992 
FXUS63 KILX 080755
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
255 AM CDT Sun Aug 8 2021

.SYNOPSIS...
Issued at 255 AM CDT Sun Aug 8 2021

A hot and humid weather pattern will dominate the region for the
next several days. Periodic thunderstorm chances will persist from
this afternoon through the first half of the week. Some of the 
storms this afternoon and evening could be strong to severe, and 
contain locally heavy rain.

&&

.SHORT TERM...(Today and tonight)
ISSUED AT 255 AM CDT Sun Aug 8 2021

MCS ongoing from central IA to northern MO aided by southwest LLJ
and shortwave over the eastern Plains, is expected to diminish 
over the next few hours as it outruns better support. CAMs are in 
good agreement that convection will re-fire over southeast 
IA/northeast MO this afternoon as the trof pushes east. Downstream
airmass across central IL will be moderately unstable with 2500 
J/kg MLCAPE but marginal shear at 20-30 kt 0-6 km. This will 
favor a loosely organized cluster or linear structure to the 
storms as they track into western/central IL late afternoon and 
evening. Sporadic damaging wind gusts are the main threat with a 
weakening trend by mid evening east of I-55. Shower and storm 
chances continue overnight as a convergent 25-35 kt LLJ focuses on
western IL. PWs rising to near 2" will bring a locally heavy rain
and isolated flash flood threat with both the late afternoon and 
overnight storms, again mainly focused west of I-55. 

Hot and humid weather persists with highs in the upper 80s to 
lower 90s today and lows in the lower 70s tonight, with low 70s 
dewpoints common. Gusty winds up to 20-25 mph this afternoon in 
southwest gradient flow.

&&

.LONG TERM...(Monday through Saturday)
ISSUED AT 255 AM CDT Sun Aug 8 2021

Hot, humid, and unsettled weather remains on Monday when the
shortwave trof axis pivots from IL into the lower Great Lakes. 
Given high instability, lingering boundaries could be the focus 
for another round of potentially severe storms and locally heavy 
rain.

Behind this wave, heights rise on Tuesday which should lead to
less storm organization, but with high instability and little to
no cap in place by late afternoon will carry chance pops. Isolated
heavy rain again a threat with slow storm motion and PWs near the
top of climatology. Oppressive heat and humidity will likely be a
bigger forecast concern Tuesday as mid to upper 70s dewpoints are
likely. This combined with highs in the lower 90s will push peak 
heat indices toward advisory criteria of 105F.

Another round of potentially intense convection is forecast by
some guidance Tuesday night into Wednesday, when an upper jet 
shifts from the Plains into the Great Lakes. With the same airmass
in place, at least a low end severe and heavy rain threat will 
exist. Heat indices may again be an issue, if organized convection
does not materialize.

Thursday into Thursday night, the longwave trof finally pushes
into the upper Midwest, steering a cold front towards the region.
The passage of this front will signal the end of the 
heat/humidity and active weather pattern. Progressively cooler and
less humid air will filter in from the northwest for Friday and 
into the weekend as strong high pressure tracks from the upper 
Midwest to lower Great Lakes.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1150 PM CDT Sat Aug 7 2021

VFR conditions will prevail at all TAF sites next 24hrs unless
storms are moving across the sites tomorrow late afternoon through
evening. Cirrus will spread over the sites overnight and should
become broken by mid tomorrow morning. Mid clouds around 15kft
will advect into the area with broken cirrus, all from a decaying
MCS that will be moving into the area. Any outflow boundary/front
will become the focus for more convection tomorrow that will move
across the sites late morning through evening. Question is
when/where it will develop and when will it arrive at the sites.
HiRes models differ slightly on timing but all show convection
moving across the sites late afternoon into evening. Will start
with VCTS and then have a 2-hr TEMPO group for when thinking best
chance of storms on site. MVFR vis and cigs around 4kft will occur
with the storms. Once this ends, could be some lingering
precip/showers in the area, but did not add another line in TAFs
to reflect that since there is still some uncertainty. Southerly
winds will occur tonight around 8-10kts but then increase tomorrow
out of the south through the day with gusts around 20-21kts in 
the morning, increasing to 22-25kts in the afternoon.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...25
SHORT TERM...25
LONG TERM...25
AVIATION...Auten