Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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861 FXUS63 KILX 021951 AFDILX Area Forecast Discussion National Weather Service Lincoln IL 251 PM CDT Thu May 2 2024 .KEY MESSAGES... - Concern remains for some strong to locally severe storms through sunset, primarily west of I-55. - While some quieter periods are expected during the weekend, an active weather pattern re-establishes itself early next week. && .DISCUSSION... Issued at 251 PM CDT Thu May 2 2024 Isolated convection has begun to fire early this afternoon near Peoria, along a subtle surface boundary. Latest SPC mesoanalysis shows close to 1500 J/kg of surface based CAPE across much of central Illinois, with steep low level lapse rates of around 8.5 C/km. Already have received some pea size hail reports with the Peoria cell. On a broader scale, numerous thunderstorms continue to develop over central Missouri and are traveling northeast. A general expansion northeast along the Illinois/Iowa border is expected over the next few hours, with storms becoming numerous over west central Illinois. Area remains in a Level 1 severe risk this afternoon and early evening, with some brief wind/hail risks. High-res models show some general weakening after sunset, though PoP`s will remain high over the eastern half of the forecast area through about 3-4 am. Timing of the overall system appears to have sped up though, and rain chances on Friday were significantly lowered and primarily limited to near/east of I-57. Overall, the upper air pattern over the coming days has not changed in the morning model suite. As the upper low over southern Saskatchewan lifts northeast, a larger low will track into northern California/Nevada this weekend, before ejecting into the Plains on Monday. The international models keep the closed low more or less intact through the period, while the GFS opens it up for a time. Net effect of this will be periods of showers and thunderstorms into the middle of next week. There are some signs of extended drier periods Friday night, and again later in the weekend, with more of an increase in PoP`s as the low moves into the Plains and gets more wound up. Tuesday remains a period of concern for potential for strong storms, with a number of European ensemble members featuring CAPE values upwards of 1500 J/kg. Overnight CSU machine learning probabilities also highlight Tuesday as a concern. Geelhart && .AVIATION... (For the 18z TAFs through 18z Friday Afternoon) Issued at 1223 PM CDT Thu May 2 2024 Main concern in the shorter term will be with timing of convective development. Initial development is expected along the IL/IA border toward 20-21Z with storms moving east, though some weakening will take place after 00Z. While some of the heavier storms may produce some brief MVFR visibility or ceilings, confidence levels are not high enough yet to introduce a TEMPO period. Later on, a more sustained period of ceilings below 3,000 feet will accompany the cold front following the rain. This should be moving into KPIA as early as 06-07Z, though not reaching KCMI until closer to 11-12Z. Morning HREF guidance suggests a 2-3 hour period of IFR conditions isn`t out of the question (30-50% probability), so this will need to be monitored. Geelhart && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$