Le Mars, Iowa 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

948
FXUS63 KFSD 121938
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
238 PM CDT Thu Jun 12 2025

.KEY MESSAGES...

- Scattered showers with isolated thunderstorms will persist
  north of I-90 through tonight. A few stronger storms remain
  this evening possible mainly across southcentral SD with large
  hail up to half dollar size (1.25") and strong wind gusts up
  to 70 mph being the primary threats.

- Isolated pockets of locally heavy rainfall will be possible
  through tonight mainly along the U.S. Highway-14 corridor
  where an additional 0.10" of an inch will be possible with any
  lingering activity.

- An active weather pattern will bring continued periodic shower
  and thunderstorm chances into next week. While some details
  remain uncertain, continue to monitor for strong storm or
  heavy rain potential.

&&

.DISCUSSION...
Issued at 235 PM CDT Thu Jun 12 2025

CURRENTS & TONIGHT: Another warm day continues! Taking a look across
the area, scattered showers with isolated thunderstorms continue to
develop along an 850mb warm front current situated along a Huron to
Brookings to Jackson, MN line this afternoon. With a weakly unstable
environment characterized by 300 to 500 J/kg of instability and 30-
45kts along with shear vectors parallel to the boundary, additional
development of showers and thunderstorms will likely persist through
this evening with most of this activity gradually lifting northwards
over time. Given the set up, an additional 0.10" of an inch of
accumulation or less is expected in the outlined areas. Our
attention will shift towards the central and southcentral portion of
SD as a cold front develops with an 850mb inverted trough and lifts
northeastwards. Given the 1000-1500 J/kg of instability and 35-40kts
of bulk shear along and ahead of the near-surface feature, a few
stronger storms will likely develop with large hail up to half
dollars size (1.25") being the initial hazard as lapse rates
approach 6.5 degrees C/km.

Similar to yesterday through, as semi-discrete cells congeal into
multi-cellular clusters things should quickly become more cold
pool/outflow dominant shifting the threat towards occasionally
strong winds up to 70 mph with collapsing storms. Nonetheless, given
the time of day; the severe threat will likely be short-lived with
the greatest threat expected between 4 pm to 10 pm mostly along and
west of highway-281. From here, expect this activity to progress
east-northeastwards with the cold front into the late evening before
gradually dissipating with eastwards extent. Lastly, given the
increased cloud cover ahead of the system; we`ll likely stay warmer
overall tonight as overnight low gradually decrease into the upper
50s to mid 60s with the coolest conditions along the U.S. Highway-14
corridor.

THE WEEKEND: Heading into the weekend, lingering areas of showers
mainly across southwestern MN will continue to push eastwards to
start the day on Friday. Quieter conditions will make a temporary
return for the rest of the day as a weak upper-level ridge begins to
build aloft. An active pattern will once again resume from Saturday
night into Sunday as a shortwave rides the ridge into our area.
While shower and thunderstorm chances will likely increase during
this period, there are still some slight differences with the
intensity of the shortwave among 12.12z model guidance which has led
a few questions about the evolution of the subsequent activity. With
this in mind, its still a little early to make any definite
statements of what could happen at this point. Nonetheless, with
PWATs in the 1.25-1.50" inch range (90th percentile) and 10-12kft
warm cloud depths at times, any developing showers and thunderstorms
will likely become capable of producing pockets of heavier rainfall.
This sentiment is further reflected in the ensemble guidance with
the Canadian/Euro showing 30%-50% probabilities in 0.25" of an inch
of QPF and the GEFS showing slightly higher probabilities of 50%-70%
for the same time parameters. From here, expect conditions to clear
as quieter conditions return by Sunday night. Lastly, temperatures
will continue to trend near to above normal between Friday and
Sunday with daily highs expected to sit between upper 70s to upper
80s with some potential for a few low 90s along the Missouri River
Valley.

MONDAY ONWARDS: Looking into the extended period, quasi-zonal flow
along with weak-flat ridging will continue to promote periodic
shower and thunderstorm chances throughout the week. However, as
medium to long-range guidance continues to diverge in terms of
solutions; uncertainty remains in the severe weather potential with
each shortwave. Nonetheless, with PWATs expected to hover around the
90th percentile through Wednesday; the risk for locally heavier
rainfall will persist with most developing activity. As we approach
this time period, the severe weather and locally heavy rainfall
potential will be something we`ll have to monitor moving forward.
Otherwise, near to above normal temperatures will continue into the
midweek with daily highs peaking in the low to upper 80s.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1245 PM CDT Thu Jun 12 2025

Mostly VFR conditions with occasional MVFR/IFR ceilings are
expected for most of the TAF period. Taking a look across the
area, scattered showers with isolated thunderstorms continue to
fire along the highway-14 corridor this afternoon. While these
conditions will likely persist through the late evening, should
start to see the lower MVFR/IFR cloud bases lift towards more
VFR ceilings by Friday morning. Otherwise, southeasterly flow
will become more northeasterly with the passage of as a surface
low to end the TAF period.

&&

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

&&

$$

DISCUSSION...05
AVIATION...05