Hail in Iowa, June 13, 2026

Area Forecast Discussion
National Weather Service Sioux Falls SD
642 AM CDT Sat Jun 13 2026

.KEY MESSAGES...

- Scattered showers and thunderstorms are expected this morning
  mainly across northwestern IA and far northeastern NE. A few
  storms could become severe mainly along the Highway-20
  corridor with up to half dollar sized hail being the primary
  threat.

- Additional showers and thunderstorms will be possible into
  early afternoon. However, the severity of storms remains
  uncertain at this time.

- Near to below normal temperatures will continue well into next
  week with highs mainly in the 70s to 80s expected.

&&

.UPDATE...
Issued at 408 AM CDT Sat Jun 13 2026

Taking a look across the area, we're continuing to watch a growing
altocumulus field across northcentral Nebraska this morning. While
we're a little early, as this field continues to expand eastwards;
this will likely become the focus for where our next shower and
thunderstorm chances (40%-60%) develop across northwestern IA.
With this in mind, the forecast remains on track for showers and
thunderstorms to develop starting around 5 am as weak shortwave
intersects a lingering cold frontal boundary. With a weakening
LLJ overhead, a few developing storms could become severe with
large hail up to half-dollar size (1.25") being the primary
threat.

While the focus continues to be across the Highway-20 corridor, the
only significant change in the forecast is that SPC has introduced a
Day 1 slight risk (Level 2 of 5) to the same areas due to the
increasing potential for larger hail. Otherwise, newer runs of short-
range guidance has continued to expand the coverage of showers and
potentially thunderstorms northwards into early afternoon. As a
result, decided to follow suit with our POPs using a blend of the
latest NBM and CONSshort. Lastly, its worth noting that the 06z HRRR
has started to hone in on additional redevelopment in the early
afternoon mainly along the cold front. If this proves to be true,
can't rule out a narrow window for a few additional stronger storms
carrying larger hail mainly across our far southeastern-most zones
(Woodbury, Ida, Cherokee, and Buena Vista counties) during the early
afternoon timeframe (12pm-4pm).

&&

.DISCUSSION...
Issued at 155 PM CDT Fri Jun 12 2026

Mostly clear skies, WAA on breezy southwest winds, and deep mixing
will help our high temperatures this afternoon warm into the
80s. Looking aloft we see a strong upper low over eastern
Canada. A cold front drapes southwest through northern
Minnesota, through North Dakota, and into Montana. This front
will drift southeast bringing chances for showers and
thunderstorms with it. As the front approaches our western
border this evening, an area of surface convergence will form
ahead of it. Increases in low- level Theta-e contributes to a
modest increase in instability, though MUCAPE remains on the low
side, around 500-800 J/kg. At the same time mid-level lapse
rates increase, and 0-6 km bulk shear will be in the 50 kt
range. While severe weather is not anticipated, the stronger
shear could allow a few isolated updrafts to organize enough to
produce small hail. Though, with cloud base heights of
8000-10,000+ ft AGL the chances small hail will survive to the
surface is low. Tall, skinny CAPE profiles on soundings indicate
that some brief heavy downpours are possible. Soundings also
indicate a deep, very dry subcloud layer. Evaporational cooling
could result in wind gusts to 45 mph, and is the most likely
threat with any stronger storms. Convection is expected to begin
as a weak mid- level short wave intersects the front around 6-8
pm. The strongest storms are expected along the Highway 14
corridor from roughly Huron east into Minnesota. Weaker, more
showery storms may drift as far south as I-90. Storms should be
east of the CWA around midnight.

