Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 160956 CCA

Area Forecast Discussion...CORRECTED
National Weather Service Bismarck ND
456 AM CDT Mon Oct 16 2017

.SHORT TERM...(Today and tonight)
Issued at 440 AM CDT Mon Oct 16 2017

Latest water vapor imagery loop overlaid with model data show a
very broad mid/upper level ridge pattern across the Northern
Rockies and into the Northern High Plains. This will subtlely
shift to a zonal flow across North Dakota as heights remain
generally neutral through the short term period. At the surface,
rising air per 3hr pressure falls continue to be maximized from
southeastern Saskatchewan into western North Dakota. This upward
vertical motion is the result of low/mid level (900-700mb) thermal
advection/warm front which is now propagating across western ND
and approaching central ND. The warm front will slide through the
James River Valley 12z-15z Monday. BUFKIT soundings show mixed
layer winds around 20kt today, especially southwest ND into the
James River Valley, with slightly weaker winds elsewhere. Overall,
a sunny/breezy day with highs in the 60s to lower 70s south central.

For tonight, 850mb isotherm packing suggest another warm frontal
passage, albeit weaker, will commence from west to east. Expect
clear conditions with overnight lows in the upper 30s to lower 40s.

.LONG TERM...(Tuesday through Sunday)
Issued at 440 AM CDT Mon Oct 16 2017

Heightened fire weather concerns Tuesday afternoon is the highlight
of the long term period. See the fire weather discussion below for
further details.

Upper level flow will generally remain zonal through Thursday,
then southwesterly Friday/Saturday ahead of an upper trough.
Zonal flow then returns Sunday.

Warm temperatures with highs 70F to 80F slated for Tuesday,
Thursday, and Friday. Highs between 55F and 65F are forecast for
Wednesday, Saturday, and Sunday. A dry cold frontal system will
sweep through Tuesday night. Preceding this front will be a
breezy/warm Tuesday afternoon, then cooling back into the mid 50s
to mid 60s Wednesday as mentioned above. Expect breezy westerly
winds ahead of the front and northwest winds behind the cold front
Wednesday. Both days will see winds between 15 and 30 mph.

For Thursday and Friday temperatures once again will increase into
the 70s. This is out ahead of an upper level trough and associated
cold front that slides into the Northern Rockies and Inter-Mountain
West. With good agreement in the 850mb temperature pattern (+16C
to +20C) on both the operational GFS/ECMWF, as well as the GEF`s
Plumes, have collaborated with neighboring offices for a target of
opportunity to increase high temperatures. Essentially high
temperatures were increased from the lower 70s into the the mid
and upper 70s both days across western/central ND. The cold front
mentioned above will eventually push through western and central
ND Friday night. Perhaps a shower or two will develop with the
passage of the upper trough Saturday. Otherwise, the main effect
of this front will be breezy and cooler conditions for Saturday
and Sunday.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 440 AM CDT Mon Oct 16 2017

Main aviation impact will be low level wind shear across all
terminals. A warm front will propagate from west to east, resulting
in low level wind shear through 17z Monday. Otherwise, mainly clear
conditions this TAF period with afternoon westerly winds of between
15kt and 25kt. Winds will relax to less than 10kt by sunset Monday.


Issued at 456 AM CDT Mon Oct 16 2017

Minimum relative humidities between 13 percent and 18 percent are
forecast to surround southwest North Dakota Tuesday afternoon.
The minimum humidities are forecast to coincide with westerly winds
of around 20 mph, coexisting for no more than three consecutive hours.
High temperatures Tuesday will range from 75F to 80F across southwest
North Dakota.

The unknown component at this point is the state of the fuels.
Field observations from our Fire Management Officers slightly more
than a week ago mentioned that fuels in portions of southwest North
Dakota were as green, if not greener than they have been all season
long. With a couple of hard freeze events since then, it remains
unknown if those fuels have cured sufficiently to support spread
rates that could/would meet Red Flag Warning criteria.

Despite critical minimum relative humidities, due to the marginal
sustained winds both in magnitude and duration, and the unknown
status of fuels, will defer from any Fire Weather Watch headline
at this time. More data can be gathered today which will guide
decision making in subsequent forecasts.




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