Storm Lake, Iowa 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

763
FXUS63 KFSD 112250
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
550 PM CDT Fri Apr 11 2025

.KEY MESSAGES...

- Strong winds return Saturday (south) and Sunday (northwest)
  along with warm temperatures which will lead to elevated to
  potentially critical fire weather conditions.

- A front will push across the region Sunday morning, bringing
  windy (30-40 mph) and much cooler conditions into Monday.
  Elevated fire weather conditions will persist through Monday.

- Oscillating temperatures will be common through much of next
  week as another frontal system moves through the area.

&&

.DISCUSSION...
Issued at 546 PM CDT Fri Apr 11 2025

(through next Thursday night)
Issued at 233 PM CDT Fri Apr 11 2025

TONIGHT-SATURDAY: With high pressure now moved off to the east,
south to southeast winds will begin to increase this evening and
overnight as a cold front approaches. By morning, pressure
gradients look to maximize, but then steadily weaken through the
day as the frontal zone pushes eastward into the area. Despite
mixing deepening during the day to above the 850 mb level, winds
aloft also weaken, and it appears winds will peak by noon then
gradually diminish. The Tri-State area should see the highest
winds around 20-25 mph with gusts around 35 mph, while areas
around the James River Valley see 15-20 mph and gusts 25-30 mph
peaking a bit earlier in the morning. Ahead of the front,
temperatures will peak in the upper 70s to lower 80s. Relative
humidity could flirt with 25 percent during the afternoon, but
it appears the strongest winds and lowest relative humidities
won`t overlap long enough for critical fire weather conditions
of any length, but this will need to continue to be watched.

SATURDAY NIGHT: A subtle shortwave arriving late Saturday
evening could bring a few light showers to the area, but not
expecting anything significant. have continued a slight
chance/20 percent chance for measurable precipitation.

SUNDAY: A more well-defined, upper-level trough will slide into
the Northern Plains by Sunday morning, helping to push an
inverted sfc trough and sharpening baroclinic zone across
Siouxland. While the forcing associated with this disturbance
looks quite robust, a dearth of available moisture should
preclude the chance for widespread precip. The greater impact
will be breezy north winds and much cooler weather through
Monday. The latest deterministic NBM guidance suggests daytime
highs in the upper 60s to lower 70s on Sunday as the front moves
through, then only mid 50s by Monday afternoon behind the
front. Meanwhile, overnight temps will cool into the upper 30s
Sunday night and lower 30s by Monday night.

A quick glance at forecast soundings for Monday afternoon provides
an inkling of concern for rapid fire spread.  A deep and dry PBL
should support an overzealous parameter space with respect to gusty
winds and minimum RH.  Ensemble guidance (EPS/GEFS) is in the 35-45
mph range for gusts, while the lower end of blended guidance (NBM
25th percentile) suggests afternoon minimum RH values around 30%.
With relatively dry antecedent conditions, thinking the GFDI for
Monday could be in the High to Very High range, setting the stage
for rapid fire spread in at least a few spots around Siouxland.

Winds will begin to relax Monday night as the upper-level trough
amplifies but departs eastward.  Temperatures will rebound Tuesday
and Wednesday as ample sunshine pours over the region beneath a
ridge of high pressure.  Daytime highs will be near 60 on Tuesday,
climbing into the upper 60s or lower 70s by Wednesday as sfc winds
increase and veer southwest ahead of a frontal system.

Some forecast uncertainty remains from Wednesday afternoon onward.
The main feature during this time appears to be a northern stream
trough that digs into the Northern Plains from the Canadian
Rockies.  Solution A offers a faster and further westward
amplification of this shortwave, bringing cooler and more
unsettled/wet weather to Siouxland to finish the work week.
Solution B offers a slower and much further eastward
amplification, meaning drier conditions and only a glancing
blow of cooler weather near the end of the week before much
warmer temperatures return by the weekend. Both solutions are
about equally likely at this juncture.

NWS Lincoln

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 550 PM CDT Fri Apr 11 2025

VFR conditions expected through the TAF period. Southeasterly
winds will increase later tonight and Saturday, gusting 20 to 30
kts most places on Saturday afternoon. As winds increase aloft
tonight, there will be a period of LLWS at all TAF sites late
tonight into Saturday morning.

&&

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

&&

$$

DISCUSSION...JH/Samet
AVIATION...JM