Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 080303
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
903 PM CST Thu Dec 7 2017

.UPDATE...
Issued at 903 PM CST Thu Dec 7 2017

A cold front was moving toward the international border at
03Z/9pm. Plenty of clouds ahead of and behind the front. Batch of
snow showers/flurries were just exiting the forecast area. This
snow was driven by a short wave/vorticity maxima dropping
southeastward through the region. May see some additional
flurries near the front.

&&

.SHORT TERM...(This evening through Friday)
Issued at 244 PM CST Thu Dec 7 2017

Low pressure remains entrenched over northern Quebec and Hudson Bay
as high pressure builds across the Central and Southern Plains. A
subtle surface ridge is in place across the Upper Midwest. However,
another weak upper trough will work through the region this
afternoon and into tonight. This will lead to chances of light snow
showers across much of the region for this evening and into
tomorrow, but with limited moisture in place, any activity will be
light and not lead to any accumulations. Winds are expected to
diminish this evening as the surface pressure gradient weakens.
Another cool night is expected, but not as cool as last night with
lows generally in the teens with some single digits in northern
areas. Cloud cover will prevent temperatures from cooling too
much, although if any breaks in the clouds can form, localized
areas may run cooler.

The pattern turns more active on Friday as the upper low over Hudson
Bay shoots off a bowling ball of vorticity that will quickly move
from Manitoba southeast through the Upper Midwest and out of the CWA
later Friday night. Light snow will move across the region during
the afternoon and quickly taper off across the Minnesota half of the
CWA heading into the early evening hours. Expecting a quick 1-2" of
snow accumulations with this system, but would not be surprised if
some areas come in a little higher than that. Thaler QG omega progs
bring a potent bullseye across the CWA making me worry this system
could be an overachiever. The system will exit the remainder of the
CWA Friday evening with lake effect snows hanging on across the
Gogebic Range that will extend into the next period. 12Z guidance
was not much different than previous runs, so no significant
changes were made with this system. Highs Friday will be slightly
warmer than today with most places seeing upper teens to middle
20s.

.LONG TERM...(Friday night through Thursday)
Issued at 244 PM CST Thu Dec 7 2017

The upper pattern will change little through the extended period. An
upper ridge will remain in some form over the western CONUS or just
offshore north into British Columbia. This will keep the Northland
in a northerly flow aloft with near or below normal temperatures.
Several shortwaves will move through the region bringing
periodic chances for snow.

Light snow will continue across much of the area Friday evening as
the clipper system passes south and east of the area. Winds will
switch to northerly during the evening and with cold temperatures
flowing over Lake Superior, lake effect snow will develop along
portions of the South Shore. Inversion heights, lapse rates, and the
low level winds will all be favorable for lake effect snow,
especially in the snowbelt region of Ashland and Iron Counties.
Snowfall during the evening will generally be a half to around an
inch over much of northwest Wisconsin with higher amounts of 2 to 4
inches from eastern Ashland County across northern Iron County. From
late evening through Saturday morning, lake effect snow will
continue with additional snowfall from 2 to 5 inches. Snow totals
from Friday afternoon through Saturday afternoon in the snowbelt of
Ashland and Iron Counties will from from 4 to around 8 inches. It`s
possible some higher amounts could occur. We will issue a Winter
Weather Advisory for Ashland and Iron Counties for now as the snow
will fall over a 18-24 hour period. It`s possible an upgrade to
warning may be needed if the drier air moving in later Friday night
is delayed.

Most areas will remain dry Saturday into Sunday with a chance for
lake effect snow continuing at times along the South Shore. Saturday
will remain cold with highs from 10 to 20 for most areas. Brief
warming will occur Saturday night into Sunday with highs reaching
the lower twenties in the Arrowhead, to the upper twenties to lower
thirties from the Brainerd Lakes Region to the Twin Ports and over
northwest Wisconsin.

Another clipper will move through the area Sunday night into Monday.
Both the GFS and ECMWF show this feature but the GFS has a stronger
low and is a bit further north and is slower with the track of the
low. The ECMWF would suggest mainly light snow amounts, a dusting to
2 inches but the GFS has more and also has winds turning more
easterly ahead of the low which would cause lake effect or at a
minimum, lake enhanced snow over portions of the North Shore to the
Twin Ports and along much of the South Shore Sunday night. Most of
the snow would fall Sunday night. Those with travel plans Sunday
night/Monday morning should monitor the forecast closely. Colder
temperatures move in Monday, with highs dropping to the teens to mid
twenties.

There will be periodic chances for lake effect snow along the South
Shore through the rest of the extended. The next chance for snow
inland from Lake Superior will be Tuesday night/Wednesday. Highs
will remain below normal, from the lower teens to lower twenties.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 528 PM CST Thu Dec 7 2017

A surface warm front was moving toward INL and BRD at the start
of the forecast. Meanwhile, an upper trof was moving through
northwest Wisconsin. A few snow showers were occurring where these
features were in the vicinity of each other. VFR cigs were found
over all terminals but INL where MVFR cigs were occurring. These
MVFR cigs will eventually affect all terminals this evening and
overnight as the warm front passes. A cold front associated with
a fast moving area of low pressure will move past the terminals
after 12Z and spread some light snow across the region. This will
lead to MVFR vsbys, with pockets of IFR, in some moderate bands
of snow. After the cold front passes, look for the wind to turn to
the northwest and the vsbys to gradually improve toward VFR.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  14  22   5  16 /  10  70  30   0
INL  10  17  -3  13 /  20  70  20   0
BRD  16  26  11  21 /  10  50  20   0
HYR  13  22   7  16 /  40  60  70   0
ASX  16  23  10  18 /  20  60  70  20

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory from 3 PM Friday to noon CST Saturday
     for WIZ003-004.

MN...None.
LS...Small Craft Advisory until 4 AM CST Friday for LSZ121-145>148.

&&

$$

UPDATE...GSF
SHORT TERM...BJH
LONG TERM...Melde
AVIATION...GSF



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