Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 151733
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1133 AM CST Fri Dec 15 2017

.UPDATE...
Issued at 1131 AM CST Fri Dec 15 2017

No major tweaks were made, forecast is on track.

UPDATE Issued at 830 AM CST Fri Dec 15 2017

A quasi-stationary frontal boundary and associated baroclinic zone
across north central into eastern North Dakota will be the focus
for snow today across the north central and east. So far teh radar
loops suggest the returns are consolidating across this area. So
far the forecast trends look ok.

UPDATE Issued at 629 AM CST Fri Dec 15 2017

Current forecast looks reasonable so no major changes. Widespread
light reflectivities showing up across western and central ND but
Bismarck sounding confirms there is still quite a bit of dry air
below the saturated mid levels. Thus most of these reflectivities
are not reaching the ground. Exception is over eastern portions of
central ND in an area of stronger warm advection.

This area of Rolette county and possibly portions of eastern
Bottineau and northern Pierce are within a favorable area of
dendritic snow growth later this morning through mid afternoon.
Omega within the snow growth zone is not overly impressive and the
zone is relatively high and not overly deep. However, this may
lead to some localized heavier snow amounts of around 3 inches.
Mesoscale models have trended a little higher within bands of snow
in this area. Certainly something the dayshift will monitor.

Otherwise no significant changes to the going forecast.

&&

.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
drizzle.

.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 12Z TAFS through 12Z Saturday morning)
Issued at 629 AM CST Fri Dec 15 2017

Widespread MVFR cigs will continue this morning over eastern
North Dakota, including KMOT/KJMS. Light snow and fog will also
contribute to the MVFR visibilities. Conditions will improve to
VFR at KMOT by around 9 am this morning, and before 18Z at KJMS.

Most of western North Dakota, including KISN/KDIK/KBIS is expected
to remain VFR.


&&

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

$$

UPDATE...AC
SHORT TERM...TWH
LONG TERM...TWH
AVIATION...TWH



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