Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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542 FXUS63 KILX 081039 AFDILX Area Forecast Discussion...Updated Aviation National Weather Service Lincoln IL 539 AM CDT Sat Jun 8 2024 .KEY MESSAGES... - A couple rounds of showers and storms are possible through this evening, with the highest chances being this morning. - Near to slightly below normal temperatures will persist through early in the week, then things turn hot and humid late in the week. && .DISCUSSION... Issued at 300 AM CDT Sat Jun 8 2024 Broad northwest flow is positioned over a good portion of the country to start the weekend, which will keep things somewhat cooler than normal the next several days. Further west, a MCS is working through central Missouri along the nose of a 40-45 kt LLJ. The LLJ will lift toward southwest Illinois closer daybreak, working to help eat away at low to mid-level dry air which was noted on the 08.00Z KILX sounding. Showers and some storm activity should become likely within a few hours of sunrise in our southwest, scraping mainly the southern half of the forecast area through late this morning. Rainfall amounts could approach 0.50" where the heavier pockets of precipitation track near/south of I-72, but otherwise generally 0.10- 0.25" or less will be seen. Later today, a shortwave trough working through the Great Lakes Region will send a cold front into the area. Although cloud cover may stick around through the afternoon, a few breaks in the clouds paired with dewpoints in the middle to upper 60s should allow instability to build. Most guidance shows 500-1000 J/kg over the area, with the 08.00Z run of the HREF highlighting closer to 1500 J/kg. The HRRR continues to be the most bullish for shower and storm chances this afternoon/evening ahead of the front, showing a line more organized activity firing near I-72 right before sunset as the CAP erodes. Despite this, the main thunderstorm activity is expected to be focused south of here over southern Missouri/southern Illinois/Kentucky where a remnant outflow boundary will be. This activity could realistically consume all the available moisture and skew our model projected instability, leading to much lower values this far north. For now, have kept precipitation chances at 30% or less, but confidence in afternoon/evening storm development is not high at this point. Upper ridging amplifies over the western CONUS at the start of the new week, with central Illinois remaining under northwest flow. Near to slightly below normal temperatures will prevail with things looking to stay mostly dry through then. The ridge will spill eastward and flatten out some due to a few upper shortwaves, turning flow more zonal here. Upper ridging over the southwest US will allow mid-level heights to increase through late in the week, turning temperatures more summer-like late in the week. Rainfall looks pretty minimal in the extended with perhaps a few passing upper waves bringing occasional chances. NMA && .AVIATION... (For the 12z TAFs through 12z Sunday Morning) Issued at 539 AM CDT Sat Jun 8 2024 Light rain showers will occur at mainly southern TAF sites (SPI, DEC) this morning with more isolated activity further north. MVFR ceilings become common by mid to late morning, sticking around until later this afternoon/evening when a cold front scours things out. South-southwest winds will shift to the north-northwest behind the front. There is a 20% chance for a few thunderstorms to develop along the front as it works through, but coverage remains far too low to add in the TAFs. && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$