Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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345 FXUS63 KILX 061523 AFDILX Area Forecast Discussion...Updated National Weather Service Lincoln IL 1023 AM CDT Mon May 6 2024 .KEY MESSAGES... - A line of thunderstorms will push through central Illinois late tonight into Tuesday morning...bringing gusty winds and downpours. - Scattered severe thunderstorms may fire along an outflow boundary along/southeast of a Champaign to Shelbyville line Tuesday afternoon/evening. - Confidence is growing concerning a more significant and widespread severe weather event across much of central and southeast Illinois Wednesday afternoon/evening. && .UPDATE... Issued at 1023 AM CDT Mon May 6 2024 A weak low evident on satellite imagery is centered just southeast of the southern tip of IL, heading slowly ENE. Bands of showers wrapping around this system continue from around Jacksonville to Bloomington southeastward, and should slowly diminish from the west over the day. A few thunderstorms will be possible as well, mainly south of a Taylorville to Danville line early this afternoon with a few hundred J/kg CAPE forecast in that area. Cloud cover will be fairly prevalent in the area, with more breaks expected to the northwest of the showers. Temperatures look on track to reach the 70s across the area, with the higher end of 70s possible northwest of the Illinois River where more sunshine should be available. Updates have been made to extend precipitation chances farther northwest late this morning and afternoon given radar trends, but otherwise the early morning forecast package was in good shape. 37 && .SHORT TERM...(Today through Tuesday) Issued at 313 AM CDT Mon May 6 2024 A short-wave trough evident on 07z/2am water vapor imagery over southern Missouri will continue lifting northeastward into the Ohio River Valley today. Showers associated with this feature will spread as far northwest as a Bloomington to Jacksonville line: however, precip amounts will be quite light. Instability will remain limited across much of central Illinois, but SBCAPEs increasing to 500-1500J/kg warrants thunder mention along and southeast of a Danville to Taylorville line. Showers will exit into Indiana before sunset as short-wave ridging leads to a period of dry weather this evening into the first half of the overnight. Meanwhile further west, an organized line of convection will develop ahead of a much stronger short-wave crossing the Rockies into the Plains late this afternoon. These storms will push eastward and spill into the Illinois River Valley after 09z/4am. While instability will be waning, think gusty winds and heavy downpours will be a good bet as the line pushes through the western KILX CWA and arrives along the I-55 corridor by dawn. All CAMs suggest the convection will continue eastward and exit into Indiana before midday Tuesday. After that, attention will focus on the exact placement of the residual outflow boundary...which will play a key role in late day thunderstorm development. At this time, it appears the boundary will likely lay out along/near I-70. With a highly unstable/sheared environment to the south across the Ohio River Valley, any cells that form will be capable of damaging wind gusts and large hail. The primary time frame will be from 3pm to 9pm before the storms shift further east out of the area. Barnes .LONG TERM...(Wednesday through Sunday) Issued at 313 AM CDT Mon May 6 2024 After another lull in precip chances Tuesday night into Wednesday morning, all eyes will be on a potential outbreak of severe weather Wednesday afternoon/evening from the Ohio River Valley southwestward into the southern Plains. Low pressure is progged to track eastward out of the Plains into central Illinois...with GEFS mean sea-level pressure suggesting the low will slide along the I-72 corridor during the evening. A highly unstable/sheared environment will once again be in place south of the low track...with GEFS probabilities of exceeding SBCAPEs of 500J/kg and bulk shear of 40kt of 30-40% along I-72 and greater than 80% along/south of I-70. NAM 0-3km VGP values increase to 0.5-0.7, strongly suggesting supercell development along the warm front as well as within the warm sector. As a result, all severe weather hazards will be in play...including damaging wind gusts greater than 60mph, very large hail, and the potential for long-track tornadoes. At this time, the greatest risk for widespread severe weather will be along/south of I-72: however, this area will be fine-tuned as exact details become more defined over the next 24-36 hours. 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 12z TAFs through 12z Tuesday Morning) Issued at 553 AM CDT Mon May 6 2024 Widely scattered showers will track through central Illinois this morning before gradually shifting eastward and exiting the region this afternoon. After a period of dry weather this evening, a line of thunderstorms will approach from the west late tonight. While the exact timing of the convection remains somewhat uncertain, HRRR/RAP have been consistently pushing it into the Illinois River Valley after 09z. Have therefore opted to carry predominant thunder at KPIA after 10z...then further east to KBMI/KSPI after 11z. Winds will initially be E/NE at 5-10kt, then will veer to E/SE from late morning through the afternoon. SE winds will increase and become gusty late tonight as the line of storms nears. Barnes && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$