844 FXUS63 KILX 291728 AFDILX Area Forecast Discussion National Weather Service Lincoln IL 1228 PM CDT Tue Oct 29 2019 .SYNOPSIS... Issued at 400 AM CDT Tue Oct 29 2019 A weak system moved through central Illinois this morning, bring a blast of cold weather into the area, along with reports of sleet and snowflakes. Another, larger system, will arrive tonight and last through mid-week. This will bring snow and rain to the region, with accumulations expected northwest of the Illinois River Valley. Temperatures will remain colder throughout much of this week. && .UPDATE... Issued at 1040 AM CDT Tue Oct 29 2019 10 AM surface map indicated the cold front had just cleared southeast IL. Abundant post-frontal low level moisture remained, resulting in widespread low clouds. Cold advection on northwest winds will continue today, with nearly steady temperatures over eastern IL, and only a few degree rise over the northwest. Have lowered highs a few degrees which gives widespread low to mid 40s. Any sunshine looks limited to the western and northern CWA where some drying below 700 mb could allow for partly sunny skies for a short time. However mid and high level clouds will be on the increase this afternoon, ahead of the next system developing to the southwest. && .SHORT TERM...(Today and tonight) ISSUED AT 400 AM CDT Tue Oct 29 2019 A weak wave of precipitation moved across the region overnight, producing sleet and snowflakes across northern Illinois. While some locations across central Illinois remained in the mid and upper 30s, allowing all precip to fall as drizzle or rain. Locations across eastern and se IL will remain dry, as the weakening wave lifts northeast into the upper Great Lakes. Winds behind this wave have shifted from the north. Current METARs show this switch along I-57, moving eastward through the CWA. Winds will remain at or below 10kts sustained today, with some gusts upwards of 15kts this morning. A strengthening Low pressure system in Canada, will be the driving force for a developing frontal system that will eject out of the Rockies today. This will then progress into the central Plains overnight, lifting a warm frontal boundary into the region. However, this boundary will stall out across the IL River Valley and mid-Mississippi River Valley regions, bringing the opportunity for additional precip to much of the area. With temperatures hovering near freezing in locations nw of the IL River, some of the precip will be able to freeze into crystals, falling as snow. While much of the area will hold onto the slightly above freezing temperatures, lingering a cold rainfall. .LONG TERM...(Wednesday through Monday) ISSUED AT 400 AM CDT Tue Oct 29 2019 As the main core of the precipitation arrives Wednesday, this will be effected by the boundary placement. Current indication is the this boundary will linger over the IL River, continuing snowfall for locations along and nw, with accumulations expected from PIA to GBG, and locations nw to DVN. Although some changes to totals are expected, based on moisture profiles, totals have increased significantly to near 6 inches possible in the GBG area. With the long duration of this event, and warmer ground temperatures, the end of event total is not expected to be 6 inches in measurement. Melting will occur on the surface, as well as the possibility of mixed precip, which could lead to a lower overall total. Locations in central Illinois, east of I-57 and north of I-72 could see some snowflakes, while places in se IL will remain rainfall throughout this event. Central Illinois is not expected to receive much in the way of accumulations, however the first event is always the one which brings the most impacts to the region. The upper level Low will progress across the western Midwest Thursday, pushing all of the precipitation out with it. Behind the system, winds will increase Thursday afternoon. This will bring blustery temperatures to the area late Thursday into Friday morning, with lows forecast in the upper teens and 20s Friday morning, with wind chills in the low teens to low 20s. The remainder of the period should be dry, with cool temperatures through the weekend. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 1228 PM CDT Tue Oct 29 2019 Cold front has cleared the area leaving widespread IFR to low MVFR clouds in place. Expect a slow diurnal rise in bases this afternoon with most sites reaching MVFR. The next weather system will approach from the southwest this evening, spreading rain across the terminals. Airmass will become cold enough at KPIA for a RASN mix. Will need to monitor trends for the possibility of a complete switchover to snow, which would reduce visibility to IFR from current MVFR forecast. Ceilings will trend lower back to IFR late tonight and through Wednesday morning, as the precipitation continues. Post-frontal northwest winds near/under 10 kt will dominate this afternoon, veering to northeast this evening. Northeast winds to persist through 18z, increasing above 10 kt late tonight as the pressure gradient gradually tightens. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...25 SYNOPSIS...Baker SHORT TERM...Baker LONG TERM...Baker AVIATION...25