Area Forecast Discussion
Issued by NWS Duluth, MN

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235
FXUS63 KDLH 220001
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
601 PM CST Tue Feb 21 2017

.UPDATE...
Issued at 541 PM CST Tue Feb 21 2017

Updated aviation section below.

&&

.SHORT TERM...(This evening through Wednesday)
Issued at 356 PM CST Tue Feb 21 2017

A weak low and cold front will traverse the Northland Wednesday into
Wednesday night bringing a mix of rain and snow, with only up to an
inch or so of snowfall expected for areas north of Highway 2 in
northeast Minnesota. Temperatures mild ahead of the front tonight
into Wednesday, but falling with some breezy winds behind the front
Wednesday night.

On the synoptic scale a weak low will approach the upper Midwest
from the west tonight, with a weak east-west oriented warm front
ahead of the low draped across the Dakotas into central Minnesota
resulting in some high clouds to develop. Little in the way of
precipitation is expected along the front due to fairly dry mid-
level air in place this afternoon, but chances increase tonight as
the warm front lifts north across the international border. This
will be due to increasing large-scale lift develops in the form of a
broad mid-level shortwave with a fairly potent vort max approaching
the region. With surface temperatures so warm, precipitation will
likely be a mix of rain and snow, leaning towards more rain than
snow. With the light rain possible and falling temperatures tonight,
areas of fog are possible tonight, especially in east-central
Minnesota into parts of northwest Wisconsin.

As the low moves from west to east across the upper Midwest
Wednesday, a light rain/snow mix (mainly rain) will fall and expand
in coverage as the colder air drops south out of Canada Wednesday
evening. Rain will change to snow, but only around an inch of snow
is expected for areas north of Highway 2. North winds will increase
with 10-15 mph winds gusting to near 25 mph overnight as
temperatures fall. Lows in the 20s across northeast Minnesota to the
low 30s in northwest Wisconsin - many locations reaching lows that
are near the normal *high* temperature for this time of year (26 at
DLH, 25 at INL).

.LONG TERM...(Wednesday night through Tuesday)
Issued at 356 PM CST Tue Feb 21 2017

The winter storm for Thursday night through Saturday has nearly all
the attention for this forecast, with the potential for some
significant accumulations across northwest Wisconsin and adjoining
areas of central Minnesota.  With the 12z runs, the GFS and ECMWF
have come into much better agreement, but am still seeing some
differences in timing, track and phasing beyond 12z Friday that
produce some significant differences in the snow amounts for the
forecast area.  The ECMWF has been so very consistent, but it has
shifted northwest from where it was before, and the GFS has made
another dramatic jump to the southeast.  The NAM is quite difference
from either of the other two, moving the upper and surface low much
faster to the northeast and is relatively weaker than the other two
models.  Have been favoring a ECMWF/GFS blend for today. Given the
preexisting thermal gradient across the Upper Midwest, am not
surprised to see some very strong QG dynamics with this storm that
should manage to produce significant snow totals somewhere along the
storm`s track. For now, have high confidence in bringing snow into
the forecast area Thursday night, with the best dynamics over the
forecast area Friday before the whole system bodily shifts northeast
and out of the area by Saturday morning. Snowfall amounts are still
a big question mark, but currently have a broad stripe of winter
storm warning potential snow for my southeastern counties beginning
late Thursday night, continuing through Friday night.  Have held off
for now as I would like to see a little better model agreement which
may come with tonight`s or even tomorrow`s model runs.

After the big winter storm, we have some small chances for snowfall
Saturday night, but am not looking at any significant accumulations.
The GFS is showing another round of snow for Monday night and
Tuesday, but it is quite dissimilar to the ECMWF solution so have
very low confidence in that. Either way, we are looking at
temperatures getting back towards normal values through the
weekend and early next week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 541 PM CST Tue Feb 21 2017

VFR conditions as of issuance time to continue until an upper
level disturbance brings a period of mixed precipitation across
the terminals. A leading wave of this may affect KINL as early as
04z tonight, but should otherwise hold off until 10z or later for
the remaining sites. Ceilings with this system is expected to
lower to IFR/LIFR in light rain, snow or sleet, with the worst
conditions for KINL and KHIB...and may not affect KBRD or KHYR
during the TAF period. Ahead of the wave at southern terminals
fog is expected to develop, with IFR or possibly even LIFR
visibilities in the 10z- 14z time range.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  35  41  26  36 /  10  60  50   0
INL  32  38  20  30 /  80  60  30   0
BRD  35  48  26  38 /  10  40  40  10
HYR  36  50  31  40 /  10  40  40  10
ASX  37  47  30  39 /  10  50  70  20

&&

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

$$

UPDATE...LE
SHORT TERM...JJM
LONG TERM...LE
AVIATION...LE



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