Area Forecast Discussion
Issued by NWS Bismarck, ND

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021
FXUS63 KBIS 220344
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
944 PM CST Sun Jan 21 2018

.UPDATE...
Issued at 940 PM CST Sun Jan 21 2018

Expanded the Dense Fog Advisory into Emmons, Logan, McIntosh and
McLean counties based on GOES16 Advanced Nighttime Microphysics
RGB and webcam trends through 0342 UTC.

UPDATE Issued at 707 PM CST Sun Jan 21 2018

Based on current satellite trends, reports, and webcams through 01
Z, we expanded the Dense Fog Advisory westward. We will continue
to monitor trends for a possible expansion further west.

UPDATE Issued at 632 PM CST Sun Jan 21 2018

Current GOES-16 imagery and surface weather stations show areas
of patchy to dense fog persisting this evening along the James
Valley into north-central North Dakota. With the recent snowmelt,
cooler temperatures, and mixing remaining weak through tomorrow
morning, low level moisture continues to be sufficient enough to
support areas of fog and low stratus. A Dense Fog Advisory has
been issued for the northern James Valley and the Turtle Mountains through
noon CST tomorrow.

The 23 UTC iteration for the RAP and HRRR suggests areas of fog
will expand westward into central North Dakota towards US Highway
83 tonight. For these reasons, the Dense Fog Advisories may need
to expand westward later tonight.

&&

.SHORT TERM...(This evening through Monday)
Issued at 150 PM CST Sun Jan 21 2018

Low level moisture from snowmelt, lack of mixing and cooler
temperatures are leading to dense fog development along the James
Valley today. This fog is expected to persist and expand westward
later tonight. Therefore, a Dense Fog Advisory has been issued
for the northern James Valley through tomorrow morning.

Tonight, it appears the low stratus/fog will overspread areas
along, north and east of Lake Sakakawea and the Missouri River.
Short-term models continue to indicate stratus mainly across
eastern North Dakota and central North Dakota seeing decreasing
mid and high level clouds tonight with good radiational cooling.
Thus fog should develop on the west edge of the stratus tonight.

.LONG TERM...(Monday night through Sunday)
Issued at 150 PM CST Sun Jan 21 2018

The long term also appears quiet, for the most part. Models keep
the Tuesday clipper further north and east, leaving most of North
Dakota dry. There still appears to be a storm that will impact
portions of the Northern Plains Friday into Saturday, but there is
a lot of uncertainty with respect to the track of the storm and
associated impacts. Temperatures over the next week should be
slightly above normal, except Thursday which may be well above
normal, ahead of the aforementioned storm system. Models have
backed off on the precipitation potential Friday into Saturday. A
model blend still brings some chance pops Friday into Saturday but
the trend is certainly drier.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 940 PM CST Sun Jan 21 2018

Widespread low to very low LIFR conditions continue across the
James Valley and into the Turtle Mountains this evening in areas
of dense fog and stratus. Fog and low stratus will expand west
towards KBIS and KMOT through the evening and overnight. Fog and
stratus will likely persist through Monday morning with conditions
slowly improving during the afternoon.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until noon CST Monday for NDZ003>005-012-013-
021>023-025-035>037-046-047-050.

&&

$$

UPDATE...PA
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...PA



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