Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 172021
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
221 PM CST Wed Jan 17 2018

.SHORT TERM...(This afternoon through Thursday)
Issued at 221 PM CST Wed Jan 17 2018

Latest water vapor imagery shows upper level ridging over eastern
ND, with a quasi zonal flow into western/central ND this afternoon.
A compact upper closed low over southern Saskatchewan with its
trough axis into northern ND continues to move east with time.
The high resolution ARW West and NMM West develop a light wintry
mix of precipitation in association with the track of the upper
low over the Turtle Mountains between 00z and 06z Thursday.
The NAM/RAP/HRRR BUFKIT soundings show light freezing rain or
snow as being possible precipitation types. The gridded forecast
has a combination of both, with support from road temperatures
being below freezing.

Downsloping/westerly winds really having an impact this afternoon.
Rolla/K06D, with a westerly downsloping wind off the Turtle Mountains
experienced a temperature rise from 25F to 41F within 30 minutes.
Elsewhere, along and east of the Coteau, temperatures have quickly
risen into the upper 30s.

The best reflection of a cold front associated with this shortwave
trough aloft is noted at 850mb per KMOT BUFKIT sounding. A surface
reflection is never realized with this feature, and a return to
warm air advection and an increase in cirrus clouds return late
tonight through Thursday.

Per surface observations and latest webcams, gusty westerly winds
and drifting snow across mainly north to south orientated highways
in northern North Dakota is the highlight in the short term. In
addition, the North Dakota Department of Transportation Road
Condition map indicates scattered wet slush between Watford City,
Williston, and Minot. The METRo Roadcast forecast indicates road
temperatures falling below freezing late this afternoon, and
remaining below freezing until noon Thursday. With that in mind,
will continue with the Special Weather Statement highlighting the
melting and refreezing leading to icy roadways expected later this
afternoon through Thursday morning.

Otherwise, for tonight, the boundary layer remains mixed enough
to inhibit fog formation. And with warm air advection continuing/increasing
tonight, no stratus/low clouds are forecast at this time. However
as mentioned above, high level moisture will be increasing after
midnight. This will help temper overnight lows which are expected
to range from the mid/upper teens to the mid 20s.

For Thursday, a transitory ridge slides across western/central ND.
Models show a stream of high level moisture/500mb-300mb riding
through the ridge during the day. Current satellite imagery
upstream conveys the same message. Thus, expecting partly cloudy
to at times mostly cloudy conditions. With lighter winds, will not
receive the degree of downsloping as we saw Wednesday. High
temperatures will still remain well above normal, with highs in
the mid to upper 30s central, to lower 40s southwest.

.LONG TERM...(Thursday night through Tuesday)
Issued at 221 PM CST Wed Jan 17 2018

Two highlights this period. The first is a light wintry mix
possible across the northwest Thursday night. The second is light
snow possibly reaching far south central and into the southern
James River Valley late Saturday night through Sunday.

In terms of temperatures, expect above normal temperatures Friday
and Saturday, with highs in the 30s to lower 40s. This will be
followed by a gradual cooling trend Saturday through Tuesday, with
highs falling back into the teens to mid 20s.

For Thursday night, the upper level flow transitions from west to
southwesterly, and a shortwave embedded within the flow will push
into northwest ND. BUFKIT soundings suggest a wintry mix of light
freezing rain, sleet, and snow. Bumped up pops to high chance
based on forecast certainty and areal coverage expected in the
northwest. Will continue to highlight this in the Hazardous
Weather Outlook. A Special Weather Statement may be issued in the
near future to address any impacts if trends/forecast certainty
continue to rise.

Dry Friday through Saturday as a split flow in the west shifts
east in the plains. A southern stream upper low begins to evolve
and eject out from Colorado Sunday. It appears that the northern
stream across North Dakota will have some influence in suppressing
the bulk of precipitation south of North Dakota. However, latest
runs of the SREF and GFS Ensembles bring the northern fringes of
snow into far south central and the southern James River Valley
late Saturday night through Sunday. The operational GFS and ECMWF
keep the moisture hovering along and south of the border. Will
continue to watch the model trends as this system evolves over
the next couple of days. A progressive pattern continues beyond
Sunday, but details on the timing of any one system is to
uncertain at this time.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 221 PM CST Wed Jan 17 2018

Main aviation impact will be low level wind shear for all
terminals except KDIK. Timing ranges from 00z Thursday through 07z
Thursday. The exception to this is KMOT, where low level wind is
ongoing and will continue until 07z. Vfr cigs/vsbys this taf
period. SKC will transition to a bkn cirrus deck based at around
25kft late tonight through Thursday.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...KS
LONG TERM...KS
AVIATION...KS


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