Sioux City, Iowa 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

900
FXUS63 KFSD 060347
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1047 PM CDT Thu Jun 5 2025

.KEY MESSAGES...

- Scattered showers with an occasional rumble of thunder likely
  this afternoon. While mostly light accumulations are expected
  south of I-90, north could see around three tenths. Isolated
  pockets of higher are possible.

- Spotty showers continue during the day on Friday. Could see a
  brief window for few weak funnels by Friday afternoon.

- A conditional risk for severe weather will be possible on
  Saturday. However, some lingering uncertainty remains.

&&

.DISCUSSION...
Issued at 245 PM CDT Thu Jun 5 2025

TODAY AND TONIGHT: A mid-level shortwave coupled with weak WAA is
slowly moving into the region this afternoon bringing chances for
rain. A few of these showers may also produce lightning. Severe
weather is not anticipated, as instability is lacking with 500 J/kg
or less, marginal shear of less than 30 kts, and shallow lapse rates
of less than 5 C/km. As far as totals are concerned, a couple
hundredths for areas south of I-90, and north 0.1 to 0.3 inches.
Isolated pockets of higher amount`s are possible if any
stronger storms should develop, mainly along and north of
Highway 14. Highs for today should top out on the cool side of
average, in the upper 60s in central South Dakota, to the mid
70s in western Iowa and Minnesota. For reference, average highs
for the early part of June are in the upper 70s. Overnight lows
will be in the 50s.

FRIDAY: A weak mid-level low pressure moves through the region
bringing more chances for showers and thunderstorms Friday
afternoon. Again severe weather is not expected due to a general
lack of instability and shear. However, with the weak low overhead,
and nearly calm winds through the boundary layer, and a broad area
of enhanced stretching potential, a few brief funnels are possible.
While we are not expecting severe weather, a few stronger storms may
produce lightning and brief heavy downpours. Coverage is expected to
be more sparse than today, and additional accumulation should
only be a few hundredths to a couple tenths. Highs will
seasonably cool, in the upper 60s to mid 70s. Lows will fall to
the 50s.

SATURDAY: Saturday our active pattern continues with renewed chances
for showers and thunderstorms. Looking aloft we see a closed upper
low swiftly moving southeast from western Canada into North Dakota
and Minnesota. This low will produce a couple waves that will
produce our rain chances. These will come in two rounds. Round one:
a prefrontal trough moves through early Saturday morning bringing
showers and thunderstorms to south central South Dakota and along
the Missouri River Valley and north into northwestern Iowa and
southwestern Minnesota. While DGZ and upper levels are fairly
saturated, a dry subcloud layer will influence if and when any
showers actually reach the ground. There is moderate instability
present, however shear is lacking. This type of set up is not likely
to produce severe thunderstorms. However, a few stronger storms are
possible that could produce lightning and small hail. Though the
better chances look to remain just to our south, where the better
dynamics are. A brief lull in activity is expected Saturday
afternoon. Breaks in clouds will allow our afternoon highs to warm
nicely into the upper 70s and low 80s.

Round two: The surface warming coupled with an influx of moisture
ahead of a strong cold front will will sharply increase instability.
Elevated CAPE of 1200-1800 J/kg, coupled with 30-40 kts of bulk
shear, and the added boost of a strong LLJ will all work together to
set the stage for strong to severe thunderstorms Saturday evening.
The area most likely to see thunderstorms is along and north of
Highway 14. A Day 3 SPC Marginal Outlook (level 1 of 5) has been
issued for this area and north into North Dakota. These storms will
be short lived as they quickly blow through the available
instability. But while they are at their peak, they may be capable
of producing frequent lightning, hail up to the size of a quarter,
and brief heavy downpours. Those with overnight outdoor plans in
this area will want to stay updated on the latest forecast.

SUNDAY-MID WEEK: Sunday storms push east of our region by mid
morning. Temperatures will be slightly cooler, with highs in the low
to mid 70s. Aloft the closed low from Saturday is continuing to push
southeast into the Great Lakes region. It will deliver us a parting
shot in the form of a shortwave that will clip areas along and north
of Highway 14 into southwestern Minnesota. Shear will be a little
better for this round but a general lack of instability will likely
keep our severe chances low. However, at this time there is low
agreement in model solutions for this system.

Once that wave finally moves out an upper ridge will build in
bringing dry conditions and a warming trend through mid week. Highs
for Monday will still be cool, in the upper 60s to low 70s, but by
Tuesday we`ll see highs right around average again for this time of
year, in the upper 70s to low 80s. Warmer Wednesday with highs in
the low to upper 80s. By Thursday, the upper pattern begins to break
down and chances for rainfall increase for the second half of next
week.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1046 PM CDT Thu Jun 5 2025

A few light showers persist across the area late this evening.
Should see the showers continue to wane over the next few hours.
Ceilings will lower to MVFR/IFR/LIFR levels mainly along and west of
the James River during the overnight hours. Though MVFR ceilings
could expand further westward into parts of southwest Minnesota and
northwest Iowa.

Light and variable winds are expected throughout the day tomorrow
while ceilings lift back to VFR levels through the morning hours.
Another round of isolated to scattered showers is expected for the
afternoon hours. The showers will wane by sunset, leaving mainly dry
conditions to end the TAF period.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.

&&

$$

DISCUSSION...AJP
AVIATION...Meyers