Cavour, South Dakota Weather Forecast Discussion

127
FXUS63 KFSD 101047
AFDFSD
Area Forecast Discussion
National Weather Service Sioux Falls SD
547 AM CDT Wed Sep 10 2025
.KEY MESSAGES...
- Areas of dense fog will continue across the area through mid
  morning. A Dense Fog Advisory remains in effect for portions
  of the area.
- Canadian wildfire smoke will linger aloft through tonight. Any
  surface impact will be minimal.
- Temperatures warm to well above mid-September normals Thursday
  through Saturday.
- The next best chance for showers and thunderstorms (30-50
  percent) will be Saturday night through Sunday.
&&
.DISCUSSION...
Issued at 335 AM CDT Wed Sep 10 2025
Light winds and mostly clear skies have resulted in fairly
widespread dense fog across a good portion of the area early this
morning. Lowest visibilities currently reside from east central SD,
through southwest MN, and into portions of northwest IA, and the
current Dense Fog Advisory covers this well. Will continue to
monitor through the morning hours for possible expansion if
conditions deteriorate farther to the south/west. Look for any fog
that develops to burn off by mid to late morning.
Otherwise, the warming trend continues for today as an upper level
ridge oriented over the eastern Rockies nudges eastward through the
day. With that, highs will climb into the mid/upper 70s east to
lower/mid 80s west. There will be a little more breeziness today
west of Interstate 29, this in response to an increasing surface
pressure gradient and slightly higher winds aloft over that area.
Guidance continues to show Canadian wildfire smoke streaming over
the region at least into tonight, though it appears there will be a
lesser chance of smoke reaching the surface. Tonight will be a mild
night with lows in the mid 50s to lower 60s. With light winds east
of Interstate 29, may again see a risk of fog over that area.
Summertime heat slowly builds into the area for Thursday through
Saturday as the aforementioned upper level ridge moves from west to
east across the region through the period. 700/850 mb temperatures
will be in the top 10th percentile or greater with respect to NAEFS
climatology, and related to that highs will rise into the 80s for
Thursday, then 80s to lower 90s for Friday and Saturday. Rainfall
chances look to remain low (less than 20%) through the period.
Model guidance shows some consensus on an uptick in shower and
thunderstorm chances by Saturday night and Sunday as an upper level
trough over the western CONUS begins to shift into the Plains
states. There may be an increase in severe storm chances during this
period as shortwaves lift out of the trough on a southwesterly upper
level flow - but this will be dependent on placement of frontal
boundaries and how much moisture return is realized across our area.
Some risk of severe weather is supported by latest CIPS analogs.
Rainfall chances become even more uncertain by the beginning of next
week with model differences, though temperatures look to remain
above seasonal averages with highs in the mid to upper 80s.
&&
.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 545 AM CDT Wed Sep 10 2025
Areas of IFR/LIFR visibility in dense fog have developed from
east central SD, though southwestern MN, into portions of
northwest IA early this morning. Outside of these areas, MVFR
visibility is common. This fog will burn off around 15Z this
morning. By late morning, conditions will improve to VFR which
will persist through the remainder of the TAF period. Some
guidance would suggest additional fog development east of
Interstate 29 late tonight, though this should remain east of
TAF sites. Winds will be light east of Interstate 29 today,
though increasing west of there with a few gusts approaching 20
kts into this evening.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Dense Fog Advisory until 9 AM CDT this morning for SDZ039-040-
     055-056-062-067.
MN...Dense Fog Advisory until 9 AM CDT this morning for MNZ071-072-
     080-081-089-090-097-098.
IA...Dense Fog Advisory until 9 AM CDT this morning for IAZ001>003-
     012>014-020.
NE...None.
&&
$$
DISCUSSION...JM
AVIATION...JM

NWS FSD Office Area Forecast Discussion