Area Forecast Discussion
Issued by NWS Bismarck, ND

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271
FXUS63 KBIS 050611
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1211 AM CST Mon Dec 5 2016

.UPDATE...
Issued at 1209 AM CST Mon Dec 5 2016

No major changes made for this update. However, new data suggests
major changes for tomorrow`s forecast.

UPDATE Issued at 954 PM CST Sun Dec 4 2016

No changes to temperatures with the late evening update. With
increasing clouds, the temperature drop over central ND has
leveled off. Did update pops a little. In general, the new NAM/GFS
and mesoscale models have slowed down the eastward progression of
precipitation overnight, thus updated pops to reflect this.
However, looks like maybe a vort lobe extending ahead of main
vorticity, into western ND this evening which is producing some
higher reflectivities, and possibly a little light snow from
around Killdeer to east of Dickinson. Will add a slight chance of
pops for this area, and spread it toward the Missouri river into
the early morning hours.

UPDATE Issued at 758 PM CST Sun Dec 4 2016

Quick update to lower min temperatures a little more over snowpack
in central ND with lack of sky cover. Also added a mention of
patchy fog around the Turtle Mountains with some occasional lower
vsbys showing up on area Observations.

UPDATE Issued at 630 PM CST Sun Dec 4 2016

Shortwave energy tracking east across the Northern Rockies and the
Northern High plains, along the International Border is producing
some light precipitation over northeast Montana. There could be a
few flurries reaching the ground in far northwest ND, but modified
pops to delay arrival of pops in the northwest for about an hour.
East of this, a good sized area of cloud free snow covered ground
in southwest and central ND. Temperatures already in the upper
teens and lower 20s here so lowered temperatures here a few
degrees this evening. May need to lower even more if clouds are
slow to move in. We will become cloudy here eventually so did not
drop temperatures drastically. Over the Turtle Mountains into the
far north central, stratus remains and it may linger through the
night. bumped up sky cover here and adjusted temperatures up a
little this evening as they will be slow to fall as long as
stratus remains.

&&

.SHORT TERM...(This evening through Monday)
Issued at 230 PM CST Sun Dec 4 2016

Mid/upper level transitory ridge will continue to slide across
central ND this afternoon then exit to our east this evening.
Attention then turns toward a shortwave currently located over far
southeast Alberta, supporting a strong surface cold front which
will shift through western ND 09-12z/3am-6am CST Monday, and
through central ND 15-18z/9am-noon CST Monday. Once frontal
passage occurs, expect northwest winds to increase with cold air
advection dominating for several days to come. Both the NAM/GFS QG
fields advertise poor alignment between the lower level frontogenetical
forcing field and the mid/upper level divergence field. The end
result is/has been for snow amounts to trend much lower across all
of western and central ND. The ECMWF is the only model that seems
to hold onto higher snow amounts in the Turtle mountains while
coinciding with the strong northwest winds. The Baggaley Blowing
Snow Model predicts patchy blowing snow with a brief period of
areas of blowing snow in the Turtle Mountains Monday night. Snow
amounts from model to model run have been trending less since
yesterday. Hence after coordination with Grand Forks WFO, we decided
to hold off on any winter weather highlights since uncertainty
remains rather high on snow amounts, and also in the timing of
the falling snow coinciding with the strong winds. Overall snow
amounts will be an inch or less in most areas. The exception(s)
will be in northern ND, along and north of Highway 2 where between
1 and 2 inches of snow is forecast. And there is potential of
between 2 and 4 inches in Bottineau/Rolette/Pierce counties. But
again, this has been shifting and trending lower the past couple
of days. There is still time for future shifts to re-evaluate any
changes to possible winter weather headlines across the Turtle
Mountains.

.LONG TERM...(Monday night through Sunday)
Issued at 230 PM CST Sun Dec 4 2016

High confidence continues for frigid air along with brisk northwest
winds Tuesday through Thursday resulting in wind chills to approach
30 below zero, especially during the overnight and early morning
hours. Will continue messaging this in the HWO/Hazardous Weather
Outlook and in social media. A backdoor cold front shifts through
Wednesday night with a round of snow showers and a reinforcement
of cold air. A quick transition toward warm air advection commences
Friday through Friday night ahead of another cold frontal passage.
This will produce light accumulating snowfall during this time.
Successive events similar to Friday and Friday night continues
through next weekend with additional light snowfall amounts with
each passage.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1209 AM CST Mon Dec 5 2016

VFR cigs begin this Taf period and will continue through the
early evening at KISN and late evening or the early overnight
hours elsewhere. Thereafter, cigs will trend downward toward
MVFR/IFR after 08z-12z Monday through 00z Tuesday. Gusty
northwest winds to around 25kt will develop after 12z Monday with
reduced visibilities in snow and possibly some patchy blowing snow
by Monday afternoon.

&&

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

$$

UPDATE...AJ
SHORT TERM...KS
LONG TERM...KS
AVIATION...AJ



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