Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 192352
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
552 PM CST Thu Jan 19 2017

.SHORT TERM...(This evening through Friday)
Issued at 419 PM CST Thu Jan 19 2017

Hopefully everyone in the area got outside today, as conditions
are going to get progressively worse tonight, with clouds
overspreading the area from the south this evening, and then
precipitation spreading in from the south as well. Stratus is
currently over southwest Minnesota, eastern South Dakota and
Nebraska, and spreading in our direction. It should advance into
the forecast area here in 2-4 hours, continuing north during the
evening. RAP 900-925 RH progs have been good indicators of this
stratus during the daytime, and I expect that to continue, even
showing the stratus accelerating some this evening as would be
expected. Towards morning, an area of lift will rotate across the
area as a shortwave and weak vort max pushes across the area,
bringing a band of precipitation and warm temperatures aloft
across the area during the early morning and most of the day on
Friday. Of great concern are the surface temperatures, which
should dip to around freezing this evening and then fluctuate
around there through the night before rising again in the morning.
Have concerns that the precipitation will be freezing
drizzle/freezing rain instead of liquid rain/drizzle, causing
icing on local roads. Road surface temperatures this afternoon are
in the 40s and low 50s, with sub surface temperatures in the low-
mid 30s. It will be a very near thing, and is going to depend on
exact values as the precipitation moves in. In addition to all of
this, the warm temperatures over the snow are going to produce
copious amounts of fog again tonight. We are likely to need
headlines once again, but the specific location of the lowest
visibilities is uncertain still, though am favoring northwest
Wisconsin for the worst conditions overnight. Friday temperatures
should warm enough to bring precipitation back to liquid for most
locations as the precipitation comes to an end from south to
north.

.LONG TERM...(Friday night through Thursday)
Issued at 419 PM CST Thu Jan 19 2017

Wintry precipitation is expected Friday night through the weekend
with another system moving into the region around midweek.

A distorted Omega Block pattern will continue over the Plains
and Upper Midwest Friday evening through the weekend. An upper low
will meander northward through the region and into the Canadian
Prairies by Saturday morning. Warm air aloft and near the surface
will continue, leading to numerous challenges regarding precipitation
type. Another shortwave trough will rotate northward into the Upper
Midwest Saturday night and Sunday with precipitation chances
continuing. A mix of rain, freezing rain, and snow is likely Friday
night gradually switching over to a rain/snow mix and eventually all
snow by Sunday night. There is a potential for around one-tenth of
an inch of ice accumulation Friday night and Saturday in the high
terrain along the North Shore, with less ice accumulation expected
elsewhere. Surface temps will be the main governing force in
precipitation type through Saturday night. If forecast temps are even
a few degrees too cool, precip will likely be all rain instead of a
mix.

The blocking pattern aloft will continue during the first half of
the week with slight chances of rain or snow. A more organized
shortwave trough and slug of vorticity will move into the Upper
Mississippi River Valley Tuesday night through Wednesday night. The
midweek system will bring another round of rain/snow to the
Northland. Temperatures will remain fairly mild through the end
of the forecast period.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 552 PM CST Thu Jan 19 2017

Largely VFR conditions have been found across the TAF sites this
afternoon, but things will change considerably as the night wears
on. An elongated area of low pressure and upper level shortwave
will lift northward across the region overnight. Any VFR
conditions are likely to give way to IFR/LIFR or even VLIFR
overnight. A wintry mix of precipitation is expected, which will
generally turn to rain on Friday.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  32  37  31  37 /  30  80  50  70
INL  28  38  30  38 /  10  70  70  50
BRD  31  37  31  38 /  50  60  40  60
HYR  33  40  33  41 /  70  70  40  60
ASX  32  40  32  40 /  40  70  50  60

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&

$$

SHORT TERM...LE
LONG TERM...Huyck
AVIATION...DAP



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