061 
FXUS63 KBIS 120822
AFDBIS

AREA FORECAST DISCUSSION
National Weather Service Bismarck ND
322 AM CDT Tue Sep 12 2023

.SHORT TERM...(Today and Tonight)
Issued at 206 AM CDT Tue Sep 12 2023

The main forecast issue in the short term period will be stratus/fog
this morning. 

Currently, surface high pressure is situated over Ontario Canada
and extending west into Manitoba and the eastern half of North
Dakota. Low pressure was situated in the lee of the Canadian
Rockies with a southeast return flow over central and eastern
Montana and into western North Dakota. An upper level trough was
situated over the northern Great Lakes Region, with another
upstream trough just offshore from British Columbia and the
Pacific Northwest U.S. Coast. In between upper level ridging was
situated from the northern High Plains into the southern
Canadian Prairie Provinces. Current satellite imagery is showing
some patchy fog over the southern James River Valley, mainly from
around Jamestown south towards Oakes. Low visibility earlier at 
the Jamestown airport has improved and area webcams are not 
showing much at this time. RAP and HRRR indicate lower vsbys 
generally 11-12 UTC to 15-17 UTC. Satellite imagery is also 
showing stratus developing over southwest North Dakota. Glen Ullin
has dropped to 6SM with a 300 ft ceiling. RAP/HRRR and NBM 
probabilities indicate stratus would be more likely here.

For today, once any fog stratus burns of later this morning, 
expect quiet weather with mainly sunny skies with some increasing 
thin high level cloudiness. High temperatures are expected to 
range from the low to mid 60s Turtle Mountains and James River 
Valley, to the low to mid 70s west. We will see an increasing 
southeast flow develop over the west today with winds of 15-25 mph
this afternoon and early evening. 

For tonight winds will diminish some but could be breezy at times,
especially at higher elevations. Temperatures will not be as cool
as this morning, but still at or a bit under climatological 
normals, ranging from the lower 40s to lower 50s. 

.LONG TERM...(Wednesday through Monday)
Issued at 206 AM CDT Tue Sep 12 2023

Wednesday morning will see the ridge across our area begin to 
flatten, as a midlevel shortwave begins to move east out of the 
northern Rockies. SSW-ly low level and surface flow ahead of this 
feature is expected to raise temperatures on Wednesday, as warmer 
air over eastern Colorado and western South Dakota is advected north 
into the state. The warmest temperatures are expected across far 
western ND, with highs in the 80s possible along the Montana border.
This feature, along with an associated cold front, will move east 
across the state late Wednesday night through Thursday, lowering the 
highs for Thursday. This front is expected to generate some showers 
as it moves east across the state, though with limited instability, 
only a few embedded thunderstorms are possible.

As surface flow becomes more NNW-ly behind the front, overnight lows 
on Thursday will decrease into the mid to upper 40s again. The 
aforementioned shortwave will eventually be ingested into a larger 
trough descending southeast from Saskatchewan/Manitoba, moving out 
of the area through Friday. Models tend to agree most with a robust 
midlevel ridge strengthening across the western CONUS, building east 
across the Rockies and High Plains and into our area through the 
weekend. Quieter weather, clear skies and seasonally average 
temperatures are currently forecast for the weekend and next Monday. 
Disagreement between models increases drastically for Tuesday, as a 
rather prominent midlevel trough may sweep across the International 
Border, potentially reducing temperatures below average through 
midweek. However, with the amount of variance between models, it is 
too early to say with confidence if this will pan out.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday Night)
Issued at 206 AM CDT Tue Sep 12 2023

Areas of fog, dense at times is expected around the James river
Valley early this Tuesday morning, including KJMS. KJMS already at
1/4SM FG just prior to the 06Z TAFS. Based on satellite it looks
patchy in nature and may vary at time 06-10-12 UTC before becoming
more dense around sunrise and continuing through 15-17 UTC. KMOT
also dropping a little down to 6SM prior to 06 UTC TAFS, but here
will not be as pessimistic with visibilities through mid morning,
probably starting off with tempo down to MVFR and will go from
there. 

Otherwise, after fog dissipates this morning only high level
clouds expected with a southeast surface flow through the period.
Southeast flow breezy at times west this afternoon and evening.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...TWH
LONG TERM...Besson
AVIATION...TWH