649
FXUS63 KDVN 131108
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
608 AM CDT Thu Jun 13 2024

...12z Aviation Update...

.KEY MESSAGES...

- Potentially a significant severe weather day today across portions
  of the area with all severe risks in play.

- Unseasonably warm temperatures will continue to be re-enforced
  into the area, especially today and late in the upcoming
  weekend into early next week. Heat Index readings today,
  Sunday and Monday may range from 95 to 100 in some locations.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 330 AM CDT Thu Jun 13 2024

Today...Ongoing isolated to wdly sctrd elevated showers and storms
should fade this morning with diurnal interruption of LLJ feed. Then
full on warm sector re-invigoration commences later this morning and
into midday with elevated debris clouds fizzling after sunrise to
lee of upstream cool front. But the north may get in on some high
based decaying debris off the now occurring SD convection. THe cool
front was seen now on sfc observations sagging southeastward along
the ND/NE border region and up through east central MN. Then ongoing
EML/cap to keep a lid on most activity into early afternoon, allowing
for a heat up into the upper 80s and lower 90s acrs the southern
3/4`s of the DVN CWA. This combined with pre-frontal sfc DPT pooling
into the upper 60s to low 70s, will make for afternoon Heat Index
readings ranging from 95-100 south of I-80.

The thermal build-up(as long as the above mentioned convective
debris clears early enough) will lead to very high MUCAPEs of 3000-
4000+ by mid afternoon along and south of I-80. This as the
upstream cool front pushes through this axis, a short wave digs
acrs the region out of the northern plains, and a mid to upper level
jet max south exit edge streams acrs the MN/IA border region.
Continue to think these forces will break the EML hold and allow for
explosive buoyancy release in the form of strong to severe
convection, but how far north or south this axis occurs is
still a bit uncertain. Some CAMs suggest initial development may
occur post- frontally and be somewhat elevated again as the CAP
erodes to the north of the boundary mid to late afternoon in
the northern CWA. Then other storms may then fire in the more
conceptual axis along the frontal scooping forcing along the
boundary by late afternoon which may occur well south of I-80
from southeastern IA and toward the southern tip of LK MI. Other
cap erosion processes may then allow post-frontal strong storms
to pop acrs central into eastern IA, with all these clusters
and cells then propagating south toward the high THTA-E pool
acrs KS-MO-central IL as the evening progresses, aided by cold
pool mechanics and becoming prolific damaging wind machines.

Storm layer shear of 50-60 KTs and available CAPEs should allow
for initial supercell structures, then evolving into bowing
clusters as the evening progresses. Currently progged shear and
thermodynamic profiles supports SPC`s very large hail potential,
but the warm thermal profiles up to the mid levels may limit
the bigger stones to golf balls or less as opposed to the
advertised baseballs. Wind mix- downs by RFD`s or cold pool
evolution support straight line winds up to 80 MPH in the mature
bows or downbursts, and of course in these environments of
lowered LCL`s a tornado not out of the question despite less
than favorable LLVL shear away from any boundary. PWAT pooling
up to near 2 inches by this afternoon and evening also support
very heavy rainfall at high rates of 2-3 inches an hour as the
storms pass by. Thus an isolated flash flood chance in a few
areas that get hit a couple of times. Otherwise hopefully storm
propagation speeds will limit the flooding threat. SPC`s
Enhanced Outlook looks on target for those areas that manage to
get in on or impacted by the organized storms as they mature.
It`s just where this prime axis lays out...shear profiles
interacting with max Deep Convective Index parameters suggest
this axis to occur from northeast KS...acrs the southern DVN
CWA, and to east central/northeast IL around 00z this evening.

Tonight...Storms to clear off  to the south and allow for post
frontal cooling with northwesterly boundary layer flow advecting
temps into the low 60s to mid 50s by Friday morning.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 330 AM CDT Thu Jun 13 2024

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

Saturday through Wednesday...Medium range ensembles still paint the
picture of thermal ridging trying to build from upstream and into
the region this period, and eventually getting implanted for higher
heat and humidity by early next week. But this process to be a
continued battle of incoming thermal ridge and heat, with ridge-
riding MCS storm track potential close by for occasional storm
cluster/MCS chances, especially at night Sat through Monday.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 555 AM CDT Thu Jun 13 2024

Isolated thunderstorms will move southeast away from the TAF
sites over the next few hours, leaving VFR conditions through
early afternoon with increasing southwest sfc winds. Then a
cool front will squeeze in from the northwest and will act as
the focus for strong thunderstorm development by mid afternoon.
The axis of development still somewhat uncertain on how far or
north the storms develop, but along or just south of the I-80
corridor still looks favorable at this time. The storms should
then propagate southeastward with high impacts to aviation ports
with hail, heavy rain reduced VSBYs, and variable strong sfc
wind gusts as they pass acrs any terminal. North sfc winds and
clearing skies tonight.

&&

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

&&

$$

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