FXUS63 KFSD 261802

AFDFSD



Area Forecast Discussion

National Weather Service Sioux Falls SD

102 PM CDT Thu Jun 26 2025



.KEY MESSAGES...



- Scattered showers/isolated storms will continue to diminish 

  in coverage through this afternoon. Still a low risk for an 

  isolated strong/severe storm in our far southeast counties 

  this afternoon, but greater threat will be east of Highway 71 

  corridor.



- Periodic thunderstorm chances continue Friday evening through

  the weekend. Some indication that storms could become strong

  to severe at times. Begin monitoring this time period if you 

  have outdoor plans.



- Warming temperatures and increasing humidity this weekend will

  bring a risk of heat indices above 100F in some areas Saturday

  afternoon. Otherwise seasonably warm temperatures will prevail

  much of next week.



&&



.UPDATE...

Issued at 1255 PM CDT Thu Jun 26 2025



A slow-moving wave has been maintaining an area of showers across

the Highway 14 corridor while coverage farther south continues to

slowly decrease. Subtle boundaries may become a focus for weak 

funnels this afternoon, but need at least some partial clearing to

boost instability a bit more. Will also be monitoring our far

southeast counties for an isolated strong-severe storm over the

next 2-3 hours, but that threat should shift east of Highway 71

fairly quickly.



&&



.DISCUSSION...

Issued at 351 AM CDT Thu Jun 26 2025



TODAY: Elevated showers and weak thunderstorms continue this 

morning, triggering along an area of convergence supported by the 

nose of the LLJ and a mid to upper level shortwave. These are 

expected to remain sub-severe due to low instability (only a couple 

hundred J/kg CAPE) and shallow upper lapse rates (< 6 Deg C). As the 

surface front makes its final push through northwestern Iowa late 

this morning into the early afternoon there is a chance of renewed 

convection. CAMS show a line of stronger thunderstorms forming along 

this boundary as it moves off, but there is disagreement in the

location of initiation. Some have storms initiating as far west

as a rough line from Sioux City to Spencer. Others don't have 

the stronger convection initializing until it's east of our 

area. Looking at the dynamics, 0-6 bulk shear of 30-40 kts could

support a few isolated stronger cells. However, the instability

is looking less favorable, only a few hundred J/kg, with the 

better thermal profile just east of our area. In either case, 

PWAT values are at or near the maximum for climatology. 

Considering this, the deep, warm cloud layer of 12,000+ feet, 

and long skinny sounding profiles, these will likely still be 

efficient rain producers. An additional quarter to an 1.5 

inches of rain is possible by the time rain ends this afternoon.

Higher pockets are possible for areas in northwestern Iowa. As 

such, will leave the Flood Watch that is already in place.



In addition, as the low passes over the region, an area of enhanced 

stretching potential and vorticity advection sets up over 

northwestern Iowa and southwestern Minnesota. Here a few brief 

funnels are possible this afternoon through this evening. Threat of 

funnels should wane as the sun sets and afternoon heating 

dissipates. 



Storms will gradually cease by late this afternoon. Clouds will 

gradually decrease from west to east this afternoon. As the sun 

comes out we can expect temperatures to begin to rise into the upper 

70s to 80s for areas along and west of the James River. Slightly 

cooler east of there where clouds last longer, in the 70s. Overnight 

lows will be in the upper 50s to low 60s. 



FRIDAY-SATURDAY: Surface high pressure moves in for Friday, keeping 

us dry. Through the day, winds will turn to the south-southeast. 

Areas to the west of James River will see winds increase in response 

to a tightening SPG as a shortwave approaches from western South 

Dakota. Gusts in the afternoon will be 15-25 mph in this area, less 

than 10 mph to the east. As the wave continues to progress east, a 

warm front will push into the region from the west. This will help 

our highs for Friday warm into the 80s to low 90s over central South 

Dakota. 



As the wave continues its progress, a quick shot of rain is possible 

early Saturday morning. The best shear remains north of the area, 

but instability and steep mid-level lapse rates could support a 

storm or two becoming stronger. The threat is short lived as the 

wave clears the area quickly. Location of activity is uncertain, as 

there is low consensus in the model guidance. The rest of the 

afternoon a very strong push of WAA on southwesterly winds will help 

our highs for Saturday reach into the 90s. Dew points will be in the 

upper 60s to mid 70s. These combine to create heat index values in 

the upper 90s to low 100s. We will need to continue to monitor this 

trend as it may become necessary to issue a heat headline in 

the future. 



SUNDAY-NEXT WEEK: The hot weather will be short lived this time as 

another short wave and cold front move through the region. Highs 

will be in the mid 80s to low 90s, with the warmest temperatures 

along and south of the HWY 20 corridor. Showers and thunderstorms 

are expected to trigger off this system late Saturday night into 

Sunday. Guidance is in low agreement on track of this system. The 

GFS keeps the track to the north, just clipping out Minnesota 

counties. The EC, CAN, and NAM vary on coverage, but all have the 

system traversing from northwest to southeast through the day 

Sunday. The best shear will lag behind the best instability. 

Soundings are well capped, but do indicate some elevated storms

are possible. Plentiful instability will be present with steep 

lapse rates, however shear will be marginal. It is possible a 

few isolated to scattered severe thunderstorms may develop. If 

they do, the primary threats will be large hail and damaging 

wind gusts. 



Next week the active pattern aloft looks to continue. Periodic rain 

chances will be in the forecast through the end of the week. That 

includes the 4th of July. If you have outdoor plans for that day, 

keep an eye on the forecast, you may need to make adjustments.



&&



.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...

Issued at 1255 PM CDT Thu Jun 26 2025



Low MVFR-IFR stratus is still rather prevalent across the 

forecast area to start this TAF period, though expect this to

slowly lift through the afternoon. Limited mixing will leave

behind plenty of boundary layer moisture, though, and with light

winds expected overnight, should see areas of fog develop later

tonight into early Friday morning. MVFR-IFR visibility seems most

likely, but cannot rule out sub-1SM LIFR visibility in some areas.

Fog should diminish pretty quickly after sunrise.



&&



.FSD WATCHES/WARNINGS/ADVISORIES...

SD...None.

MN...None.

IA...None. 

NE...None.



&&



$$



UPDATE...JH

DISCUSSION...AJP

AVIATION...JH

