394
FXUS63 KFSD 130516
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1216 AM CDT Wed May 13 2026

.KEY MESSAGES...

- Critical fire weather may return again Thursday as winds gust
  above 40 mph, along with a risk for isolated to scattered
  thunderstorms. Severe storms are not expected.

- Temperatures continue to warm though the weekend, with high
  temperatures expected to be 10 to 20 degrees above normal.

- Regional rain chances increase Saturday and especially Sunday.
  A great deal of uncertainty remains, but a few signals present
  for strong storms late Sunday.

&&

.UPDATE...
Issued at 904 PM CDT Tue May 12 2026

Late this evening winds will become light and variable. Clear skies
and calm winds will allow for good radiational cooling tonight. Lows
are expected to fall to the mid to upper 40s. Wednesday winds will
remain light and variable through the morning as an upper ridge and
surface high pressure passes through the region. By the late
afternoon the high will have pushed off to the southeast and winds
will become southerly and increase over central South Dakota as the
SPG tightens ahead of the next incoming upper trough and surface
frontal system. Highs for Wednesday look to climb into the mid 70s
to low 80s. conditions are expected to remain very dry with
relative humidity near or at critical values in the afternoon.
However, the generally light winds keep Fire Danger low. Still,
remain cautious to avoid fire starts.

Thursday morning a few elevated showers and thunderstorm are
possible as modest moisture advection flows into the region coupled
with weak WAA. The latest guidance indicates a slight uptick in
available instability, around 800-1000 J/kg. While this is enough
for some thunder severe weather is not anticipated. A second round
of showers and thunderstorms are possible in the late afternoon with
the passage of the cold front. Slightly better dynamics may allow
for a few stronger thunderstorms to develop, but severe weather is
not anticipated with this round either.

Thursday has the potential to become a critical Fire Weather day.
Highs will be warm in the upper 70s to mid 80s. Surface conditions
will be dry with relative humidity less than 30% for most of the
region, and between 21-25% over central South Dakota. Late Wednesday
night and Thursday strong winds will push in from the west ahead of
a cold front, with gusts of 35-45+ mph possible. Fire and possibly
wind headlines may be necessary. However, if there are lingering
clouds from morning storms this may work to limit highs, which may
in turn limit fire potential.

&&

.DISCUSSION...
Issued at 1239 PM CDT Tue May 12 2026

THIS AFTERNOON: Hot, dry, and windy conditions which have been the
story of much of May, continue this afternoon.  We`ll continue to
see gusts 35 to 45 mph at times this afternoon as relative humidity
continues to fall into the 20 percent range. Some reports this
afternoon of blowing dust from farm fields, so will include patchy
mention in the forecast until wind relax.

TONIGHT:  Winds gradually relax this evening, turning light and
variable into Wednesday morning as the surface ridge of high
pressure slides southeast. With temperatures in the 40s, no frost
concerns.

WEDNESDAY: Winds remain light and variable into early afternoon
before a steady increase in southerly winds across central
Nebraska/South Dakota by late afternoon.  High temperatures rise
through the 70s and may reach the 80s near the MO river valley.

THURSDAY: A mid-lvl ridge axis will slide east Wednesday night,
pushing east of I-29 by daybreak Thursday.  Models continue to show
signals for low-lvl moisture convergence by daybreak Thursday
which could spark elevated showers and a few thunderstorms
moving eastward into the afternoon. MUCAPE remains limited AOA
700 J/KG, so not anticipating severe weather. Further west, a
frontal boundary forms in central South Dakota and become a
potential focal point for surface based convection late in the
afternoon. Dew points ahead of the boundary may only reach the
low 50s, but the increase in synoptic lift and steepening lapse
rates may support an isolated storm or two marching eastward in
the evening. Winds and fire weather may be the bigger story
during the day as NBM probabilities for wind gusts over 40 mph
surpass 70% by mid-day. Should dew points mix into the lower
40s, then RH may fall near 25% at times, leading to critical
fire danger. Fire weather watches may be needed if forecast
conditions remain as currently projected. One alternative
scenario to watch is a stalled area of mid-lvl clouds east of
I-29 that could temper the rise of temperatures in the afternoon
and keep fire weather danger in check.

FRIDAY: A stronger frontal boundary pushes southeast by daybreak
Friday, lowering dew pints and bringing slightly cooler
northwesterly surface winds into the area. Another dry day with low
RH is anticipated.

SATURDAY-MONDAY: There remains quite a bit of model discrepancy
heading into the upcoming weekend, focusing on precipitation
chances as well as severe weather risks. By Saturday morning
we`ll begin to see some influence of broadening southwesterly
mid-lvl flow and slowly increasing moisture return. First likely
in the form of increased cloud cover, but then by increasing
PoPs Saturday night. Sunday poses considerably more uncertainty
as Mid-lvl flow tries to turn more southerly and results in
stronger poleward return flow. The latest LREF 24 hour POP over
0.10" has continued to increase on Sunday, as high as 60-70% in
some locations but especially focused along and east of I-29.
The high probabilities of lower totals followed by lower
probabilities of higher totals (>0.50") would signal agreement
in the risk for rain, but minimal agreement in where meaningful
rain might develop. Severe weather risks also remain very
uncertain especially given uncertainty in just how far north the
warm sector may lift. Conditional probabilities would suggest
greatest potential is focused south of I-90, and this is
supported by the AI-learning outlook products. Temperatures this
weekend will be highly dependent on cloud cover and rain, but
there remains potential for highs to climb into the 80s. A cold
front sweeps southeast on Monday, lowering temperatures for the
new work week.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1216 AM CDT Wed May 13 2026

VFR conditions and mostly clear skies are expected to prevail for
this period. Winds will be light and variable through the overnight
and most of Wednesday. By the afternoon winds become southerly but
remain light through the end of the period.

&&

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

&&

$$

UPDATE...AJP
DISCUSSION...Dux
AVIATION...AJP