019 FXUS63 KDMX 080701 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 201 AM CDT Sun Jun 8 2025 .KEY MESSAGES... - Scattered showers and storms this afternoon with chances waning quickly toward and after sunset. - Shower and isolated storm chances along a cold front Sunday. Low chance of severe weather in southeast Iowa late morning and early afternoon. - Gusty winds of 20 to 30 mph after the front passes Sunday and again during the day Monday. - Seasonal to a bit below normal temperatures through Monday, then warmer and turning more humid. && .UPDATE... Issued at 201 AM CDT Sun Jun 8 2025 A surface trough has entered far northwest Iowa and will sweep across the state this morning. Initially a few showers and thunderstorms will accompany the front and just scrape our northeastern counties around sunrise, but with no impacts expected. Meanwhile, a mid-level shortwave impulse will round the cyclonic flow aloft over the High Plains early this morning and cross about the southern half of Iowa in the late morning to afternoon, generating a swath of showers roughly between I-80 and the Missouri border. This feature will not arrive in those areas until after the surface front has passed, so only elevated showers are expected. The CAMs are locked in on the band of showers, but with subtle differences on timing and location, thus have raised POPs to likely (60%) and should be able to refine/raise them even further as the morning progresses. The advancing surface front is also expected to generate more robust thunderstorms this afternoon during peak heating, but all indications are this will be southeast of our service area more toward Illinois and Missouri. Along with raising POPs in the south today, also decreased daytime temperatures in the same area accordingly. Behind the advancing trough, subsiding air should allow some of the smoke aloft streaming down from Canada to descend toward the surface, and have introduced Areas of Smoke into the outgoing forecast accordingly. This may linger into tonight across the south, while in the north the next round of scattered showers comes down from Minnesota overnight into Monday as the large low continues to spin to our north. Most of those showers will be limited to our northern and northeastern counties, with a few non-severe thunderstorms possible there Monday afternoon, before fading out after sunset. With gusty northwest winds and partly to mostly cloudy skies on Monday, also lowered high temperatures a bit farther. && .DISCUSSION... Issued at 221 PM CDT Sat Jun 7 2025 GOES-East upper level water vapor imagery shows the compact shortwave trough tracking over the Iowa-Missouri area this afternoon. This shortwave along with its associated QG convergence and low level theta-e advection have been the impetus for the showers and storms today. A broad area of rainfall has been over southern Iowa closer to the shortwave, but there have been isolated pockets of heavy rainfall elsewhere in central Iowa including northern Dallas into Boone and northern Wright and southern Hancock into Cerro Gordo counties. RAP mandatory level analysis shows weak flow, generally around or less than 5 knots in the lower half of the atmosphere. Midday KOAX RAOB confirms this weak flow with no higher than 10 knots from 700mb to the surface. This has resulted in prolonged rainfall with moderate to at times high rates. The highest rainfall totals have been over parts of southern and eastern Taylor County where personal weather stations have reported over 2.5 inches of rainfall, which is supported by MRMS and radar estimated amounts. While several basins were nearing over an inch of flash flood guidance, FLASH streamflow and annual recurrence intervals (ARIs) were more muted. While smaller streams likely have experienced rises in the area of highest rainfall, Taylor County public safety has not reported any issues as of early afternoon. The showers over southern Iowa are scooting off to the east with other showers over parts of northern and central Iowa slowly moving that direction as well. We have also seen additional isolated storm development, which will be possible the remainder of the afternoon, along the cloud shield and its differential heating boundary. While this has allowed for some instability to build, severe weather is not expected given weak midlevel lapse rates and the weak shear as stated above. Attention overnight will turn to a cold front that is associated with a more potent longer wave trough, which will drop out of Canada into the Great Lakes region early this upcoming week. Scattered showers and isolated storms should be able to form along this front given the ribbon of theta-e advection. The best phasing of low and mid-level forcing continues to look to be over northeastern Iowa and points northeast. Thus, the higher chances for this scattered activity will be over northeastern into eastern Iowa. Farther west, activity may be more broken/hit and miss, but there may be a more prolonged window as the forcing is spread more east to west. SPC`s day 2 outlook has maintained a low risk of severe weather over our far southeastern forecast area. This could materialize if the front doesn`t clear out all the instability first, in which case a short window of severe weather is possible late morning and early afternoon. This is when soundings show over 1000 J/kg of instability, but a largely unidirectional wind profile with weak effective shear. So, hail would be the primary concern with gusty winds a secondary concern if storms can form over our area. Behind the front, winds from the northwest will increase and average 10 to 20 mph with gusts of 20 to 30 mph mid to late morning into the afternoon. The highest wind speeds and gusts will be over north central into northwest Iowa. Also behind the front will be the next round of high level smoke, which may add vibrancy to the sunset where the clouds do clear by Sunday evening. Monday will feature another round of breezy winds from the northwest as the longer wave trough moves east over the Great Lakes region. Another lobe of vorticity will rotate around in the cyclonic flow and bring clouds back over northern Iowa along with shower chances from north central into parts of east central Iowa. The more amplified flow over our region will flatten as a mid-level ridge enters the central part of the US into midweek. Temperatures and increasing humidity will be present by then through the end of the week as dewpoints climb into the 60s. A cold front will descend from Canada, but stall north of Iowa and with the fast moving shortwave flow, we will see storm chances at times in the latter half of the week. Initial National Blend of Models guidance is likely overdone on temporal extent of these chances, but it seems reasonable that the higher chances will be over northern Iowa and points north closer to the stalled boundary. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 1132 PM CDT Sat Jun 7 2025 Mostly VFR conditions are expected overnight though some localized fog could occur, including vicinity of KOTM. A boundary will arrive late tonight and Sunday morning and will bring shower and thunderstorm chances to parts of the area. Have included Prob30 groups at KOTM/KALO. Did not include at KDSM but that may need to be added. The south winds will become breezy/gusty west/northwest before diminishing in the evening. Cigs could briefly become MVFR at areas with precipitation. && .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Lee DISCUSSION...Ansorge AVIATION...Donavon