Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 060657

Area Forecast Discussion
National Weather Service Bismarck ND
1257 AM CST Tue Dec 6 2016

Issued at 1231 AM CST Tue Dec 6 2016

No major changes made for this update. A significant winter storm
continues to impact the region. Blizzard conditions are expected
through Tuesday as additional snowfall tonight and tomorrow
morning combines with very strong winds to produce whiteout
conditions at times.

UPDATE Issued at 934 PM CST Mon Dec 5 2016

No significant changes to the going forecast. Very strong winds
continue across most of western and central North Dakota this
evening. Winds gusting to 48 MPH at Crosby and Mandan in the past
hour with many locations gusting in the 40 to 50 mph range. This
is producing widespread blowing and drifting snow, especially in
areas that received significant snowfall today. Even in areas that
did not receive much snow today can still expect some blowing and
drifting of the older snow, due to the very strong winds. From the
NDDOT website, no travel is advised across most of northwest and
central North Dakota. Interstate 94 remains closed between
Dickinson and Jamestown.

Currently, surface low pressure is situated near Fargo with the
associated upper level low between Dickinson and Bismarck. The
large deformation snow band associated with the surface low is
currently lifting northward through eastern ND and northwest MN.
However, the back edge of the snow is slowly pivoting back west
through central ND. Latest mesoscale models are depicting the
greatest snow amounts tonight through midday Tuesday from east
central ND into north central ND, or from Carrington, Harvey and
Rugby west through Velva, Garrison and Minot. In these areas
another 3 to 6 inches of snowfall could fall, with locally higher
amounts. Farther west, from Crosby to Beulah and Washburn,
Bismarck and Mandan, current mesoscale models are depicting
another 1 to 3 inches of snow through midday Tuesday. Again with
some locally higher amounts possible.

If this band does rotate back west as models depict, it`s possible
we could see very bad conditions in the Bismarck/Mandan area late
tonight through mid morning Tuesday as the additional snow
combines with the already strong winds gusting between 40 and 50
mph. Especially in open country outside of town.

No changes to current Warnings and Advisories. Updated text
products will be sent shortly.

UPDATE Issued at 626 PM CST Mon Dec 5 2016

Only changes with the early evening update were to adjust pops
slightly based on latest radars. All Advisories and Warnings
remain in effect. Snow is tapering off in the far west but strong
winds are producing blizzard conditions. Strong winds will move
into central ND this evening producing blizzard or near blizzard
conditions with the newly fallen snow. In addition, another inch
or two of snow is expected later tonight into Tuesday morning.
Snow, heavy at times continues over eastern portions of central
ND. Strong winds will move into this area after midnight. Thus the
Blizzard warning goes into effect for this area at Midnight.

UPDATE Issued at 453 PM CST Mon Dec 5 2016

Quick update to add Billings and Golden Valley counties to the
Blizzard warning. These counties remain in the deeper snowpack,
compared to the southwest. Area webcams also show significant
blowing and drifting snow.


.SHORT TERM...(Tonight)
Issued at 414 PM CST Mon Dec 5 2016

Headlines have been upgraded to a Blizzard Warning for much of
western and central North Dakota. Blizzard conditions are
occurring in northwest areas, supported well with observations
and public reports of visibilities of a quarter of a mile or less
and winds sustained around 30 mph.

An Upper level trough and an associated surface front were pushing
eastward across North Dakota. Sufficient mid-level lapse rates of 7
C/Km and atmospheric instability, in combination with ample
mid/upper level moisture, were creating a dynamic setup for snowfall
to continue through Tuesday.

The surface low is projected to phase with the upper level low, as
the system scoots north and east today and through the overnight
hours. Chances for snow are expected to linger over central areas
through Tuesday. Northwest winds will also remain strong through
Tuesday with gusts near 50 mph, creating the continued likelihood of
reduced visibilities and dangerous travel conditions.

A Blizzard Warning has been issued for much of western and central
North Dakota. Blizzard headlines have started in the northwest and
will progress eastward this evening and through Tuesday. As of now,
southwest areas remain in a Winter Weather Advisory until 16Z

.LONG TERM...(Tuesday through Monday)
Issued at 414 PM CST Mon Dec 5 2016

Blizzard conditions are expected across most of western and
central ND late tonight through Tuesday.

The 12 UTC model suite, including the GFS, NAM, and ECMWF, is in
good agreement showing a strong stacked low ejecting to near Grand
Forks by early Tuesday morning. The low is then forecast to move
slowly eastward during the day. Strong northwesterly winds are
forecast behind the low, with mean boundary layer winds near 35
kt and peak speeds at the top of the mixed layer pushing 50 kt.
Stout cold air advection will promote efficient momentum transfer
and wind gusts to 50 mph should easily be achieved, especially
in open/rural areas across central ND late tonight and Tuesday
morning. Guidance is also in agreement showing light to possibly
moderate snow continuing to fall in the cyclonic, "wrap-around"
moisture regime late tonight and Tuesday. Determining the westward
extent of that area of snow is one challenge to the forecast, but
the multi-model consensus is generally on board with it extending
to the Highway 83 corridor. The Baggaley Blowing Snow Model
supports blizzard conditions over a wide expanse of the area
through Tuesday afternoon, especially in rural areas, due to the
snow on the ground and light falling snow. Interrogation of that
model does suggest falling snow will be required to sustain near-
zero visibilities, so the westward extent of "wrap-around" snow
will ultimately be critical. The 12 UTC ECMWF is particularly
robust with higher amounts of snow all the way westward into the
Highway 83 corridor from 09 to 15 UTC, but even the GFS and NAM
simulated enough light snow that we were confident enough to post
a blizzard warning for that area. The fresh snowpack of 4 to 6
inches that fell Monday afternoon in south central ND will also
readily blow and drift.

Thereafter, strong cold air advection will continue to bring
Arctic air into the region the rest of the week. Forecast wind
chills to 25 below zero in multiple periods from Tuesday night
through Friday morning will likely require wind chill advisories
in later forecast releases. Model guidance suggests 500 mb flow
may back more westerly by this weekend, yielding some moderation
in temperatures, but that could come at the expense of more
snowfall occurring along the resultant tightening baroclinic zone.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1231 AM CST Tue Dec 6 2016

Widespread IFR and LIFR conditions are forecast across western
and central ND through Tuesday afternoon due to snow and blowing
snow. Gusty northwest winds to 45 kt in western and central ND
this evening will spread into the eastern part of the state late
tonight and then continue into Tuesday.


Blizzard Warning until 6 PM CST /5 PM MST/ this evening for

Blizzard Warning until 9 AM CST /8 AM MST/ this morning for

Winter Weather Advisory until 11 AM MST Tuesday for NDZ040-041-



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