734 
FXUS63 KBIS 221706
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
Issued by National Weather Service Grand Forks ND
1206 PM CDT Tue Oct 22 2019


.UPDATE...
Issued at 1205 PM CDT Tue Oct 22 2019

Updated temperatures to reflect a slower warming response this
morning. Otherwise, the forecast remains on track for mostly sunny
skies through much of the day with increasing clouds this
afternoon from the southwest.

UPDATE... 
Issued at 620 AM CDT Tue Oct 22 2019

Updated PoPs early this morning to add in a very small area of
light snow that developed over Dickinson. It appears this is in
association with weak lift aided by a vort lobe across western ND. 
This area continues to shift away, closer to southern border and 
have a mention of light snow through 12z. Otherwise expect a 
mostly sunny morning and afternoon for central ND, while clouds 
will increase west this afternoon with a chance of rain late. 

SHORT TERM...(Today and tonight)
Issued at 320 AM CDT Tue Oct 22 2019

Rain, some thunder, and light snow accumulations highlight the 
short term period across western and portions of south central ND. 
Nothing is anticipated across the north central and the James 
River Valley through tonight.

Latest water vapor imagery shows a northwest flow aloft with a 
shortwave/vorticity center noted over southern Saskatchewan. An 
area of weak 3hr surface pressure falls continues to push through 
western North Dakota, now nudging into central North Dakota. 
Pockets of mid level clouds out ahead of this shortwave can be 
seen on satellite moving from northwest to southeast. Expect 
scattered clouds through the morning as this shortwave progresses 
through, otherwise mostly sunny with increasing clouds west later
this afternoon. Highs today will be in the 40s to around 50 west.

Our next vigorous upstream shortwave trough is now located over 
British Columbia, and this will support the development of an 
Alberta Clipper type cold front this morning. As the entire system
pushes into eastern Montana and western North Dakota this 
evening/tonight, the potential for a couple thunderstorms are 
possible given the instability and large scale ascent that is 
forecast to slide across western and portions of south central ND 
tonight. An 850mb baroclinic zone really tightens up by 06z 
Wednesday across the west. On the warmer side of the baroclinic 
zone, mainly southwest and far south central ND, SPC continues to
advertise a General Thunderstorm area for this evening through
most of tonight. The SPC 03z SREF 3hr calibrated thunderstorm 
probabilities do show a weak signal for thunderstorms across far 
southwest and far south central between 00z and 09z Wednesday. Our
gridded data picked this up based on the steep mid level lapse
rates that are forecast. 

Both the GFS and NAM show strong ascent, steep mid level lapse 
rates, and low level frontogenesis between 00z and 12z Wednesday 
for western and portions of south central ND. The RAP13 Bowman 
BUFKIT forecast sounding at 03z Wednesday shows potential for 
thunder. Low level lift/Omega is maximized around 4000ft, which is
the level where parcels need to get. Most Unstable CAPE is very 
narrow, around 200 J/Kg per NAM12, and weaker per GFS. At the same
time, on the colder side of the baroclinic zone, expect a quick transition
from rain to snow later this evening with snowfall accumulations 
of between 1 and 2 inches by daybreak Wednesday from Williston to
Killdeer, Dickinson to Elgin and to Selfridge in Sioux County. 
The area of snowfall lines up well with a sharp 700mb shortwave 
trough and 700mb low which tracks from McKenzie County southeast 
into Stark and Grant counties 06z-12z Wednesday.

Bismarck/Mandan will remain on the far eastern fringes of little 
or no snowfall accumulation. North central and the James River 
Valley will not be impacted with this clipper system.

LONG TERM...(Wednesday through Monday)
Issued at 320 AM CDT Tue Oct 22 2019

Precipitation from the departing clipper lingers Wednesday through
Wednesday night across southwest North Dakota. Expect chances of
snow in the morning and night, with a mix of rain/snow Wednesday
afternoon. Any accumulations at this point will be light. It will
be dry but colder across the rest of western and central ND
Wednesday with highs in the upper 30s to lower 40s. Warm air
advection kicks in later in the day Thursday west, then propagates
across central ND Thursday night through Friday. Dry Thursday and
Friday with highs in the lower 40s Thursday, then mid to upper 50s
Friday. A strong clipper swings through Saturday, mostly with an
increase in northwest winds, and some chances of rain/snow. Highs
will once again be in the 50s Saturday, then the colder air
arrives Sunday and Monday with high temperatures dropping back
into the 30s. 

AVIATION...(For the 18Z TAFS through 18Z Wednesday) Issued at 1200
PM CDT Tue Oct 22 2019

Look for VFR conditions to prevail through much of the day at all
TAF sites with northwest winds. Gusts of 20 to 30 knots will
continue through the afternoon at KJMS and KMOT before tapering
off this evening. Rain chances increase this evening at KXWA,
KDIK, and eventually KBIS. This shower activity will mix with snow
later in the evening with the better chances remaining west of
Bismarck. CIGs will be reduced accordingly as precipitation 
impacts the region, with MVFR to IFR conditions likely.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...99
LONG TERM....99
AVIATION...FGF