457 FXUS63 KILX 091752 AFDILX Area Forecast Discussion National Weather Service Lincoln IL 1252 PM CDT Tue Oct 9 2018 .UPDATE... Issued at 1056 AM CDT Tue Oct 9 2018 Breezy southerly winds 10 to 15 mph with gusts to around 20 mph can be expected today as southerly flow ahead of low pressure and a frontal zone in the Plains continues. A warm and humid air mass will result in highs in the 80s, dewpoints in the upper 60s, and heat index approaching 90 degrees. Isolated afternoon thunderstorms appear possible north of I-72 and mainly west of I-55 according to various convective allowing model solutions, and have trimmed PoPs for a few areas accordingly in morning updates. Otherwise, forecast is in good shape with the above features. && .SHORT TERM...(Today and tonight) ISSUED AT 409 AM CDT Tue Oct 9 2018 The country is divided this morning between a deep trough over the western half...and an upper ridge centered just off the Atlantic Coast. The swath of southerly flow up through the Plains is keeping the temperatures in the region well above seasonal normals, as well as plenty of low level moisture...resulting in muggy conditions. Temperatures today will climb into the 80s, with heat indexes south of Interstate 70 around 90 this afternoon. The precip associated with the weakened frontal boundaries is confined in quasi parallel flow out of the S/SW just west of the Miss River Valley. Pops today have been pulled before 18Z as NAMNest/HRRR and others have delayed rain to the afternoon, more warm advection cellular type showers/storms early. Later this evening, veering winds and a low level jet to the west will result in more of a severe weather threat for IA/MO/KS. Models bring the storms into areas NW of the Illinois River around and after midnight, diminishing as they move into ILX CWA. Main concerns with these storms will be damaging winds. Pops spread across the state throughout the overnight as the storm system deepens. Cloud cover will be enough to inhibit much in the way of cooling and overnight lows are in the low to upper 60s with the continued southerly winds. .LONG TERM...(Wednesday through Monday) ISSUED AT 409 AM CDT Tue Oct 9 2018 The front associated with the next system will be on the western border of the state by midday Wednesday. Much of the northern and central portions of IL are in a Marginal Risk on SPC convective outlook. Although the storm threat will be somewhat conditional on cloud cover/available instability for the afternoon/evening hours, the actual deepening sfc low crossing into the Great Lakes will provide an assist for severe potential in the early afternoon hours. Models have more agreement with the timing of the system in general, clearing it out in time to drop temperatures Thursday morning into the 40s, a good 20 degrees cooler than the prev night. The midweek system will usher in cooler air with the pattern shift to a more zonal flow. A cutoff low in a deep western trough will retrograde slightly off the Baja peninsula. ECMWF/GFS still bringing the next wave through the Midwest for Friday, although producing little, if any QPF than they did 24 hrs ago. Pops return to the forecast for Saturday night and dominate the remainder of the weekend. This system moves out of the SW and into the region, developing the sfc low over the region, resulting in an prolonged pd of showers and thunderstorms in the forecast. Given the upper trough and a positive tilt...moving a little slower than what the surface system reflects...not a lot of confidence in the details for the second half of the weekend. Either way, much cooler air in place will drop Sat and Sun morning lows into the upper 30s/lower 40s. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 1252 PM CDT Tue Oct 9 2018 Isolated TSRA expected this afternoon across the central IL terminal area, with less likelihood toward the east. Have included VCTS in all TAFs through the afternoon except KCMI. Have included tempo TSRA at KBMI 18-20Z as a developing thunderstorm appears headed for that terminal. Aside from isolated thunderstorms, VFR conditions look to be predominant until late in the period. After sunset, most terminals should see a decrease in thunderstorm activity until later in the night when clusters of thunderstorms will likely develop and potentially affect the terminals through 18Z. Winds S 10-15 kts with gusts to around 20 kts today, then gusts decreasing after 00Z. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...37 SHORT TERM...HJS LONG TERM...HJS AVIATION...37