Area Forecast Discussion
Issued by NWS Bismarck, ND

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000
FXUS63 KBIS 211741
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1141 AM CST Tue Nov 21 2017

.UPDATE...
Issued at 1137 AM CST Tue Nov 21 2017

Little change with this update other than for observed trends
through 17 UTC. Extended a mention of flurries for lake effect
south of Lake Sakakawea into the afternoon per surface observation
and GOES16 trends.

UPDATE Issued at 826 AM CST Tue Nov 21 2017

Quick update to added PoPs for a band of lake effect snow evident
on GOES16 imagery this morning streaming off of the Van Hook arm
with cold northwest flow over the warm lake water. Hazen has
fallen to 2 miles in light snow.

UPDATE
Issued at 608 AM CST Tue Nov 21 2017

Will allow the wind advisory to expire at 6 AM CST with winds
winding down the past few hours.

Other update was to mention scattered flurries through mid-
morning northwest/north central associated with an area of MVFR
ceilings and south of Lake Sakakawea with some lingering lake
affect light snow showers. Stratus should burn off 15-16Z and the
lake affect stratus/flurries will dissipate with the decreasing
winds.

&&

.SHORT TERM...(Today and tonight)
Issued at 359 AM CST Tue Nov 21 2017

Strong winds early this morning...cold conditions today highlight
the short term portion.

Currently, the strong clipper low pressure system was centered just
north of Lake Superior and the arctic high pressure center behind it
was centered over southern Alberta/Saskatchewan. Temperatures near
the high center were around 10 below zero at 2 am cst. Strong and
gusty northwest winds continued across the eastern Dakotas, where a
wind advisory was in effect.

Winds remain in advisory criteria (sustained at 30 mph and/or gusts
to 40 mph) across the James Valley, while farther west the winds had
begun to decrease to below 30 mph. Collaborated with eastern ND and
eastern SD offices to extend the wind advisory until 6 am cst for
counties in the James Valley area, namely Foster, Stutsman, LaMoure,
Dickey, Logan, McIntosh counties. Winds should continue to decrease
through the day, with cold arctic air continuing to push into the
state. By evening the high pressure center is forecast to be across
eastern Saskatchewan through the Dakotas. This will make for a cold
November day across ND. Highs today are expected to reach the teens
north and 20s south.

Tonight the arctic high continues moving southeast, and warm
advection begins moving in from the west. Surface winds will become
southerly at around 5 to 10 mph, but strong southwest/west winds
just above the exiting dome of arctic air will increase to 25-40
knots by daybreak Wednesday morning. This will be associated with an
approaching upper level shortwave and developing low pressure system
moving out of the Rockies along the international border. Some light
precipitation out ahead of the system should reach northwestern ND
after midnight. Temperature profiles suggest this should be in the
form of light snow - that is until right before sunrise, when a
chance of sleet or freezing rain is possible in
Divide/Williams/northern McKenzie counties.

.LONG TERM...(Wednesday through Monday)
Issued at 359 AM CST Tue Nov 21 2017

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

Wednesday:

The surface low associated with this system is forecast to track
from the border of Sask/MT at sunrise southeastward across ND,
mainly from the northwest corner of ND to the southeast corner of ND
by Wednesday evening. The 00z models are all indicating the best
frontogenesis/upward motion/forcing will be farther east than the
previous model runs from the past few days. This change will result
in lighter precip amounts for northwestern ND, with the best chance
of light precip amounts to fall near the Bottineau/Minot/Rugby
areas. This places the measurable precipitation farther east and
ahead of the stronger warm advection. Thus, the thinking is that we
should see lighter amounts of a freezing rain/sleet mix and more
light snow with this system over that north central part of North
Dakota. This is good news for travelers on Wednesday morning.
However, even though northwest North Dakota may receive trace
amounts of precipitation, those traces are more likely to be in the
form of freezing rain or sleet.

By afternoon the precipitation should have exited east of the Turtle
Mountains and James Valley. Gusty west winds behind the system can
be expected, with the strongest winds across southwestern ND. There
should be a strong temperature gradient from northeast to southwest
across the state, with the strong warm advection moving in from the
southwest. High temperatures should reach the lower 60s in far
southwestern ND, with only mid 20s in the Turtle Mountains.

For Thanksgiving:

The warming continues with ridging ahead of the next clipper system
setting up over the Canadian Rockies. High temperatures should reach
the lower and mid 60s in southwestern ND, with near record highs
within reach for Williston and Dickinson. The record High for
Dickinson is 63 set in 1984, with a forecast of 62. The record high
for Williston is 56, with a forecast high of 56.

Thursday night the aforementioned clipper system moves out of the
Canadian Rockies, reaching Manitoba by daybreak Friday. The
clipper`s upper level trough and associated trailing cold front will
move across western and central ND late Thursday night. This will
bring a slight chance of light rain to western and northern ND
Thursday night, and to the James Valley on Friday. Only light
amounts are expected.

On Friday the main concern is gusty northwest winds that will linger
into Friday evening. The rest of the holiday weekend should be quiet
weather-wise. The next low pressure system moving in from the west
will bring a chance of rain or snow to our area Monday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1137 AM CST Tue Nov 21 2017

Scattered decks of MVFR stratus will continue this afternoon
across northwest and central North Dakota, possibly continuing
north central into the evening. Light lake effect snow is possible
south of Lake Sakakawea. A wintry mix of snow, sleet and freezing
rain is possible across northwest and north central North Dakota
Wednesday morning. Strong northwest winds with gusts around 30
kts are forecast across southwest North Dakota Wednesday.

&&

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

$$

UPDATE...PA
SHORT TERM...JV
LONG TERM...JV
AVIATION...PA



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