258 FXUS63 KDVN 110553 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 1253 AM CDT Thu Oct 11 2018 ...06z AVIATION UPDATE... .SYNOPSIS... Issued at 320 PM CDT Wed Oct 10 2018 Latest sfc analysis was indicating the main cold front sweeping acrs the eastern CWA ATTM, with an associated fine line of light to moderate showers and gusty 30-35 MPH winds as they pass. Aloft, water vapor imagery was showing upper trof axis shearing out northeastward acrs the upper MS RVR Valley. Behind this system, the advertised big change cool down is still on track for the end of the week and into the weekend, with a couple of possible cool season- like light precip events to monitor for Friday, and again at the end of the weekend. && .SHORT TERM...(This Evening through Thursday) ISSUED AT 320 PM CDT Wed Oct 10 2018 Tonight...Most any lingering precip should be out of the eastern CWA by 00z, with extensive wrap around stratocu deck still to cloak the area well into tonight. There may be some breaks or clearing patches in this deck later tonight and into Thu morning, especially south of I80. But the main story will by the tight sfc pressure gradient pivoting around the low and acrs the area, as the sfc cyclone migrates northeastward to the U.P. of MI later tonight. Expect westerly to northwesterly sfc winds of 15 to 25 MPH tonight, with gusts to 30 MPH or more especially if the cloud cover maintains and limits normal nocturnal mixing interruption. Upstream source air mass getting advected in acrs the area tonight come from NE and SD, which are in the 40s to mid 30s right now in the middle of the afternoon. Will keep the idea of lows in the mid 30s to around 40, taking into account the cloud cover and robust mixing winds. But would not be surprised with the extent of the advection, for some temps in the low to mid 30s to make it into the northwestern and western CWA by Thu morning. These temps combined with the winds will make for wind chills in the 20s. But will also bank on the mixing winds and cloud cover to limit frost potential in these colder areas. Thursday...A cool blustery day on tap as Canadian high pressure continues to dump down the plains and MO RVR Valley. Low confidence on the extent of cloud cover and think there will be plenty of instability CU with daytime heating especially along and north of I- 80, but the CU rule parameters suggest scattered CU or even mainly clear skies Thu even in the north. Most temps to struggle to get out of the 40s for highs. West to northwest winds of 15 to 25 MPH , with gusts to 35 MPH through early afternoon, before some decrease occurs into late afternoon and early evening. ..12.. .LONG TERM...(Thursday Night through next Wednesday) ISSUED AT 320 PM CDT Wed Oct 10 2018 Major pattern change to colder with frost potential both Thursday night and Friday night. Later shifts will need to monitor for possible frost/freeze headlines. Little if any precipitation is expected during the extended as systems track to our north and south for the most part. Highs will be in the 40s and 50s with lows in the upper 20s and 30s. Haase && .AVIATION...(For the 06Z TAFS through 06Z Thursday Night) ISSUED AT 1242 AM CDT Thu Oct 11 2018 MVFR to VFR ceilings in stratocumulus, with some erosion possible at times through daybreak and then expected this afternoon into early evening. A weak upper level disturbance will begin to approach late tonight and bring increasing mid/high cloudiness. Winds will remain gusty from W/NW at 15-25 kts through much of today before diminishing below 10 kts tonight, as high pressure builds in. && .HYDROLOGY... Issued at 1027 PM CDT Wed Oct 10 2018 Significant changes from the last update: 1) The forecast was upgraded from Moderate to Major flooding at Maquoketa on the Maquoketa River, 2) Minor flooding is now expected at Colmar on the La Moine River, and 3) Augusta on the Skunk River was lowered slightly to just under Major flood stage. Previous Discussion: A swath of heavy rain with widespread amounts of 1 to 2 inches and local amounts over 2.5 inches fell across eastern Iowa into far west central IL fell overnight into early this morning. With today's cold frontal passage, the threat of heavy rain has ended. The incoming, more typical fall weather regime will feature systems with less moisture to work with, leading to mainly light rain amounts. However, widespread significant river flooding will remain an issue through at least next week as the runoff from the past couple weeks of very wet weather makes its way through the river system. On the Mississippi River: Moderate to Major flooding is occurring from the Quad Cities downstream to Keokuk with forecasts of Major flooding along the entire stretch persisting through most of next week. The latest forecasts, which are now adjusting to known flow in the river system and no longer have QPF to deal with, have trended toward faster rises, and in some locations, higher crests along this stretch. Just downstream, this flow is still expected to result in Moderate flooding at Gregory Landing. Upstream from the Quad Cities, all sites except Bellevue are forecast to reach at least minor flood stage over the next week. Routed flow from heavy rainfall further upstream across MN and WI results in forecasts of continued rises well into next week. Will maintain a flood warning at Dubuque lock and dam 11 for the strong likelihood of flooding from routed flow developing just beyond the current 7 day forecast. Significant flooding continues along most tributary rivers in eastern Iowa and northwest Illinois. Here are the most significant changes from this morning's forecasts: On the Cedar River, the crest was lowered at Vinton, Cedar Rapids and Conesville. The crest was lowered well over one foot at Cedar Rapids, where the weekend crest is now expected to stay within Moderate category flooding. On the Iowa River, the latest heavy rain axis had more of a direct impact on the basin, resulting in earlier, higher crests from the Coralville dam downstream to Oakville. At Iowa City, the combination of local runoff and adjusted flow out of the reservoir will result in Minor flooding until tonight. On the flip side, the crest at Marengo was adjusted earlier and lowered. On the Rock River, levels are cresting at Joslin and receding upstream. With less rainfall in the basin than forecasted, levels are now expected to recede faster, but still remain close to previous crests at Joslin and Moline. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...12 SHORT TERM...12 LONG TERM...Haase AVIATION...McClure HYDROLOGY...Uttech/Sheets