Sunrise 5:49 AM   Sunset 8:00 PM Moonrise 4:25 AM   Moonset 5:20 PM

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FXUS63 KILX 051520 AFDILX

Area Forecast Discussion...Updated National Weather Service Lincoln IL 1020 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.

UPDATE
Issued at 1020 AM CDT Sun May 5 2024

No significant updates needed this morning, as the early morning forecast package is in good shape for today. Areas of low clouds this morning mainly from I-55 will dissipate in the early afternoon just in time for more mid and high cloud cover poised to the southwest to move into the area and dim the sunshine again.
However, any rain with the responsible shortwave will hold off until after sunset, and target areas mainly south of I-72.
Temperatures will be substantially cooler today behind last night's cold front, with highs ranging from around 70 for most areas from I-72 northward, to the mid 70s south of I-70. Winds will be fairly light form the northeast, influenced mainly by the high pressure center tracking eastward across northern IL and southern WI today.

37

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.

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