414 FXUS63 KDMX 050403 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 1103 PM CDT Fri Apr 4 2025 ...Updated for the 06z Aviation Discussion... .KEY MESSAGES... - Light rain continues mainly southeast into the evening with some, but much lower chances farther north and west - Dry Sat through Tue, but low chances (<=30%) return Tue night through Thu - Cool temps to start the weekend, and again early next week. Widespread lows in the 20s Sat and Mon nights. Turning warmer for the middle to latter portions of next week && .DISCUSSION... Issued at 242 PM CDT Fri Apr 4 2025 Our current southwest flow aloft influences will soon give way to a prolonged period of northwest flow to varied degrees with the primary weather stories cooler temperatures and dry conditions to start the next work week. The former effects are still present however as noted 1-3km dry air from this morning continues to erode and saturate farther into central and east central IA. The rain is aided by strong, but departing ageostrophic divergence in the right-entrance region of the Upper MS Valley jet segment but mainly driven by relatively higher based thermodynamic effects as the H85/H5 baroclinic zone lifts into the Mid MS Valley. The rain isn`t expected to make much more progression north and west as the H85/H7 theta-e advection delivers only a glancing blow as it moves into MO and IL by 00z ahead of its KC metro circulation at that level. Most precipitation should end by later this evening, although northern stream influences will sustain token chances for light rain or sprinkles northwest ahead of the approaching ND PV anomaly. This PV trough will drive our transition to cooler temperatures with a deep cold frontal passage early Saturday. This will start a dry period into early next week with our attention turning to cooler temperatures with brisk NW winds for a period Saturday. Another strong PV trough will pass through the Great Lakes early Monday with more brisk winds and cool high pressure into the Upper MS Valley. While the forcing associated with this wave is quite strong, it will be moisture starved and too far removed to the northeast for any precip in IA. The main sensible weather reflection will be below normal temperatures with another cold frontal passage resulting in highs staying mainly in the 40s Saturday and Monday, and widespread lows in the 20s and freezing temps those following nights. The next precip window appears to be toward the middle of next week, but the timing and strength of the system are still uncertain. The GFS suite appears to be a tad quicker, but both the GFS and EPS model suites appear to be converging on the solution with warm/theta-e advection starting late Tue and kinematic effects lagged 6-18 hours behind a bit closer to the surface features. This may result in a semi-extended period with low chances for showers and possibly isolated thunder Tue night into Thu depending on timing. This northwest flow pattern and general Pacific origin of the waves for the midweek trough will keep temps mild and above normal through the end of the period (Fri). && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 1103 PM CDT Fri Apr 4 2025 Clouds are widespread across the state, but are in the VFR category to start the period. A period of MVFR ceilings lasting 6 to 8 hours at a given terminal will move across central Iowa from around midnight to midday Saturday. There could be a 1 to 3 hour window of IFR ceilings with confidence highest over northern Iowa with TEMPO groups elsewhere due to slightly lower confidence in impacts. Winds from the north-northwest will increase behind these clouds and stay brisk through much of Saturday before diminishing Saturday evening. Wind gusts of 25 to 30 knots will be common. && .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Small AVIATION...Ansorge