688 FXUS63 KDMX 220452 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 1152 PM CDT Sat Mar 21 2020 ...Updated for 06z Aviation Discussion... .DISCUSSION.../Tonight through Saturday/ Issued at 243 PM CDT Sat Mar 21 2020 Light southerly flow and weak warm air advection across Iowa today has allowed temperatures to warm, at least relatively comparative to yesterday, into the upper 30s and low 40s this afternoon. Meanwhile, a compact shortwave across the northern plains will drop towards the midwest tonight. This will allow for a brief window of light snow across our very far north/northeastern counties. No more than a dusting a best is expected there as qpf is very light and lift into Iowa is weak. Synoptic models fail to develop anything in the way of qpf with this system, however nearly all of the CAMs show light precipitation across Minnesota and into northern Iowa as the shortwave quickly slides across the area. The more prominent system across the southwest US will lift into Iowa by Sunday morning. Thermal profiles indicate a brief period of snow is possible across southern Iowa Sunday morning before warming and transitioning over to rain across central and southern Iowa. A few tenths of snow accumulation is possible on grassy or elevated surfaces, however with warm ground temperatures and the narrow window for snow, do not anticipate any impactful accumulations. After transitioning over to rain for most of the day, another brief period of light snow is possible after sunset tomorrow evening as this system exits east. Monday will be fairly quiet between system, however with weak warm air advection into the state, expect to see fog development Monday morning, which could have impacts on the morning commute. Otherwise temperatures will warm back towards more seasonal highs in the upper 40s and low 50s. A setup similar to the weekend system will be in place Tuesday as another system lifts out of the southwest US into the midwest, however model trends indicate much better forcing and theta-e advection compared to the weekend system. Previous runs showed some variability in qpf, however the latest runs show improving agreement between the Euro and GFS for on half to one inch of qpf. Return flow as this system departs will allow for temperatures Wednesday to warm into the 50s and near 60 degrees. There is some uncertainty with Wednesday highs, as a shortwave and tight surface low will pull a cold front across the area Wednesday afternoon. Depending on how quickly cloud cover/rain moves in and the progress of the cold front, high temperatures could be several degrees too high. This will be something to monitor as the system get closer. Models continue to diverge towards the end of the week and yet another system moves through to cap off another active week of weather. While previous runs showed a quicker Euro and slower GFS, solutions appear to have "flip-flopped", with the GFS arriving earlier ahead of the much slower Euro solution. With such uncertainty amongst models, confidence with this late week system is quite low. && .AVIATION.../For the 06Z TAFS through 06Z Sunday night/ Issued at 1152 PM CDT Sat Mar 21 2020 Primary concerns this period will be the arrival of precipitation and restrictions Sunday morning and low ceilings and visibility after the precipitation ends into Sunday evening. Ceilings will lower from south to north Sunday morning with precipitation arriving in a similar fashion over southern into eastern Iowa. The precipitation may be snow at times over the far south towards OTM, though little accumulation on runways is expected. Precipitation will end from west to east later in the afternoon. Diminishing wind late Sunday into Sunday evening along with abundant low level moisture should foster widespread low ceilings and fog with IFR restrictions common and perhaps LIFR restrictions over southern Iowa. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...Hagenhoff AVIATION...Ansorge