756 FXUS63 KILX 121602 AFDILX Area Forecast Discussion National Weather Service Lincoln IL 1102 AM CDT Thu Sep 12 2019 .SYNOPSIS... Issued at 259 AM CDT Thu Sep 12 2019 One more hot and humid day in store, before a quick break back to slightly cooler temperatures to end the week and begin the weekend. However, this comes at the expense of shower and thunderstorm activity which will increase today across northern Illinois, and then ramp up tonight as a cold front slides through the region. && .UPDATE... Issued at 1055 AM CDT Thu Sep 12 2019 Forecast looked on track today and just a few minor updates needed. Isolated showers and thunderstorms possible today mainly north of I-72 closer to a frontal boundary over northern IN/IL. This front extends back over ne IA to 1008 mb low pressure near the southern MN/SD border. Most of the CAMs keep more widespread convection nw of IL thru sunset with cold front moving se toward the IA/IL border by 03Z/10 pm this evening. Best chance of convection still appears to be over nw CWA late this evening and overnight as cold front moves into central IL during overnight. Skies becoming partly sunny this afternoon with scattered cumulus clouds developing once again in the tropical airmass. Highs in the upper 80s to around 90 degrees with muggy dewpoints in the low to mid 70s, giving heat indices peaking in the mid to upper 90s this afternoon. A few cities approaching 100F especially from Lincoln south. && .SHORT TERM...(Today and tonight) ISSUED AT 259 AM CDT Thu Sep 12 2019 Taking a look at regional radar this morning, showers and thunderstorms continue to impact far northern Illinois and southern Wisconsin. This activity will remain situated north of the CWA, as a frontal boundary lingers across this area. The only impact currently from this boundary that is moving south, is the outflow. This is the main concern for this morning and early afternoon's forecast. No precipitation is developing on this boundary as it sinks south into the northern CWA. Southerly winds will continue to slow this line down through the early morning, stalling it out near the I-74 corridor. I kept some slight chance of showers in the forecast early this morning, however decreasing toward midday. As diurnal heating ramps up late morning, PoPs were increased across the northern CWA to account for the probable development of showers and isolated storms. CAMs indicate the presence of precipitation this afternoon, mainly north of I-72, ahead of the main activity that will pass through tonight with fropa. Will pass along this information to the day shift, allowing them to monitor for development. As High pressure shifts out of the se US today, this will allow the cold front to slide through the region tonight. At this time, models have modest agreement on timing, with the system reaching the mid-Mississippi River Valley this evening. This will then shift into central Illinois around midnight, then reach eastern Illinois Friday morning. Although this system will not be very fast, the chance of precipitation will be greatest this evening through midnight. Dissipation is expected from this system as it progresses through the state, due to distance between the Low core and the CWA, as well as loss of daytime heating. Total precipitation from this storm is forecast to range from 0 inches in the se CWA to 0.75 in the northern CWA. .LONG TERM...(Friday through Wednesday) ISSUED AT 259 AM CDT Thu Sep 12 2019 No major changes were made for this time period as the focus tonight was on today's forecast and the overnight period. Behind fropa on Friday, clear skies will return to the region, along with slightly cooler temperatures. Unfortunately, the cooler temps will not linger long, as summer warmth arrives to end the weekend and remain in place through the first half of next week. Models have another flattening pattern of the upper levels through the weekend, which will allow for a west to east weather flow. This will play a role late Saturday night as another weak disturbance moves through the Midwest. Current models indicate a northern Illinois passage, with the possibility of skirting the northern CWA...north of the I-74 corridor. Otherwise, High pressure will dominate the weather around the Midwest through the middle of next week, bringing dry conditions and above average temperatures. && .AVIATION...(For the 12Z TAFS through 12Z Friday morning) Issued at 633 AM CDT Thu Sep 12 2019 Main concern will be with timing of thunderstorms this evening. In the short term, VFR conditions will prevail. Can't rule out a few storms near KPIA by late afternoon, but think the main period of concern will be from 00-06Z from KBMI-KSPI west. East of there, the models have been showing some breakup of the line of storms, so went with only a VCSH mention at KDEC/KCMI for now. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...07 SYNOPSIS...Baker SHORT TERM...Baker LONG TERM...Baker AVIATION...Geelhart