Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 200705

Area Forecast Discussion
National Weather Service Bismarck ND
105 AM CST Mon Feb 20 2017


Issued at 105 AM CST Mon Feb 20 2017

Two main updates for the early morning forecast package.

The first was to expand the dense fog advisory over all of
northwest and north central ND. High res models are persistent in
developing dense fog east of the current advisory, with recent
observations and web cam imagery backing this idea up.

The second update was to add a isolated thunderstorm mention over
my far southeast. Have been tracking a small cluster of weak
thunderstorms south of this area in northern SD, tracking
northeast towards the southern James River Valley of ND. More
favorable chances will then be east of our area after 10Z.

UPDATE Issued at 935 PM CST Sun Feb 19 2017

Dense fog continues over northwest North Dakota per latest webcams
and observations. Latest HRRR tries to spread the dense fog east
but so far it has been a bit reluctant to do so and visibilities
further east have been holding above a couple miles so far. Will
continue to monitor and if need be expand the advisory if
visibilities start to diminish. As for rain chances, have brought
a slight chance of precip in a bit earlier over the far west with
development over eastern Montana. Otherwise, remaining changes
were minimal.

UPDATE Issued at 630 PM CST Sun Feb 19 2017

Dense fog has developed over portions of northwest North Dakota,
with visibility in the Tioga and Stanley area dropping under a
quarter mile. Latest HRRR spreads this out over the northwest
this evening so have issued a Dense Fog Advisory for the northwest
5 counties in North Dakota. Will keep it until early Monday
morning when models suggest things starting to clear out. Will
monitor surrounding areas to see if they need to be added as the
evening wears on, but for now they look to be good with a few
areas dipping down a bit.


.SHORT TERM...(This evening through Monday)
Issued at 314 PM CST Sun Feb 19 2017

Tonight, a shortwave trough will begin to sweep across the
Northern Plains. A cold front associated with it will shift
through western and central North Dakota, with increasing chances
for precipitation after midnight. The bulk of the precipitation
should be rain, however, light freezing rain is a possibility
across north central North Dakota tonight into Monday morning.
Temperatures should only marginally support freezing rain for a
few hours during the early morning hours. Therefore, impacts
should be limited, but even a brief period of freezing rain can
cause hazardous travel.

.LONG TERM...(Monday night through Sunday)
Issued at 314 PM CST Sun Feb 19 2017

Monday looks breezy as the surface cold front and upper shortwave
trough sweep through. The system looks a little faster than
previously forecast, so the bulk of the low level cape and
shear should be further east by the time afternoon heating kicks
in. This will limit chances for thunderstorms to far southeast
North Dakota.

Another system slides through beginning Tuesday afternoon through
Wednesday afternoon, mainly affecting northern North Dakota.
Colder air will filter in behind this system late Wednesday into
Thursday. Rain is forecast to change over to snow across the
north Tuesday night. There is the potential for up to one inch in
the far north. Across the south, expect mild temperatures Tuesday
with highs in the 50s, and possible lower 60s southwest. Cooler
Wednesday with highs in the lower 30s north to mid 40s south.
Another system slated for Thursday through Friday continues to
trend snow chances south of Interstate 94. Because of this more
southerly track, colder air via a northerly flow will encompass
all of western and central North Dakota. Expect highs only in the
20s Friday and Saturday.


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

Issued at 105 AM CST Mon Feb 20 2017

Widespread LIFR/VLIFR conditions in fog and stratus will persist
over northwest North Dakota (KISN) and eventually expand east
early this morning into KMOT and possibly southeastward around
11-12Z perhaps impacting KBIS and/or KJMS. Conditions will improve
Monday afternoon from west to east.


Dense Fog Advisory until 9 AM CST /8 AM MST/ this morning for



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