DISCUSSION
Issued at 300 PM CDT Sun Sep 15 2024

A 1026 mb high pressure ridge over southern New England and ridging westward across the Great Lakes region and into central and northeast IL was bringing in drier air into the CWA Dewpoints ranged from the mid to upper 50s in eastern IL, to the low to mid 60s from I-55 west. Warm temps were in the mid to upper 80s over CWA with Springfield at 90F. Scattered cumulus clouds and tufts of cirrus clouds was giving partly sunny skies overnight at mid afternoon. Scattered showers and thunderstorms were sw of I-64 near St Louis. Aloft a strong 590 dm 500 mb high pressure was over the eastern Great Lakes and ridging westward toward Lake MI and ne IL.

A few of the latest CAMs models like the HRRR shows isolated convection developing over west central IL near Scott and Schuyler county late this afternoon and early evening and sets up again Monday afternoon but further west of CWA Continue slight pops until sunset from Jacksonville west and kept Monday dry across area. Latest CAMs also not showing much fog development over CWA overnight and mainly over river valleys in MO and possibly lower IL river valley. Temps a bit cooler tonight with lower dewpoints in area today, with lows in the lower 60s, with a few upper 50s in east central IL. Very warm again Monday with highs in the upper 80s to near 90F and dewpoints slipping into the mid to upper 50s, with lower 50s possible in east central IL.
Partly to mostly sunny skies Monday with more cumulus clouds over the IL river valley.

A tropical system off the southeast Atlantic coast will track nw into the central Carolinas later Monday, with a cutoff mid/upper level low over the central Appalachians Tue night and Wed and weakening and pulling away into mid Atlantic States Thu. Blocking Rex upper level pattern keeps this system well east/se of IL with its precipitation likely east of Indiana next few days. Ample sunshine Tue with highs in the upper 80s with dewpoints in the low to mid 50s and light ENE winds.

A strong upper level trof along the West Coast to slowly emerge over the Rockies by mid to late week and have a frontal boundary moving into the upper MS river valley and Central Plains by weeks end. It's convection appears to stay west and nw of CWA through at least Saturday. Blended forecast has 20-30% chance of convection moving into the IL river valley Sat night and Sunday (next weekend). Highs in the mid to upper 80s Wed and upper 80s to near 90F Thu through Saturday.

The Climate Prediction Center (CPC) 6-10 Day outlook for Sep 21-25 has 70-80% chance of above normal temperatures over central IL. CPC's 8-14 Day outlook for Sep 23-29 has 55-60% chance of above normal temperatures over central IL, so looks like September will end up warmer than normal and likely drier than normal too as drought likely expands northward from southern IL.

07

AVIATION
(For the 00z TAFs through 00z Monday Evening)
Issued at 600 PM CDT Sun Sep 15 2024

High pressure off to our east will keep VFR conditions in place again this forecast cycle. Expect SCT-BKN high clouds and light east winds.

25

ILX WATCHES/WARNINGS/ADVISORIES
None.