As the cold front continues to progress southeast through the
overnight, another surface low and attendant warm front will be
moving northeast out of Colorado/Wyoming. Between the two fronts
will be a slightly stronger area of convergence. Similar to Friday
evening, instability increases as an area of rich Theta-e moves
north into the region. Mid-level lapse rates increase into the
favorable range for stronger storms, as well as bulk shear at 40-50
kts. However, several questions remain. First, the environment is
strongly capped, for storms to form they will have to fire along the
925 mb front. The second question is how far north the richer
Theta- e air will advect. The CAN and NAM12 have higher values
working into the area as far north as Highway 18 and east into
northwest Iowa, while the GFS and EC are more conservative and
higher values remaining south of Highway 20. Third, when will
the mid- to upper wave arrive? There is enough variance in
guidance to leave confidence in strong storm formation low
(10%). Enough forcing looks to be present to initiate isolated
to scattered elevated showers and thunderstorms. The main threat
will again be wind gusts to 45 mph and brief heavy downpours.
Unlike Friday, the cloud base heights are around 900 ft AGL. So
while small hail is still unlikely, it has a better chance
surviving to the surface should it form. Any stronger storms are
most likely to occur as convection initiation begins around
daybreak, 5-7 am. Storms will weaken and gradually move east
through the early afternoon Saturday.

Behind the cold front, winds will become northwesterly and cooler
air will flow into the region. Highs for Saturday will depend on
where you are within the CWA. For those north of I-90 low to mid 70s
are expected. To the south, mid to upper 70s. Clear skies Sunday
with a couple of dry short waves reinforcing the CAA limit highs to
the low to mid 70s. Monday a return to westerly flow and mostly
sunny skies will bring highs back into the mid 70s to low 80s.
Monday evening a stronger shortwave will work through the pattern,
bringing chances for showers and thunderstorms. While some thunder
is possible, severe weather is not anticipated at this time. Tuesday
will be mostly sunny with a stronger push of WAA. Highs will be in
the mid 70s to mid 80s along the Missouri River Valley. Highs for
the second half of the week will remain in the 70s and 80s for the
most part. From here guidance begins to diverge. Multiple chances
for showers and storms exist, though details are uncertain at this
time.

One final note: Those with outdoor plans, rejoice! This weekend
through the first half of next week will not only be on the cool
side of average for this time of year, but relative humidity values
will also be low. Get out and enjoy the pleasant weather!

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 636 AM CDT Sat Jun 13 2026

Mainly VFR conditions with occasional MVFR cigs will be possible
this TAF period. Taking a look at satellite imagery, we're
continuing to monitor a few showers and thunderstorms progress
across northcentral and northeastern NE this morning. While its
looking less and less likely thing will move into the Highway-20
corridor, decided to at least keep a PROB30 at KSUX just in case
a pop up shower or storm decides make its way into the area.
Otherwise, could see additional chances for showers across
northwestern IA from late morning into early afternoon promoting
occasional MVFR cigs. Lastly, light northerly winds will become
more northwesterly with wind gusts up to 30 mph possible.

&&

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

&&

UPDATE...05
DISCUSSION...AJP
AVIATION...05

Hazardous Weather Outlook
National Weather Service Sioux Falls SD
413 AM CDT Sat Jun 13 2026

IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097-
098-NEZ013-014-SDZ038>040-050-052>071-140915-
Lyon-Osceola-Dickinson-Sioux-O'Brien-Clay-Plymouth-Cherokee-
Buena Vista-Woodbury-Ida-Lincoln-Murray-Cottonwood-Nobles-Jackson-
Pipestone-Rock-Dixon-Dakota-Beadle-Kingsbury-Brookings-Gregory-
Jerauld-Sanborn-Miner-Lake-Moody-Brule-Aurora-Davison-Hanson-McCook-
Minnehaha-Charles Mix-Douglas-Hutchinson-Turner-Bon Homme-Yankton-
Union-
413 AM CDT Sat Jun 13 2026

This Hazardous Weather Outlook is for northwest Iowa, west central
Iowa, southwest Minnesota, northeast Nebraska, central South
Dakota, east central South Dakota, south central South Dakota and
southeast South Dakota.

.DAY ONE...Today and tonight.

Scattered showers and thunderstorms will return to the area this
morning mainly across northwestern IA. A few storms may become severe
mainly along the Highway-20 corridor with large hail up to half
dollar size being the primary threat.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.