207 FXUS63 KDVN 101138 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 638 AM CDT Wed Oct 10 2018 ...12z AVIATION UPDATE... .SYNOPSIS... Issued at 400 AM CDT Wed Oct 10 2018 As of 2 AM, a surface low was located over central and north central Iowa with a trailing cold front extending SW into NW MO. A band of moderate to heavy rain showers was streaming NNE from NE MO along the MS River Valley. As of 230 AM, KDVN has picked up about 0.80 inches in the past 90 minutes. Temperatures were in the upper 60s to lower 70s, with dew points in the mid and upper 60s. && .SHORT TERM...(Today and Tonight) ISSUED AT 400 AM CDT Wed Oct 10 2018 The low will lift NE into central WI today, dragging the cold front through the area from west to east from mid morning to mid afternoon. Some CAMs show the current slug of precipitation lifting north of the area this morning with some scattered convection developing along the actual cold front as it moves eastward through the area later this morning and into the the afternoon. The SPC has a Marginal Risk area east and southeast of a line from Dubuque to Muscatine for an isolated severe storm producing a damaging wind gust. Heavy rainfall will still be possible along and east of a line from Dubuque, to Keosauqua, and south to Memphis, MO through early afternoon as rain continues to stream across these areas. Thus the the Flash Flood Watch will remain in effect for these areas. We did trim off some west and northwestern counties as there is no longer a flash flood threat there. Rain should end from west to east from 9 AM to about 3 PM. Temperatures will fall through the afternoon with readings by the evening commute in the upper 40s west to low to mid 60s east. Strong west winds will surge in behind the front with some gusts of 25 to 30 MPH at times. .LONG TERM...(Thursday through Tuesday) ISSUED AT 400 AM CDT Wed Oct 10 2018 The extended is characterized by NW flow, clipper type systems every other day followed by a cool down a some am frost potential. Tonight gusty NW wind will continue as the low moves into the upper Great Lakes. With lingering cloud cover and the wind, lows Thu morning will be in the mid and upper 30s, and frost shouldn't be an issue. Highs Thu will only be in the mid 40s to low 50s with continued brisk NW winds. High pressure brings some partial clearing and light winds Thu night and Fri morning, with lows in the low to mid 30s. Frost is possible especially north of I 80. Highs Fri will be in the mid and upper 40s. Models have come into better agreement now with a low chance rain period skirting the southern half Friday. Light amounts are expected. Frost is again possible mainly NE early Sat, with lows in the 30s. A clipper type system and southern disturbance then bring some slight/low chc Pops for Sat night and Sun. Another frosty morning is possible early Monday with lows in the 30s. Tue into Wed yet another clipper possible with low chc Pops. && .AVIATION...(For the 12Z TAFS through 12Z Thursday Morning) ISSUED AT 624 AM CDT Wed Oct 10 2018 Showers and embedded storms along the Mississippi River will gradually shift east of the river sites through late morning. Additional scattered showers may develop late morning through early afternoon with the cold frontal passage. Conditions will generally be VFR outside of the precipitation with MVFR and IFR in the showers and embedded storms. In general expect mainly MVFR conditions this afternoon into evening in wake of the cold front with gusty westerly winds 15-25 kts. Conditions may improve to VFR from south to north this evening and just beyond the TAF period. && .HYDROLOGY... Issued at 953 PM CDT Tue Oct 9 2018 Main point...one more round of heavy rain is expected tonight into Wednesday. A broad swath of 1 to 2 inches of rain, with locally higher amounts, is expected from central Iowa into southeast Minnesota and Wisconsin. Soils generally north of I-80 and especially across Minnesota and Wisconsin are saturated so any additional rainfall will rapidly run off into area waterways. After sunset Wednesday, the overall weather pattern will change. Rain will still be possible over next weekend but amounts will be much lighter than what has been seen over the past 10 days. Mississippi River... The new forecasts for the Mississippi river still show rises occurring all the way through October 16th. However, the new forecasts show a slight delay of 6 to 12 hours compared to the morning forecasts. Delays like this can be expected due to slight changes in how runoff from the rain moves into the river system and in the overall timing of the routed flow moving downstream. With more heavy rain expected across Minnesota and Wisconsin, crests on the Mississippi river will occur October 17th through the 24th. Confidence remains high that moderate to major flooding will be seen from LD 14 at Le Claire, IA down through Gregory Landing, MO. North of LD 14, minor to moderate flooding is expected. Iowa Tributary rivers... Routed water is already moving downstream through the basins. With the addition of heavy rainfall through sunset Wednesday, confidence is high that moderate to major flooding will continue along the Cedar, English, Iowa, North Skunk, Skunk, and Wapsipinicon rivers. The evening forecasts have lowered the crests considerably along the Cedar river and to a lesser extent on the Iowa river. Such changes show the sensitivity of the model to predicted rainfall, saturated ground, and the overall timing of routed flow moving downstream. From Columbus Junction down to the mouth of the Iowa river, the Cedar river will be providing a majority of routed flow that will result in moderate to major flooding. At Iowa City, runoff from creeks and streams below Coralville from the next round of heavy rain and increased releases from Coralville dam will push the Iowa river close to 23 feet by the weekend. With heavier rainfall expected in central Iowa, major flooding will continue on the North Skunk river with moderate flooding on the Skunk river. The current forecasts are based on predicted rainfall and routed flow moving downstream. Crest forecasts for the North Skunk river have changed very little while a delay and lowering of the crest has occurred on the Skunk river. Pecatonica and Rock rivers... Heavy rainfall of 1 to 1.5 inches is expected in the Pecatonica and Rock river basins through sunset Wednesday. Thus the forecasts are based on a combination of predicted rainfall and routed flow moving through the river system. Crest forecasts have changed very little along the Pecatonica and Rock rivers from this morning. Confidence remains high that moderate flooding will be seen on the Pecatonica river and major flooding from Joslin to the Mississippi. As the Mississippi continues to rise, the rate of fall on the Rock river is likely to slow down and thus prolong the flooding. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...Flash Flood Watch until 1 PM CDT this afternoon for Cedar- Clinton-Des Moines-Dubuque-Henry IA-Jackson-Jefferson- Johnson-Jones-Lee-Louisa-Muscatine-Scott-Van Buren- Washington. IL...Flash Flood Watch until 1 PM CDT this afternoon for Bureau- Carroll-Hancock-Henderson-Henry IL-Jo Daviess-McDonough- Mercer-Putnam-Rock Island-Stephenson-Warren-Whiteside. MO...Flash Flood Watch until 1 PM CDT this afternoon for Clark- Scotland. && $$ SYNOPSIS...14 SHORT TERM...14 LONG TERM...14 AVIATION...McClure HYDROLOGY...08