Waverly, Iowa 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

727
FXUS63 KDMX 010846
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
346 AM CDT Sun Jun 1 2025

.KEY MESSAGES...

- Warm temperatures and smoky skies continue today into Monday.
  Some patchy surface smoke possible today, mainly west.

- Shower and thunderstorm chances return to the area Monday
  night, lasting through Tuesday into early Wednesday. Potential
  for heavy rainfall Tuesday and severe weather Tuesday
  afternoon into early evening. Details continue to be fine-
  tuned.

&&

.UPDATE...
Issued at 313 AM CDT Sun Jun 1 2025

Few changes from previous in the short term. Upper level smoke
remains the main weather highlight today into Monday with
RAP/HRRR smoke guidance in pretty good agreement of lessening
concentrations west to east aloft through the day Monday. This
aligns well with overall expectations as winds shift to be out
of the south to southwest overnight into Monday. Monday will
become breezy by the afternoon with sustained winds around 15-25
mph and gusts to around 35 mph in northwest Iowa and should
make the increasing temperatures towards the upper 80s or even
touching 90 a bit more tolerable. Did knock down temperatures a
few degrees from NBM today, as in past nights, with the smoke
aloft, though still in the 80s. Although limited highs a small
amount Monday too, not quite to the same extent with the
lessening smoke concentrations aloft as previously noted. At the
surface, it remains a bit more uncertain what the extent of
smoke impacts will be with HRRR/RAP smoke guidance not
completely handling current trends well. Although impacts are
noted through ND, SD, and eastern NE, extent of impacts in Iowa
are more limited, though a few lower visibilities have been
observed in northwest Iowa. Changed wording to be patchy surface
smoke and limited more to western areas (extending into
portions of central Iowa by the afternoon) with main impacts,
should any occur, occasional visibility drops and/or the smell
of smoke. Any surface smoke that does occur will largely clear
up by tonight, but the hazy skies linger into Monday. Any air
quality concerns will be evaluated by the Iowa DNR.

Shower/storm chances return by Monday night with the potential
for heavy rainfall Tuesday and severe weather Tuesday afternoon
into early evening. See previous discussion below or SPC Day 3
outlook for further details.

&&

.DISCUSSION...
Issued at 247 PM CDT Sat May 31 2025

A nearly perfect end to May has been slightly squandered by the
wildfire smoke that continues to stream south out of Canada today,
filtering sunshine and muting what would otherwise be blue skies
over Iowa. Fortunately, most of this smoke has remained aloft
through mid-day, keeping the impacts limited to the gray skies. Its
possible some light concentrations of smoke will diurnally mix down
to the surface this afternoon, as evidenced by the HRRR and RAP
smoke models. However, the smoke aloft has been thinning out on
visible satellite through the day and ceiling observations imply
that the smoke aloft is at around 20 kft. Therefore, confidence is
pretty low in this happening. As we get into the evening, a
shortwave passing to the west of the forecast area will pull another
plume of smoke down behind it. Reduced visibilities and haze/smoke
have been observed in the Dakotas, indicating that subsidence behind
the wave has allowed smoke to work its way down to the surface.
Most of this smoke should remain to the north and west of the
forecast area, but we may still see some spill into the northwestern
portions of Iowa. Even then, this smoke should be spreading out and
dispersing as it continues south. Weather conditions remain
generally the same through Sunday as upper level ridging builds in
from the west, keeping temperatures warm and skies smoky. HRRR and
RAP smoke modeling suggests another chance for smoke to diurnally
mix down to the surface tomorrow afternoon in western Iowa  a
similar signal to todays. However, tomorrows surface smoke may be
more plausible than todays given the recent shortwave passage, so
will want to keep an eye on that through tonight and into tomorrow.
Any air quality impacts tonight or tomorrow will be assessed by the
Iowa DNR.

Upper level ridging continues eastward over the area on Monday
but will be short lived as two waves begin to merge into broad
troughing Monday night into Tuesday. This will bring the return
of showers and thunderstorms to the forecast area. Showers and
storms in the area begin with the initial push of theta-e
advection starting late Monday night into Tuesday morning.
Instability will be fairly low (< 1000 J/kg) overnight, but will
have support from a moist low level jet to help precipitation
along through the night. Showers and thunderstorms persist
through the day on Tuesday low and mid level moisture transport
persist through the day. As we progress through the day on
Tuesday, the cold front will slowly track north with instability
increasing ahead of it, and maximizing in the eastern half of
the state by Tuesday afternoon. This currently looks to be the
most likely time and location for severe weather, given the
current guidance. Deep layer shear wont be overly impressive
ahead of the front (~30 to 40 kts of 0-6 km shear), but there
will be a modest supply of low level shear (also ~30 kts of 0-1
km and 0-3 km shear). Likewise, looping hodographs boast 100+
m2/s2 of SRH, although become quite messy further aloft. All
this to say there is certainly the potential for organized
storms and severe weather on Tuesday afternoon, although will
want to see how high resolution guidance handles the saturated
profiles from the overnight and morning convection. Better shear
will be present along and behind the cold front, which may
indicate the potential for linear storms along the boundary, but
this will also be better discerned by the high resolution
models. The storm prediction center has issued a Day 4 15% risk
for severe weather (comparable to a slight risk, which is level
2 out of 5) for the eastern half of the forecast area on
Tuesday, echoing this potential for strong storms.

Finally, in addition to the severe weather chances, anomalously
moist profiles will be present with this system as the gulf
opens up, resulting in precipitable water (PWAT) values of 1.8
2 over much of central Iowa through Tuesday. These values are
roughly 175 to 200% of typical values in central Iowa this time
of year (average PWAT is around 0.90 to 1.00), which suggests
the potential for some decent rainfall. Grand ensemble
probabilities for over 1 of rainfall in 24 hours is roughly 50
to 60% over central Iowa and NBM probabilities for 1 of
rainfall in 24 hours is similar, but with a band of slightly
higher probabilities around 60 to 70% in central Iowa. A few
deterministic models also suggest an area of 2+ rainfall over
southern Iowa. Area rivers should be able to handle an inch or
two of rainfall, but will certainly want to monitor for any
higher amounts Tuesday given the moisture profile present.

Precipitation moves out Wednesday morning, with another wave
passing to our south Wednesday night into Thursday, although
guidance is a bit split on if this will reach up into Iowa. Will
continue to evaluate conditions into the second half of next
week through the coming days.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1042 PM CDT Sat May 31 2025

Incoming smoke remains mainly aloft over Iowa, with smoke
reaching the surface over much of the Dakotas and now edging
slightly into northwest Iowa. Potential for surface visibility
reductions is the main concern tomorrow, although confidence is
still low in timing and intensity.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

UPDATE...05
DISCUSSION...Dodson
AVIATION...DMD