Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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280 FXUS63 KILX 070828 AFDILX Area Forecast Discussion National Weather Service Lincoln IL 328 AM CDT Tue May 7 2024 .KEY MESSAGES... - A line of thunderstorms will push into central Illinois early this morning...bringing a few damaging wind gusts to locations west of the I-55 corridor. - Scattered strong to severe thunderstorms will re-develop east of I-55 this afternoon. - Wednesday afternoon severe event is shifting southward...with the latest guidance suggesting the highest probability for damaging winds, large hail, and tornadoes focusing along/south of the I-70 corridor. && .SHORT TERM...(Today through Wednesday) Issued at 328 AM CDT Tue May 7 2024 08z/3am regional radar mosaic continues to show a line of strong to severe convection approaching the Mississippi River. The airmass further east across central Illinois has been relatively stable with MLCAPEs of only 100-300J/kg: however, the RAP is showing an uptick to 500-1000J/kg over the next couple of hours as the LLJ transports richer moisture northward into the region. While the line of convection will weaken with time, think it will have enough energy to work with to produce scattered damaging wind gusts along/west of I-55 through 11z/6am. The storms will then continue eastward and will exit into Indiana by mid-morning. After a brief lull in precip chances behind the early morning line, scattered convection will develop by 17z/12pm...primarily east of the Illinois River. Given modest instability characterized by SBCAPEs of around 1500J/kg and very strong 0-6km bulk shear in excess of 60kt, many of the cells will rotate and will be capable of producing damaging wind gusts, large hail, and isolated tornadoes. The primary threat area will be east of I-57 between 12pm and 6pm. After that, the cells will exit into Indiana...leaving behind dry conditions this evening through Wednesday morning. A push of dry air will surge into central Illinois from the west tonight...with both the NAM and GFS showing surface dewpoints dropping to 50-55F everywhere north of I-70 by Wednesday morning. Thanks to this dry air intrusion, the main baroclinic zone will shift slightly further south than previously thought, which will have major implications for the next round of severe convection expected Wednesday afternoon/evening. It now appears low pressure will track eastward out of the Plains along the boundary generally along/near the I-70 corridor. With the strongest instability/shear focused south of the front, the highest probabilities for severe weather will focus from the Ozarks northeastward into the Ohio River Valley. Latest SPC Day 2 Convective Outlook reflects this change, as the Enhanced Risk area has shifted southward to include locations along/south of a Carlinville to Martinsville line. While pockets of strong to severe convection are possible as far north as I-72, widespread severe will likely remain further south where damaging wind gusts greater than 70mph, hail larger than golf balls, and several tornadoes will be possible. Barnes .LONG TERM...(Thursday through Monday) Issued at 328 AM CDT Tue May 7 2024 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 06z TAFs through 06z Tuesday Night) Issued at 1200 AM CDT Tue May 7 2024 Line of severe storms is moving across NE/KS this evening and approaching KS/IA this hour. Latest CAMs suggest this line will reach the lower Illinois River Valley by around 09/10Z or 400/500 AM CDT isolated storms popping up ahead of the main line around 08Z/0300 CDT. Given the unfavorable diurnal timing, storms should be in a weakening trend, but couldn`t rule out some strong/severe storms reaching as far east as central Illinois. Latest RAP suggests pockets of 1000 J/kg MLCAPE will still be in place as the line arrive with deep layer shear of around 30kt which would support a continuing severe threat. Deubelbeiss && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$