948
FXUS63 KDVN 120059
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
759 PM CDT Tue Jun 11 2024

.KEY MESSAGES...

- Rain/Storms possible midweek, with strong to severe storms
  possible. Main activity will be seen late afternoon and
  through the night.

- Unseasonably warm temperatures will invade the area,
  especially through to the upcoming weekend. Many will see
  temperatures approach or exceed 90. Humid conditions may
  result in excessive heat for some!

&&

.UPDATE...
Issued at 755 PM CDT Tue Jun 11 2024

00z DVN RAOB shows a few inversions above 800 mb with a rather
shallow moisture layer around 800 to 750 mb. Given this along
with weak instability, and forcing becoming rather neboulous in
the wake of a departing mid level shortwave into S WI and N IL,
convective potential continues diminishing this evening.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 224 PM CDT Tue Jun 11 2024

This afternoon and evening, high pressure continues to slide east,
as a trough digging in from the west brings a weak boundary through
the area tonight. Some short term guidance brings in the
storms, while others do not. The factor leading to this
discrepancy is moisture. The guidance that brings thunderstorms
into the area have much higher dewpoints moving in, which is
allowing more convective coverage. Current dewpoints are around
the upper 40s to low 50s, but guidance brings them well into the
mid 60s. This seems unattainable, which is lowering our
confidence in seeing much convection. If we do see storms, the
best chance will be in our northwest, where the best moisture
pools, with the action shifting east towards Dubuque in the mid-
late evening. Timing for any storms seems to be between 4pm-
11pm, with severe risk drastically dropping off after sunset.
There is a Marginal Risk (level 1/5) for Severe Weather with
these storms, highlighted by the SPC, for the storm potential
this evening. Main hazards will be winds and hail. Aside from
the chance for precipitation, we will mainly see an increase in
cloud coverage and a wind shift. Temperatures tonight will
remain mild for most, with much of the area in the low-mid 60s.

Tomorrow will be a mostly clear and toasty day. Behind the wave
pushing through tonight, we will start to see rapid return flow
spread east through Iowa tomorrow during the day. This will allow
dewpoints to increase into the mid 60s, with some approaching
near 70 in our northwest, where the best moisture flux is. This,
combined with widespread temperatures in the upper 80s to 90,
will allow for quite a warm day. Fortunately, bulk of the
moisture doesn`t make it until later in the afternoon, with
mixing and breezy southwest winds giving some relief as well.
Thus, we will start to feel the more humid air work it`s way in
during the afternoon and evening, but should be safe from the
oppressive heat tomorrow. Another weak wave will pass through
the area late on Wednesday, bringing the chance for more
showers/storms, which will be discussed more below.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Issued at 224 PM CDT Tue Jun 11 2024

Wednesday Night...

Weak wave approaching from the northwest through the evening and
into the night, which will bring the potential for two rounds of
convection Wednesday evening and then again after midnight. Moisture
will once again be a limiting factor, with the best moisture
along/north of a line from Fairfield to Dubuque Iowa. Also, the best
forcing will be near this similar area, if not farther north. Thus,
the window for best chances of strong to severe will be limited and
confined to our northwest. As these storms continue to push
southeast towards to the Quad Cities, we will see them quickly
deteriorate as they move out of a good environment, mainly being
rain and isolated thunder as they approach the metro. Latest
guidance has pushed the wave a little farther north as well. If this
trend continues, the threat will continue to go down, which may
limit this to one main line of convection, where many remain dry.
In either case, the confidence is low on the severe potential,
but the footprint of rainfall will be a bit larger than the
previous day, albeit low accumulation. Those along and north of
Interstate 80 may see upwards to 0.25", with amounts dropping
off south of the interstate. SPC also highlights our northwest
in a Marginal Risk for Severe Weather once again tomorrow night
and into Thursday morning, highlighting winds and hail as the
main threats in any strong storms we see.

Thursday...

Cold front from the previous night will continue to pass south
through the area on Thursday, which will allow for passing clouds
and sun through the day. We are forecast to be quite warm,
especially ahead of the front. This, collocated with higher
moisture, will not only make it quite toasty, but also increase
the instability ahead of the front. Thus, as we approach peak
heating in the afternoon on Thursday, we may see storms erupt
along it. Given location of the front and jet aloft, we will see
a zone of shear ahead of the front, aiding in organization.
Thus, some of these storms may become strong to severe.
Although, forcing remains relatively low. In either case, the
best chance to see these showers and storms will be along and
south of Interstate 80, with the best chance for severe weather
south of the interstate. In these areas, we do have a Slight
Risk (level 2/5) for severe weather, with a Marginal risk up
north towards Highway 20. All hazards will be in play on
Thursday, with the primary threats being hail and winds.

Moisture will be highest in our south, which will be collocated with
the warmest temperatures. Thus, we may see some periods of heat
index values between 90-100. Confidence is low on the need for
any heat headlines, but we will continue messaging that it will
be a hot day for much of the area, especially the south.

Have plenty of water and sunscreen handy!

Beyond...

Incoming LLVL ridging under temporary northwesterly steering flow
will make for some nice summer days Friday through Saturday, with
the bulk of the warm-up being seen Saturday into Sunday. One of the
failure modes for these very warm temperatures will be the track of
the ridge-riding MCSs that result from this pattern. This would
bring residual cloud cover and convection in the mornings, shunting
much of the morning heating. Although, if we fall south of that
track, we will fall under that dome of hot air. Guidance remains
quite aggressive with the heat this weekend into next week, showing
widespread low-mid 90s. If this ends up being the case, some heat
headlines may be necessary. Although, much uncertainty exists and
will refrain from any further details.

Have plenty of water and sunscreen handy!

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 550 PM CDT Tue Jun 11 2024

Isolated shra/tsra are possible this evening, mainly north of
I-80 and near to west of DBQ to CID terminals within a corridor
of stronger moisture flux convergence. We`ve kept out any
mention in the TAFs however, due to the low coverage (20% or
less) should convection develop, which is uncertain as
observational dew points are running a few to several degrees
lower than CAM guidance. Otherwise, VFR conditions will abound
through the TAF period. A boundary will move into the area
tonight before becoming diffuse. Ahead of this boundary until
sunset, WSW winds will remain gusty at times up to 20 kts. Winds
then diminish after dark to 5-10 kts predominantly from SSW. On
Wednesday, WSW winds will become gusty at times once again by
late morning through afternoon with gusts to around 15-25 kts.

&&

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

&&

$$

UPDATE...McClure
SHORT TERM...Gunkel
LONG TERM...Gunkel
AVIATION...McClure