FXUS63 KFSD 271135

AFDFSD



Area Forecast Discussion

National Weather Service Sioux Falls SD

635 AM CDT Mon Oct 27 2025



.KEY MESSAGES...



- Rainfall onset looks slower today, but spotty light showers or

  sprinkles should develop by this afternoon. Rainfall amounts 

  may approach 0.10" toward central South Dakota, but most areas

  will see a few hundredths of an inch at best through sunset.



- More widespread rain is expected later this evening through

  Tuesday evening, especially along/east of I-29. This area

  continues to see 40-60% chances for rainfall exceeding a half

  inch. 



- Near to slightly below normal temperatures dominate this 

  week, but warmer temperatures may be more promising for the 

  latter half of next weekend.



&&



.DISCUSSION...

Issued at 330 AM CDT Mon Oct 27 2025



TODAY: Well-advertised mid-upper level trough moving across the

northern Rockies toward the High Plains of the Dakotas early

this morning. With a strong downstream blocking ridge, timing of

this trough has trended slower, with impacts for our forecast

area two-fold for today. While areas west of U.S. Highway 281

may see a few light showers this morning, most areas will remain

dry until a couple of weak mid-upper level waves move into the

area this afternoon. This should still promote development of

light showers/sprinkles for most of our area, though amounts

through the daytime hours will be quite light with most areas

seeing a few hundredths at best. Weak mid-level instability 

toward central South Dakota may support a few moderate showers 

or even an isolated thunderstorm by late afternoon, which could

push amounts toward a tenth of an inch. Despite lower rainfall

chances, cloud cover will be abundant, limiting highs to the 50s

for most locations.



TONIGHT-TUESDAY NIGHT: The blocking ridge over the Great Lakes

and eastern Canada will force additional energy to dig into the

central Plains. A north-south band of mid-level frontogenesis 

strengthens ahead of the trough late tonight, with some model

solutions showing this frontogenesis persisting along/east of

I-29 through much of Tuesday. This lift will interact with a

plume of deeper moisture over the eastern half of our forecast 

area, resulting in more widespread rain development by late 

tonight. Periods of rain will persist near and especially east

of I-29 Tuesday into Tuesday evening before the upper level low

pulls southeast into the mid-lower Mississippi Valley. Rainfall

amounts should be higher with this phase of the system and while

totals are still being ironed out, ensembles continue to show

moderate (40-60%) probabilities of 24-hour rainfall exceeding a

half inch, highest east of I-29. The rain/clouds along with a

generally cooler air mass will lead to below normal highs on

Tuesday in the upper 40s to lower 50s.



WEDNESDAY ONWARD: Seasonably cool northerly flow will dominate 

much of the mid to late week period, though any periods with a 

more westerly low level flow could see a brief warm-up. While 

there is some consensus among 00Z deterministic models showing 

weak ridging Thursday ahead of stronger low pressure dropping 

southeast through North Dakota/Minnesota Friday-Saturday, the 

broader ensemble still shows more variance in possible timing 

and strength of any waves. Thus, confidence in seeing greater

temperature swings or light precipitation chances by late week

into next weekend is low.



&&



.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...

Issued at 635 AM CDT Mon Oct 27 2025



Deteriorating ceilings are expected through this morning as 

deeper moisture builds across the area from the south. MVFR 

ceilings should be widespread by 18Z, with further lowering 

after sunset. IFR to locally LIFR ceilings will become more 

prevalent along and east of U.S. Highway 81 by 28/06Z, while 

areas west of Highway 81 begin to see improving conditions.



The lowering ceilings will be accompanied by scattered light

rain showers this afternoon, with more widespread rain and areas

of MVFR visibility developing after sunset and persisting into

Tuesday morning.



South-southeast winds will become breezy, with gusts 25-30kt at

times today across portions of southeast South Dakota/southwest

Minnesota. Wind direction will swing to the west and northwest

with an approaching front tonight, which will also lead to the

aforementioned improving conditions in our western counties 

late tonight.



&&



.FSD WATCHES/WARNINGS/ADVISORIES...

SD...None.

MN...None.

IA...None.

NE...None.



&&



$$



DISCUSSION...JH

AVIATION...JH