KBIS issues Area Forecast Discussion (AFD) valid 2019-12-02T00:38:00Z    

525

FXUS63 KBIS 020038

AFDBIS



Area Forecast Discussion

National Weather Service Bismarck ND

638 PM CST Sun Dec 1 2019



.UPDATE...

Issued at 630 PM CST Sun Dec 1 2019



For early evening update main change was to increase fog coverage

for central and parts of western North Dakota. Latest high-res

models show this fog continuing to develop, but then gradually

shifting to the east as modest warm air advection develops on the

back-side. In the meantime, some of this fog is becoming dense, 

as shown on a few surface observations. Since this is not 

widespread, will forgo issuing a dense fog advisory but will cover

with a special weather statement.



&&



.SHORT TERM...(This evening through Monday)

Issued at 227 PM CST Sun Dec 1 2019



Currently, surface high pressure was over central North Dakota, 

between the exiting storm system now over the Great Lakes, and weak 

low pressure in the lee of the Rockies as a minor upper level 

shortwave traverses east across southern Saskatchewan. 



Winds this afternoon over western North Dakota were already 

southerly on the west side of the surface high, and we expect 

decreasing winds in central North Dakota to also become southerly 

and light tonight. Clearing skies in western North Dakota this 

afternoon and partial clearing in central North Dakota today is 

expected. 



Tonight an open upper level shortwave moves east along the 

US/Canadian border from the Rockies into the western Plains, with 

the trough axis approaching western North Dakota by Monday evening. 

This will be associated by mid and upper level clouds moving into 

western North Dakota late tonight and spreading/expanding across the 

state on Monday. 



The recent snowfall, light winds, and partial clearing in central 

North Dakota will allow temperatures tonight to fall to around 5 to 

10 above zero. Stratus clouds are expected to re-develop in central 

North Dakota, with some fog potential. Farther west, the increasing 

mid/high cloud cover, combined with some light southwesterly winds 

and warm advection aloft should help keep temperatures from falling 

too far - thus expecting overnight lows in the west to be mainly in 

the teens.



On Monday, the southwesterly and westerly winds will help usher in 

some warmer air. Expect temperatures to reach the mid to upper 30s 

in most of western North Dakota, highs in the lower 30s for parts of 

central North Dakota...except for mid/upper 20s in areas with deep 

snow cover in the James River Basin. Lowered consensus blend of 

model max temperatures in this area for this reason.



.LONG TERM...(Monday night through Sunday)

Issued at 227 PM CST Sun Dec 1 2019



Monday night the aforementioned upper level shortwave trough will 

move east across the Dakotas. This will keep the atmosphere mixed as 

surface winds remain westerly around 10 to 15 mph. A breezy day on 

Tuesday with west/northwest winds of 15 to 20 mph with neutral to 

warm advection. Expect lows Monday night mainly in the 20s and highs 

Tuesday mainly in the 30s.



Mainly zonal flow aloft will be in place for the majority of the 

work week. A couple of upper level shortwaves and surface fronts 

ahead and cold fronts behind the waves will move across the region. 

However, each wave is expected to be dry with mainly an increase in 

cloud cover. Overall temperatures during this term period will 

remain seasonably mild. Average highs this time of year are 20-30F, 

with lows around 5 to 10 above zero. We are expecting highs mainly 

in the 30s through much of next week with lows mainly in the teens 

and lower 20s. 



By the end of next weekend, an upper level low will expand from 

central Canada across much of the central US. This upper level 

cyclonic flow regime will result in small chances of light snow by 

Sunday with more seasonable temperatures.



&&



.AVIATION...(For the 00Z TAFS through 00Z Monday evening)

Issued at 630 PM CST Sun Dec 1 2019



VFR conditions will prevail far west. Over remaining areas of

western and central North Dakota, fog and low ceilings have

developed producing IFR/LIFR conditions. Expect this to continue

this evening, with improvement late tonight into early Monday

morning from west to east as the clouds/fog shift to the east. 

Thereafter, VFR conditions are expected through the remainder of 

Monday.



&&



.BIS WATCHES/WARNINGS/ADVISORIES...

NONE.

&&



$$



UPDATE...JJS

SHORT TERM...JV

LONG TERM...JV

AVIATION...JJS