898
FXUS63 KDVN 091127
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
627 AM CDT Sun Aug 9 2026

.KEY MESSAGES...

- Storm chances ramp up again today for portions of the area, as
  the battle between heat and convection continues(and will
  continue through at least mid week). Daily severe storm risks
  also continue with high instability possibly through at least
  Tuesday.

- A Heat Advisory posted for today for over the southern half of
  the area with heat indices 100 or higher. Depending on clouds
  and storms, Monday may be just as hot.

- Cooler temperatures may occur later in the week and into next
  weekend if the warm dome of air can get shunted off to the
  southwest.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 300 AM CDT Sun Aug 9 2026

Challenging near term with respect to convective trends and possible
evolution, as well as temperatures and maximum values. The clusters
of elevated convection ongoing acrs southwest into central IA being
fed by profiler indicated southwest 25-35+ KT H85 MB jet is not
being handled well/underdone by the CAMs. With the LLJ expected to
feed eastward this way, some of that activity would seem to make it
acrs the area this morning. Not erode suddenly or dive south into MO
after 12z like some CAMs suggest. Even if this activity diurnally
wanes into our area of concern by mid morning, eyes turn to the
ongoing storm cluster and associated short wave aloft now over north
central SD and the THTA-E building thermal gradient that it will
look to propagate along southeastward toward the southern third of
WI by early afternoon. A southwest tailing portion of this potential
MCS could clip at least the northeast third of the DVN CWA by midday
and early afternoon. As it does, it very well could be severe with
damaging winds and meso-vortice tornadoes if the fcst sounding 30-40
KT effective shear values and building MLCAPEs by that time up to at
least 3000 J/kg verify. How far southwest acrs the rest of the CWA
this MCS may try to develop toward is uncertain and the soundings
do indicate a building EML as you head that way.

In the wake of this convective system, there may not be much more
storm activity for the rest of the afternoon and early evening. This
may allow for cloud debris to erode and south winds to warm air and
moisture advect at least acrs areas along and south of I-80. Good
thermal guidance agreement suggesting these areas to recover back
into the upper 80s to near 90 degrees, with sfc DPTs at least into
the mid 70s. This allows these areas to attaining heat index readings
of a 100 to near 105. Despite the chance for cloud cover, storm
outflow, and even increased western wildfire smoke aloft tempering
the ambient temp warm up potential, have leaned toward the cautious
side and issued a Heat Advisory for this afternoon for areas
generally along and south of I-80.

Tonight...with another short wave dropping down acrs the western GRT
LKS, several models and ensembles develop strong evening convection
acrs northern IL into lower MI as a renewed LLJ impinges on a
lingering storm outflow boundary or even a type of sfc front acrs
those areas. As this activity will look to feed southward, some risk
of the western end of this activity affecting the eastern DVN CWA
into the overnight period. Hopefully the brunt of this activity
stays just off to the east of the local area of concern. Late night
toward Monday morning, another round of general WAA may produce
sctrd showers and thunderstorms acrs MO and into the southern DVN
CWA, but these should not be strong at least thru 12z Mon looking at
the shear and lapse rates.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 300 AM CDT Sun Aug 9 2026

Monday...Another day of building heat to potentially values needing
another heat headline, but with the same uncertainty of convection
and associated debris limiting ambient temp warm up in places. Thus
will take heat headline issuance day-by-day. Right now for Monday
and Monday night, the local area will continue under the storm track
but may be in between the more prime organized convective zones of
the northern/central plains and especially just off to the east of
the area extending to the eastern OH RVR Valley. Saying that, still
plenty enough energy locally to fuel strong to severe storms if they
get going. Bouts of heavy rain may also start to add up, as will be
the case into Thursday.

Tuesday through Saturday...With the flattening ridge transition, the
local area may be under the battle zone of the LLVL thermal gradient
and upper level short wave propagation path for almost daily chance
of showers and storms for much of the week and even into the
weekend. This deep summer-like MCS-track for much of the week from
the central plains over to the southern GRT LKS and OH RVR Valley
may add up to quite a bit of rainfall by Friday. At least temps look
cooler by late week and into the weekend as well, with a day or two
possibly held down in the 70s with cloud cover and east winds.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 620 AM CDT Sun Aug 9 2026

Showers and storms will continue to push east into the area this
morning. Confidence is greatest at KCID and KDBQ to warrant
prevailing shower mention and TEMPO for thunder. Watching for
some evolution to wind upstream into far N Iowa, which if occurs
could roll ESE and result in some strong to isolated severe
wind risk for KCID, KDBQ and possibly even KMLI from 15z-18z.
Late this afternoon and evening in the wake of the earlier
storms there is some uncertainty on additional development,
although a ramping nocturnal LLJ and boundaries will support a
chance particularly 00z-05z and have handled with general PROB30
mention at the sites. Winds outside of any storms or even
possible wake low surges will generally be from the south to
southeast at 5-15 kt, becoming light northeast late in the TAF
cycle.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Heat Advisory from noon today to 8 PM CDT this evening for
     IAZ063>065-067-068-076>078-087>089-098-099.
IL...Heat Advisory from noon today to 8 PM CDT this evening for
     ILZ015-016-024>026-034-035.
MO...Heat Advisory from noon today to 8 PM CDT this evening for
     MOZ009-010.

&&

$$

SHORT TERM...12
LONG TERM...12
AVIATION...McClure