ASX  23  40  27  37 /   0  10   0   0




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