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FXUS63 KBIS 230440
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1040 PM CST Tue Jan 22 2019

.UPDATE...
Issued at 921 PM CST Tue Jan 22 2019

Latest satellite imagery loop and surface observations show the
back edge of low clouds/stratus just exiting Minot and should see
that occur over Mandan/Bismarck within the next hour. Mid and high
clouds continue to overspread western and central ND as warm air
advection leads to rising motion. Surface map reflects this with
3hourly pressure falls lining up within the mid/high cloudiness
area per satellite imagery. Current trends look good.

Latest NAM shows the actual arctic front/sfc-850mb baroclinic
zone sweeping from north to south 18z Wednesday through 06z
Thursday. For Bismarck, 850mb temps of -6C at 3PM CST, then -10C
by 6PM CST, -16C by 9PM, and -23C by 3AM Thursday. So actual front
probably in the 5PM to 9PM Wednesday timeframe, which will be
accompanied by strong northwest winds and pockets of light
snowshowers. Strong winds will continue Wednesday night into early
Thursday morning.

UPDATE Issued at 535 PM CST Tue Jan 22 2019

Latest satellite imagery loop shows an area of stratus clouds
slowly advancing east toward Minot and south to Bismarck. Timing
of these clouds are between 7PM through 10PM, however the area as
a whole continues to show a decrease in coverage. Higher clouds
already spreading across northwestern ND will soon overtake the
lower clouds. Minor adjustments to sky grids based on the above,
with the rest of the forecast on track.

&&

.SHORT TERM...(This evening through Thursday) Issued at 300 PM
CST Tue Jan 22 2019

A powerful Arctic cold front will produce strong northerly winds
across North Dakota Wednesday afternoon through Thursday morning,
resulting in significant blowing and drifting snow and dangerous
wind chills. A Winter Storm Watch is in effect for possible blizzard
conditions.

Quiet conditions across the area this afternoon, with pesky low
clouds over western North Dakota. A slow dissipating trend in the
clouds is expected through this evening. Quiet weather will continue
tonight into Wednesday morning as a surface ridge slides across the
Northern Plains.

The Arctic front will move across the Canadian border early
Wednesday afternoon and quickly plunge southward through the
evening. A quick burst of light snow is expected along the leading
edge of the colder air given a cyclonic flow regime and steep low-
level lapse rates. Accumulations are expected to remain below half
an inch at this time, but model guidance has a reputation for under-
performing QPF in these setups and has struggled with QPF within
similar thermodynamic environments as of late.

The bigger story will be strengthening northerly winds. Models
remain in agreement with strong pressure rises and cold air
advection, with mix-down potential of 35 to 40 kts. Given recent
rounds of snowfall with high snow-to-liquid ratios and colder
temperatures outside far southwest North Dakota, the expectation is
that snow will be easily blowable. Just how much so is where
lingering uncertainty plays in. Forecast wind gusts are 5 to 10 kts
above traditional blizzard criteria, but falling snow is expected to
essentially be a non-factor, and it takes stronger winds to produce
true a true ground blizzard.

Given the aforementioned uncertainty, will keep the watch in tact
for now. The expectation is that at least a Winter Weather Advisory
for blowing snow will be needed across most, if not all of the
watch area.

On top of all that, temperatures are forecast to plummet below zero
by sunrise Thursday morning, and not recover much during the rest of
the day. This will result in dangerous wind chills to near 40 below
zero, coldest in the Turtle Mountains area.

.LONG TERM...(Thursday night through Tuesday) Issued at 300 PM
CST Tue Jan 22 2019

Global models are in agreement with a northwest flow pattern
persisting through the extended period, with numerous clipper
systems passing through. The strongest of these is forecast to
impact the area late Saturday into Monday. The GFS and ECMWF are in
agreement with a higher potential for accumulating snow and winds as
strong, if not stronger than the upcoming Wednesday/Thursday system.
A short-lived warming trend is forecast through the weekend before
Arctic air returns next week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1040 PM CST Tue Jan 22 2019

An area of low clouds can be expected early in this taf period for
KJMS, from 06z through 11z Wednesday, then vfr returns until late
afternoon. A potent arctic cold front will push from north to south
Wednesday afternoon and evening resulting in deteriorating cigs from
vfr to mvfr. Strong northwest winds to 35kt will develop quickly behind
the front resulting in blowing snow and MVFR vsbys, to possibly IFR
vsbys at times. This is expected to continue through Wednesday night.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from Wednesday afternoon through late
Wednesday night for NDZ001>005-009>013-021-022.

Winter Storm Watch from Wednesday afternoon through Thursday
morning for NDZ023-025-035>037-046>048-050-051.

&&

$$

UPDATE...KS
SHORT TERM...Hollan
LONG TERM...Hollan
AVIATION...KS
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