Area Forecast Discussion
Issued by NWS Duluth, MN

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561
FXUS63 KDLH 182344
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
544 PM CST Sat Nov 18 2017

.UPDATE...
Issued at 539 PM CST Sat Nov 18 2017

Clouds will be slower to erode tonight and we increased cloud
cover for most areas into early morning. We also expanded on the
mention of flurries across much of the Northland.

&&

.SHORT TERM...(This evening through Sunday)
Issued at 230 PM CST Sat Nov 18 2017

Minimal impact snow is expected for portions of the Northland
tonight through Sunday as some lake effect snow is expected this
evening and overnight along the Gogebic Range of the Lake Superior
snow belt. Also, some lighter snow is possible from Koochiching
county southeast to the Twin Ports and into northwest Wisconsin.

For tonight, lake effect snow should develop and continue through
tonight as colder 850 mb level air moves across the region. Delta-Ts
are looking more favorable with values dropping to near 20 below
zero. Considering steadily increasing lake induced CAPE between 300
to 400 J/kg on the RAP soundings at IWD, some decent lift will also
be in place. New snow between 1" to 2" along the Gogebic Range are
expected, with some isolated higher amounts. Also, there may be some
light lake effect snow over northeast Koochiching/northern St. Louis
this evening with moisture coming off Lake of the Woods, but not
expecting much impact or accumulations from this. Due to the colder
air moving in tonight, overnight lows should range from the middle
to upper single digits over the Borderland region, to the lower
teens over the south.

For Sunday, a sfc high pressure ridge will translate across the
region during the morning hours. The southerly return flow with 850-
700 mb layer warm air and moisture advection, which will support
some chances of light snow from Koochiching and Itasca counties
southeast towards the Twin Ports and into northwest Wisconsin Sunday
morning and afternoon. NAM soundings show a decent bit of dry air in
the low-levels, which should limit snow amounts, but still think
this will be a higher PoP/low QPF kind of event, so put in some high
chance PoPs along this WAA wing. Another cold day expected for most
of the Northland, except for our extreme southwestern counties,
which should be on the warm side of the WAA wing. Highs Sunday
should range from the upper teens/lower 20s over the Arrowhead and
into the middle 30s over the Brainerd Lakes.

.LONG TERM...(Sunday night through Saturday)
Issued at 328 PM CST Sat Nov 18 2017

The main story is there does not appear to be any substantial
weather to affect travel for related to Thanksgiving until possibly
after the holiday, sometime late this week. The beginning of the
week will be relatively mild, but it will get colder for the middle
of the week.

Southerly flow will develop across the Northland Sunday night and
continue into Monday, bringing relatively warm air into the region,
in response to a Canadian Clipper moving across southern Canada.
Highs will likely hit the 40s over much of the region Monday.

The Clipper will move through Ontario Monday night and Tuesday. It`s
cold front will blow through the Northland overnight Monday into
early Tuesday, bringing a rush of Arctic air. Strong increases in
pressure and cold air advection will mean strong and efficient
mixing Monday night into Tuesday. The GFS and NAM have 30 to 40
knots within the mixing layer. The wind forecast was ramped up to
gusts of 25 to 35 mph Monday night and early Tuesday, but may need
to trend even higher with subsequent forecasts. It would not be
surprising to see some gusts over 40 mph. Those with garbage service
Tuesday morning may want to weigh down their garbage cans!
Temperatures will plummet overnight into Tuesday morning. Wind
chills will be in the single digits Tuesday morning. There will only
be a little and slow improvement through the day Tuesday, with highs
getting to upper 20s to middle teens, but with wind chills in the
single digits to lower teens.

An area of high pressure will move through the Northland late
Tuesday and early Wednesday. This will bring a period of a bit more
mild weather, with highs in the lower to middle 20s. The latest GFS
and European suggest there could be a passing wave mid-level trough
which could bring very light precipitation (probably snow) through
the Northland Wednesday and/or into Wednesday evening. Added low
precipitation chances based on these latest runs.

Northwest flow will redevelop Thanksgiving Day as high pressure
moves into the Upper Midwest. Expect partly cloudy skies and highs
ranging from the middle 20s near the Canadian border to the low 30s
from central Minnesota into northwest Wisconsin.

It is not until after the holiday where there could be any
significant weather to affect travel across the region. The GFS,
European, and Canadian are suggesting another Canadian Clipper will
likely pass through somewhere in the region, but confidence is low
on timing and track based on significant model differences. The most
concerning model is the European, which has the most intense Clipper
and takes its track right through the Northland. This European run
has the Clipper`s center of low pressure tracking across North
Dakota, central Minnesota, and into northern Wisconsin Friday night
through Saturday morning. The European`s Clipper would mean a big
impact travel conditions across the Northland Friday night and much
of Saturday, with up several inches of snow and accompanied by
gusty, cold winds. On the other hand, the Canadian Clipper is much
farther north, well into Canada, and only bring a little light snow
to the Arrowhead. The GFS`s Clipper`s track and intensity is
somewhere in between, but much less threatening than European`s
Clipper. We will need to keep a close eye on this anticipated
Clipper and for its potential to significantly impact travel
conditions for the Northland late this week.

No matter the track of the late week Clipper, it looks like
temperatures will take another dive this weekend. Arctic air will
return, sending highs down from 30s on Friday to lower to middle 20s
on Saturday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 544 PM CST Sat Nov 18 2017

The MVFR ceilings will be slower to diminish tonight and we
delayed the clearing at all sites. Flurries will be possible under
any of these MVFR ceilings with snow showers reducing the
visibility at KINL and along portions of the South Shore where
lake effect snow will occur. The gusty winds will gradually
subside and back tonight, becoming southwest on Sunday. An area of
warm air advection will spread in mainly low VFR ceilings and
some light snow to portions of the Northland on Sunday. We went
with VCSH for most areas but later forecasts may have to include a
2 to 4 hour period of light snow.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  10  26  20  40 /  10  50   0   0
INL   5  23  14  38 /  70  20   0  10
BRD  12  35  23  45 /  10   0   0   0
HYR  12  29  21  44 /  10  20   0   0
ASX  17  28  23  44 /  30  30   0   0

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Small Craft Advisory until 4 AM CST Sunday for LSZ121-144>148.

&&

$$

UPDATE...Melde
SHORT TERM...JTS
LONG TERM...Grochocinski
AVIATION...Melde



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