Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 140040
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
740 PM CDT Fri Oct 13 2017

.UPDATE...
Issued at 719 PM CDT Fri Oct 13 2017

The main concern for this update was to adjust precipitation
chances through the night based on radar, observations, and the
latest short term guidance. Also tweaked sky cover based on the
latest IR satellite imagery and a blend of the previous forecast
and the 23z iteration of CONSSHORT. For all other fields, the 22z
observations were blended with the previous forecast. Thinking
regarding light snow accumulations in the far northwest and north
central overnight remains the same.

&&

.SHORT TERM...(This evening through Saturday)
Issued at 340 PM CDT Fri Oct 13 2017

Water vapor imagery depicts a broad western trough with multiple
impulses flowing through southwest flow over the Northern Plains.
At the surface a lee cyclone is centered over southeast Montana
with a warm front draped over central and western North Dakota.
Isentropic lift over the front is responsible for the current
cloud cover and light rain over areas of northwest North Dakota.

This evening a jet max rounds the western trough, deepening a low
pressure system over the state. On the nose of associated
mid-level southerly flow, enhanced 850-700mb frontogenesis will
increase precipitation beginning with the far northwest corner of
the state. In a battle of timing, a stronger push of cold air from
the northwest will struggle to catch up to this enhanced forcing
as it moves east. In areas of the northwest where colder air
begins to filter in, a mix of rain and snow is possible. As the
cold front catches up to the forcing further east, accumulating
snow becomes possible. Areas of the far north-central portion of
the state along the International Border will be most likely to
see measurable snow. Uncertainty of accumulations on this event
lies with the timing of the cold push and the movement of the
dynamic forcing eastward, as well as surface temperatures. Less
than two inches is expected for the areas with the greatest
accumulations, with the likeliest spots being grassy surfaces.
However if the atmospheric column can cool quicker than expected,
a few higher accumulation totals could be found.

As the aforementioned cold front moves northwest to southeast
overnight into Saturday, the surface front will be a focus of rain
early Saturday morning through the day as well as high
temperatures in the 40s and breezy northwest winds behind the
front. Likeliest areas for rain will mostly be focused in the
James River Valley area and in the far south-central until the
front clears to the southeast by the evening.

.LONG TERM...(Saturday night through Friday)
Issued at 340 PM CDT Fri Oct 13 2017

A second upper level low passes through from the northwest on
Sunday, with a lack of sufficient moisture the main impacts will
be cloud cover across the north with breezy northwest winds for
most of the state.

Through next week the upper level pattern transitions from
northwest to quasi-zonal, bringing seasonably warmer temperatures
and dry conditions through the forecast period.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 719 PM CDT Fri Oct 13 2017

An upper level trough located over eastern Montana and
northwestern North Dakota will continue pushing its way into the
state overnight. This system is bringing light to moderate rain
across the northern tier of counties over western and central
North Dakota.

Through the overnight hours, mainly light precipitation will
increase in coverage as it moves east. Another center of low
pressure will move northeast from north central South Dakota
Saturday morning, increasing precipitation chances over the James
River Valley as well. Mainly light rain is expected, but a mix of
light rain and light snow will be possible across the far north
and east as temperatures fall overnight.

Lower ceilings will move in from the northwest bring MVFR
conditions to KISN, possibly KMOT, and eventually KJMS. Any rain
or snow that fall over any site could bring brief IFR conditions.
Finally, breezy northwest winds will bring 25 to 30 mph gusts over
much of southwestern, central, and eastern North Dakota by
tomorrow afternoon.

&&

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

$$

UPDATE...ZH
SHORT TERM...AE
LONG TERM...AE
AVIATION...ZH



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