638
FXUS63 KDVN 292318
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
618 PM CDT Mon Jun 29 2026

.KEY MESSAGES...

- Extreme Heat Warning continues through Wednesday evening due
  to a prolonged period of hot and very humid conditions. Daily
  peak heat index values of 100 to 110 and nighttime low
  temperatures only dropping into the mid 70s.

- Increasing thunderstorm chances into midweek onward (including
  the July 4th weekend), with the resultant cloud cover
  potentially having an impact on high temperatures. Very humid
  conditions will remain.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 230 PM CDT Mon Jun 29 2026

Upper ridge to continue across the central and southeastern US
with southwesterly flow across the Plains into the Great Lakes.
This pattern continues to allow the heat to build across the
area with very humid conditions as well with flow off the Gulf.
Heat index values already into 100-105 range or higher at many
sites today, and even warmer air aloft expected to push into the
area Tuesday. Little relief expected at night with the humid
airmass and warm temperatures keeping overnight temperatures
dropping into the upper 70s to around 80. The Extreme Heat
Warning will continue with the heat expected through midweek.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 230 PM CDT Mon Jun 29 2026

The upper ridge across the central/southern US to begin to break
down some into the middle to end of the week allowing the
southwesterly flow aloft to become oriented more across the
forecast area. This will bring increasing chances for
thunderstorms by Wednesday into the weekend, especially into the
weekend as the ridge breaks down further with a more zonal flow
pattern setting up with stronger shortwave troughs impacting the
region. Therefore the continuation of the heat and high
temperatures into the end of the week and this weekend are
somewhat uncertain dependent on thunderstorm chances due to
cloud cover and overall storm chances, etc. Continued moisture
flow off the Gulf remains, so humid conditions will continue
through the forecast period. For now the threat of strong to
severe storms is still uncertain for any one period, however the
pattern would suggest more organization with the storm chances
into the weekend with the stronger upper level troughs helping
force the storm chances.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 615 PM CDT Mon Jun 29 2026

Southerly winds will be the main factor in all sites through
Tuesday, as high pressure remains in control of our weather
locally. Skies may see some additional cumulus tomorrow, but
with hotter air over the region, this should be higher based and
less widespread than today`s diurnal cumulus, which is breaking
up at this time, and by 00z, skies will be mainly clearing.

Winds Tuesday will shift more towards southwest during the day,
with gusts to the 20-25 kt range much like today, albeit a
little bit lower.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Extreme Heat Warning until 10 PM CDT Wednesday for IAZ040>042-
     051>054-063>068-076>078-087>089-098-099.
IL...Extreme Heat Warning until 10 PM CDT Wednesday for ILZ001-002-
     007-009-015>018-024>026-034-035.
MO...Extreme Heat Warning until 10 PM CDT Wednesday for MOZ009-010.

&&

$$

SHORT TERM...MJB
LONG TERM...MJB
AVIATION...Ervin