463
FXUS63 KDVN 081836
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
136 PM CDT Sat Aug 8 2026

.KEY MESSAGES...

- After a dry and seasonably warm day today, precipitation
  chances increase late tonight into Sunday. Strong to severe
  storms remain possible, with the primary focus Sunday evening,
  and then again Monday afternoon and evening. Additional
  severe storms are possible on Tuesday as well.

- An active pattern keeps rain chances going through most of
  next week, but with plenty of dry hours in between. Rainfall
  amounts may exceed 2" (35-45% chance at any one location)
  through next Saturday.

- Increasing heat and humidity Sunday and Monday may require
  heat headlines, but will be dependent on clouds and
  precipitation. Cooler temperatures are expected later in the
  week into next weekend with highs likely only in the 70s.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 129 PM CDT Sat Aug 8 2026

Surface high pressure is providing lovely conditions today with
lower humidity, plenty of sunshine, and temperatures expected to top
out near normal in the lower half of the 80s.

Shortwave energy pushes east into our area late tonight into
Sunday which will help kick off showers and storms. Surface
winds become southerly as the low level jet strengthens ahead of
the wave. CAMs are rather varied in the evolution of convective
development late tonight into Sunday morning. NAM3km/FV3/NSSL
are suggesting a MCS develops across MN and propagates it
southeast into our northern counties by or shortly after 12z.
Meanwhile, the HRRR/RRFS suggest primarily elevated convection
developing over central IA, that would likely be less organized,
and move it through during the morning. While the latter
solution seems the slightly more likely outcome, we can`t
discount the first solution. The overall kinematic and
thermodynamic environment would largely suggest a sub-severe
threat Sunday morning, with perhaps some hailers being the main
threat as mid level lapse rates look to exceed 7C. However, if
an organized MCS can sneak into our north then a stronger wind
threat may materialize associated with a healthy cold pool.

Depending on how the convection Sunday morning evolves and how
quickly we clear out in the afternoon will influence both the severe
storm threat later (primarily evening) and how high
temperatures/heat index levels reach. LREF probabilities of reaching
100+ heat index readings are in the 30-50% range across our
southwest (primarily south of I-80 in IA and southwest of I-74
in IL). There will likely be a rather strong thermal gradient
positioned across our area though. Low level convergence may
become maximized from WI southwest into parts of our area by
late afternoon/early evening, with rapid strom development
possible. Effective shear of 35-45 kts in conjunction with
MLCAPE of at least 2000-3000 j/kg would support a combination of
supercells and linear segments. All severe hazards appear
possible, including a few tornadoes, as 0-1km SRH increases to
at least 150 m2/s2 after 00z.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 129 PM CDT Sat Aug 8 2026

The upper level flow will remain out of the west-northwest through
much of next week, allowing a series of shortwaves to sweep though
our region. The low level boundary will reside across our area early
in the week, which will keep a more favorable environment in place
for severe storms through Tuesday. LREF guidance has the highest
probability (40-50%) of surface CAPE exceeding 2000 j/kg along with
at least 35 kts of effective shear across our north on Monday before
nudging it south on Tuesday. The boundary likely slips to our south
by Wednesday and beyond, but remains close enough to keep daily
shower and thunderstorm chances in place as additional upper level
waves move across. The GFS appears to be an outlier at this time,
depicting dry surface high pressure taking control of our weather by
next Fri/Sat. Ensemble guidance generally keeps the wetter pattern
in place. The LREF probability of receiving at least 2" through next
Saturday is around 35-45% across our region.

Temperatures start off the week on the hot side, ranging from the
mid 80s to around 90. High humidity levels will also be in place,
which may allow heat index readings to exceed 100 on Monday and
possibly again on Tuesday (which may require additional heat
headlines). Much cooler temperatures are expected during the latter
part of the week with the LREF suggesting a 60-90% chance highs
remain below 80 by Thursday along and north of I-80 and the entire
area by next Fri-Sat.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1240 PM CDT Sat Aug 8 2026

Surface high pressure is centered over the flight area at this
time. The high will shift to the east tonight, as another wave
rides along a return warm sector boundary and approaches in the
dampened nwly flow aloft. It will bring increased/lowering
bases, with some restricted cigs/vsbys in associated convection
by late tonight into early tmrw morning.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.

&&

$$

SHORT TERM...NWS Paducah
LONG TERM...NWS Paducah
AVIATION...NWS Paducah