Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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836 FXUS63 KILX 260448 AFDILX Area Forecast Discussion...Updated Aviation National Weather Service Lincoln IL 1148 PM CDT Tue Jun 25 2024 .KEY MESSAGES... - Slight Risk (15% within 25 miles) of severe storms today and tonight, tapering to a Marginal Risk (5%) Wednesday across southeast Illinois. - Expect a break from the heat starting Wednesday with highs generally in the lower to mid 80s through Friday. There will be a brief break from the humidity briefly Thursday with dew points dipping into the 50s. && .UPDATE... Issued at 941 PM CDT Tue Jun 25 2024 Storms continue over parts of the area, but appear to be weakening as they move to the south-southeast Will update pops/wx to reflect current situation for the rest of the night. Auten && .DISCUSSION... Issued at 202 PM CDT Tue Jun 25 2024 As of 2pm this afternoon, storms are ongoing from near Mt Sterling to Springfield in west central Illinois, and from Effingham to Dennison in east central/southeast Illinois. These storms have kicked out an outflow boundary that has surged well ahead, except for the storms in east central Illinois which are riding the outflow boundary and consequently have been much stronger. Ahead of the outflow boundary, SPC meso-analysis suggests that around 3000-3500 J/kg MLCAPE is present coinciding with marginal effective shear of around 25-30kt. There parameters continue to support a chance for severe weather, but so far most of the storms quickly fall behind the boundary where the severe threat is much lower. While the outflow boundary continues to surge south and southwest, it is encountering moderate WSW flow gusting to around 20kt which will help impede its progress. Until there is notable slowing of the boundary, storms forming on the front will continue to fall behind and become elevated with low end wind/hail threat. 18Z WoFS run suggests that new severe convection is most likely near the I-70 corridor through 22Z, then diminishes in coverage through 00Z as storms exit the forecast area. This evening, a modest low level jet will set up across portions of Kansas and Missouri with strongest focus near the IA/MO state line initially. This should cause a renewed uptick in thunderstorm activity within a still strongly unstable atmosphere (MLCAPE in excess of 3000 J/kg per latest RAP). These storms followed the cloud bearing flow and instability axis east- southeast into portions of west central Illinois mid to late this evening and elsewhere across central Illinois overnight. Some of this activity may end of being shunted further south due to ongoing convection, so will have to monitor trends with these storms as some could once again be severe. Several CAMs indicate these storms will grow upscale with a QLCS impacting areas from eastern KS into central IL, though the further eastern solutions may not pan out due to ongoing convection this afternoon. Main H5 trof and attendant cold front (possibly locally enhanced by remnant MCV) is poised to move across central Illinois Wednesday morning and afternoon. Some modest destabilization is possible across portions of SE Illinois by early afternoon, but it remains uncertain if storms will be able to tap into this before exiting the area with the cold front. Better chances for severe storms are in place just S/E of the forecast area but will need to keep a close eye on the counties south of I-70 before frontal passage midday Wednesday. High pressure will build across the Upper Midwest Wednesday behind the departing cold front and precip chances will diminish accordingly from the northwest through the day. Temperatures and humidity levels will turn briefly more comfortable particularly Thursday under the influence of this air mass. Highs will be in the lower to mid 80s both days with dew points eventually bottoming out in the upper 50s to lower 60s Thursday. As the ridge axis shifts to the east coast late in the week, return flow will overspread the lower and mid Mississippi River Valley with dew points building back up to around 70 degrees Friday. The chance for showers and storms will accompany the increase in humidity as mid level warm air advection overspread the area Friday, followed by more showers and storms as a cold front sweeps across the region Saturday. Both the GFS and ECMWF indicate that portions of the region will have instability and shear favorable for severe storms, but details will have to be ironed out in the coming days. Deubelbeiss && .AVIATION... (For the 06z TAFs through 06z Wednesday Night) Issued at 1147 PM CDT Tue Jun 25 2024 Convection is weakening over some of the TAF sites, but lightning is still present underneath the cirrus shield of the storms and affecting PIA, BMI, and SPI. CMI and DEC are not seeing any precip and think that will continue through the overnight hours. Will have thunderstorm on station at PIA, BMI, and SPI, but not DEC & CMI. Storms will only last about 1-2hrs. MVFR cigs around 3kft will advect into the area and affect all TAF sites during the overnight hours. Cigs will rise during the late morning hours and then become clear tomorrow late afternoon/early evening. A front is moving south through the area, but winds are relatively light and will remain that way through the night. Tomorrow, winds will become northerly and be around 8-12kts. Light north winds are expected tomorrow evening at all sites. Auten && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$