Rock Rapids, Iowa Weather Forecast Discussion

204
FXUS63 KFSD 201725
AFDFSD
Area Forecast Discussion
National Weather Service Sioux Falls SD
1225 PM CDT Sat Sep 20 2025
.KEY MESSAGES...
- Sprinkles and a few showers possible Saturday afternoon,
  mainly along and east of Interstate 29.
- Temperatures warm Sunday and Monday, bringing a risk for a
  few thunderstorms. Severe weather risks remain low, but not
  zero.
- Latest guidance continues to trend towards a drier and cooler
  middle and end of next week. Temperatures though will be near
  seasonal normals in most areas.
&&
.DISCUSSION...
Issued at 232 AM CDT Sat Sep 20 2025
THIS MORNING: A longwave trough axis continues to linger through the
Red River and Minnesota River valley areas early Saturday morning.
On the western side of this trough, we continue to see stratus pivot
southward, with embedded areas of fog.  Most areas of NW Iowa remain
clear this morning, and with temperatures falling into the upper 40s
to lower 50s, river/valley fog could form by daybreak.
TODAY: Low-lvl moisture remains in place through the region as the
aforementioned trough continues to slowly drift eastward.  Sprinkles
to scattered showers may develop in areas along or east of I-29 by
early to mid afternoon.  Coverage should be fairly limited however,
with any precipitation that falls resulting in only light QPF.
Temperatures will warm into the upper 60s to lower 70s.
TONIGHT: Light winds will again prevail into Sunday morning, as mid-
lvl warm advection begins.  Scattered mid-lvl clouds could help
insulate against any sharp fall in low temperatures. Though
overnight lows may be quite variable.
SUNDAY:   An upper trough will shift eastward toward the Great Lakes
early on Sunday, leaving a stretched out warm front bisecting the
CWA through the day.  Along and south of this boundary temperatures
may rise into the lower 80s, with highs north of the front only in
the lower to middle 70s.  Guidance continues to suggest that
isolated to scattered thunderstorm may try to form in portions of
Southern Minnesota by the evening.  With the stronger focus of lift
moving away from the area, coverage of storms should be focused more
to the east of the CWA. However it`s uncertain if the surface front
could also serve as a forcing mechanism, so will maintain a very low
PoP further southwest into the evening and overnight hours. Severe
weather risks remain low, given rather thin CAPE profiles and weak
shear.
MONDAY:  Most of the daytime hours of Monday are expected to remain
dry as the surface warm front remains stationary across the Tri-
State area. Once again, we should see temperatures rise into the
upper 70s to lower 80s.  An increase in low-lvl convergence in the
evening and overnight hours could lead to scattered thunderstorms
trying to develop, focused primarily along the Missouri River and
eastward into western and northwestern Iowa.  Sounding indicate a
bit more instability Monday evening, but again shear remains weak
enough to prohibit any widespread severe weather risk.
TUESDAY-FRIDAY: The latest deterministic and ensemble guidance is in
a bit better agreement for the middle and end of next week,
indicating falling precipitation chances and slightly warmer
temperatures.   While a longwave trough will be positively tilted
from the Great Lakes through the Central Plains, it appears that the
majority of the moisture and forcing will be focused over the the
Lower Missouri River valley region for the middle and end of
the week. The latest probabilistic data from the ECE/GEFS/CMC
all show less than a 30% probability for measurable
precipitation focused mostly along and south of the Missouri
River. Winds are expected to remain light through the week, with
temperatures holding near the seasonal normals.
&&
.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1219 PM CDT Sat Sep 20 2025
Mix of predominantly MVFR stratus and VFR stratus/developing
cumulus should continue through the early afternoon, with VFR
conditions over most of the area this afternoon and evening.
Most of the morning fog/drizzle has dissipated, and have now
seen some showers/sprinkles being to develop - mainly along the
US Hwy 14 corridor. This should continue to move southeast with
additional development east of I-29 this afternoon and evening.
Will keep mention out of KHON and KFSD at this time.
Some uncertainty with how much cloud cover clears out during the
day. If we see more clearing, expect fog to redevelop late
tonight into Sunday morning with continued light and variable
winds. For now, kept the fog mention out of any of the TAF
sites, but did add some IFR SCT ceilings to KHON and KFSD. Will
definitely be watching trends.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
DISCUSSION...Dux
AVIATION...SG

NWS FSD Office Area Forecast Discussion