Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 071749
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1149 AM CST Thu Dec 7 2017

.SHORT TERM...(Today through Friday)
Issued at 352 AM CST Thu Dec 7 2017

The Northland remains between a surface low situated over western
Quebec Canada and high pressure over eastern Colorado. There is some
subtle surface ridging over the Northern Plains this morning, which
should keep much of the region dry through this morning. The only
areas that could see some light snow will be along the South Shore
as some light lake enhancement will be possible. The convective-
allowing models, including the NAMNest/NMM/ARW, are progging a band
of light snow developing over the Bayfield Peninsula of northern
Wisconsin due to a weak gravity wave feature. However, precipitation
amounts should be limited as the moisture profile looks fairly dry
in the low-levels. Still, it wouldn`t surprise me to see some flakes
over the Bayfield Peninsula through the afternoon as the NAM/RAP
model soundings both indicate a shallow saturated layer in the
dendritic snow growth zone. Increased PoPs a little into the chance
category to account for this, but limited the QPF due to minimal
moisture. Westerly winds will remain slightly gusty today due to a
moderate surface pressure gradient still in place. Some small
chances of light snow will increase north of Minnesota Highway 2
this afternoon as a weak surface wave moves in with some weak lift,
per the Thaler QG omega progs. Introduced some slight chance PoPs
along the International Border this afternoon, expanding southward
across the region tonight. Not expecting any accumulation with this
wave, however, as minimal moisture remains in place. Temperatures
today and tonight remain on the chilly side, with highs ranging from
the middle to upper teens. Lows tonight dip into the single digits
above zero north to the lower teens to the south.

Our weather pattern becomes a bit more active for Friday as a mid-
level shortwave trough quickly dives southward from Manitoba, with
an embedded lobe of positive vorticity advection. Some enhanced mid-
level isentropic lift will accompany this shortwave, along with a
strong maxima of 850-300 mb layer omega. NAM model soundings
indicate a deeper saturated profile as well, so chances of snow look
to increase. The best chances of precipitation will occur Friday
afternoon and evening, with generally 1 to 2" of new snowfall
possible across the Northland. Temperatures Friday will once again
remain cold, but temps slightly warming up, with highs in the teens
north, to the lower to middle 20s south.

.LONG TERM...(Friday night through Wednesday)
Issued at 352 AM CST Thu Dec 7 2017

A fast-moving upper level shortwave will continue to push southward
across the Northland on Friday evening, resulting in widespread
light snow across the southeast half of the CWA. The shortwave will
exit the CWA overnight, with the focus then shifting to the south
shore of Lake Superior. Lake effect snow is expected to develop
behind the departing system, and continue into Saturday, before
winds become westerly in the afternoon. Several inches of new snow
will be possible, especially along the Gogebic Range of Iron County.
The meridional upper level flow at the beginning of the period will
gradually become a bit more northwest over the weekend, allowing
somewhat warmer air into the region. Highs on Saturday will be in
the teens, with highs on Sunday ranging from the 20s to lower 30s.
Another clipper-type system will move through the region on Sunday
night and Monday, bringing another chance of light snow to the
Northland. Lake effect snow will again be found in the wake of this
system, namely Sunday night through Monday night. The next clipper-
type system will move southward across the region on Tuesday and
Tuesday night. The GFS is a bit slower with this system, but
otherwise the deterministic models are in pretty good agreement
concerning this low pressure system. More snow will be possible on
Tuesday and Tuesday night, with a few inches of snow possible. Lake
effect snow will again be possible after this system moves through.
Temperatures for the upcoming work week should generally be in the
teens and 20s for daytime highs. Lows will range from the single
digits below zero to the single digits and teens.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1149 AM CST Thu Dec 7 2017

VFR conditions covered much of the Northland as of late morning
with some patchy MVFR in light snow over portions of the Iron
Range/Arrowhead. A trough will be moving through the Northland
late today into tonight and will bring increasing MVFR ceilings
and the chance for more snow showers. MVFR with possible IFR
visibilities will occur with the snow showers. MVFR ceilings will
continue through Friday morning for most areas.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  18  13  21   5 /  10  20  70  40
INL  15   6  16  -2 /  20  30  70  20
BRD  19  15  26  11 /  10  10  50  30
HYR  18  12  22   8 /  10  20  60  70
ASX  19  15  23  10 /  20  30  60  70

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Small Craft Advisory until 4 AM CST Friday for LSZ121-145>148.

&&

$$

SHORT TERM...JTS
LONG TERM...DAP
AVIATION...Melde



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