Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 210657

Area Forecast Discussion
National Weather Service Bismarck ND
1257 AM CST Tue Nov 21 2017

Issued at 1200 AM CST Tue Nov 21 2017

Extended wind advisory until 3 am cst...and also expanded it south
to include all counties east of Highway 83. 3-Hour pressure rises of
5-7 mb were associated with current wind gusts of 40-53 mph along
and north of I-94 and mainly east of Highway 83. Pressure rises
should continue to expand farther south as decided to
include Burleigh/Emmons counties and areas east along the SD border
for the wind advisory.

The pressure rises move south and east...but will revisit at 3 am
cst as to whether we will need to extend the advisory until 6 am or
so. For now we are well collaborated with eastern ND.

Otherwise blended current hourly temps with ongoing forecast. A cold
and blustery night with lows near zero northwest to the low to mid
teens in the James River Valley. Wind chills of 10 to 20 below
expected across the northern counties.

UPDATE Issued at 943 PM CST Mon Nov 20 2017

Strong cold advection jet dynamics and FG forcing are combining
to produce some light snow over southeast Montana into western
South Dakota, with some light snow extending into southwest ND.
Not expecting any accumulations but did mention some light snow or
flurries southwest late this evening into the early overnight
hours. Also seeing some very light returns over the north central
with wrap around moisture behind the exiting surface low. Did
see Rolla pick up a period of light snow but this is much lighter
than the snow in the southwest. Will monitor but not really worth
a mention at this time. Do have area of blowing snow continuing
over the Turtle Mountains area through around midnight with the
strong winds. For temperatures, we did cool them some but with
considerable clouds dropping south from Canada, not certain how
far to drop. Winds are also blowing pretty good, limiting
radiational cooling in any clear spots. But with the strong cold
advection, we did drop them some, but mainly cooled everyone off a
little quicker than previously forecast.

UPDATE Issued at 915 PM CST Mon Nov 20 2017

Winds still gusting between 40 and 50 mph from Minot and Garrison
east to Rolla, Harvey and Carrington. Winds have diminished in the
west and have allowed the advisory to expire over the northwest.
Otherwise No significant changes to the going forecast. There are
a few nuisance spotty flurries showing up from time to time, with
no impacts. Will take a look at webcams and may add a mention of
flurries. Will need to adjust temperatures a bit lower than
previously forecast.

UPDATE Issued at 536 PM CST Mon Nov 20 2017

Dry cold front has moved through western and central ND.
Currently, strongest winds are within the fall/rise pressure
bubble and tightest gradient from Minot to Rolla and south into
the James River Valley. Winds here are gusting in the 40 to 50 mph
range. Farther west, winds are not as strong but many locales are
gusting in the 30 to 40 mph range. Current Wind advisory remains
in effect until 9 pm CST. No need to make any changes at this
time. Will revisit with the evening update.

Strong cold advection will keep winds breezy through the night.
Temperatures are already in the lower to mid 20s far northwest,
and will continue to fall through the night across the forecast
area. Made some adjustments to sky cover to account for increased
mid clouds over the west. May see a few flurries/sprinkles this
evening as this area moves across the southwest during the
evening. Not expecting any accums.


.SHORT TERM...(This evening through Tuesday)
Issued at 254 PM CST Mon Nov 20 2017

Strong winds this afternoon into tonight, near critical fire
weather conditions south this afternoon, and a much colder
Tuesday highlight the short term forecast.

The strong cold front extending from the clipper across southeast
Manitoba has cleared all of western and central North Dakota as of
21 UTC. Strong post-frontal winds continue to develop across the
area. The strongest winds with gusts of 40-45kts are expected
along and north of North Dakota Highway 200 where isallobaric
forcing will be maximized into the early evening. However, winds
have already peaked across the far northwest, and a slow decrease
in winds are expected through the evening and overnight as
isallobaric forcing focuses into Minnesota. A Wind Advisory
remains in effect until 03 UTC for generally west of US Highway
83, and through 06 UTC to the east. This may be allowed to be
cancelled a bit early.

See the fire weather discussion below regarding a brief period of
near critical fire weather conditions south this afternoon.

A much colder Tuesday is expected area wide as cold high pressure
builds across western and central North Dakota in the wake of the
cold front today. Highs will likely be 20 to 30 degrees colder on
Tuesday for most areas based on the 12 UTC global consensus.

.LONG TERM...(Tuesday night through Monday)
Issued at 221 PM CST Mon Nov 20 2017

A wintry mix Wednesday, possible record highs southwest on
Thanksgiving, and a windy Friday highlight the extended forecast.

The 12 UTC global suite is in agreement on a warm front
propagating into western and south central North Dakota on
Wednesday, and stalling out. A clipper will propagate along this
baroclinic zone and support the potential for a wintry mix of
freezing rain, sleet and snow with an warm layer aloft above sub-
freezing air and road temperatures across northwest and central
North Dakota. Overall QPF amounts are expected to be light,
however, even a small amount of freezing rain will impact
travel on Wednesday. The areas of most concern for light ice
accumulations are across northwest and north central North
Dakota, into the James River Valley.

For Thanksgiving, the baroclinic zone remains, bisecting North
Dakota from northwest to southeast. The 00 UTC NAEFS 850 mb mean
temperatures climb to their 99th percentiles across the west,
supporting the top of the forecast envelope for highs for November
23. The record High for Dickinson is 63 set in 1984, with a
forecast of 65. The record high for Williston is 56, with a
forecast high of 57. With the aforementioned baroclinic zone in
place, a large temperature gradient is favored from southwest to
northeast with highs only in the 20s across the Turtle Mountains.

On Friday, another windy day is possible behind a cold front
extending from a southern Canada clipper system.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)

Issued at 1257 AM CST Tue Nov 21 2017

Strong northwest winds will persist through the night and into
Tuesday morning. Winds will diminish from west to east during the
day Tuesday. Minaly VFR conditions through the forecast period.
There will be a period of MVFR ceilings as moisture wrapping
around an exiting surface low moves southward across North Dakota
through Tuesday AM hours.


Issued at 254 PM CST Mon Nov 20 2017

A period of near critical fire weather conditions is ongoing this
afternoon across southern North Dakota where relative humidity
has fallen to near 20 percent with mixing, coincident with strong
post-frontal winds. However, with sunset around 5 pm CST, and
cooler air with higher dewpoints advecting in from the north, the
overall threat should be rather limited in time.


Wind Advisory until 3 AM CST early this morning for NDZ003>005-



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