Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Bismarck ND
635 am CST sun Dec 28 2014
issued at 628 am CST sun Dec 28 2014
The previous forecast is on track. Light snow will likely
continue through at least 15 UTC...per hires arw and nmm
runs. Up to two inches are possible along and southwest of the
Missouri River by midnight tonight. Frigid temperatures spilling
into the northern plains will cause temperatures to drop steadily
as soon as skies clear in the wake of snow.
Short term...(today and tonight)
Issued at 340 am CST sun Dec 28 2014
Forecast highlights in the short term period will be light
accumulating snowfall through the period and colder temperatures.
Currently...long wave upper level trough over much of North
America. Region of enhanced overrunning flow/isentropic lift along
to east of a frontal boundary stretched from southern Saskatchewan
southeast across western into south central North Dakota early
this morning...with a surface high pressure ridge building southeast
across eastern North Dakota and low pressure over much of Montana.
Increased probability of precipitation to likely/def some locations this morning as we are
accumulating here at the Airport at the moment and should continue
to do so for a few hours. Main area of light snow will sag south
with the enhanced easterly upslope flow with time through this
morning. Up to an inch of snow will be possible within this band
if it can continue.
Snow will continue across the southwest for much of the day as the
current activity moves south and another area of snow associated
with a middle level wave moves east from Montana into my southwest.
Near two inches of snow still possible over the four southwest
counties of North Dakota through this evening. Chances for snow
end overnight as high pressure continues to build south out of
Attention then turns towards colder air and dangerous wind chills
developing tonight from north to south. Cold air advection will combine with
clearing skies to allow for temperatures to fall to below
zero...nearing 20 below far north. Pressure rises ahead of the
building surface high will maintain a steady northerly wind allowing
wind chills to reach advisory criteria for all but the southwest.
Current Wind Chill Advisory spot on so no changes are needed to
headlines with this forecast package other than to modify wording
a bit to keep it consistent with the gridded forecast.
Long term...(monday through saturday)
issued at 321 am CST sun Dec 28 2014
The return of Arctic air Sunday through Tuesday and a chance for
snow Thursday night through Friday highlight the long term.
Models and ensembles remain in great agreement that Arctic high
pressure will remain over the northern High Plains until Tuesday.
The Wind Chill Advisory remains in line with this forecast update.
Warm air advection on new years evening and New Years Day will likely be
short lived as average agreement among ensemble members calls for
broad cyclonic flow on the back side of the Hudson Bay upper level
low to direct another Arctic air mass...and associated cold
front...into the northern plains. Forecast moisture profiles and
Omega fields are sufficient for at least light snow across much of
the state Thursday night through Friday...though the last four
GFS/European model (ecmwf) runs have been inconsistent with location and amounts.
Cold air behind the system will have similar characteristics to the
air mass currently dropping down out of Alberta.
Aviation...(for the 12z tafs through 12z Monday morning)
issued at 628 am CST sun Dec 28 2014
Band of MVFR ceilings and MVFR/IFR visible in light snow will continue
this morning over western and south central terminals at times.
Conditions should improve through the day and into this evening
from north to south.
Wind Chill Advisory from midnight CST /11 PM MST/ tonight to
noon CST /11 am MST/ Tuesday for ndz017>020-031>037-042-045>048-
Wind Chill Advisory from 8 PM this evening to noon CST Tuesday
Wind Chill Advisory from 5 PM Monday to 11 am MST Tuesday for
short term...New Hampshire