Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 150948

Area Forecast Discussion
National Weather Service Bismarck ND
348 AM CST Fri Dec 15 2017

.SHORT TERM...(Today and tonight)
Issued at 251 AM CST Fri Dec 15 2017

Mean upper level western ridge begins to break down in the short
term period. Shortwave energy propagating over the top of the
ridge is currently inducing lee cyclogenesis in the Canadian
Rockies with warm advection light snow across Saskatchewan and
southwest Manitoba, with a period of light snow into Rolla ND.

During the day today isentropic lift and synoptic scale forcing
will be aligned from northern Saskatchewan, south southeast into
southern Saskatchewan and western Manitoba, and into the eastern
Dakotas and Minnesota as shortwave energy slides down the ridge.
Precipitation will start as snow this morning and will likely
change to a mix of rain and snow or possibly all rain on the
western fringes of the precipitation shield.

This will bring warm temperatures to southwest North Dakota with
readings possibly reaching the 50s, while light snow and much
colder temperatures are confined to our far northeast CWA and
mainly into northeast ND. Thus temperatures will range quite a bit
today from the lower 50s southwest to around 30 or so in the
Turtle Mountains.

This forcing will continue into the evening hours and before
tapers off late tonight we will see some light snow accumulations
along and east of a line from Westhope to Rugby to Grace City,
with a couple inches in the Turtle Mountains.

As the snow tapers off tonight, we do lose the ice aloft and there
could be a short period of light freezing precipitation before the
precipitation completely ends. At this time, we think the
precipitation will be mostly over and any amounts would be very
light and we have limited this to a mention of light freezing

.LONG TERM...(Saturday through Thursday)
Issued at 251 AM CST Fri Dec 15 2017

Cold front moves through the area Friday night with a period of
breezy conditions late Friday night into Saturday. Utilized the
typically higher MOS based guidance for winds Saturday and this
did not yield much greater than given guidance. Global models are
depicting some very light precipitation late Friday night into
Saturday morning over the southwest. Soundings do indeed show a
saturated supercooled water regime but bufkit models are mixed
with the amount of vertical motion/omega for freezing rain.
For consistency, will keep this in the forecast.

After Saturday morning, dry weather resumes through Sunday.
Another clipper/cold front shifts through late Sunday night into
Monday morning. This will result in another chance of snow mainly
northern ND and a breezy to windy day Monday. Another system
(with potential moderate to high impacts) is slated for Tuesday
night and Wednesday. Widespread accumulating snow will be possible
though much depends on where the sfc low sets up and tracks. Once
this system departs, very cold air is then forecast to pour into
the region, lingering beyond the long term based on long range
outlooks such as the MJO and ensemble runs.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 251 AM CST Fri Dec 15 2017

Widespread MVFR cigs will continue tonight over central and
eastern North Dakota, including KMOT/KBIS/KJMS.
Conditions will improve to VFR at KMOT/KBIS before sunrise, and
before 18Z at KJMS.

Most of western North Dakota, including KISN/KDIK is expected to
remain VFR. However, there is some uncertainty with KISN, as the
western edge of the MVFR cloud shield may reach KISN at times before
sunrise...but more likely the prevailing condition should be VFR.




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