Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 220618

Area Forecast Discussion
National Weather Service Bismarck ND
118 AM CDT Thu Mar 22 2018

Issued at 1244 AM CDT Thu Mar 22 2018

Issued a dense fog advisory for all counties north and east of
Lake Sakakawea and the Missouri River. Latest GOES-16 night-time
microphysics RGB and night fog difference channel imagery shows
widespread dense fog rapidly developing across the James River
Valley. This fog will continue to spread northwest and west, and
falling visibilities have been noted with the latest observations
at Minot, Bismarck, Jamestown, and Harvey.

UPDATE Issued at 940 PM CDT Wed Mar 21 2018

For the late evening update the only significant change was to
delay the onset of fog.

Currently, there is an area of stratus/fog along the Canadian
border from Columbus and Portal eat to Kenmare and then more
patchy in nature from westhope to Rugby and Bottineau. Weather
Cameras in this area do not show much in the way of reductions in
visibility, with the exception of Kenmare. Also a quarter mile
visibility at Estevan so there is likely some patchy dense fog
along the Canadian border.

Elsewhere dense fog has yet to form, but we do see some
visibilities dropping down under 10SM. Too many factors pointing
to fog to back off, but we did delay the onset most areas and
limited fog to just patchy in nature over the southwest.

UPDATE Issued at 646 PM CDT Wed Mar 21 2018

For the early evening update we lowered sky cover across the CWA
this evening. Fog and stratus that lingered into the afternoon
finally dissipated except for a few areas remaining over the north
central and into the Turtle Mountains. Otherwise skies were clear.
This will likely set the stage for another round of fog/stratus
developing later this evening and overnight across northwest and
central ND.


.SHORT TERM...(This evening through Thursday)
Issued at 146 PM CDT Wed Mar 21 2018

Short term highlights include patchy fog overnight and the
oncoming winter storm beginning Thursday night.

Synoptically a ridge axis was centered over the northern Rockies
with northwesterly flow over the northern Plains. A surface high
remains in place under anticyclonic flow aloft. Light winds
associated with the high pressure and continuing snowpack
sublimation were enough to continue patchy fog in the forecast for

Thursday mid-level winds turn southerly in response to an upstream
trough approaching from the west. Warm air advection, focused to
the southwest, will bring surface highs into the low to mid 40s
across our west/southwest.

.LONG TERM...(Thursday night through Wednesday)
Issued at 146 PM CDT Wed Mar 21 2018

Overnight Thursday a potent shortwave ejects out of the deep
Pacific trough. Strong mid-level southerly winds reaching 50 kts
will amplify moisture transport ahead of the wave as NAEFS
guidance has been consistent on anomalous precipitable water
values reaching the 99th percentile with this system. Strong lift
associated with deep frontogenesis under broad synoptic ascent
above will create a swath of moderate to at times heavy precipitation
across northwest to south-central and southeast ND.

Precipitation type will be heavily dependent on the surface
temperature and ice presence within the atmospheric profile. A
thermal gradient oriented along the band of precipitation will
cause rain to be the dominant precipitation in the southwest with
a transition to snow towards the Missouri River and eastward.
Uncertainty in accumulation totals along and west of the Missouri
River through Lake Sakakawea exist with surface temperatures
around or above freezing early Friday morning.

The greatest snowfall accumulations continue to be favored across
north central North Dakota through the James River Valley where
thermal profiles will be coolest under the coupling of intense
synoptic/mesoscale forcing. As this band of snow passes to our
east late Friday the threat for freezing drizzle on the back end
arises with ice loss aloft.

The 12Z global model suite continues to indicate additional
opportunities for accumulating snow Saturday night into early next
week under an active southwesterly flow pattern, with uncertainty
in intensity and exact location of precipitation.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1244 AM CDT Thu Mar 22 2018

Widespread LIFR/VLIFR conditions in freezing fog tonight and
Thursday morning across most of northwest and central North
Dakota. Conditions improving late Thursday morning and through the
afternoon. Some uncertainty exists if the fog will impact
southwest North Dakota.


Dense Fog Advisory until noon CDT today for NDZ001>005-009>013-

Winter Storm Watch from Friday morning through Saturday morning
for NDZ002>005-010>013-021>023-025-035>037-047-048-050-051.



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