Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 160856
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
256 AM CST Sat Dec 16 2017

.SHORT TERM...(Today through Sunday)
Issued at 254 AM CST Sat Dec 16 2017

A broad area of surface low pressure stretched from southern
Minnesota northwest into Saskatchewan this morning. The low will
move little and gradually weaken over the next 12-18 hours.
However, a shortwave will move in from the northwest today with
low level warm air advection/FGEN continuing. Light snow was
falling early this morning from the Phillips/Park Falls area,
northwest through the Twin Ports toward Bigfork, Walker, and Grand
Rapids. Easterly low level flow will was also producing some lake
effect snow as seen on KDLH radar between Two Harbors and Silver
Bay as of 0850Z. Light snow will continue this morning and
gradually move east and north. Lake enhanced snow will be
possible through the evening along the North Shore. Forecast
soundings show some drying aloft which will cause a loss of ice
today into tonight over much of the area. This may lead to areas
of freezing drizzle this morning over parts of central and
northern Minnesota with chances then developing over the rest of
northeast Minnesota into northwest Wisconsin. At this time,
amounts look light and we will not be issuing a Winter Weather
Advisory but will issue a Special Weather Statement to highlight
the threat. Most areas will receive less than an inch of snow
today with the exception of locations along the North Shore. The
low level flow was east early this morning but is forecast to veer
to east southeast through the morning, then to south this evening
and to southwest overnight. We expect snowfall from just
northeast of the Twin Ports to Grand Portage to range from 1 to 4
inches today with some locally higher amounts possible.

The precipitation will come to end tonight with Sunday expected to
be dry. Plenty of clouds are expected today and tonight but a
decrease in clouds should develop through the day Sunday over
northern Minnesota but clouds are expected to remain over much of
northwest Wisconsin.

Expect highs today in the teens over the Arrowhead and Borderland,
to the lower to middle twenties most other areas. Sunday will be
warmer with highs from the mid twenties to around thirty.

.LONG TERM...(Sunday night through Friday)
Issued at 254 AM CST Sat Dec 16 2017

A brief period of above-normal temperatures to start off the work
week, then the arctic air and below-normal temperatures return mid
to late week and stick around for the foreseeable future. A chance
for light snow Monday across northern Minnesota then a widespread
chance for snow Wednesday into Wednesday night, with periodic
chances for light lake effect snow showers along the south shore
snow belt region through the long term forecast period.

On the synoptic scale a warm front builds into the Upper Midwest
this weekend with warm air advection causing 850mb temps to rise to
near 0C in central Minnesota on Monday afternoon with highs in the
30s across the Northland, around ten degrees above normal. The warm
air does not last long as a cold front moves from west to east
across the region late Monday with a chance for snow along and ahead
of the front. Snowfall amounts are expected to be on the light side,
around an inch or so mainly limited to northern Minnesota during the
day and evening hours on Monday.

A more organized pattern develops towards mid-week as an amplified
mid-level shortwave trough enters the the Pacific Northwest Tuesday
night and digs southeast towards the Four Corners region on
Wednesday. A secondary mid-level shortwave trough will track east
across the Canadian Prairie into the northern Plains during this time
along the same trough axis, causing two areas of low pressure to
deepen - one over the Northern Plains and another over the southern
High Plains. As the northern low deepens a broad precipitation
shield will develop and build into the region Wednesday as a warm
front lifting north then pivoting and transition to a cold frontal
boundary as the two areas of low pressure combine and a strong cold
front with 850mb temps below 0C reach as far south as Texas tracks
east across the Mississippi River Valley towards Appalachia late-
week. For the Northland this pattern will result in a broad area of
precipitation chances Wednesday into Wednesday night followed by
below-normal temperatures into next weekend. Snowfall amounts
Wed/Wed night could be in the 3-5 inch range for a broad area of
Minnesota and Wisconsin, but determining exactly where the axis of
higher snowfall amounts will be at this point is difficult. The 00z
ECMWF, GFS, and many GEFS members have this axis over northern MN/NW
Wisconsin, but the Canadian has the axis further south which would
result in little snowfall for the Northland. There is a potential
for this pattern to support heavier snowfall amounts per GEFS and
ECMWF ensembles, but the spread of ensemble guidance and the
difficultly of predicting where the frontal axis will line up due to
complexities in the broad pattern lead to below normal confidence in
the forecast.

Beyond the snowfall chances mid-week temperatures will plummet to
below normal values as arctic air returns. The holiday weekend into
Christmas Day on Monday looks to be especially chilly with some
model solutions limiting high temperatures to the single digits
above or below zero Sunday and Monday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1144 PM CST Fri Dec 15 2017

Light snow has brought an area of MVFR/IFR ceilings and MVFR
visibilities to mainly KBRD, KDLH, KHIB and KHYR as of issuance
time. Expect this to continue through no later than 12z as the
snow band moves across the area, with no worse than IFR conditions
expected. Another, weaker round of light snow or flurries to move
in after 15z and continue through about 21z, with mainly MVFR
ceilings and visibilities. A drying trend may bring improving
conditions to KINL and KBRD after 03z, but timing is uncertain and
have left out for now.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  22  15  29  18 /  70  10   0   0
INL  18  14  29  18 /  60  40   0   0
BRD  26  17  32  19 /  30  10   0   0
HYR  24  17  30  17 /  60  10  10   0
ASX  23  16  31  18 /  40  10  10   0

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Small Craft Advisory until 4 PM CST this afternoon for
     LSZ141>143.

&&

$$

SHORT TERM...Melde
LONG TERM...JJM
AVIATION...LE



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