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Area forecast discussion 
National Weather Service Bismarck ND
111 am CST sun Dec 28 2014

Update...

Issued at 111 am CST sun Dec 28 2014

Frontal boundary stretched from southern Saskatchewan southeast
across western into south central North Dakota...in between high
pressure to our north and low pressure over central Montana.
Cloudy conditions persist...but should see a gradual clearing over
my northeast early this morning as a ridge of surface high pressure
builds southeast into eastern North Dakota.

Main area of light snow will reside along the boundary mainly over
my northwest quarter through 12z near the more favorable
overrunning flow. Will go with a high pop/low quantitative precipitation forecast wording. Frontal
boundary sags south with time through Sunday with the best low
level forcing west into south central. While my southwest may see
an inch of snow...not much to the north or east but will remain
consistent with a high pop/low quantitative precipitation forecast wording elsewhere west and
south central. Leaned heavily on a blend of the latest
sref/NAM/nmm west output.



Update issued at 923 PM CST Sat Dec 27 2014

Broad swath of very light snow has developed along the northern
portion of the area this evening as cold airmass works its way
in...which is not reflected well in latest model output. For
evening update have addressed this by increasing probability of precipitation through the
remainder of the evening...and then shifting the snow south late.
Do not expect much in accumulation. Updates have been sent.

Update issued at 621 PM CST Sat Dec 27 2014

Area of light snow over southeast North Dakota continues to push
off to the southeast...while next area of light snow settles into
the north as cold airmass starts to nudge its way in. Have
adjusted forecast to spread snow chances through much of the area
as this continues to work its way south. Updates have been sent.

&&

Short term...(this evening through sunday)
issued at 305 PM CST Sat Dec 27 2014

Arctic high pressure across Saskatchewan will move south tonight
and Sunday. A brief period of warm advection ahead of this cold
air appears to support an area of light snow across the north
central into the eat central this afternoon. Radar loops show its
fast moving and will exit the east by 6 PM. Will include a period
of snow for this afternoon with high probability of precipitation but low snow amounts.

Tonight...an area of snow associated with the baroclinic zone and
frontogenesis on the leading edge of the cold air will progressively
move from the northwest to the southwest tonight then remain across
the southwest on Sunday. Upslope conditions will assist in snow
generation of up to 2 inches southwest by Sunday evening.

Wind chill values of 25 below across the north central Sunday
morning will not last but a few hours...so will wait for the better
wind chill values expected Sunday night for headlines.

Long term...(sunday night through saturday)
issued at 305 PM CST Sat Dec 27 2014

A minor issue at the start of the long term is the light snow
winding down in the southwest. Snow totals from Sunday short term
through Sunday night long term should be around 2 inches maximum in
Bowman County area. With the cold air pouring in I continued the
snow flurries over the state into Sunday night then gradually ended
them from the northeast by Monday morning.

The bigger issue in the long term is the coldest air of the season
..so far...Over the entire area for Monday through Tuesday.
Apparent temperatures are coming out in the 25 to 35 below zero
range and so have given a little more than 24 hours advance notice
on the wind chill headline that will be issued soon. In collaboration
with Grand Forks have opted to piece meal the advisory in...then
keep it going through noon Tuesday...in order to limit the
confusion with start and stop times. Keeping in mind...at the same
time...that the actual forecast conditions needed to be considered
as well. Noon Tuesday may be too soon for the advisory to be
lifted from Bottineau to Jamestown...it may need to be extended
once we get closer to that time...but again...limiting confusion
as much as possible is important.

The center of the 1055mb surface high passes through eastern Montana
Monday night / Tuesday morning with the flow out of the high
contributing to keeping the wind up close to 10 miles per hour and adding to
the chill of temperatures in the teens below zero. A few limiting
factors to how cold it will get Monday night are...the lack of fresh
deep snow cover locally and upstream...coupled with what could be a
dirty high with low clouds as model soundings show very high low
level relative humidity over the area...especially west half.

Warm air advection gets underway by Tuesday night on the back side
of the high on a 15 miles per hour southwest wind. That breeze will add to the
chill even though temperatures are on the rise. That not so cold
spell lasts until the next cold frontal passage Thursday night /
Friday morning. There is better middle level energy associated with
that passage so a widespread light snow is possible for Friday...on
the order of an inch or two. The European model (ecmwf) long range model has come
more in line with the GFS for that time period increasing confidence
in at least some snow then.

&&

Aviation...(for the 06z tafs through 06z Sunday evening)

Issued at 111 am CST sun Dec 28 2014

Band of MVFR ceilings will continue/develop from north to south along
a frontal boundary this morning...including areas of light snow.
Conditions should improve through the day and into this evening from
north to south.



&&

Bis watches/warnings/advisories...
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-
050-051.

Wind Chill Advisory from 8 PM this evening to noon CST Tuesday
for ndz001>005-009>013-021>023-025.

Wind Chill Advisory from 5 PM Monday to 11 am MST Tuesday for
ndz040-041-043-044.

&&

$$

Update...New Hampshire
short term...warm air advection
long term...jpm
aviation...New Hampshire

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