Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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594 FXUS63 KILX 181100 AFDILX Area Forecast Discussion...Updated Aviation National Weather Service Lincoln IL 600 AM CDT Thu Apr 18 2024 .KEY MESSAGES... - Severe threat remains for counties along and south of a line from Schuyler to Vermilion counties. The greatest risk (enhanced, level 3/5) is located from Scott to Clark counties and south. - The system should be entering west-central Illinois by 10-11am and exit southeastern Illinois by midnight tonight. Storm mode is expected to be QLCS in nature. However, supercells could develop early on. - There is a 30-40% chance of temperatures dropping below freezing Sunday morning for areas north of I-72 and west of I-55. && .DISCUSSION... Issued at 310 AM CDT Thu Apr 18 2024 Good morning, central Illinois! As the world wakes, we prep for another round of severe weather this afternoon. The 00z NAMNest and HRRR, along with a couple HRW models, indicate that the showers and thunderstorms will enter west-central Illinois by 15-17z (10am- 12pm). This early round will primarily affect areas north of I-72. There could potentially be some supercells around/after noon, ahead of the line of storms arrival. The line of storms we are most concerned about develops and arrives from the west by mid-afternoon (21-22z, 4-5pm). The system should be departing the southeastern counties by midnight tonight. Today`s hazards primarily should be damaging winds and isolated tornadoes. The biggest risk for tornadoes looks to be closest to the low track. The low is progged to track along the I-72 corridor, where the SPC has placed the 5% tor risk and 30% damaging wind risk regions. That area is where the higher sig tor parameter values can be found (values: 1-2). 0-6km bulk shear values range from 30-40 knots ahead of the front which could support the early, discrete cells. Along the front, as the QLCS moves across the state, the 0-3 km shear vectors are practically parallel to the boundary. This points towards the line having damaging winds as the main threat, but spin ups can`t be completely ruled out, especially closer to the low center track. SPC has a slight risk (level 2/5) for along and south of a line from Schuyler to Vermilion counties. The greatest risk (enhanced, level 3/5) is located from Scott to Clark counties and south. Following the cold frontal passage this evening, colder temperatures will move into the state. We will be going from well above normal temperatures to below normal temperatures. Overnight lows will get pretty chilly this weekend, with lows in the 30s. There is a frost/freeze threat as the CWA is within growing season and many sensitive vegetation types are blooming. Saturday night into Sunday morning will be the coldest night of the weekend. There is a 30-40% chance of temperatures dropping below freezing Sunday morning for areas north of I-72 and west of I-55. After Sunday, temperatures will begin to warm back up for the new week. The weekend appears to be dry, albeit chilly. The next chance for showers comes Monday afternoon. Copple && .AVIATION... (For the 12z TAFs through 12z Friday Morning) Issued at 600 AM CDT Thu Apr 18 2024 A strong cold front is set to move across central Illinois. Some showers and thunderstorms could move through the northern sites (BMI/PIA) around noon before the main round. A line of strong thunderstorms will move through the area this afternoon/evening. Lowered visibilities are possible as the storms move over. MVFR ceilings will accompany the low passage, along with a brief window of IFR for SPI/BMI/PIA. VFR ceilings and visibilities are expected to return overnight before 12z tomorrow morning. Copple && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$