093 FXUS63 KDMX 282012 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 312 PM CDT Sun Jun 28 2026 .KEY MESSAGES... - A prolonged period of hot and humid conditions will continue through the coming week and potentially the Fourth of July weekend. An Extreme Heat Warning is in effect for the entire area, except in northeastern Iowa where it begins on Monday. - Additional storm chances are possible Monday evening into Tuesday and again at times midweek. && .SHORT TERM /THROUGH MONDAY NIGHT/... Issued at 312 PM CDT Sun Jun 28 2026 Quite the eventful morning unfolded as a Mesoscale Convective System (MCS) that was over the Dakotas last night made its way eastward across the northern to north-central portions of Iowa, which lead to some severe wind reports in Hancock county (Britt and Garner in particular at 58mph), along with hail reports that were small in size and more sparse. Otherwise, a much needed dose of rainfall was received across northern and north central Iowa, with a nice swath of 1-2 inches that should provide at least a little relief given the ongoing drought conditions over these areas. Lingering storms from this decaying complex continue to move over far eastern Iowa along the instability gradient, which is expected to further weaken given the decrease in upper level support as it moves out of Iowa through the rest of the afternoon. Otherwise, a broader look at the upper level synoptic features today shows the large trough covering much of the western half of the CONUS, while broad ridging slowly intensifies over the central and southeastern parts of the country. Increasing southwesterly flow will continue to lift a much warmer and humid airmass over the region today, which marks the beginning of the well known heatwave that will impact the area over the next several days. Temperatures have been steadily increasing so far for most areas with values through the 70s in the northeast half of Iowa, and even warmer through the 80s in the southwest half where breaks in the clouds have been occurring per satellite imagery. The trend in decreasing cloud cover is expected to continue further east and north with time for the rest of today, which should allow for temperatures to increase even further. Given the lingering clouds though, and especially the coverage of storms in northern Iowa this morning, have bumped down forecast highs a few degrees over much of the area, with highs expected to top out in the upper 80s to low 90s across the area, warmest west and south. High dewpoints through the 70s are common across the area, which should allow heat index values to top out above 100 degrees over much of the forecast area. The Extreme Heat Warning remains unchanged as a result across the southwestern two-thirds of the state today. Please make sure to practice appropriate safety measures to avoid heat-related illnesses. Dry conditions are expected to continue across the forecast area through Monday, starting out the day with minimum temperatures prior to sunrise in the mid to upper 70s. The warm and humid airmass will continue to lift north and east as the Upper Ridge ascends across the southeastern CONUS and portions of the Great Lakes, with mostly sunny skies and strong southwesterly low level flow. This will allow for temperatures to quickly climb through the 90s across Central Iowa, paired with heat indices up to 110 degrees and breezy surface southerly winds. The Excessive Heat Warning will continue for the southwestern two thirds of the forecast area, but also the remaining northeast counties given the higher confidence setup. By the evening into Monday morning, a defined shortwave within the western trough is expected to lift across the Dakotas and into Minnesota, with a trailing cold front expected to arrive into northwestern Iowa. Deterministic models generally indicate the development of showers and storms after 00z in northwestern Iowa, with this activity generally variable in evolution between various members. The elevated warm layer will likely be somewhat of a limiting factor in storm development, along with limited moisture aloft, given the drier profile above the cap. If elevated convection is able to develop, the main concern would be large hail given more than favorable MUCAPE values over 4000 J/kg and steep lapse rates around 8km, paired with effective shear values around 30-35 knots that should allow for longer hail residence times. The SPC Slight Risk area remains over this area and will need to continue to be closely monitored over the next 24 hours. PWATS near 2 inches and warm cloud depths will also allow for heavy rain with this activity, though given the capacity soils across the north, concerns are minimal for a flooding risk at this time. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Issued at 312 PM CDT Sun Jun 28 2026 There remains the signal for another period of showers and storms as another wave within the larger scale trough lifts near Iowa Tuesday evening into Wednesday, along with an increasing low level jet overhead. Showers and storms are suggested to develop across portions of northern and western Iowa per Euro, while the GFS and NAM are on the drier side as any activity is further north into Minnesota closer to the warm front. These details are more on the uncertain side at this time, so will need to monitor this over the next few days. A Marginal Risk covers this area per SPC, with hail and gusty winds the main hazards where storms do develop and grow upscale. Otherwise, the main story will continue to be the long stretch of extreme heat as the upper ridge moves very little through the mid to late week period, including the 4th of July holiday. General highs are expected through the 90s each day, with heat indices above 100 degrees for much of the area, while overnight lows generally ''bottom out'' in the mid to upper 70s, providing little relief from the heat. Additional heat headlines are certainly possible in the coming days, but will need to monitor potential limiting factor such as overnight storm activity prior to each day, which models indicate are certainly possible over parts of Iowa. Specific details regarding coverage and intensity of these periods of active weather will be better known in the coming days. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 1257 PM CDT Sun Jun 28 2026 Low clouds continue to bring MVFR conditions across the forecast area this afternoon, with more isolated IFR conditions over northern Iowa. Spotty showers are also tracking near KALO and will remain in the area over the next hour or two, until conditions dry out across the terminals. Should see ceilings gradually lift above 3 kft within the next 3-6 hours, leading to the return of VFR conditions for the rest of the period. Otherwise, winds will remain breezy but decrease slightly into the evening and through early Friday, though LLWS is expected to develop across KFOD, KDSM and KOTM after 00z before fading beyond 12-13z. && .DMX WATCHES/WARNINGS/ADVISORIES... Extreme Heat Warning until 9 PM CDT Tuesday for IAZ004-005-015- 023>025-033>037-044>050-057>062-070>075-081>086-092>097. Extreme Heat Warning from noon Monday to 9 PM CDT Tuesday for IAZ006-007-016-017-026>028-038-039. && $$ SHORT TERM...Bury LONG TERM...Bury AVIATION...Bury