246 FXUS63 KDMX 111127 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 627 AM CDT Thu Oct 11 2018 ...Updated for 12z Aviation Discussion... .SHORT TERM.../Today through Tonight/ Issued at 313 AM CDT Thu Oct 11 2018 Thermal trof moving across northern Iowa early this morning with brisk winds persisting on backside of strong low pressure over the upper Great Lakes. Broad expanse of stratus remains across the state and will likely remain across much of the area this morning before cyclonic curvature decreases and surface ridge approaches. Clearing is then expected to progress from southwest to northeast during the afternoon. Temperatures will have a hard time recovering given the cloud cover but some warming is expected by afternoon as more sunshine is anticipated, especially in the west and south. Winds will remain brisk for much of the day although as the gradient begins to relax by later this afternoon, some diminishment is expected. With the surface ridge sliding into the state and clear skies initially this evening, strong radiational cooling is expected with winds dieing off. Temperatures are expected to cool rapidly in this scenario with frost likely forming across much of central Iowa. However, clouds will quickly arrive by late evening and spread east overnight as isentropic lift/warm advection intensify ahead of system moving into the Plains. This will effectively kill off any frost formation from west to east overnight as the clouds thicken. However, temperatures across the north will still drop below freezing by a degree or two before stabilizing later tonight. Therefore, will issue a freeze warning along and north of Highway 20 along with Marshall and Tama counties. Otherwise, some light rain/snow is expected to approach far southwest portions of the forecast area toward the end of the period as saturation deepens with continued isentropic lift. .LONG TERM.../Friday through Wednesday/ Issued at 313 AM CDT Thu Oct 11 2018 Models continue to indicate the system will produce ample lift across Iowa on Friday, however moisture is generally lacking for widespread heavier precipitation. Low level saturation will occur only in the south half of the area where areas of light rain are expected. The QPF will remain light and certainly not enough to affect the ongoing river flooding. Subsidence will spread back across the state by later Friday with any precipitation ending by late afternoon. Friday night may see some more frost in the east although clouds may once again limit overall coverage. The rest of the forecast is relatively quiet over central Iowa with northwest flow aloft initially but broad ridging spreading across the central United States toward the middle of next week. This should allow temperatures to begin warming through next week with little threat of precipitation. && .AVIATION.../For the 12Z TAFS through 12Z Friday morning/ Issued at 627 AM CDT Thu Oct 11 2018 Notable change from previous TAFs is that have held onto MVFR ceilings a few hours longer based on current satellite trends. After these clouds break and lift out, will have VFR conditions. Winds from the northwest will be gusty through early afternoon and transition to more light and variable overnight. Clouds will begin to increase with ceilings lowering, but still VFR through 12z. Light precipitation is possible toward 12z at DSM and OTM, but have left out mention at this time. && .DMX WATCHES/WARNINGS/ADVISORIES... Freeze Warning from 1 AM to 8 AM CDT Friday for IAZ004>007- 015>017-023>028-033>039-049-050. && $$ SHORT TERM...Cogil LONG TERM...Cogil AVIATION...Ansorge