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Area forecast discussion 
National Weather Service Bismarck ND
627 am CST Wednesday Nov 25 2015

issued at 624 am CST Wednesday Nov 25 2015

The ndot map and webcams show light snow across the west and
north central. Will adjust highest probability of precipitation from the west into the
north central for the morning. Also upped snow amounts there to
around an inch per webcams. Snow will trend down this late this
morning and afternoon.


Short term...(today and tonight)
issued at 334 am CST Wednesday Nov 25 2015

Chances for light snow and light freezing drizzle highlight the
short term period.

Currently...surface low pressure was over eastern South Dakota with
an inverted trough extending northward through the James Valley
through the ND/MN/Manitoba border and into southwestern Ontario.
Cold high pressure was centered over southern Alberta and pushing
into western Montana. Southeast winds east of the surface trough
with warm and moist air - and some low clouds in the vicinity of the
trough. Meanwhile at upper levels...a longwave trough extended from
north central Canada southwestward across Manitoba/Saskatchewan
to Montana and to a closed low over Nevada/California. This upper
level trough and associated vorticity energy impulses...combined with the
surface low/trough system...were associated with precipitation over
south central Canada...through Montana and Wyoming...and
southwestward across The Rockies.

The models forecast the closed upper level low to become cutoff from
the westerlies and the northern stream trough tracking eastward
slowly into Hudson Bay by Thursday morning. As a result...the models
keep the light snow currently over south central Canada moving east
and expanding northeastward across much of Ontario. Meanwhile the
area of light snow over Montana pushes south into Wyoming along and
behind the surface cold front pushing southward towards the closed
upper level low.

For western and central North Dakota...the models are bringing light
snow to northwestern North Dakota and moving into the southwest
during the day. The far northern tier of counties of North Dakota
may receive light snow amounts this morning as the aforementioned
area of light snow in south central Canada progresses eastward. The
latest run of the models indicate only around an inch of light snow
in the southwest...and perhaps as much as 1/2 inch across the
northern tier...with a trace to only a few tenths of an inch over
the rest of western and central North Dakota.

Along the inverted trough...fog and some drizzle are possible this
morning...and temperature profiles still indicate any precipitation
would be in the form of freezing drizzle - thus still kept a mention
in the James Valley this morning. Not enough to warrant any special
statements or advisories.

Cold high pressure with cold advection today...a decent pressure
gradient and h850 winds of around 25 knots...will result in brisk
northerly winds of 15 to 25 miles per hour. Only looking at highs in the 20s
over western and north central North Dakota today...with lower 30s
south central.

The cold advection continues tonight...with decreasing clouds as the
high pressure center settles over Montana by Thursday morning.
Overnight lows should range from around 5 above northwest to the
teens in the James Valley.

Long term...(thursday through tuesday)
issued at 334 am CST Wednesday Nov 25 2015

Global models continue to develop a Rex block across the
intermountain region leaving the northern plains in the middle of
The Block with initially weak flow aloft. This will maintain a
period of quiet weather starting on Thanksgiving day and going
through Saturday. Considered the possibility based on weak flow
aloft and weak ventilation for a low level inversion to set up
resulting in stratus or even fog Friday night into Saturday.
However this seems remote at this time as the low levels have a
well mixed layer with the GFS/European model (ecmwf) a good 20 to 30kt h850 wind.
This should maintain mostly clear skies. So the next chance for
snow will be Saturday night through Monday as the southern
component of the Rex block moves northeast into the northern
plains and brings a chance for snow. However models have again
become less enthusiastic about this features giving only an inch
or two of snow across the south with relatively low probability of precipitation.
After cool temperatures Thursday...middle 20s...highs will warm into
the 30s fro Friday and Saturday. Sunday through Tuesday highs will
be in the low to middle 30s.


Aviation...(for the 12z tafs through 12z Thursday morning)
issued at 624 am CST Wednesday Nov 25 2015

Ceilings and visible had deteriorated to MVFR/IFR with light snow falling over
parts of the west and north central. MVFR/IFR ceilings will
continue into Wednesday evening. Northern tafs should become VFR
around 03z...and become VFR after 06z at kdik/kbis/kjms.


Bis watches/warnings/advisories...


Update...warm air advection
short term...jv
long term...warm air advection

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