FXUS63 KABR 191115

AFDABR



Area Forecast Discussion

National Weather Service Aberdeen SD

615 AM CDT Tue Aug 19 2025



.KEY MESSAGES...



- Pockets of patchy fog will expand over portions of mainly 

  eastern SD and west central MN and slowly improve from daybreak 

  through 10 AM.



- Heat index values will top out in the upper 90s to near 100 

  degrees today and Wednesday afternoon over south central SD. A 

  few locations are forecast to reach heat index values of 100 to 

  104 degrees south of a line from Mission Ridge to Onida and 

  Highmore Thursday afternoon.



- The passage of a low pressure system and cold front late 

  Thursday afternoon through Thursday night will bring a 40 to 70 

  percent chance of precipitation, with a marginal risk, or level 

  1 out of 5, of severe storms.



&&



.DISCUSSION...

Issued at 303 AM CDT Tue Aug 19 2025



The 08Z surface map shows high pressure over Manitoba extending a 

ridge over our forecast area. Low pressure was set up across the 

intermountain west. Light winds remain in place under the ridge 

today, with another round of early morning fog that is currently 

more focused over portions of southeastern SD but will be expanding 

at least patchy fog over much of eastern SD and west central MN by 

daybreak before improving through 10 AM. The fog is not expected to 

be as dense or cover as much of the area as Monday morning. Given 

mainly dry weather and the surface ridge sliding east Tuesday, the 

focus weather wise will be on temperatures. Dewpoints will remain in 

the upper 60s to low 70s. These higher dewpoints and the 

temperatures in the 90s over portions of central SD will result in 

higher heat index values. Heat index values will top out in the 

upper 90s to near 100 degrees today and Wednesday afternoon over 

south central SD. A few locations are forecast to reach heat index 

values of 100 to 104 degrees south of a line from Mission Ridge to 

Onida and Highmore Thursday afternoon. We will continue to monitor 

the trends and wait and see if any heat headlines will be needed. At 

this point we will start advertising the potential in the HWO. 



Upper-level low pressure over British Columbia starts to 

develop and move east Wednesday evening into Thursday. This low 

pressure will interact with the upper-level ridge, pushing the ridge 

out of SD. An associated surface low pressure in Canada will start 

to push a cold frontal boundary into SD, with models varying the 

time of arrival slightly between late Thursday morning into the 

early evening. The front will move over the state through the night 

and into Friday morning. This frontal passage will most likely bring 

precipitation and potentially storms with it as it moves through

SD. There is now a marginal risk of severe storms over much of the

forecast area for late Thursday afternoon into Thursday night.



The front will also bring colder air into SD, causing the 

temperatures to start to lower into the weekend. Max temperatures 

are currently forecast to drop down into the 70s and even the upper 

60s over far northeastern SD by the weekend. Additionally, the 

frontal passage will cause the winds to shift to be mainly from the 

northwest through the weekend. There is the potential for wildfire 

smoke to travel aloft along those winds and into the area.



&&



.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...

Issued at 615 AM CDT Tue Aug 19 2025



Terminals KABR,KATY,KPIR,KMBG



While VFR conditions are expected most of the period, LIFR to IFR fog

will remain at ATY until 14-15Z. Daybreak fog is also at PIR this

morning, mainly in the MVFR range. We'll continue to monitor

showers and a few storms over southern ND that will attempt to

slide over mainly ABR this morning.



&&



.ABR WATCHES/WARNINGS/ADVISORIES...

SD...Dense Fog Advisory until 9 AM CDT this morning for SDZ020-022-

     023.



MN...None.

&&



$$



DISCUSSION...06/12

AVIATION...06