Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Bismarck ND
1221 PM CST Monday Dec 22 2014


Issued at 1221 PM CST Monday Dec 22 2014

Winter weather continues with impacts on travel today. Main
changes were to issue a Winter Weather Advisory for the James
River Valley into far south central North Dakota for the
anticipated trowal induced snow band starting to develop across
the southeastern part of North Dakota now. A period of rain or a
rain/snow mix is likely from eastern portions of Foster south
through LaMoure and Dickey before becoming all snow later. Winter
Weather Advisory northeast in good shape...and the Winter Weather
Advisory west also good for this update. Did add Grant County
which has been receiving snow for much of the morning and may get
grazed with the wrap around snow tonight.

Dense fog advisory was expired with the issuance of the west-southwest.

issued at 1005 am CST Monday Dec 22 2014

Another complex weather scenario across the northern plains this

Deformation zone well established across western North Dakota
contributing to accumulating snowfall as expected. Regional
satellite imagery depicts the axis of dilatation well...stretched
from western/central South Dakota back north-northwest across
western North Dakota into southern Saskatchewan. Current Winter
Weather Advisory in good shape there.

Models yesterday accurately predicted the unsaturated atmosphere
now in place across the northeastern quarter of the state.
Widespread freezing drizzle has been ongoing and continues there.
My counties bordering the Devils Lake basin are on the edge of middle
level clouds/saturate air aloft to the west. We made a few calls to
those locations and based on those reports and in collaboration
with weather forecast office Grand Forks opted to hoist a Winter Weather Advisory for
the freezing drizzle. Ended at 00z as models suggest we should be
well saturated through the middle levels by late this afternoon.

Dense fog advisory was extended through 19z with visible still 1/4
mile or less many locations. Will reevaluate over the next 3 hours
in case it needs to be re extended...or portions of it.

Next weather hazard will be snow development across the James
River Valley and over my far south central as a trowal becomes
established and wraps over the eastern Dakotas. A Winter Weather
Advisory may be needed there in the near future and will make that
decision before 3pm CST today.

Update issued at 655 am CST Monday Dec 22 2014

With this update issued a dense fog advisory through 16 UTC for
south central North Dakota and the James River Valley given
current observations and webcams. Also highlighted the freezing
drizzle potential for these areas as well. Will issue an Special Weather Statement for
the north central where fog is not dense...but...patchy freezing
drizzle is also possible. In regards to the Winter Weather
Advisory...added Divide and Williams counties as the 06 UTC
NAM/GFS...00 UTC Gem and 10-11 UTC rap runs all highlight this
area for three to four inches of snow today.


Short term...(today and tonight)
issued at 412 am CST Monday Dec 22 2014

Forecast highlights in the short term will include fog and the
possibility of freezing drizzle in central North Dakota this
morning. Then attention turns to developing snow in the west
spreading into central North Dakota...with accumulating snow and
some blowing snow.

Currently...a surface low was centered over western North Dakota -
over Western Lake sakakawea...with a trough extending southeastward
into central South Dakota. Low stratus clouds below 500 feet and fog
with visibilities from 1/2 mile to 5 miles. At upper levels a broad
trough was in place across the Front Range and plains states. Water
vapor Sat loop indicates a small circulation across southwestern
North Dakota and into western South Dakota...indicative of embedded
shortwave and a minor upper low. Regional radar mosaic loops
indicate increasing coverage in light returns from northeastern
Montana across western North Dakota into central/western South
Dakota. Dickinson reported "unknown precipitation" this past
hour...which could be rain changing to snow.

The upper level low/trough is expected to continue developing a
closed low over South Dakota this afternoon. This will induce the
surface low center to develop south into central/eastern South
Dakota today. Thus the main energy...upper level circulation and
lift...and best surface convergence will develop south of the ND/South Dakota
border. Since the evolution of this system has slowed and expected
precipitation has been later than previously forecast...combined
with the southward movement of the storm system...we do not expect
quite as much snowfall across western and central North Dakota.
Instead the bulk of the snow is expected in South Dakota and into
southern Minnesota.

Expect developing snow over western North Dakota this
morning...spreading into central North Dakota later this
morning...and continuing mainly across the southern half of North
Dakota tonight and into Tuesday.

Total snowfall expected today through tuesday: northern North Dakota
snowfall totals should range from 1/2 inch in The Turtle mountains
to around 2 inches at Williston. Across southern North Dakota
snowfall totals of 2 to 2 1/2 inches along and south of a line from
Watford City to Harvey and Carrington.

Northwest winds of 15 to 30 miles per hour are expected over southwestern North
Dakota today and tonight. This will create areas of blowing and
drifting snow that would impact Holiday travel. A Winter Weather
Advisory had been issued for this effect today and
tonight. Will keep this advisory going because of the blowing snow
hazard reducing visibilities...despite the lower snow amounts
expected. Will also keep a Special Weather Statement running for the
rest of western and central North Dakota to highlight the expected
snow for Holiday travel.

Long term...(tuesday through sunday)
issued at 352 am CST Monday Dec 22 2014

Diminishing snow on Tuesday and light snow Christmas day highlight
the extended forecast.

To begin the period...the 00 UTC deterministic and ensemble suites
are in agreement on wrap around light snowfall ending from west
to east through Tuesday across North Dakota as the upper level low
slowly fills and propagates into the Great Lakes. Travel on
Wednesday across the northern plains looks good. However...for
Christmas day Thursday the models begin to diverge on their timing
and evolution of the Pacific northwest wave as it propagates
across The Rockies...with an associated snow band in isentropic
lift possible across the Dakotas. While uncertainty
remains...some travel impacts are possible for Christmas day
across western and central North Dakota. Thereafter...temperatures
trend below normal a as abroad long wave trough envelops the Continental U.S..


Aviation...(for the 18z tafs through 18z Tuesday afternoon)

Issued at 1221 PM CST Monday Dec 22 2014

Hazards to aviation today involve low IFR conditions with patchy
freezing drizzle central and east today...snow west...and
developing snow south central and southeast today into tonight.
MVFR/IFR conditions in snow and blowing snow at kisn-kdik with
gusts to 30 kts and visibilities less than 1 mile at times in blowing
snow. MVFR/IFR in snow west spreading east. Widespread IFR
conditions will persist through Tuesday morning.


Bis watches/warnings/advisories...
Winter Weather Advisory until 6 PM CST Tuesday for ndz025-036-

Winter Weather Advisory until 6 am CST /5 am MST/ Tuesday for

Winter Weather Advisory until 6 PM CST this evening for ndz005-



Update...New Hampshire
short term...jv
long term...ayd

National Weather Service Glossary of Abbreviations