894
FXUS63 KILX 051042
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
542 AM CDT Sun May 5 2024

.KEY MESSAGES...

- Severe weather potential is increasing for locations
  along/southeast of a Champaign to Shelbyville line Tuesday
  afternoon and evening.

- Another round of strong to possibly severe thunderstorms will
  impact parts of central Illinois Wednesday afternoon/evening.

- Much cooler conditions will return for the end of the week.

&&

.SHORT TERM...(Today through Monday)
Issued at 334 AM CDT Sun May 5 2024

Cold front that brought a gusty line of thunderstorms to central
Illinois last evening has pushed into Indiana early this morning.
Cooler/drier conditions have filtered into the region behind the
front: however, quite a bit of cloud cover lingers across the
eastern half of the KILX CWA. Several CAMs suggest patches of low
clouds observed on 0730z/230am IR satellite imagery will expand
over the next few hours, resulting in mostly cloudy skies
along/east of I-55 after sunrise. High pressure will build in from
the west as the day progresses, so subsidence/drier air will
eventually result in partly to mostly sunny skies across the board
this afternoon. High temperatures will mostly top out in the
upper 60s and lower 70s, with middle 70s south of I-70.

A short-wave trough evident on latest water vapor imagery over
Oklahoma/Texas will track E/NE and interact with a stalled
frontal boundary along the Ohio River tonight. As a result,
scattered showers will develop across the Ozarks this evening,
then spread/develop into the Ohio River Valley tonight. Given dry
NE boundary layer flow from high pressure over the Great Lakes,
have limited northward spread of precip to locations south of I-72
late tonight. As the wave tracks further northeast, best shower
chances will focus along/south of I-70 on Monday:however, cannot
rule out a stray shower further north across the remainder of the
CWA Monday afternoon as low-level moisture increases.

Barnes

.LONG TERM...(Tuesday through Saturday)
Issued at 334 AM CDT Sun May 5 2024

A deep upper low currently churning over northern California will
cross the Rockies...helping trigger a major severe weather outbreak
across parts of Kansas/Oklahoma Monday afternoon and evening. Some
of this convection will pivot northeastward into central Illinois
in a greatly diminished state late Monday night into Tuesday morning.
While gusty winds will be possible with this initial round of convection,
we will need to keep a close eye on where the resulting outflow
boundary eventually lays out...as this will provide the focus for
another round of storms later in the day. The atmosphere will
become moderately unstable/highly sheared as the day
progresses...with the 00z May 5 GEFS indicating a high probability
(40-60% chance) of SBCAPEs exceeding 500J/kg and bulk shear
climbing over 40kt along/southeast of a Champaign to Shelbyville
line. As a result, any storms that form along the boundary will be
capable of producing damaging wind gusts and large hail.

The severe weather threat will shift into the Ohio River Valley
Tuesday evening, followed by a lull in precip chances overnight
into Wednesday morning. As low pressure approaches from the west,
another round of storms appears likely Wednesday afternoon/evening.
While the exact location and scope of the severe risk remains
somewhat in question, GEFS suggests greatest instability/shear
will focus along/south of I-72.

Once the low passes, deep upper troughing is progged to develop
over the Great Lakes/Ohio River Valley by the end of the week. End
result will be much cooler temperatures with diurnal shower
chances Thursday through Saturday.

Barnes

&&

.AVIATION...  (For the 12z TAFs through 12z Monday Morning)
Issued at 542 AM CDT Sun May 5 2024

Patches of MVFR clouds will drift southward across central
Illinois this morning...primarily impacting KCMI. NAM/HRRR
forecast soundings suggest the low clouds will scatter by early
afternoon, with only high/thin cloud cover observed for the
remainder of the day. As the next weather disturbance approaches
from the southwest, clouds will once again thicken/lower tonight:
however, latest CAMs keep MVFR ceilings and showers south of the
central Illinois terminals through 12z Mon. Winds will initially
be N/NW at 5-10kt, then will veer to NE by mid to late morning.

Barnes

&&

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

$$