Glendon, Iowa Weather Forecast Discussion

286
FXUS63 KDMX 180338
AFDDMX
Area Forecast Discussion
National Weather Service Des Moines IA
1038 PM CDT Wed Sep 17 2025
...Updated for the 06z Aviation Discussion...
.KEY MESSAGES...
- Scattered showers and storms this afternoon through tonight.
  A few stronger storms may produce hail or gusty winds. Pockets
  of heavy rain are possible but widespread flooding is not
  expected.
- Scattered showers and storm chances continue for the next
  several days. It will not be a washout with rain the entire
  period, but scattered storms will be possible each day.
&&
.DISCUSSION...
Issued at 208 PM CDT Wed Sep 17 2025
Widespread scattered thunderstorms have persisted across the area
with the surface low to the west slowly easing east. An axis of
instability in the form of 1000-1500 J/kg of MLCAPE has developed
from central to southern Iowa where clearing earlier in the day
allowed for quick heating. Along this axis the thunderstorms are
more robust with periodic stronger cores. Even so, shear is quite
weak at 15-20 kts or less, limiting more robust and persistent storm
development. As such the severe threat remains low today, however a
few stronger cores may produce hail or gusty winds as those cores
collapse. While a few stronger cores have had pixels of 60-65dbz,
this has generally been shallow and short-lived today. These may
have produced brief hail, however no reports have been received so
far. A few of these stronger cores have produced gusty winds with
isolated gusts of 30-40 mph observed so far.
Aloft, the upper level cutoff low will remain across the area for
the next several days (through Friday and into the weekend)
with continued chances for scattered showers and thunderstorms.
As we saw yesterday and have seen so far today, activity is more
widespread than CAMs would have us believe and expect that this
trend will continue until the low finally lifts out of the area
early next week and the pattern changes. The environment
remains the same through the end of the week and weekend, so
pulsey storms producing hail or gusty winds will remain possible
while widespread storms are less likely. With little flow,
storm motions are fairly slow. These slow moving storms are
efficient rain producers in an environment with deep warm cloud
layers of 3500+ m and PWATs over 1.5". After several fairly dry
weeks, flood concerns are low at this time. While convection
remains scattered, pockets of heavy rain with some of the
stronger cores may produce areas of ponding. Any potential for
flash flooding would come from stronger cells setting up in town
where drainage is slower.
Another upper level cutoff low drops across the area early next
week, pushing the current one out of the area. Differences
remain with regards to timing and placement of this low,
lending towards uncertainty in precipitation chances into early
next week.
&&
.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1037 PM CDT Wed Sep 17 2025
Showers are expected to continue lifting over portions of
eastern Iowa this morning, mainly impacting KOTM and KALO before
12z. The signal for patchy fog continues to increase for this
morning, with main impacts over KFOD, KDSM, and KMCW that may
lead at least MVFR conditions. Will likely need amendments
during this time as conditions set up. Otherwise, scattered
showers and storms are expected Thursday, with the highest
chances into the afternoon to evening, though confidence on
exact timing and location are more uncertain. PROB30 mentions
have been included in KDSM and KFOD, but otherwise no direct
mentions in this issuance and will need updates as needed given
trends through the day.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION...Hagenhoff
AVIATION...Bury

NWS DMX Office Area Forecast Discussion