Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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217 FXUS63 KILX 220843 AFDILX Area Forecast Discussion National Weather Service Lincoln IL 343 AM CDT Sat Jun 22 2024 .KEY MESSAGES... - Strong to severe thunderstorms are possible tonight...with the highest probability of damaging wind gusts and hail focused along and northwest of a Jacksonville to Bloomington line. - After a brief cool-down on Sunday, temperatures will once again climb early next week. Heat index readings will exceed 100 degrees by Tuesday. - A second cold front will arrive Tuesday night into Wednesday, bringing another chance for much-needed rainfall. && .SHORT TERM...(Today through Sunday) Issued at 343 AM CDT Sat Jun 22 2024 Low pressure currently over Nebraska will track northeastward into the Great Lakes, pulling a cold front into central Illinois tonight. Given the trajectory of the low, the front will not have a strong southward push and will instead gradually sag into the area. The airmass ahead of the boundary across eastern/southern Iowa will become moderately unstable/sheared this afternoon...with HREF ensemble mean SBCAPEs of 2000-3000J/kg and 0-6km bulk shear increasing to 30-35kt. As a result, scattered thunderstorms will initiate across this area...then congeal into a broken line as they push across the Mississippi River into west-central Illinois this evening. CAMs have slowed the arrival of the convection by a couple of hours...with consensus suggesting thunderstorms reaching the far NW KILX CWA around Galesburg between 7pm and 9pm. Given favorable instability/shear parameters, a risk for large hail and damaging wind gusts will initially accompany the storms. However, as the activity drops further southeastward, the atmosphere will decouple and become more stable with time. The severe risk will therefore diminish later in the evening, with only a 5-10% chance of a severe wind gust reaching the I-72 corridor around midnight. Areal coverage of storms will continue to decrease overnight as they push into an even less favorable environment south of I-72. Storm total rainfall tonight will be greatest along/north of a Rushville to Bloomington line where amounts of 0.75 to locally greater than 1 inch will be likely. Amounts will rapidly decrease further southeast with locations along/south of a Taylorville to Paris line only picking up 0.25 or less. Scattered showers/thunder may linger and/or re-develop across east-central and southeast Illinois on Sunday before the cold front settles into the Ohio River Valley: however, am not expecting any substantial rainfall from the few showers that persist on Sunday. The main story will be the slightly cooler/less humid conditions as highs drop into the upper 80s to around 90 degrees. Barnes .LONG TERM...(Monday through Friday) Issued at 343 AM CDT Sat Jun 22 2024 After a warm/dry day on Monday, another cold front will drop into the region by Tuesday. With temperatures spiking back into the middle 90s and dewpoints climbing into the lower 70s ahead of the boundary, peak afternoon heat index values will exceed 100 degrees. As the front arrives, another round of scattered strong convection will be on tap Tuesday night into Wednesday. After that, upper troughing over the Great Lakes will bring a more substantial cool-down for the end of next week as highs drop into the middle to upper 80s Wednesday through Friday. Barnes && .AVIATION... (For the 06z TAFs through 06z Saturday Night) Issued at 1100 PM CDT Fri Jun 21 2024 Mostly clear skies will continue overnight. CU will redevelop tomorrow morning across the area at around 5kft with some cirrus as well...ahead of the next weather system that will approach the area from the west and northwest. Mid clouds will begin to advect in around the 00z time frame as storms should have developed to the northwest of IL. Lower clouds and precip will begin to move into the area around 03z at PIA. Some CAMs are showing the precip diminishing as it moves toward the TAFs, but other are showing storms arriving during the evening hours. Have decided to add a PROB30 group starting at 03z for PIA and then 04z for SPI and BMI. DEC and CMI would be closer to 06z. Winds will be southwest through the forecast period. Speeds will remain light overnight but then increase again tomorrow with gusts up to around 20kts tomorrow morning into the afternoon. Gusty winds will continue into the evening hours. Auten && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$