Alvord, Iowa Weather Forecast Discussion

911
FXUS63 KFSD 062124
AFDFSD
Area Forecast Discussion
National Weather Service Sioux Falls SD
424 PM CDT Sat Sep 6 2025
.KEY MESSAGES...
- Frost is possible Sunday morning. Better chances will be in
  southwest MN and east central SD where temperatures may fall
  into the lower 30s.
- Chances for isolated to scattered thunderstorms Monday. Some could
  be strong to severe.
- Additional chances for thunderstorms in the latter half of
  next week. Temperatures should be near to a bit above normal
  all week.
&&
.UPDATE...
Issued at 419 PM CDT Sat Sep 6 2025
Latest data providing a stronger suggestion that temperatures
will drop into the middle 30s a bit more widespread than earlier
though. Winds are expected to weaken rather quickly this
evening, with diurnal CU field dissipating and leading to rapid
radiational cooling. Based on Saturday morning`s lows, could see
a few areas fall into the lower 30s, especially in areas from
Brookings to Pipestone, to Sheldon. Will go ahead and issue a
frost advisory in areas where probabilities of sub-36 degree
temperatures are the highest (>60%). Additionally, areas near
Sioux City may once again see near to record low temperatures.
&&
.DISCUSSION...
Issued at 209 PM CDT Sat Sep 6 2025
Any diurnally driven cumulus this afternoon will rapidly diminish
around sunset as high pressure builds in from the northwest.
This will lead to light winds and cool temperatures with patchy
frost possible. The better chances will be in east central SD
and southwest MN. While widespread frost is not expected, if you
have anything outside that might be susceptible to frost, bring
it inside. Otherwise lows should be in the mid 30s to lower
40s.
Sunday morning will start off chilly, but with abundant sunshine,
light winds and highs in the upper 60s to lower 70s a very pleasant
late summer/early fall day is expected.
Sunday night into early Monday morning upper level support spreads
across the High Plains and warm advection develops in the mid levels
ahead of this energy. Model soundings continue to indicate some
moisture around 800 mb as the warm air advection develops which
brings some weak instability, but confidence too low to include any
shower or thunderstorm threat. Would not be surprised if some
activity develops, just low confidence on where.
On Monday this upper level energy moves into western and northern SD
with a surface front expected to work into central SD. Ahead of this
front the atmosphere becomes moderately unstable with CAPE values
round 1500 J/kg like. Shear is weak, but given the expected
instability an isolated severe storm is not out of the question. The
better chances would be in central SD late afternoon and early
evening if anything can break the capping inversion and then across
the remainder of the area from mid evening into the early overnight
hours as the wave moves east and LLJ veers and focuses east of I-29
after midnight.
Tuesday into Wednesday should be mainly dry as upper level ridging
slowly builds ahead of a deepening large scale trough to the west.
Some lingering warm air advection east of I-29 on Tuesday morning
could support and isolated shower or thunderstorm.
Wednesday night into Saturday will see this upper level ridge
partially break down with southwesterly upper level jet energy
bringing occasional waves onto the Northern Plains during this time.
This will likely bring a few rounds of showers and thunderstorms and
with some instability some isolated chances for severe weather.
Currently the deeper shear does not appear to support any organized
severe weather potential.
&&
.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1202 PM CDT Sat Sep 6 2025
VFR through the period. High pressure builds into the area
tonight with light winds tonight into Sunday morning. Patchy
frost will be possible.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Frost Advisory from 3 AM to 9 AM CDT Sunday for SDZ038>040-
     052>056.
MN...Frost Advisory from 3 AM to 9 AM CDT Sunday for MNZ071-080-089-
     090-097-098.
IA...Frost Advisory from 3 AM to 9 AM CDT Sunday for IAZ001>003-
     012>014-021.
NE...None.
&&
$$
UPDATE...Dux
DISCUSSION...08
AVIATION...08

NWS FSD Office Area Forecast Discussion