KLOT issues Area Forecast Discussion (AFD) valid 2024-05-31T20:12:00ZKLOT issues Area Forecast Discussion (AFD) valid 2024-05-31T20:12:00Z150% of normal), and the slow moving nature of the trough could result in some formidable rainfall totals. Widespread rainfall of a half inch to around an inch and a quarter are likely, with some locally heavier totals possible. The steadier nature of the rain should limit any significant flooding concerns, but a many areas will see a good soaking with standing water in typical poor drainage areas. Rain should end from west to east late Sat afternoon into Saturday evening. Given the expected cloud cover and rain, have lowered high temps for Saturday, with highs now generally expected to be in the mid- upper 60s (possibly still a bit generous). Given the expected rainfall and likelihood of winds going calm, will need to watch for some patchy fog overnight Saturday night. - Izzi Sunday through Friday: Weak high pressure over Lake Michigan will bring seasonable weather to the area on Sunday. Cloud cover will decrease throughout the day with temperatures rising into the high 70s and low 80s. Winds will be light, however, onshore flow will allow for the development of a lake breeze, keeping temperatures a little cooler along the lakeshore (high 60s to low 70s). Late Sunday evening, a shortwave will move across the Plains with an associated surface low lifting through the northern Plains and into Canada. Convection will fire along the cold front of this system well to our west and begin advancing east overnight. The instability gradient appears to be fairly sharp and with the surface low and cold front lifting into Canada, the storms will be in the weakening phase by the time they reach the western portions of the CWA early Monday morning. The precipitation will continue to dissipate as it advances eastward and it appears possible that areas in the eastern portion of the CWA may not see any precipitation Monday morning. Monday's forecast has a lot of uncertainty still remaining with it due to the remnant convection that will be present Monday morning and the associated leftover cloud cover from the dissipating showers and storms. A warm front will lift across the area on Monday with southerly flow bringing increased dew points. If the sun is able to peak out for a bit then pockets of 1000-1500 J/kg of CAPE may be able to develop along the frontal boundary. Forcing for convection looks uncertain as large scale forcing appears to be limited and poorly placed with the instability as the shortwave continues to lift northeast. Any storms that are able to develop will likely not be strong as deep layer shear will be weak, however, it cannot be ruled out that storm is able to produce some strong winds or small hail. Diurnal heating and moisture return on Tuesday will once again allow for CAPE values to grow Tuesday afternoon. However, pretty stout capping appears to be in place. If the cap is able to erode throughout the afternoon, it is possible that some storms may be able to form, however, deep layer shear will not be present, so there will not be any severe storms. On Tuesday another shortwave will push across the Northern Plains and Canada with a surface low in southern Canada. A cold front will push east across the Mississippi River Valley bringing convection into the area late Tuesday night. The exact timing is still uncertain, but it appears that the cold front and associated convection will move through later Tuesday night or early Wednesday morning. There appears to be potential for severe storms across the Mississippi Valley Tuesday afternoon and evening, however, instability will be quickly decreasing after dark Tuesday night, so the convection will likely be weakening as it reaches the CWA. Following the passage of the cold front early Wednesday morning, storm chances look marginal Wednesday afternoon. PoPs chances were left in the forecast, but it looks possible that Wednesday could be a completely dry day following the overnight convection and cold frontal passage. The overall synoptic pattern will shift to a primarily northwest flow pattern as the low gets stuck in southern Canada, near Lake Superior. This will allow cooler temperatures and dry conditions through the remainder of the work week. Carothers && .AVIATION /18Z TAFS THROUGH 00Z SUNDAY/... Issued at 1231 PM CDT Fri May 31 2024 VFR conditions are expected through tonight. Winds around 10 knots will remain VRB from SW to SE through much of the afternoon, though a lake breeze is expected to reach MDW/ORD and shift winds ESE around 22-23Z. Confidence on timing remains low as the lake breeze could stall just east of both terminals. If that were to occur, wind direction would remain S/SSE. Periods of SHRA are expected to spread across the area on Saturday from mid-morning through the afternoon. VFR ceilings will eventually lower into MVFR levels during the afternoon, with a low chance of a few brief periods of IFR ceilings late in the afternoon. Kluber && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ Visit us at weather.gov/chicago ]]>