Woodburn, Iowa Weather Forecast Discussion

420
FXUS63 KDMX 091954
AFDDMX
Area Forecast Discussion
National Weather Service Des Moines IA
254 PM CDT Tue Sep 9 2025
.KEY MESSAGES...
- Scattered showers and isolated non-severe storms mainly north
  into this evening.
- Warning up this week into the 80s mid-week and potentially
  some 90s Friday and into saturday.
&&
.DISCUSSION...
Issued at 253 PM CDT Tue Sep 9 2025
Short wave moving across southern Minnesota has been evident as
circulation on both radar and satellite. Convection has been most
prevalent to the east of the short wave where the greatest forcing
resides but some weak convection continues to percolate over parts
of north central Iowa. This scattered convection will remain
possible over northern Iowa into early this evening and there is a
chance some lingering kinematic forced showers and isolated storms
occur over the far northeast overnight. The other forecast challenge
overnight is fog potential. Higher dew points in the upper 50s to
lower 60s along with a wetting rainfall over the north and light
winds may lead to some fog development. The amount of cloud cover
overnight is a bit uncertain as there is a mix of clear patches and
patches of stratocumulus this afternoon. The stratocumulus should
thin with the loss of diurnal heating but it will be a slower
process than general cumulus. Cumulus should reform early Wednesday
morning as the low level moisture lifts and forms cumulus.
Currently have Wednesday dry as a modest elevated mixed layer (EML)
forms and should prevent convective development but will continue to
monitor the status of the EML. Should the EML remain weak enough for
surface based instability, the overall forcing is quite low but it
would still lead to an isolated shower/storm chance.
The remainder of the forecast has the upper level ridge moving more
eastward and eventually over Iowa for the end of the week and into
Saturday. Have continued the trend of using the NBM 50th percentile
compared to the straight up NBM which is over the 90th percentile.
Note the NBM has not verified well all year when sitting above the
90th percentile. This appears to be another case for that trend. The
850 mb temperatures in the upper teens to low 20s C and dew points
in the upper 50s to low 60s do not correlate to highs in the low to
mid 90s. The GFS is way over mixed this time period while indicating
mostly cloudy skies, which is another red flag. The upper ridge will
move slightly east late this weekend as a negatively titled trough
extends into the state, bringing increasing precipitation
chances.
&&
.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1226 PM CDT Tue Sep 9 2025
VFR to start the period though MVFR cigs have developed over
portions of northwest Iowa and south central Minnesota. Light
rain is in vicinity of KFOD/KDSM/KMCW to being the period and
that will gradually become more focused north through the
afternoon and there is a low potential for a thunderstorm at
KMCW. Cigs around 4-5 kft should develop across much of the area
by mid-afternoon. MVFR cigs are possible overnight, mainly north
along with some fog also. Additional cumulus development may
occur Wed morning as the low level moisture evaporates leading
to cumulus development below 3 kft though at this time the
potential for additional MVFR BKN cigs appears 

NWS DMX Office Area Forecast Discussion