Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 141915
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
115 PM CST Thu Dec 14 2017

.UPDATE...

Issued at 115 PM CST Thu Dec 14 2017

Forecast on track for today. Made some tweaks to sky cover and
hourly weather elements based on observations. Light snow
continues to be reported at various locations along with radar
imagery showing weak echos about. Light freezing rain potential
remains over my eastern counties.


UPDATE
Issued at 902 AM CST Thu Dec 14 2017

Regional radar continues to show light returns with the stratus
across the area, along with a few observation points reporting
flurries or light snow. Will maintain low chances for snow today
with decreasing chances through the day as mid level forcing
dissipates.

ECMWF and high res guidance maintain chances for light
precipitation across my eastern counties tonight near a baroclinic
zone and underneath an upper level jet streak. The probability of
ice aloft decreases this evening before increasing overnight,
which BUFKIT and time-height cross sections support. For now left
precipitation type as mainly snow but will take a closer look at
things over the next few hours for the possibility of light
freezing precipitation this evening.

UPDATE Issued at 643 AM CST Thu Dec 14 2017

Widespread area of light snow associated with a weak clipper
continues top drop southward across North Dakota. Current forecast
looks on track. Updated latest sensible weather elements and
interpolated to mid-morning values.

&&

.SHORT TERM...(Today and tonight)
Issued at 325 AM CST Thu Dec 14 2017

Pockets of very light snow this morning will trail off through
the afternoon as vertical motion wanes from northwest to southeast.
Otherwise, expect a cloudy and brisk day.

Latest water vapor imagery shows two shortwaves. The first
shortwave was sliding from eastern Montana into southwest ND,
with ascent and resultant pockets of light snow now into western
and south central ND. Upstream, another shortwave in western
Saskatchewan will follow behind the initial one this morning, and
gently pass through during the afternoon. Ascent with this second
shortwave is much weaker than the initial one currently sliding
through, thus patchy areas of light snow or flurries expected
through the afternoon today. Stratus clouds for the most part
extend all the way up into northern Saskatchewan and Manitoba,
thus will maintain a cloudy sky condition with support from the
NBM cloud cover. As the main forcing field exits southern ND this
morning, used a blend of the high resolution models for capturing
pops/precipitation trends for the remainder of the day. RAP BUFKIT
sounding analysis shows the low level saturated layer reaching
high enough into the ice crystal production zone, resulting in any
threat for light freezing drizzle spotty/remote at best. Thus,
have gone with light snow as the precipitation type. High
temperatures today will be fairly uniform with expected cloud
cover and brisk winds. Highs will range from the upper 20s to
lower 30s. Brisk northwest winds between 15 and 25 mph across
western and central ND, with the exception will be in far
southwest ND where sustained wind will be closer to 25 mph, and
gusts up to 35 mph. Windchill temperatures will be in the 15F to
20F range across western/central ND.

For tonight, low level warm air advection initiates from west to
east. Weak ascent mostly attributed to warm air advection per NAM
Rolla BUFKIT sounding, results in light snow developing late tonight.
Dry elsewhere but remaining mostly cloudy. Lows will range from
the upper teens to lower 20s.

.LONG TERM...(Friday through Wednesday)
Issued at 325 AM CST Thu Dec 14 2017

The next in a series of shortwaves and associated clipper cold
fronts shifts through Friday night. A warm front will reside
across northeast ND/Turtle Mountains Friday. Light snow is forecast
Friday through Friday night with accumulations between 1 and 2
inches - from Bottineau to Rolla and south to Rugby. Elsewhere,
little or no snowfall accumulation, as the rest of western and
central ND will be in the warm sector Friday. Highs Friday will
range from the upper 20s in Rolla, to the mid 40s southwest. The
clipper sweeps through Friday night with winds shifting to the
northwest by daybreak Saturday. Gridded data shows some areas of
light freezing rain late Friday night into Saturday morning. The
GFS BUFKIT sounding taken at Watford City does indeed show a
saturated supercooled water regime with sufficient vertical
motion/omega for some mention freezing rain potential. After
Saturday morning, dry weather resumes through Sunday. Another
clipper then shifts through late Sunday night into Monday morning.
This will result in another chance of snow mainly northern ND.
Another system is slated for Tuesday night and Wednesday. Once
this system shifts through, very cold air is then forecast to pour
into the northern high plains, and continue well beyond this long
term period. So from Thursday of next week, through the Christmas
Holiday, trends for much below normal temperatures remain on
track.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)

Issued at 115 PM CST Thu Dec 14 2017

The aviation hazard for the 18Z TAF period will be MVFR-to-LIFR
ceilings, which will also be a forecast challenge. Current HiRes
models have a handle on low stratus moving southeastward across the
state. Clearing is occurring in the west as stratus shifts towards
the east. Ceilings at KISN/KDIK are lifting though intermittent
pockets of lower ceilings may occur. Gradual lifting is forecast at
KBIS while KMOT/KJMS will possibly see low ceilings through much of
the 18Z period.


&&

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

$$

UPDATE...NH
SHORT TERM...KS
LONG TERM...KS
AVIATION...AC



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