Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 140555

Area Forecast Discussion
National Weather Service Duluth MN
1255 AM CDT Sat Oct 14 2017

Issued at 1255 AM CDT Sat Oct 14 2017

Updated for the new 06Z Aviation Discussion below.

UPDATE Issued at 831 PM CDT Fri Oct 13 2017

Temps have dropped into the 30s at all but a few locations as of
830 pm. A few high clouds have formed over northwest Wisconsin
with some mid clouds just off to the southwest. Other mid clouds
in northwest Minnesota have been eroding as they move into the
drier airmass over the forecast area. Have made some minor
adjustments to account for these factors.


.SHORT TERM...(This evening through Saturday)
Issued at 338 PM CDT Fri Oct 13 2017

Cool air advection continues tonight. Loitering cloud cover over
Sawyer, southern portions of Ashland and Iron, and Price counties
will continue to erode during the next few hours. Clouds will
gradually move eastward into the Northland ahead of a developing
low pressure system arriving on Saturday. The cool air advection
should work to keep the boundary layer mixed overnight limiting
radiational cooling. Have lowered min temps in climatologically
cool areas, some as cold as the low 20s, where winds should
subside for several hours overnight. Rain showers chances increase
Saturday morning and especially Saturday evening as frontogenetic
forcing for ascent increases. Strong northeast winds are expected
along the Lake Superior shoreline during the afternoon, including
the Twin Ports and much of northwest Wisconsin.

.LONG TERM...(Saturday night through Friday)
Issued at 336 PM CDT Fri Oct 13 2017

The main story will be Saturday night into Sunday morning as a
deepening low pressure crosses Wisconsin and creates a deformation
zone across the Arrowhead of Minnesota. The latest model trends
have warmed the lower atmosphere a smidge which should be enough
to reduce snowfall accumulations. So for now, only have a half an
inch or so of accumulation away from the lake on Sunday morning.
Will have to keep a watch on a frontogenetic band the 12Z GFS is
portraying as that could locally increase snowfall rates and thus
accumulations though the axis falls over Lake Superior which would
help to mitigate snowfall. Either way, its best to be prepared in
case models are not picking up on the dynamic cooling that can
occur with higher snowfall rates especially in the overnight hours
when temperatures are at their lowest.

A weak shortwave on Sunday night may temporarily bring a precip
threat otherwise most energy goes north of the forecast area.
Afterwards, high pressure builds in for a string of beautiful fall
weather days.


.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1255 AM CDT Sat Oct 14 2017

VFR through much of the forecast. As low pressure moves into
Iowa, models indicate some timing with the beginning of the rain.
Used a VCSH mention to resolve some of the timing issues, then
predominate light rain after 00Z/15.


DLH  31  53  36  47 /   0  70  80  10
INL  25  50  30  47 /   0  60  40  10
BRD  30  53  34  49 /   0  80  80   0
HYR  29  57  38  49 /   0  70  90  20
ASX  31  56  39  50 /   0  60  90  30




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