Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Bismarck ND
1231 am CST Thursday Nov 26 2015
issued at 1230 am CST Thursday Nov 26 2015
Currently...a large cold surface high pressure was over southern
Alberta/Saskatchewan and over Montana. At upper levels a northern
stream trough extend from north central Canada to near the
Montana/ND/sask/man border area. The southern stream portion of the
westerlies was in the form of a nearly cutoff low over Nevada...with
upper level energy impulses moving northeast from the low across the
Latest satellite loops and surface observations continued to show
overcast conditions over western and central North Dakota...with
some clearing skies over northern Montana. Light snow continued
across the far southern counties with light snow or flurries over
parts of northern North Dakota. As mentioned in previous
update...low confidence in high res models regarding cloud cover but
the rap 13 h925 relative humidity field may have the best solution with a very
gradual clearing from west to east.
Light snow and flurries along the southern border of the state
should continue for much of the overnight hours as upper level
impulses associated with the aforementioned southern stream energy
look to maintain enough instability for light precipitation.
Made some temperature changes in the west...as apparent clearing or
at least temporary clearing in the far west near beach has allowed
temperatures to drop to around zero. Adjusted minimum temperatures and
Update issued at 853 PM CST Wednesday Nov 25 2015
The latest fog/stratus satellite loop and surface observations
continue to show overcast conditions across western and central
North Dakota. Light snow continues in the far south with light
snow and flurries across northern North Dakota. There is clearing
in eastern Montana approaching the western border. However a
shortwave trough in southeast Saskatchewan will make little
progress southeast overnight. The rap13 925rh has the best handle
on the current low clouds and will continue to follow. Expect
decreasing clouds west towards 12z Thursday with central North
Dakota remaining cloudy through middle/late morning. Followed the
high resolution nmm east which is the only model that has this
evenings light snow captured in the south. Have extended the snow
in the southern James River Valley and entire far south through
12z Thursday. Otherwise light flurries will continue north overnight.
In the west expecting some clearing overnight resulting in low
temperatures in the lower single digits. The previous forecast had
this covered well and the trend still looks on track given above
Update issued at 552 PM CST Wednesday Nov 25 2015
Latest regional/local radar shows an area of light snow continuing
to straddle the far southern border...with light snow/flurries
covering most reporting stations across the north. Snow amounts
over the last couple hours in the north have varied from a trace
at Williston and Minot...to between 0.01 to 0.02 at Watford City
and Tioga. Latest water vapor imagery shows an upstream shortwave
trough slowly approaching from Saskatchewan. The rap13 seems to
have the best handle on the areal coverage of the overcast
conditions along and ahead of this shortwave trough. The rap13
maintains a swath of high 925mb-850mb relative humidity across central North
Dakota until Thursday afternoon. However...will await the 00z
suite of data evaluate beyond tonight. For this update will slow
down the decreasing clouds in the north this evening and maintain
areas of light snow/flurries in the north associated with the
clouds and incoming upper trough.
Short term...(this evening through thursday)
Issued at 200 PM CST Wednesday Nov 25 2015
Forecast highlights in the short term period will be lingering
light snow south this afternoon/early evening...and cold
temperatures for Thanksgiving.
Currently...split flow aloft with an open wave trough over central
Canada extending into the northern plains...and the closed upper
level low anchored over the Desert Southwest. Two areas of light
snow remains across western and central North Dakota...the first
very light if anything across the north associated with the
northern stream trough...and the second a band of light to
possibly embedded moderate snow across the far southwest into the
far south central associated with an embedded shortwave which ejected
out of the southwest upper low last night. Will maintain higher
probability of precipitation for the southern activity with the more enhanced radar
returns. Will also continue to mention this area in the severe weather potential statement for
reduced visibilities in falling snow this afternoon.
Cold and dry air advection spread west to east tonight into
tomorrow as high pressure builds across the northern High Plains
of Montana and Wyoming. This will act to end the snowfall across
the south this evening...along with an overall decrease in sky
cover from north to south tonight into Thursday. Cold night with
lows in the single digits above to middle teens...and a cold day for
Thanksgiving with highs only in the 20s.
Long term...(thursday night through wednesday)
issued at 123 PM CST Wednesday Nov 25 2015
The main focus for the long term is the potential for snow late
this weekend into early next week.
A wide array of model solutions have been depicted over the past
several days with respect to this weekend's storm.
Therefore...there is a great deal of uncertainty with respect to
timing and location of precipitation. General model consensus of
the 12 UTC runs would place the bulk of the moisture south of
North Dakota. However...the GFS and Canadian models do wrap in a
swath of snow across the James Valley Monday. Utilizing a blend of
the operational models yields around an inch or two total of snow
along and south of I-94 for from late Saturday into Monday.
However...temperatures are currently forecast to rise to near or
slightly above freezing Sunday and Monday afternoon. This would
likely melt most or all snow that accumulates overnight.
Therefore...at this time little to no impacts are expected with
this storm. However...this could change if the main low shifts a
bit further north.
Otherwise...the long term appears quiet...with temperatures in the
30s for highs and teens/twenties for lows.
Aviation...(for the 06z tafs through 06z Thursday night)
issued at 1230 am CST Thursday Nov 26 2015
MVFR ceilings at all terminals begin the taf period. Low confidence in
various models determining when conditions should improve. Western
edge of the cloud shield in Montana had been nearly stationary
despite various computer models suggesting clearing. Thus tafs
indicate MVFR ceilings will generally be maintained through 12z
Thursday. Expect improving conditions across the western aerodromes
of kisn/kdik Thursday morning 12z to 15z...with MVFR ceilings lingering
over kmot/kbis/kjms through 18z Thursday.
short term...New Hampshire