Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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695 FXUS63 KILX 250441 AFDILX Area Forecast Discussion...Updated Aviation National Weather Service Lincoln IL 1141 PM CDT Fri May 24 2024 .KEY MESSAGES... - Saturday will be dry and warm. Highs in the 70s, clear skies, and dry weather makes for a beautiful Saturday. - There is a 80-100% chance of thunderstorms on Sunday. These storms have the potential to be severe, with an enhanced risk (level 3 of 5) for severe weather that day. && .UPDATE... Issued at 854 PM CDT Fri May 24 2024 At 8 PM an approaching cold front was just east of the Mississippi River about to enter the central IL forecast area. An axis of 1000-1500 J/kg MLCAPE was maintained just ahead of the front, which should gradually slip southeastward through the evening as the front continues to move eastward. The front should exit the forecast area to the east by a few hours after midnight, eliminating the thunderstorm threat across central IL. Until then, strong to severe thunderstorms ahead of the front should continue, gradually weakening as they move into a region of weaker deep layer shear. Corridors of repeated thunderstorms have produced areas of flash flooding, especially south of the area where 6-7 inches have fallen. Amounts in excess of 3 inches have been estimated through portions of Scott, Morgan, and Sangamon Counties, mainly far south. Champaign County has received estimated 4 inch amounts earlier. While current activity doesn`t support much threat of new flash flooding imminently, this will need to be watched the next several hours. A severe thunderstorm watch until 9 PM has been expired. An isolated storm with large hail has just pulsed up in Schuyler County moving eastward, but this activity is expected to be too isolated to extend the watch, as moisture transport into the area looks as if it will be cut off by storm development toward the St. Louis area and southward. Thunderstorms this far north will likely remain sub-severe. Updates this evening have been to address areas of short term thunderstorm activity associated with multiple disorganized clusters of storms ahead of the front, as well as winds driven by the thunderstorm clusters. 37 && .DISCUSSION... Issued at 245 PM CDT Fri May 24 2024 The storms this afternoon continue to have a severe aspect to them, with damaging winds, large hail, and an isolated tornado being possible. They are quite chaotic in motion and where they are initiating. There are multiple boundaries interacting with each other. They are seemingly merging to create a linear formation and will move off to the east towards the Indiana border this evening. There is a flooding risk with these storms as they are moving slower and the axis of higher PWAT values is across the CWA, east of I-55. The severe risk should subside before midnight tonight. Saturday a surface high pressure will set up over the area, providing us a brief breather before the next round of active weather arrives Sunday morning. There is a low pressure system bringing frontal passages through the region on Sunday with a risk of severe weather along with the cold front. A warm front will quickly move north through central Illinois early Sunday morning, placing us in the warm sector. This should allow us to destabilize and break any cap that is in place ahead of the cold front. Highs that day are in the upper 70s to mid 80s, with dewpoints near 70. The GFS is showing about 3000-4000 J/kg of SBCAPE, 40-55 knots effective bulk wind shear, and very steep mid- level lapse rates of ~9 C/km by 18z Sunday. DCAPE is showing around 1000 J/kg on forecast NAM and GFS soundings at that same time. This round of severe weather will have an all hazards risk, damaging winds, large hail, and a tornado or two. Monday (Memorial Day) has a 20-30% of any showers that day but will be mainly dry. However, it will be quite windy. So those on the lake or tent camping should stay aware of any stronger wind gusts that may occur Sunday night into Monday. There is a 50-70% chance of wind gusts 40+ mph overnight. Temperatures look to be in the mid 70s for the holiday. Further passed Monday, highs slowly warm back up but stay in the mid 70s to low 80s through the week. Copple && .AVIATION... (For the 06z TAFs through 06z Saturday Night) Issued at 1141 PM CDT Fri May 24 2024 A cold front will slowly work its way southeastward across the central IL terminals overnight. Ahead of the front, scattered showers and a remote possibility of a thunderstorm can be expected. Winds will be S-SW around 10 kts. Behind the front, winds will shift to NW around 10 kts, then high pressure will settle into the area by mid morning bringing clear skies and light and variable winds. Skies look to remain clear until high clouds associated with the next storm system spread into the area Saturday evening. Winds will return out of the SE 6-12 kts after 00Z. 37 && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$