494 FXUS63 KILX 120452 AFDILXArea Forecast Discussion...Updated Aviation National Weather Service Lincoln IL 1152 PM CDT Thu Sep 11 2025
.KEY MESSAGES...
- An extended period of well above normal temperatures continues across central and southeast IL through at least next Thursday.
- Little to no precipitation is expected during the next 7 days, introducing the risk for flash drought conditions through mid September for central and southern IL.
&&
.DISCUSSION... Issued at 230 PM CDT Thu Sep 11 2025
Mid afternoon surface map shows 1027-1029 mb high pressure over James Bay Canada and ridging southward into the Great Lakes region, and influencing central/ne IL with weak east to NE flow. Scattered cumulus clouds were over central and eastern parts of CWA with few cumulus clouds from Peoria and Springfield west. Warm temps were in the low to mid 80s over central/se IL with Olney at 88F and Mt Carmel airport in southern Lawrence county at 89F. Dewpoints were in the 50s over central IL 60-65F in southeast IL. Aloft an omega block pattern was occurring over US, with a strong mid/upper level ridge was over the central plains with upper level trof over the Atlantic States and a stronger upper level trof/low over the Pacific States (a 572 decameter 500 mb low was near the OR/CA/NV border).
Broad surface high pressure ridge to slowly shift eastward into Quebec, New England and into the central Appalachians on Friday with south to SSE flow developing over central IL. Strong upper level ridge to also build more over IL as 500 mb heights rise above 588 decameters. Diurnally driven cu field to dissipate after dusk with fair wx expected again tonight. Latest CAMs hint at some fog develop over northeast IL, mainly ne of CWA and fog more prevalent closer to Lake MI and marine layer. Far southern IL also could see patchy fog develop overnight while most of our CWA should not see too much fog. Lacon and Robinson had patchy fog early this morning with vsbys 1-2 miles and may see a few spots with similar conditions in eastern IL. Lows overnight in the upper 50s to around 60F. Hot on Friday with highs around 90F to lower 90s from Peoria to Effingham west. Few to scattered cumulus clouds to develop by midday Fri into Fri afternoon with more cumulus clouds expected over the IL river valley/western CWA by Fri afternoon.
The stronger upper level ridge near IL this weekend into middle of next week to continue the heat wave with highs in the low to mid 90s Saturday through Wednesday, and likely lower 90s yet next Thursday. Continued to blend the raw NBM high temperatures from Friday through Wed with the 50th percentile NBM to bring some of the erroneously high values down. Temperatures remain elevated through much of next work week, though should come down slightly late next week.
Models begin to diverge with convection chances starting this weekend as short waves start ridging over top of the subtropical ridge and question is how far south convection chances can get and coverage. Overnight Friday night could see isolated convection move over northern IL though most of this convection appears to miss central IL. But more model solutions show some convection chances over parts of CWA especially ne CWA on Saturday and Sat night. GFS still appears too wet over area this weekend and NBM keeps pops closer to 10% over much of area. Cutoff lows moving over the mid and southern Atlantic States by mid week with another cutoff low moving into the central and northern high plains to keep better convection chances se of IL and to our nw. Maybe a better chance of needed convection later next week around next Friday.
The Climate Prediction Center (CPC) 6-10 Day outlook for Sep 17-21 has 70-80% chance of above normal temperature over IL. CPC 8-14 Day outlook for Sep 19-25 has 50-60% chance of above normal temperatures over IL. So we may need to keep our air conditioning units going this month.
07
&&
.AVIATION... (For the 06z TAFs through 06z Friday Night) Issued at 1152 PM CDT Thu Sep 11 2025
Another set of VFR TAFs with mostly clear skies and east to southeast winds under 10 kt.
25
&&
.ILX WATCHES/WARNINGS/ADVISORIES... None. &&
$$
NWS ILX Office Area Forecast Discussion