280
FXUS63 KILX 070828
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
328 AM CDT Tue May 7 2024

.KEY MESSAGES...

- A line of thunderstorms will push into central Illinois early
  this morning...bringing a few damaging wind gusts to locations
  west of the I-55 corridor.

- Scattered strong to severe thunderstorms will re-develop east
  of I-55 this afternoon.

- Wednesday afternoon severe event is shifting southward...with
  the latest guidance suggesting the highest probability for
  damaging winds, large hail, and tornadoes focusing along/south
  of the I-70 corridor.

&&

.SHORT TERM...(Today through Wednesday)
Issued at 328 AM CDT Tue May 7 2024

08z/3am regional radar mosaic continues to show a line of strong
to severe convection approaching the Mississippi River. The
airmass further east across central Illinois has been relatively
stable with MLCAPEs of only 100-300J/kg: however, the RAP is
showing an uptick to 500-1000J/kg over the next couple of hours as
the LLJ transports richer moisture northward into the region.
While the line of convection will weaken with time, think it will
have enough energy to work with to produce scattered damaging wind
gusts along/west of I-55 through 11z/6am. The storms will then
continue eastward and will exit into Indiana by mid-morning.

After a brief lull in precip chances behind the early morning
line, scattered convection will develop by 17z/12pm...primarily
east of the Illinois River. Given modest instability characterized
by SBCAPEs of around 1500J/kg and very strong 0-6km bulk shear in
excess of 60kt, many of the cells will rotate and will be capable
of producing damaging wind gusts, large hail, and isolated
tornadoes. The primary threat area will be east of I-57 between
12pm and 6pm. After that, the cells will exit into
Indiana...leaving behind dry conditions this evening through
Wednesday morning.

A push of dry air will surge into central Illinois from the west
tonight...with both the NAM and GFS showing surface dewpoints
dropping to 50-55F everywhere north of I-70 by Wednesday morning.
Thanks to this dry air intrusion, the main baroclinic zone will
shift slightly further south than previously thought, which will
have major implications for the next round of severe convection
expected Wednesday afternoon/evening. It now appears low pressure
will track eastward out of the Plains along the boundary generally
along/near the I-70 corridor. With the strongest instability/shear
focused south of the front, the highest probabilities for severe
weather will focus from the Ozarks northeastward into the Ohio
River Valley. Latest SPC Day 2 Convective Outlook reflects this
change, as the Enhanced Risk area has shifted southward to include
locations along/south of a Carlinville to Martinsville line. While
pockets of strong to severe convection are possible as far north
as I-72, widespread severe will likely remain further south where
damaging wind gusts greater than 70mph, hail larger than golf
balls, and several tornadoes will be possible.

Barnes

.LONG TERM...(Thursday through Monday)
Issued at 328 AM CDT Tue May 7 2024

Once the low tracks into Indiana Wednesday night, the severe
potential will come to an end and a much cooler/more stable
airmass will arrive by the end of the week. High temperatures will
be in the 60s while overnight lows drop into the 40s Thursday
through Sunday. In addition, periodic shower chances will occur as
the Great Lakes/Midwest remains in a northwesterly flow pattern
aloft.

Barnes

&&

.AVIATION...  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1200 AM CDT Tue May 7 2024

Line of severe storms is moving across NE/KS this evening and
approaching KS/IA this hour. Latest CAMs suggest this line will
reach the lower Illinois River Valley by around 09/10Z or 400/500
AM CDT isolated storms popping up ahead of the main line around
08Z/0300 CDT. Given the unfavorable diurnal timing, storms should
be in a weakening trend, but couldn`t rule out some strong/severe
storms reaching as far east as central Illinois. Latest RAP
suggests pockets of 1000 J/kg MLCAPE will still be in place as the
line arrive with deep layer shear of around 30kt which would
support a continuing severe threat.

Deubelbeiss

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$