Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 201446
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
946 AM CDT Fri Oct 20 2017

.UPDATE...
Issued at 942 AM CDT Fri Oct 20 2017

Increasing southerly flow over eastern ND today as low pressure
continues to develop over eastern MT and the western Dakotas. Made
some minor adjustments to sky cover. Otherwise no significant
changes to the going forecast.

UPDATE Issued at 635 AM CDT Fri Oct 20 2017

No changes with this product issuance. See below for details.

&&

.SHORT TERM...(Today and tonight)

Issued at 405 AM CDT Fri Oct 20 2017

Forecast highlights in the short term period will be near record
highs this afternoon, followed by strong winds this evening into
the overnight.

Currently, upper level ridge axis extends north-northwest across
the Upper Mississippi valley into south central Canada, with
southwest flow aloft across the Northern Plains as a potent upper
level trough moves onshore over the west coastal region. Surface
low pressure forming well to our west ahead of the trough results
in a light south-southeast flow across the Dakotas this morning. A
few upper level clouds about but mostly a clear sky for most
areas. The steady southeasterly low level wind has kept
temperatures mainly in the 40s through 3AM CDT.

For today, a clear to partly cloudy sky is forecast with a upper
level moisture streaming north across the eastern third of the
state as southerly flow increases there. This is in response to
the surface trough strengthening and moving into eastern MT as the
upper trough moves into the Rockies. Thermal profiles ahead of
the trough within the boundary layer are very similar to Thursday
which saw temperatures will into the 70s many locations along with
a few lower 80s southwest. Forecast highs west and central are
near or above record highs for today for all but Jamestown:

LocationRecord Temperature/Year Forecast High
Williston      78F in 2014         80F
Minot       80F in 1947 80F
Dickinson  81F in 1901 82F
Bismarck  82F in 1901 80F
Jamestown  88F in 1918     77F

SPC has parts of far southeastern Dickey county in the general
T-storm outlook for Day1. Plume of moisture referenced above will
increase instability across the eastern Dakotas this
afternoon/evening. However, model derived MUCAPE is brief with CAM
models all suggesting any convection will remain to our
southeast/east.

For tonight, upper level trough continues east into the Northern
High Plains by 12Z. Surface trough and a strong associated cold
front will move east ahead of the upper trough into western North
Dakota this evening, then into central ND overnight. Strong
pressure rise bubble is advertised by both the GFS/NAM to enter
western ND 02-04Z, with a 3-HR pressure rise max of 10MB
southwest. Pressure rise bubble continues east into my central and
eastern counties after midnight, but does decrease in intensity
with time. We opted to increase winds to max GFE guidance values
after 00Z, and even increasing some from there based on latest
nam/gfs BUFKIT analysis of winds within the mixed layer. It
appears there will be some potential Friday evening for near high
wind warning criteria gusts southwest, though this is uncertain
and if it does occur these should be short lived so at this time
there are no plans for any wind headlines. Will let the day shift
look at latest guidance for any headlines for the tonight period.

Other than the gusty winds, models are in agreement with an area
of showers developing across central South Dakota into south
central North Dakota late. Otherwise dry conditions prevail.

.LONG TERM...(Saturday through Thursday)

Issued at 405 AM CDT Fri Oct 20 2017

Active pattern prevails in the long term period.

Upper trough from the short term moves across the Northern Plains
Saturday and Saturday night. Showers developing late tonight will
continue over my eastern counties Saturday morning. Much cooler
behind tonight`s front with highs mainly in the 50s. After the
first strong push of winds along the cold front tonight, winds
taper off in the early AM hours only to ramp back up during the
day Saturday. Near wind advisory gusts are possible via the gfs
BUFKIT data, though nam BUFKIT would suggest sub-advisory. Will
take another look later today when new model data comes in.

Series of SW`Vs push across our region Sunday-Monday night.
Another cold front is advertised later in the day Sunday, then
yet another on Monday associated with these waves. Both days will
see strong wind potential along with chances for precipitation.

Ridging rebuilds Tuesday night - Wednesday bringing another period
of warm temperatures mid-week along with dry conditions.
Increasing attention for Wednesday night-Thursday when both the
GFS and ECMWF push a very strong cold front across the state.
Another strong wind event looks to unfold if models stay their
present course. -4 to -10C 850mb temperatures are also advertised
for Thursday to advect into the area on the backside of this
potential front.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 942 AM CDT Fri Oct 20 2017

VFR conditions are forecast for the 12Z TAF period. Increasing
low level winds ahead of a cold front should be greatest in the
James Valley and KJMS for the daytime hours today. Southerly LLWS
at KJMS beginning early this morning and continuing until surface
winds increase by around 16-18z.

The strong cold front enters western ND after 00z and sweeps east
across the state to the James Valley by daybreak Saturday morning. A
westerly LLWS sets up at KISN-KDIK before the cold front arrives
around 03z with westerly winds of 25G35 knots. A southerly, then
southwesterly LLWS sets up at KMOT-KBIS ahead of the cold front as
well on Friday evening after 00z.

&&

.FIRE WEATHER...
Issued at 405 AM CDT Fri Oct 20 2017

Near critical fire weather conditions possible early this evening
over western North Dakota. Fire managers should be aware of an
approaching cold front, likely arriving early this evening - but
caution is advised should the cold front move in faster than
forecast.

A very warm day today ahead of a strong cold front. Dry air in
western North Dakota, along with afternoon highs in the upper 70s
and lower 80s will result in minimum relative humidity values of
around 13 to 20 percent across most of western North Dakota. A
strong cold front will move east across Montana today, reaching
western North Dakota by early evening. The first few (around 3)
hours after the cold frontal passage should see sustained winds of
over 30 mph with gusts to 40 mph. At this time, we think the timing
of the cold front arrival in far western North Dakota should be
early this evening - after the peak heating and lowest relative
humidity for the day. However, should the cold front move in faster
than forecast, the late afternoon or very early evening would see
those low humidity values coincident with the strong and gusty
westerly winds.

Southerly winds ahead of the front today should be strongest in the
James Valley, with sustained speeds of around 20 mph with gusts to
around 30 mph this afternoon. Increasing low level humidity will
move into the eastern half of the state today along with the strong
southerly winds. In contrast to the western half of the state,
minimum relative humidity values in the James Valley should be
around 40 percent.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...TWH
SHORT TERM...NH
LONG TERM...NH
AVIATION...WAA
FIRE WEATHER...JV



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