Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 200837

Area Forecast Discussion
National Weather Service Bismarck ND
337 AM CDT Wed Sep 20 2017

.SHORT TERM...(Today and tonight)
Issued at 337 AM CDT Wed Sep 20 2017

Main highlight today will be near critical fire weather conditions
southwest this afternoon. Please refer to the fire weather discussion
below for more details. Otherwise, breezy, but dry weather dominates
the short term period.

Potent shortwave trough from Tuesday is now pushing into southern
Manitoba into Minnesota. Large scale subsidence behind this upper
trough per latest GOES16 satellite imagery dominates today with
mostly sunny conditions. BUFKIT soundings show mixing heights just
above 850mb today, tapping into 20kt to 25kt winds. Expect
southwesterly surface winds increasing to around 20 mph this
afternoon. High temperatures will be in the mid to upper 60s.

Water vapor imagery shows an elongated upper low/trough sprawled
out from southwestern British Columbia into southwest Saskatchewan.
For tonight, an area of synoptic scale ascent ejecting from
Oregon and Idaho will weaken as it moves into eastern Montana and
western/central North Dakota. Low level warm air advection/vertical
motion increases across southern North Dakota tonight as 850mb
winds begin to increase between 40kt and 50kt. With increased
ascent/vertical motion west and central, expect an increase in
clouds tonight. Overnight lows will range from 40F northwest to
lower 50s far south central.

.LONG TERM...(Thursday through Tuesday)
Issued at 337 AM CDT Wed Sep 20 2017

An upper level low/longwave trough develops in the intermountain
west Thursday/Friday, then slowly edges east into the northern
high plains by Tuesday. The end result is a cooling trend with
increasing chances for showers through the long term period.

For Thursday, a subtle cold front will slide west to east, but get
hung up in the southern James River Valley Thursday night as the
front parallels the southwest flow aloft. A few showers along the
front in the north central and Turtle Mountains are possible
during the day. Highs Thursday will range from the mid 60s west
to around 80F in the southern James River Valley. A low level jet
will be in place Thursday night with increasing instability in the
far southeast. SPC has the the southern James River Valley in a
Marginal Risk through 12z Friday. NAM BUFKIT for Oakes certainly
has potential for elevated thunderstorms and will continue to
monitor this area in future runs.

Increasing jet dynamics and shortwaves ejecting from the longwave
trough will enhance large scale ascent and result in increasing
showers across western/central ND Friday through Sunday. Brunt of
the forcing shifts east Monday/Tuesday as the upper trough scoots
through. Slight chances continue but not as wet as the weekend.
Temperatures will cool into the 50s Saturday through Monday, then
rebound into the lower 60s Tuesday.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 337 AM CDT Wed Sep 20 2017

Expect vfr cigs/vsbys this TAF period. Low level windshear is
forecast at KBIS/KJMS near the end of the period with an increase
in low level southerly winds.


Issued at 337 AM CDT Wed Sep 20 2017

Southwesterly winds sustained at/near 20 mph will occur across
southwestern North Dakota this afternoon, briefly coinciding with
minimum relative humidities between 20 and 25 percent. Due to the
limited areal coverage, short/intermittent duration (2 to 3 hours)
no fire weather highlights are warranted at this time.




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