249
FXUS63 KDVN 121711
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1211 PM CDT Wed Jun 12 2024

.KEY MESSAGES...

- Showers and storms chances increase by tonight and again on
  Thursday. Strong to severe storms possible especially Thursday.

- Slight Risk (Level 2 of 5) for severe storms on Thursday south of
  I-80.

- Unseasonably warm temperatures will advect into the area,
  especially today and on the upcoming weekend. Many will see
  temperatures approach or exceed 90. More humid conditions may
  result in excessive heat for some!

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 313 AM CDT Wed Jun 12 2024

Today...South to southwesterly return flow to increase and continue
to warm air advect(WAA) today, boosting thermal profiles to support
high temps in the upper 80s to around 90 acrs much of the fcst area.
Mixing and dry top soil to temporarily keep sfc DPTs from climbing
much out of the lower 60s until later tonight. Thus heat index
readings not much more than the ambient temp. Ridge-riding
westerlies with embedded short wave aloft to make today`s unsettled
convective region be the eastern Dakotas into MN, with some of this
activity bleeding down acrs the MN/IA border region this afternoon.
With fcst soundings suggesting the local area to be capped/EML
affected, we may just get some elevated weakening debris into the
northwest through 00z Thu. With convective temps by late afternoon
being in the upper 80s to around 90, may still have to be on guard
for an isolated blow up if the cap can`t quite hold in spots.

Tonight...While the EML looks to maintain acrs the area, all
convective support parameters continue off to the north and
convective clusters to MCS`s should be ongoing acrs eastern MN and
evolving acrs the north half of WI. MCS ensemble convective support
parameters and steering lower level thermal ribbons may allow for a
portion of the northern activity to propagate southward down acrs
western IA and the MO RVR Valley in area of lesser EML impact. The
WI activity should look to tail down toward southern LK MI and
lower MI/northeast IL into Thu morning. Either some of this to make
it acrs the local area mainly after midnight, or we could have
elevated WAA-type sctrd showers/storms develop overhead aided by 30-
40 KT LLJ. Thus unless something changes drastically, it appears
like a limited sever risk for the local area especially if the EML
wins out.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 313 AM CDT Wed Jun 12 2024

Thursday...If we have limited activity/staying elevated and
decaying early out of Wed night, less convective debris and further
north boundary placement may allow for a big CAPE build up with
ambient temps in the upper 80s to low 90s, and conservative sfc DPTs
in the upper 60s to around 70...SBCAPEs still 2000-4000+ J/kg by mid
afternoon. Still some capping to overcome, but the higher sfc DPTs,
forcing of the front squeezing southeastward, and digging short wave
aloft could allow for strong developing convection overhead and
along/north of the current day 2 Slight Risk. All severe parameters
plus heavy rainfall could happen under this scenario, if the 1.8 to
2 inch PWATs pooling along the boundary verify for Thu. All in all,
still much uncertainty for thermodynamic and kinematic set ups for
a severe wx scenario to unfold, but Thu remains a day to watch
indeed.

Friday...Still looking like a decent summer day in the wake of what
ever happens on Thursday, with backdoor high pressure and seasonable
temps along with lowered humidity.

Saturday through Tuesday...Thermal ridging trying to build from
upstream and into the region could make Saturday a warming to above
normal scenario. Sat night through the rest of the extended will be
the continued battle of incoming thermal ridge and heat, with ridge-
riding MCS storm track potential close by. Some 90s likely through
this stretch, depending on storm debris or track lay out, but the
blend again looks to gone overly aggressive with max temps and heat
index readings into early next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1203 PM CDT Wed Jun 12 2024

VFR conditions will prevail through the TAF period, with some
periods of MVFR vis possible late tonight. After 06z, a line of
showers and storms are expected to pass through the area. These
storms will mainly lead to brief downpours and frequent
lightning, with lower vis resulting from stronger storms. Severe
weather probability remains low, but small hail will be possible
in stronger storms. Confidence on timing and spatial coverage
remains low. Thus, we have opted to cover this with a PROB30
group for the time being. Storms should largely be out of the
area shortly after 12z tomorrow. Winds will remain out of the
southwest today and through the night, with some gusts upwards
to 20 KTs possible at times.

&&

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

&&

$$

SHORT TERM...12
LONG TERM...12
AVIATION...Gunkel