758
FXUS63 KDMX 060908
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
408 AM CDT Wed May 6 2026

.KEY MESSAGES...

- Frost Advisory in effect until 8am this morning. Dry and
  cooler today with additional frost potential tonight.

- Low chance (30-40%) for showers Friday, then more widespread
  showers and thunderstorms Saturday into Sunday, with highest
  potential over southern Iowa (50-60%)

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 408 AM CDT Wed May 6 2026

Dry and cool conditions are common across the forecast area early
this morning, with satellite imagery depicting a stream of mid to
upper level clouds across much of Central Iowa, while a broader area
of mid level clouds is dropping south across Minnesota, with its
southern extent just touching the IA border. The broad synoptic
pattern features a large area of troughing over the Upper Midwest
into Canada that has more or less moved very little over the past
few days, while further west, an area of surface high pressure is
currently sitting over Montana/western Dakotas and extending its
influence into the Central Plains. Continued cold air advection from
northwest flow into Iowa is keeping cooler conditions overhead, with
current temperatures in the upper 30s in northern and western Iowa,
and warmer in the south in the 40s. Mostly clear skies and
temperatures expected to bottom out in the low to mid 30s over
northern Iowa may still allow for some areas of frost development
through sunrise, hence the continuation of the current Frost
Advisory over this area until 8am this morning. As the
aforementioned high pressure moves closer to the state through
today, will see the continuation of dry conditions and cooler
temperatures, with forecast highs in the 50s. Boundary layer mixing
is expected later this morning into the afternoon, with the presence
of low level dry air leading to breezy conditions as gusts up to 20-
25 mph are expected, especially north. Winds relax into this evening
through early Thursday, becoming variable in direction as the area
of surface high pressure drops further south/southeast across the
Central Plains. Overnight lows turn chilly once again, though more
widespread with values in the mid to upper 30s. Regarding frost
potential, there remains the potential in patchy cloud cover
that would limit frost formation, but is still possible. Will be
keeping an eye on trends, with the possible issuance of
additional frost headlines later today. Stay tuned for updates.

A shift to low level southwesterly flow through the morning is
expected to allow for a push of warmer air into Iowa, with forecast
highs in the mid to upper 60s by the afternoon. Theta-e advection
from this southwesterly flow increases dew points in the upper 30s
to low 40s over south/southeast Iowa, creating a subtle boundary as
drier air remains north/west. A close look at model soundings shows
an impressive layer of keep mixing all the way up to around 3km,
leading to very dry air overhead, along with cumulus development
given elevated instability and some mid-level moisture. Have
therefore decreased dewpoints, especially northwest with this
forecast package, which has also lowered RH values as minimum values
drop into the low 20s, though likely lower given the degree of
airmass drying that short-range guidance is indicating. These
conditions may lead to at most some concern for elevated fire
weather conditions in northwest Iowa, though rather isolated in
nature given increasing greenup of fuels. The weak boundary slowly
shifts south into Thursday evening, with a low level wave passing
through as well that models are indicating some development of
showers mainly east of I-35, but especially over IL/WI where forcing
and moisture is maximized. With the presence of dry air overhead as
mentioned earlier, it would seem unlikely that any hydrometeors
would be able to reach the ground, so have left the forecast dry at
this time and will continue to monitor.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Issued at 408 AM CDT Wed May 6 2026

As ridging builds west into Friday, mid-level northwest flow
persists into Iowa, while another shortwave and attendant surface
low developing east of the Rockies moves into the region. Models
generally keep this system over Missouri, with its northern
periphery into southern Iowa where forcing for lift is suggested to
develop rain showers later in the morning and through the afternoon
before moving off east out of the area. Little instability over this
area could lead to some thunder, but otherwise little in the way of
storm development is expected with this activity at this time.
Temperatures will remain warmer as highs are expected to reach into
the upper 60s to low 70s.

Dry conditions and warmer temperatures are expected to start the
weekend, with long range guidance showing more widespread chances
for showers and storms into Saturday evening/early Sunday,
especially over southern Iowa, and highs reaching through the 70s,
warmest south. Instability values under 500 J/kg should limit any
potential for severe weather with this activity. As the boundary
departs into Sunday, temperatures will be slightly cooler with highs
in the 60s. High pressure dropping through the region into the start
of the next work week keeps conditions on the quiet side, then turns
rainy again by early Tuesday as another area of low pressure arrives
into the Midwest.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1100 PM CDT Tue May 5 2026

VFR conditions to prevail with BKN to OVC cloudiness focusing
south overnight. Additional cumulus development expected in the
north after 16z. Northwest winds with 20kt gusts will be common
for northern terminals after 18z. Winds will become light and
variable after 00z.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Frost Advisory until 8 AM CDT this morning for IAZ004>007-
015>017-023>028.

&&

$$

SHORT TERM...Bury
LONG TERM...Bury
AVIATION...Jimenez