Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 101023

Area Forecast Discussion
National Weather Service Bismarck ND
423 AM CST Sun Dec 10 2017

.SHORT TERM...(Today and tonight)
Issued at 345 AM CST Sun Dec 10 2017

Another very mild day today, followed by strong winds tonight
highlight the short term forecast.

With a very mild start with 10 UTC temperatures in the 30s across
most of the area, favorable westerly winds through the day,
dwindling snow, and the same airmass in place as Saturday, another
very mild day is expected across most of western and central North
Dakota. Trended above the 00 UTC guidance consensus, maintaining
the thinking of highs in the 50s southwest and south central
today, 40s northwest and north central with increasing cloud
cover, and 30s across the James River Valley through the Turtle
Mountains with far less mixing.

For tonight, a cold front will rapidly propagate from northwest to
southeast across western and central North Dakota associated with
an Alberta Clipper. Strong northwest winds are expected behind the
front tonight into Monday. The timeframe of the strongest winds
are expected in the 06-12 UTC window when low level lapse rates
and cold air advection increase, coincident with the greatest
isallobaric forcing. However, the 6mb/3 hr pressure rise bubble
and greatest isallobaric forcing are forecast to impact eastern
North Dakota to a greater degree. With 45-55kts at the top of the
mixed layer, wind headlines are certainly possible. However, there
is some uncertainty how efficient momentum transfer will be as
both cold air advection and isallobaric forcing will be modest.

.LONG TERM...(Monday through Saturday)
Issued at 345 AM CST Sun Dec 10 2017

The impacts of two to three clipper systems highlight the
extended forecast.

The 00 UTC global suite is in agreement on two to three clipper
systems to impact western and central North Dakota as the upper
level pattern remains generally unchanged most of the week as a
high over low western CONUS blocking pattern is slow to break
down. The first clipper is expected Tuesday into Wednesday, a
second weaker clipper Friday, and a potential third on Sunday.
Thus, expect a pattern of a mild Tuesday, Friday and Sunday ahead
of the clippers. The 00 UTC suite does suggest the western CONUS
upper level ridge may break down late next week.


.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 345 AM CST Sun Dec 10 2017

Low level wind shear is expected across most of western and south
central North Dakota early this morning with strong winds off the
surface in an inversion. A strong cold front will overtake
western and central North Dakota Sunday evening from northwest to
southeast. Strong northwest wind gusts of 25-35kts are expected
behind the front Sunday night into early Monday morning. VFR
conditions are expected this morning through the evening. However,
MVFR/IFR stratus is possible behind the front tonight.




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