Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 131656

Area Forecast Discussion
National Weather Service Bismarck ND
1156 AM CDT Tue Mar 13 2018

Issued at 1155 AM CDT Tue Mar 13 2018

Surface high continues its trip down through eastern South Dakota.
High clouds were moving into the east/central, otherwise mostly
clear conditions continue across the area. Current forecast
remains on track.

UPDATE Issued at 948 AM CDT Tue Mar 13 2018

Remaining dense fog advisories have been cancelled with this
update. GOES-East Day Snow-Fog RGB still indicates some fog in
low lying areas of the northwest, southwest, and central Burleigh
and Kidder county. Would expect this patchy fog to mix out in the
next couple hours. Updated temperatures as well with the observed
trends as the lower elevation temperatures have been slow to
climb out of the single digits. Temperatures should rise quickly
once the shallow inversion layer begins to mix.

UPDATE Issued at 831 AM CDT Tue Mar 13 2018

Cancelled fog advisory for most of the central. GOES-East Night
Fog Difference product still indicates fog for areas of the
northwest and southwest so we continued the advisory in those

UPDATE Issued at 619 AM CDT Tue Mar 13 2018

Debated about cancelling portions of the dense fog advisory
across the area. The GOES 16 nighttime microphysics channel
continues to show areas of fog in between the main surface
observation sites. Will maintain the advisory for now as the
transition to daylight and weak mixing can often lead to fog
formation. Otherwise current forecast looks ok.


.SHORT TERM...(Today and tonight)
Issued at 352 AM CDT Tue Mar 13 2018

Fog this morning is the main highlight of the short term period.
Will expand the dense fog advisory to include all counties north and
east of the Missouri River...along with McKenzie County...and also
adding the 4 southwest ND counties (Bowman/Slope/Adams/Hettinger).

Currently, a strong upper level ridge was over the Rockies extending
well north into the Yukon Territory of northwestern Canada. This was
providing north/northwest flow aloft over North Dakota. At the
surface, a 1036mb high was centered over the Turtle Mountains/Devils
Lake Basin, extending into Manitoba to the north and South Dakota to
our south. Clear skies and light winds have allowed plenty of
radiational cooling, and evaporation/snow melt the past couple of
days has added plenty of low level moisture to much of the Northern
Plains. Areas of fog - some dense - have formed across parts of the
region. In western and central North Dakota, the fog first developed
along the Missouri Coteau area, and has since expanded into south
central ND, as well as the McKenzie County area (Watford City area)
and to much of Bowman County in the southwest. Nighttime sat pic
channels indicate fog expanding in the far southwest, as well as
across areas north and east of the Missouri River.

Each hourly run of the short term high res models in the past
several hours has depicted a successively more widespread expanse of
fog. These models indicate the areal extent of the dense fog
shrinking/dissipating by mid-morning, so will keep to the ending
time of the advisory of 10 am cdt/9 am mdt.

Later today the surface high is forecast to drift southeastward to
MN/IA/NE/KS/MO area, and the upper level ridge over the Rockies
expands eastward slightly. This will provide westerly winds aloft
bringing warm air advection from west to east today, resulting in
high temperatures in the low to mid 30s north and east of the
Missouri River...and upper 30s to lower 40s to most areas of the
south and west.

Another night of mainly clear skies and light winds tonight, as our
area remains between the exiting high to our southeast, a north
central Canadian high to our north, and developing low pressure over
the Rockies. It is possible we could see another night of patchy to
widespread fog, as continued evaporation of the snowpack resumes
today, providing more moisture to the lower levels of the
atmosphere. Looking at lows tonight to range from around 10 to 20F.

.LONG TERM...(Wednesday through Monday)
Issued at 352 AM CDT Tue Mar 13 2018

Warm air advection continues Wednesday as the upper level ridge
moves east into the Plains, and a large upper level low/trough moves
onshore on the west coast. This will result in southwest flow aloft
over the Rockies, and a lee side surface trough develops over
eastern Montana, with more warm southerly/southeasterly mid-level
flow. Wednesday should be one of the warmer days this week with
highs in the mid 40s southwest, and 30s northwest and central ND.

Early Thursday southwest flow develops over the Northern Plains as a
deep western trough sets up. The 00z global models are in decent
agreement with an embedded wave bringing a chance of a wintry mix of
freezing rain/sleet/rain/snow mix to western North Dakota on

For the latter portion of the period global models diverge on the
progression of the upper level western low. However with the
persistence of the low pressure to our west and an active pattern,
chances for rain and snow are in the forecast Sunday and Monday.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1155 AM CDT Tue Mar 13 2018

Overall this taf period, expect mostly vfr cigs/vsbys. The
exception is KBIS which will likely see patchy fog/mvfr vsbys
(5sm) from 06z Wednesday through 15z Wednesday. KJMS will experience
sct003 and vcfg between 11z and 17z Wednesday. There is low confidence
at this time of lifr cigs/vsbys at KJMS.

For planning purposes, an area of mvfr cigs will spread into KMOT
and KJMS just beyond this taf period, between 18z and 20z Wednesday,
and likely continue through Wednesday evening.




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