Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 120030
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
630 PM CST Wed Jan 11 2017

.UPDATE...
Issued at 630 PM CST Wed Jan 11 2017

Cirrus clouds were streaming over the forecast area ahead of the
area of low pressure forecast to affect the region late tonight
and Thursday. With high pressure overhead, lowered the wind speeds
tonight, but not enough to change the headlines. Adjusted sky
grids to account for current and anticipated cloud cover.

&&

.SHORT TERM...(This evening through Thursday)
Issued at 300 PM CST Wed Jan 11 2017

A surface ridge of high pressure will pass through the Northland
this afternoon through tonight, promoting clear skies and light
wind speeds. It will be a great recipe for radiational cooling
tonight, especially considering the fresh snowpack. Temperatures
are expected to plummet to well below zero, and probably fairly
quickly beginning after sunset. Much of the Northland should drop
to -10 to -20 degrees, but our typical cold spots like Embarrass
and Brimson will likely make a run for -25 degrees. There will
likely be just enough wind, about 5 mph at times, overnight to
result in wind chills of 15 to 30 below zero across much of the
Northland overnight. The coldest of those wind chills will be
across most of northeast Minnesota, where a wind chill advisory
has been issued. Leaned on the some of the colder model guidance
for tonight`s low temperatures considering the set up.

A potent Canadian Clipper, currently over central Saskatchewan,
will make a swiping pass through southern Manitoba and northwest
Ontario late tonight and Thursday. It`s snowfall will be meager
because of its very cold and relatively dry air, but some snow
flurries might pass through far northern Minnesota. The bigger
impact from this Clipper will be its strong cold front, which will
bring one last big blast of Arctic air for the foreseeable future.
Strong pressure rises and cold air advection will make for more
efficient boundary layer mixing, likely tapping into considerable
wind aloft. The GFS and NAM model soundings have about 25 to 35
knots in the mixing layer. The GFS is the stronger model, with
even about 40 knots across far northern Minnesota during the
afternoon. Increased the sustained wind and wind gusts forecast.
Expect westerly to west-northwesterly winds of 10 to 20 mph,
gusting at times to 20 to 30 mph. Duluth, the Iron Range,
Borderland, Arrowhead, and North Shore could see stray gusts to
35 mph.

While the air temperatures will recover to the single digits above
zero by Thursday afternoon, the gusty winds will maintain wind
chills well below zero. The wind chills could plummet will likely
plummet into the 20 to 30 below zero range late Thursday afternoon
and evening.

A large area of high pressure will shift into the Northland from
the west Thursday night, resulting in weakening winds through the
night. This will be an even better night for radiational cooling
due to even clearer skies and lighter wind speeds, at least by the
wee hours of Friday morning. Air temperatures will likely plummet
to -15 to -30 degrees across much of the Northland, with the
coldest conditions across northeast Minnesota. Our typical cold
spots across northern Minnesota could make a run for -35 degrees.
The lack of wind for later in the night will mean wind chills
probably fairly close to the air temperature. We typically would
not issue wind chill advisories for situations where there is no
wind, but considering there will be enough wind late Thursday
afternoon and Thursday evening to justify a wind chill advisory,
we will might issue one tomorrow to continue through the night.

.LONG TERM...(Thursday night through Wednesday)
Issued at 300 PM CST Wed Jan 11 2017

A frigid end to the work week, then a slow but steady warm up
through the weekend into next week. Temperatures start off 15-20
degrees below normal on Friday with highs in the single digits
near zero, but warm up to around 15 degrees above normal next
Wednesday. As temperatures warm, there is chance for a wintry mix
Tuesday as

On the synoptic scale, Friday begins with a strong ~1048mb arctic
high pressure centered over the Northland. An upper low over
southern California will dig into the Baja peninsula over the
weekend, eventually ejecting into the southern Great Plains early
to mid next week. The northern stream will remain generally active
with a series of weak mid-level shortwave troughs moving across
the upper Midwest over the weekend before a ridging pattern
develops towards Tuesday. In earlier guidance, this mid-level
ridging was enough to direct the upper low over the Great Plains
towards southern Wisconsin into Michigan, limiting impacts to the
Northland, but the latest guidance is trending farther west with
the track of the low which could lead to a wintry mix late Monday
night into Tuesday. Temperatures aloft will warm enough to produce
a period of freezing rain or sleet across northwest Wisconsin -
wet bulbs rising to around +1 to +2C - but surface temperatures
will remain in the mid to upper 20s as precipitation begins,
warming up to near/above freezing Tuesday afternoon for a short
time. While difficult to pin down exactly when precipitation will
change over and what precip type will fall, the good news is that
the best large-scale forcing and low level moisture will remain
off to the south and east, so any mixed precip that does fall will
be light.

From mid-week on a fairly messy pattern at the surface and aloft,
but in general a lack of arctic air across the lower 48 into
southern Canada and a mid-level ridging pattern developing over
the Great Plains will lead to milder temperatures. Aloft, 850mb
temps will hover around 0C which is around the 90th percentile of
climatology for mid-January, with surface temperatures reaching
above freezing in some locations by the end of the week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 546 PM CST Wed Jan 11 2017

High pressure was covering the terminals at the outset with VFR.
A patch of MVFR cigs was near INL at the start of the forecast and
have a TEMPO through 01Z for a broken MVFR cig. An area of low
pressure with its cold front is progged to move past the terminals
from roughly 09Z to 17Z. Only some scattered to broken VFR cigs
are expected with the fropa with some light snow at INL. After
fropa, gusty winds are expected through the end of the forecast.
Some LLWS is possible at INL from 09Z to 12Z in the vicinity of
the surface low with a low level jet nearby.


&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  -9   6 -21   3 /   0   0   0   0
INL -16   1 -28   2 /   0  10   0   0
BRD -11   6 -26   5 /   0   0   0   0
HYR  -8   9 -21   6 /  10  10   0   0
ASX  -5  10 -14   7 /  10  10  10   0

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...Wind Chill Advisory until 10 AM CST Thursday for MNZ010>012-
     018>021-025-026-033>037.

LS...Small Craft Advisory from 9 AM to 10 PM CST Thursday for LSZ121-
     144-145-148.

     Small Craft Advisory from 9 AM Thursday to 4 AM CST Friday for
     LSZ141>143-146-147.

     Gale Warning from 9 AM to 10 PM CST Thursday for LSZ140.

&&

$$

UPDATE...GSF
SHORT TERM...Grochocinski
LONG TERM...JJM
AVIATION...GSF



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