Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 210650

Area Forecast Discussion
National Weather Service Bismarck ND
1250 AM CST Sat Jan 21 2017

Issued at 1247 AM CST Sat Jan 21 2017

Will expand the dense fog advisory north and west to include all
the area except the far southwest with this update.

UPDATE Issued at 1011 PM CST Fri Jan 20 2017

Little change with this forecast update. Webcam and surface
observation trends through 04 UTC do not warrant an expansion of
the Dense Fog Advisory at this time. Will continue to monitor
through the night and into Saturday morning.

UPDATE Issued at 735 PM CST Fri Jan 20 2017

Quick update to expand the Dense Fog Advisory into McLean, Mercer
and Oliver counties per webcam trends through 0130 UTC.

UPDATE Issued at 608 PM CST Fri Jan 20 2017

Based on surface observation and webcam trends through 23 UTC,
issued a Dense Fog Advisory for much of the James River Valley and
portions of south central North Dakota through 18 UTC Saturday.
Will continue to monitor trends through the evening for a
potential expansion of the advisory.


.SHORT TERM...(This evening through Saturday)
Issued at 216 PM CST Fri Jan 20 2017

A continuation of low clouds/fog/areas of light freezing drizzle
across mainly central North Dakota is the theme for the short term
period. Far western North Dakota will mostly be detached from the
worst of the fog and any freezing drizzle threat at this time.

Latest water vapor imagery shows an upper low circulating over the
far southern James River Valley, with a 994mb surface low over
Mobridge South Dakota. The RAP13 is slightly too deep with the
surface low, while the NAM/GFS are both a bit too weak as compared
to the current surface observations. However the main message is
for a near vertically stacked system to emerge over south central
North Dakota Saturday. Surface convergence right over central ND
with northwest winds across western ND, and southeast to east winds
in central ND. The result will be for more of the same with
clouds/areas of fog and light freezing drizzle initially. The HRRR
visibility product maintains a wides swath of fog continuing
through tonight in central ND. BUFKIT soundings indicate
supercooled water droplets in the saturated layer with enough
vertical motion for light freezing drizzle. Not a lot of change
until Saturday night before soundings begin to moisten through the
column. High temperatures Saturday will be similar to Fridays,
especially with the low cloud canopy remaining overhead.

.LONG TERM...(Saturday night through Friday)
Issued at 216 PM CST Fri Jan 20 2017

The vertically stacked system from the short term period gets
nudged eastward late Saturday night. Sounding profiles moisten up
through the column allowing for a transition from light freezing
drizzle/light freezing rain to light snow Saturday night into
Sunday. However vertical motion remains weak behind the departing
system, and despite a chance of pops in the forecast, actual
amounts of liquid precipitation will remain very little, up to a
hundredth or so. Thus, despite a chance of pops, only a few spots
will receive a tenth of an inch of snow Saturday night.

Shortwave ridging Monday will be followed by a chance of snow
Monday night through Tuesday. A low ejecting northeast from the
Great Basin and into the northern high plains will provide for a
chance of snow mainly confined to southern North Dakota. Pops are
mostly delineated along and south of Interstate 94. At this time,
both the GFS and ECMWF keep the bulk of snow south of North
Dakota. Forecast snow amounts of between 1 and 2 inches possible
in far southern North Dakota Monday night through Tuesday. Along
with the snow in the far south, some potential for blowing snow
with boundary layer winds from the north between 10 and 20 mph.

Wednesday through Friday, overall a cyclonic north to northwesterly
flow dominates with mainly dry weather and highs in the 20s.


.AVIATION...(For the 06Z TAFS through 06Z Saturday night)

Issued at 1250 AM CST Sat Jan 21 2017

Widespread LIFR/VLIFR conditions in fog and stratus will continue
across northwest and central North Dakota overnight into Saturday.
Patchy freezing drizzle is also possible. Far southwest ND the
one area that may remain VFR for the 06 UTC TAF cycle.


Dense Fog Advisory until noon CST /11 AM MST/ today for



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