788 FXUS63 KDMX 032010 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 310 PM CDT Wed Jul 3 2019 .DISCUSSION.../Tonight through Wednesday/ Issued at 308 PM CDT Wed Jul 3 2019 The primary focus for the forecast is the potential for heavy rainfall and isolated severe storms beginning this afternoon. A warm front has lifted into central Iowa this afternoon and is approaching Interstate 80. The main focus for storms is expected within the Highway 20 and Interstate 80 corridor, which is along and north of the warm front. MLCAPE across this region is in excess of 2500 J/kg though deep layer shear remains quite weak at 20 kts or less. Low level shear remains quite weak as well at 10 kts or less. 0-3 km CAPE is high at 150 J/kg with some surface vorticity available north of the warm front. This will help maximize low level stretching potential so cannot rule out an isolated tornado especially early this afternoon before cold pool development occurs. Microburst are also possible and 0-3 km theta-e differences > 30 do support cold pool surges. Quarter sized hail is possible with any initial strong updrafts though the damaging wind threat is the primary severe threat. Heavy rainfall is the other concern and have issued a Flash Flood Watch for portions of central Iowa for the potential for very heavy rainfall locally and due to locally heavy rainfall pockets over the past 24 hrs. An area of heavy rainfall is now developing over Greene and Boone Counties. PWAT values in excess of 2 inches and warm cloud depths approaching 14 kft at times will lead to very efficient rainfall producing storms. In addition to slow moving storms and repeated storms will lead to the heavy rain potential. Rainfall amounts of 2 to 4 inches are possible in the localized areas and rainfall rates with individual storms will exceed 2 inches per hours leading to accelerated ponding and pooling of water. The bulk of the activity is expected to be done by 06z, therefore the watch will end then. A few isolated storms are possible through the day on Thursday. A short wave lifting through the flow may cause redevelopment over southern Iowa in the afternoon in addition other storms may develop along a weak boundary moving into northwest Iowa during the afternoon. Again, isolated severe storms and locally heavy rainfall will be possible but convection is not expected to be as vigorous as today. A stronger shortwave will arrive on Friday and bring renewed convection. Another round of strong storms will be possibly from Friday into Saturday until the system and boundary finally pass to the south. Will certainly be monitoring this period for the heavy rain potential considering potential heavy rain ongoing recently. A pattern change will occur Sunday through Tuesday with the transition from zonal flow to a building ridge into mid next week. This will bring warm and humid weather back to the stat && .AVIATION.../For the 18Z TAFS through 18Z Thursday afternoon/ Issued at 1200 PM CDT Wed Jul 3 2019 The main aviation hazard through the period will be scattered thunderstorms and changing wind directions and speeds with associated outflow. The greatest chances to impact sites will be from 21z to 03z. Otherwise VFR conditions are expected between storms. && .DMX WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch until 1 AM CDT Thursday for IAZ033>036-044>050- 057>062. && $$ DISCUSSION...Donavon AVIATION...Donavon