309
FXUS63 KDVN 030457
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1157 PM CDT Sun Jun 2 2024

...Updated for 06z Aviation...

.KEY MESSAGES...

- An active, summer-like pattern will be found through early
  week, with warm/muggy conditions and multiple chances of
  showers and storms. Monday PM and Tuesday PM will be monitored
  for strong to severe storms.

- Mainly dry mid week to late week with seasonal temperatures.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 200 PM CDT Sun Jun 2 2024

It`s taken through early afternoon, but we`ve finally broken through
the fog and stratus that was over the area this morning.  This has
allowed temperatures to break into the lower to mid 70s, and highs
around 80 still seem possible, given the high sun angle, and longer
daylight hours of June 2.

Looking west, the main focus of warm advection continues to be over
the Plains states, as a next short wave in the eastern Rockies
begins to move out into the Plains tonight. The convection over
Omaha dissipated quickly as it moved out of this axis this morning,
with only high level debris clouds moving into our area.  Thus,
we`re looking at a dry afternoon and evening ahead, as the next
short wave is well to our west.

Tonight, the LLJ should be focused into Nebraska and western Iowa
through Midnight, then is expected to veer to the east towards late
night/early Monday. There are widely varied model solutions
regarding the convection to the west, but the vast majority of
solutions show a weakening band of showers and storms moving into
our northwestern counties around 3 AM to 6 AM. I`ve kept pops in the
high chance to likely range there, but otherwise, have lower chance
pops going late tonight into Monday. We`ll have plenty of moisture
for storms, but we`ll need to have activity shift into us, and
that`s a few dominoes down the line in this low predictability
of QPF placement summer pattern.

Monday, both a remnant rain area, or outflow will move into the area
in the morning. This will offer a few things confidently...One,
we`ll need to wait until debris clouds thin before we can warm up to
any new convective process, and I believe the NBM highs are too warm
in the upper 80s in most locations because of that evolution. I`ve
gone with the 25th percentile NBM highs, in the upper 70s north to
mid 80s central and south. Secondly, this outflow could provide
adequate focus for afternoon strong to severe storms, assuming we
can heat up along it.  While global models are not showing this, it
can clearly be seen in some CAMs runs, especially the NAMnest and
FV3. Storms near any boundary are likely to experience notable
augmentation to the deep layer shear in the presence of moderate
instability (MLCAPE progged around 1500+ j/kg).

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
Issued at 200 PM CDT Sun Jun 2 2024

Monday night, activity may be ongoing during the evening, and
shifting east of our area by overnight.  This remains a low
confidence time, as the short wave exits, but another stronger
wave moves out into the Midwest Tuesday. The upper wave moving
through Tuesday continues to show synoptic support for strong to
severe storms, but there`s lots of potential for a large MCS to
move through Tuesday evening, thus, we`re leaning towards a
wind threat in storms. Heating is not a certainty Tuesday, with
the whole region in broad warm Will continue to
message the thunder potential in PROB30 groups for now. Brief
MVFR/IFR is possible in the vicinity of storms, along with gusty
erratic winds.advection through the day. In any
case, this remains a high probability of rainfall, and the best
chance for organized severe weather in our week`s forecast.
Behind this strong upper wave and low pressure (in Canada) the
strong cold front should sweep across the region Tuesday night,
with another dry, pleasant air mass found behind it. Highs in
the 70s, and lows in the 50s are in store for Thursday through
the weekend, with Wednesday being a warmer, but breezy
transition day, represented by lowering humidity levels through
the day. Certainly active, but turning very pleasant!

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1150 PM CDT Sun Jun 2 2024

Precipitation chances/timing/location is the main challenge for
this set of TAFs. There will be plenty of dry hours and expect
predominantly VFR conditions outside of any precipitation. That
being said, there is a signal in the CAMs for isolated to
scattered coverage of showers and storms developing Monday AM
through midday ahead of a convectively enhanced disturbance and
an attendant veering and slowly weakening nocturnal LLJ. Given
lower confidence on coverage due to the waning LLJ we`ve handled
this potential with VCSH or PROB30 mention. There`s also a signal
in the CAMs for redevelopment of scattered showers and storms
toward peak heating and into this evening, aided by initial
lift from a passing convectively enhanced disturbance then by a
weak nocturnal LLJ and attendant warm, moist advection. This
potential was also handled with PROB30 mention for now due to
uncertainty in location. As typical in this summer-like pattern
expect additional fine tuning of the precipitation details in
subsequent TAF updates, as mesoscale features and trends become
better defined. Winds will be predominantly southerly throughout
at around 10 kts, but may occasionally gust to near 20 kts by
late AM through afternoon. Winds may also gust higher in/near
any storms.

&&

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

&&

$$

SHORT TERM...Ervin
LONG TERM...Ervin
AVIATION...McClure