Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 221801

Area Forecast Discussion
National Weather Service Bismarck ND
101 PM CDT Sun Oct 22 2017

Issued at 100 PM CDT Sun Oct 22 2017

Slight changes were made to POPs to reflect the current radar

UPDATE Issued at 922 AM CDT Sun Oct 22 2017

Made some minor adjustments to slow the eastward progression of
clouds and showers this morning. Otherwise current forecast looks
on track. Updated latest sensible weather elements and
interpolated to late morning values. No changes to current
headlines. Updated text products will be sent shortly.


.SHORT TERM...(Today and tonight)

Issued at 445 AM CDT Sun Oct 22 2017

Forecast highlights in the short term period will be mild and
breezy conditions today followed by cold frontal passages tonight
and resultant strong winds.

Currently, upper level trough moving off to our east with a
subtle SW/V mid level ridge moving into the Dakotas. Subsidence
underneath the ridge results in a clear sky over western and
central North Dakota at the moment along with weak pressure rises
contributing to a steady west/southwest wind. Despite the mixing
temperatures have dropped into the upper 20s to lower 30s over
areas of western ND with very dry air in place.

For today, a weak warm front will move east across the area
quickly followed by a potent embedded SW/V trough. Boundary layer
WAA across the south will combine with a breezy southwest flow to
help temperatures warm into the 60s south. 50s north where
temperature advection will be near zero. BUFKIT analysis indicates
winds today should remain sub-advisory with 30-35KTS within the
mixed layer at most so no headlines are planned for the today
period. Increasing clouds ahead of the wave after 12Z with most
areas with the exception of parts of the James River Valley
clouded over by 18Z. Left exit region upper jet dynamics pushing
into the Northern Plains coupled with moisture advection west to
east should contribute to light rain development across my
counties later this morning and afternoon once cigs lower to below
10K FT AGL. Chances decrease Sunday evening when models diminish
jet forcing and moisture.

For tonight, primary cold front sweeps east across western and
central ND this evening maintaining a steady and breezy westerly
wind. Secondary cold front then moves into northwest/north central
ND after 08Z accompanied by a strong embedded mid level impulse.
This secondary FROPA will be accompanied by a moderately strong
pressure rise bubble with 3-HR pressure rises 4-8MB (nam/gfs/high
res EC) moving into my north after 08Z and continuing south-
southeast before washing out mid morning Monday. Two recent events
during the nighttime we had 10MB 3 hour rises contributed to wind
gusts well over 45 MPH. Difference this time around we noticed is
the pressure surge will be accompanied by stronger CAA and
steeper lapse rates which would contribute to deeper mixing. Wind
advisory values should easily be reached with this pressure rise
bubble, with nam/gfs BUFKIT even higher advertising 50-55KTs
within the mixed layer. Opted to hoist a high wind watch from
08-15Z Monday morning across the north and central.

Mid level impulse driving the secondary cold front will also bring
a chance for rain and low level clouds into the north late tonight
then south-southeastward through Monday AM. Any precipitation
could also increase the mixing potential for stronger winds to
reach the surface.

.LONG TERM...(Monday through Saturday)

Issued at 445 AM CDT Sun Oct 22 2017

Active pattern prevails in the long term period.

Tight pressure gradient during the day Monday will see strong
northwest winds across the region. Highest winds are advertised
across the higher terrain of the southwest where BUFKIT is near
high wind warning criteria. Additional wind headlines are thus
looking likely for Monday across much of western and central North
Dakota during the day. Ongoing precipitation Monday morning should
diminish into the day as forcing decreases.

Upper level ridge over the western CONUS tries to rebuild
eastward Tuesday night into Wednesday. Some WAA on Tuesday will
see mild temperatures try to move back into our area. On Wednesday
a subtle mid level ridge and surface high pressure will be over
the Dakotas. Expect a tight temperature gradient with low 50s in
the northeast part of the state and 60s southwest.

We continue to watch closely the Wed night/Thursday (and onward?)
time period closely. Vigorous SW/V diving east-southeast from
southwest Canada Wed afternoon into the Northern Plains Wednesday
night will bring a strong surface low/cold front across the
Dakotas Wed night/Thursday. Both the GFS and ECMWF remain in
agreement with this though there still remain subtle differences
on timing and placement of the low. Strong CAA/gradient forcing
will likely result in a period of strong winds during and after
the FROPA.

Both models suggest a rain to snow changeover late Wed night into
the day Thursday from north to south when temperatures aloft
become subzero. Blended models have cooled temperatures the last
two days now, with daytime highs Thursday now in the 30s west and
north and 40s elsewhere. Another drop would not be surprising.

Biggest difference between the GFS/ECMWF is the evolution of the
SW/V as it moves into the north central CONUS. The GFS has
consistently been more progressive keeping this feature an open
wave and taking all forcing to our east by Friday. The EC the past
couple runs morphs the SW/V into a closed low over the Northern
Plains and maintains precipitation through the end of the work
week. The EC is also colder and thus puts moderate accumulating
snow across my northeast. We will continue to watch this system
closely and will also continue to mention in the HWO and social


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 100 PM CDT Sun Oct 22 2017

VFR conditions are expected. Hazards to aviation include strong
surface winds at all TAF sites. Also LLWS where winds diminish this
evening. Gusty southwest winds today will usher in warmer conditions
and mid level clouds with a few sprinkles. Winds will increase
tonight into Monday behind a cold front that will push southeast
across our area.


High Wind Watch from late tonight through Monday morning for



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