Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 101612
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1012 AM CST Wed Jan 10 2018

.UPDATE...
Issued at 1012 AM CST Wed Jan 10 2018

Winter storm looks on track. Cold front is propagating through the
northern FA. Strongest winds and snowfall will be post-frontal.
There is no mist/freezing drizzle being reported ahead of the cold
front, so that is good. The strongest synoptic forcing from the
northern upper level wave still across Montana. Latest radar
imagery indicates mesoscale forcing (mid- level frontogenesis)
beginning across western/central North Dakota, which will continue
to propagate eastward through the day (with associated snowfall).
The strongest synoptic forcing will lag the mesoscale forcing,
which may hinder organized banding. Two main questions at this
point: 1) Will there be an area of 6+ inches of snow within the
heaviest band? and 2) will the winter storm warning need to be
upgraded to a blizzard warning? There remains low predictability
in both of the questions. Given the mesoscale forcing, there is
still a slight risk for 6+ inches of snow, although the strongest
synoptic forcing will not be aiding the frontal circulation. High
resolution models are coming in with higher QPF (0.40-0.50
inches), although location still uncertain. Will need to wait and
see if/where strongest radar returns set up before updating. For
potential blizzard conditions, again will need to wait and see.
Winds will likely be 25-35mph, so not quite 35 mph or greater.
With that said, with colder temperatures (single digits
above/below freezing) combined with concurrent falling snow may
not require as high of wind speeds to produce very low
visibilities. Will continue to monitor and update as needed.

&&

.SHORT TERM...(Today through Thursday)
Issued at 356 AM CST Wed Jan 10 2018

Winds and snow amounts continue to be the main headache for the
period.

Winter weather impacts of some sort continue to be expected across
the region. There is decent agreement of the surface trough axis
continuing to push into the CWA this morning, with the cold front
following behind it. Think the Arctic front will continue to push
south and eastward through the day, with falling temps in many
areas. While there will be some patchy fog out ahead of the front,
think that most of the precip will be along and behind the
boundary. The models have some precip starting to enter our
western counties by early afternoon. The global models continue to
show a trend of a fairly broad area of precip across much of our
CWA, including the northern counties. A few of the recent high-res
runs have been going a bit back south with the heavier precip
band, but not enough continuity to jump on it at this point. There
could be a very brief period of freezing drizzle as precip starts,
but think this band will be very narrow with minimal impact as
precip quickly changes over to snow. Snow amounts of 2 to 5 inches
across much of the area will be possible. A few of the models show
some weak mid level frontogenesis, but not very well positioned
with the synoptic scale lift. Thus, while there is the potential
for some banding, not overly impressed to include heavier amounts
in the grids.

Models have shown a slight decrease in wind speeds for this
afternoon and tonight. 925mb winds are 30 to 35 kts, which is
strong but could be higher. Cold air advection will provide a
strong wind push as the front comes down, but at this point think
that sustained winds will be mainly in the 20 to 25 kt range with
gusts to around 35. Baggley Blowing snow model has isolated to
scattered areas of blizzard visibility in portions of eastern ND
and the Red River valley counties. And that is dependent on the
snow band not trending back to the south. Given uncertainties and
the fact impacts will not be until late this afternoon into
tonight, have elected to keep headlines lower than the B word for
now. Highlighted our central counties with a winter storm warning,
as we should hit our 4 inches and 25 mph wind criteria and will
include near blizzard wording. Northwestern as well as the eastern
tier will see less snow or less wind, so will go with a winter
weather advisory for that area.

The snow will begin to taper off Thursday morning, with winds
decreasing. With the return of Arctic air wind chills will be down
in the 25 to 35 below zero range for a good chunk of the day on
Thursday with only minimal recovery.

.LONG TERM...(Thursday night through Tuesday)
Issued at 356 AM CST Wed Jan 10 2018

For Thursday night through Tuesday, Arctic air continues to build
into the Northern Plains. Upper troughing digs in through Saturday
morning and persists with nighttime radiational cooling and a strong
Arctic surface high building in to provide ideal conditions for
frigid overnight temperatures several nights in a row. Overnight low
temperatures Thursday night through Saturday night will be in the
teens to 20s below zero. Winds will be light, but still yield
dangerous wind chill values in the -20 to -40 degree range. Minor
relief may be felt Sunday as slightly warmer 850 temperatures allow
for high temperatures increasing to near or even perhaps a bit above
the zero degree mark, but a plunge back to frigid weather and
dangerous wind chill values will be felt again Sunday night through
Monday night.

As the Northern Plains sits in northwest flow aloft through the
weekend, two weaker clipper systems race through, producing
additional chances for light snow.  The first round of snow chances
arrive for Friday and continue to trend further southward run-to-
run. If this trend continues, light snow would likely only affect
areas along and south of I-94, if those areas even see snowfall. The
second round of potential light snowfall is for Sunday, but
confidence is much lower for this round.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 642 AM CST Wed Jan 10 2018

Expect VFR conditions early this morning for most of the area,
except perhaps along and north of DVL-GFK where patches of dense fog
are possible. Cigs will deteriorate to IFR/LIFR from NW to SE this
morning, remaining IFR/LIFR through tonight. As a cold front pushes
through from NW to SE today, winds will shift sharply from S to NW
and increase from 10 kts to 20 kts gusting to 35 kts. Snow to follow
the front, beginning near DVL and GFK around mid day. This combo
will cause BLSN and IFR/LIFR vsbys this afternoon through tonight.


&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...Winter Storm Warning from 3 PM this afternoon to noon CST
     Thursday for NDZ028>030-038-039-049-052-053.

     Winter Weather Advisory until noon CST Thursday for NDZ006-014-
     015-024.

     Winter Storm Warning until noon CST Thursday for NDZ007-008-016-
     026-027-054.

MN...Winter Storm Warning from 3 PM this afternoon to noon CST
     Thursday for MNZ002-003-029.

     Winter Weather Advisory from 3 PM this afternoon to noon CST
     Thursday for MNZ005-006-008-009-013>017-022>024-027-028-
     030>032-040.

     Winter Storm Warning until noon CST Thursday for MNZ001-004-007.

&&

$$

UPDATE...TG
SHORT TERM...JR
LONG TERM...BP
AVIATION...BP



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