Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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539 FXUS63 KILX 231046 AFDILX Area Forecast Discussion...Updated Aviation National Weather Service Lincoln IL 546 AM CDT Sun Jun 23 2024 .KEY MESSAGES... - After a cool-down today and Monday, hot weather will briefly return on Tuesday when afternoon heat index readings exceed 100 degrees. - Thunderstorm chances come back into the picture by late Tuesday...with the latest guidance suggesting a Slight Risk (15-30% chance) for severe weather along and north of the I-72 corridor. && .SHORT TERM...(Today through Monday) Issued at 339 AM CDT Sun Jun 23 2024 08z/3am radar imagery shows a line of thunderstorms extending from Danville to Shelbyville. These storms will continue to track eastward and will exit into Indiana within the next 3-4 hours. After that, am expecting cooler/drier conditions across the board today. Thanks to northwesterly winds behind a departing cold front and at least partial cloud cover through midday, high temperatures will be several degrees cooler than in recent days with readings primarily topping out in the middle to upper 80s. As high pressure builds overhead and winds become light/variable, radiational cooling will help low temperatures tonight drop into the lower to middle 60s. Another pleasant summer day will be on tap for Monday with highs in the upper 80s to around 90 degrees and low relative humidity values. Barnes .LONG TERM...(Tuesday through Saturday) Issued at 339 AM CDT Sun Jun 23 2024 As the high shifts off to the east, a warm front will lift northward through central Illinois Monday night. Models have been suggesting the potential for widely scattered thunderstorms along/north of the boundary...particularly late Monday night into Tuesday morning. Have therefore added 20 PoPs along/north of the I-74 corridor. Stronger forcing will be present further north in conjunction with a short-wave trough tracking through the Northern Plains, which could potentially lead to the formation of an MCS across Wisconsin into far northern Illinois/Indiana. With the warm front well to the north and southwesterly winds in place, a hot/humid airmass will return to central Illinois on Tuesday. NBM guidance continues to be too warm based on the projected thermal profile and the potential for convective debris from the early morning MCS, so have once again undercut those numbers to feature highs in the lower to middle 90s. With surface dewpoints progged to reach the lower 70s, afternoon heat index values will climb to near Heat Advisory criteria in the 100-105 degree range. While a few thunderstorms will be possible during the day Tuesday, it appears a much better chance for convection will materialize Tuesday night as a cold front drops southward into the moderately unstable/sheared environment. While precise details are still not clear, confidence is growing for another round of strong to potentially severe thunderstorms...with the highest probability for severe focusing along/north of the I-72 corridor. The front will drop southward through the region late Tuesday night into Wednesday. Once it passes, another airmass change will bring cooler/less humid conditions back. High temperatures will drop into the 80s for Wednesday/Thursday before returning to the 90s by Friday/Saturday. Barnes && .AVIATION... (For the 12z TAFs through 12z Monday Morning) Issued at 546 AM CDT Sun Jun 23 2024 10z/5am obs show a cold front has passed just east of I-55. Winds will remain SW at 5-10kt at both KDEC/KCMI for the next hour or two before veering to NW after FROPA. NW winds will then increase and gust 18-22kt at all terminals from late morning through the afternoon before decreasing to less than 10kt by sunset. Skies have partially cleared behind the departing front: however, patches of MVFR ceilings are drifting southward into central Illinois. Based on satellite trends and the HRRR forecast, have included a period of MVFR at all sites before clearing the low clouds from west to east later this morning. Have scattered the MVFR ceiling at KPIA/KSPI by 15z, then further east to KCMI by 17z. After that, mostly clear skies will prevail through the remainder of the 12z TAF period. Barnes && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$