DISCUSSION
Issued at 330 PM CDT Fri Jul 26 2024

Mid afternoon surface analysis shows weak 1023 mb high pressure over the central Great Lakes and ridging into central and northeast IL. This was providing a fair amount of sunshine over central IL while more cumulus clouds and high clouds seen over west central and southern/southeast IL. Temperatures were mostly in the lower 80s at 3 pm with some upper 70s from Bloomington and Paris northeast. More comfortable dewpoints in the upper 50s and lower 60s from Peoria, Decatur and Mattoon ne while more muggy dewpoints in the upper 60s/lower 70s from Galesburg to Springfield to Flora sw. Aloft a 590+ dm 500 mb skinny ridge was over the western parts of the central and southern Plains and arching into the upper MS river valley. 500 mb heights over IL were 588-590 dm, highest near the Iowa border.

Fair weather expected tonight across central and southeast IL under influence of nearby high pressure drifting slowly eastward over the Great Lakes region. Some fog expected over southern/sw IL mainly south of CWA overnight into early Sat morning where dewpoints/airmass more moist. Lows tonight mostly in the lower 60s, with some upper 50s from BMI and CMI ne and near 65F from highway 50 south where more cloud cover over and higher dewpoints.

Developing southeast flow around back side of surface high pressure on Saturday to bring dewpoints up into the mid to upper 60s Sat afternoon and may see an isolated shower or thunderstorms sw of a Springfield to Effingham line by late Sat afternoon.
Clouds will also be increasing from the south during Sat afternoon and Sat night with tropical moisture advected into the area.
Seasonable highs Saturday in the mid 80s in central IL and upper 80s se of I-70. Pops increase to 20-30% during Sat night especially overnight Sat night as tropical plume of moisture continues to stream northward over IL ahead of approaching weak upper level low/trof moving into central IA/MO by Sunday morning.
Milder lows in the upper 60s to around 70F.

Have likely chances of showers and isolated thunderstorms over CWA on Sunday, with highest pops and qpf in eastern/se IL as tropical moisture continues to stream northward ahead of weak upper level trof moving into the MS river valley by late Sunday afternoon.
Rainfall amounts overnight Sat night into Sunday is a quarter to half inch with locally higher amounts especially in eastern IL and nw of the IL river. SPC day3 outlook keeps marginal risk west of IL for Sunday afternoon/evening. More clouds and showers on Sunday to keep highs a bit cooler than Saturday with highs Sunday in the low to mid 80s. More humid as dewpoints get in the low to mid 70s with southerly flow.

Upper level ridge building into IL from Monday into Wed to bring central/se IL a heat wave much of this work week. Highs in the mid to upper 80s Monday with dewpoints in the 70s giving afternoon heat indices in the mid to upper 90s east of the IL river and around 100F west of the IL river. Tue through Thu likely see highs in the lower 90s with dewpoints in the 70s, with afternoon heat indices of 98-110F. We may eventually need a heat advisory for part of our area during mid week but we are also looking at a few more rounds of showers and thunderstorms with possible MCS activity over top of the ridge. Monday afternoon and Monday night looks like a high chance of convection. Another enhance chance of convection Wed afternoon and Wed night. SPC does not have any severe risk over central/se IL this upcoming week. But the CPU Machine Learning has some risk from Monday through mid week. Some upper level trof digging into IL late this week to keeping chances of convection around along with temps getting closer to normal with highs in the mid to upper 80s next Friday and Saturday, though still humid with dewpoints likely in the lower 70s next Friday.

07

AVIATION
(For the 00z TAFs through 00z Saturday Evening)
Issued at 638 PM CDT Fri Jul 26 2024

VFR conditions will prevail at all TAF sites next 24hrs. A little bit of cirrus will be possible this evening, but thin enough to not warrant a mention. So, will go clear skies through the night.
CU could develop tomorrow as things change so have scattered CU around 4kft tomorrow from late morning through afternoon. Wind will be light and variable through the night then become southeast around 8kts tomorrow.

Auten

ILX WATCHES/WARNINGS/ADVISORIES
None.