079 
FXUS63 KBIS 130533
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1233 AM CDT Mon Sep 13 2021

.UPDATE...
Issued at 1224 AM CDT Mon Sep 13 2021

Previous updated had a good handle on the convection moving in
from the west. Made some minor updates to sky cover, otherwise
no changes needed.

UPDATE Issued at 1025 PM CDT Sun Sep 12 2021

Main change with this update was to freshen up PoPs for tonight
through tomorrow with latest model guidance. The shortwave 
approaching the forecast area is already producing scattered 
showers in central Montana, and timing them out puts their arrival
at the MT/ND state line around 9 UTC, which is about what we've 
expecting. Showers and a few thunderstorms will continue spreading
through the forecast area during the rest of the night and into 
Monday, with the highest chances for precipitation in the south 
central and James River Valley in the morning through the 
afternoon. The chance for severe weather is still looking low, 
with a better environment just to the south of the forecast area. 

UPDATE Issued at 635 PM CDT Sun Sep 12 2021

No changes needed with this update. Showers in the north central
have moved off to the east of the forecast area, with partly
cloudy skies and somewhat breezy winds continuing this evening.
Attention then turns to precipitation chances starting overnight
tonight, with showers expected to move into western North Dakota
after midnight. 

&&

.SHORT TERM...(This evening through Monday)
Issued at 219 PM CDT Sun Sep 12 2021

A few light showers continue to linger across the north central
early this afternoon as a small area of vorticity remains in the
atmosphere. These showers will either dissipate or move off to the
east over the next few hours.

Attention then turns to the incoming shortwave trough currently
over the northwestern CONUS. This shortwave will push east through
the day today and into tonight, arriving in the northern Plains by
tomorrow morning. As the shortwave moves east across the Rockies,
it will induce surface cyclogenesis across the northern Plains 
and provide lift for showers and storms to develop. Overall, 
instability and shear is looking marginal at best with more 
favorable conditions located to our south, however areas across 
the south central and southeast may be able to tap into enough 
instability to see a strong storm or two Monday morning. QPF 
amounts will likely be highly variable with greater amounts 
expected in thunderstorms. In general, 0.25" to 0.5" is expected 
from the south central eastward, however a few areas in the 
southeast could see near an inch if lucky. 

Showers and storms push east through the day with skies clearing
behind. Expect highs in the upper 60 to upper 70s, with cooler 
temperatures where rain and clouds linger the longest.

.LONG TERM...(Monday night through Sunday)
Issued at 219 PM CDT Sun Sep 12 2021

A relatively quiet weather period is expected through the long
term. Temperatures will be in the 60s and 70s on Tuesday as 
troughing remains aloft. A brief warm up is expected on Wednesday
with ridging building in behind the departing system. A deep
upper trough moving through Canada later in the work week will 
result in southwest flow setting up across the northern Plains. No
major systems are forecast to move through, but southwesterly 
flow results in slight chance PoPs in the forecast Thursday and
Friday along with high temperatures back in the 60s and 70s and
lows possibly dipping into the upper 30s across the northwest.
Another warm up is expected heading into the weekend, with
negligible precipitation chances.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1224 AM CDT Mon Sep 13 2021


VFR conditions at all terminals to start the TAF period, with
chances for showers and a few thunderstorms beginning after 09
UTC. Expect chances increasing in central North Dakota after 12Z.
Higher chances exist at southern terminals, with only VCSH at 
KMOT and no mention of showers at KXWA. Precipitation will 
continue moving east through the day, tapering off in the James 
River Valley 21-24 UTC. Best chances of MVFR cigs/vsbys in shower
and possible thunder activity will be at KBIS 13-17 UTC and KJMS 
16-21 UTC.

&&

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

$$

UPDATE...TWH
SHORT TERM...Gale
LONG TERM...Gale
AVIATION...TWH