


Area Forecast Discussion
Issued by NWS Des Moines, IA
Issued by NWS Des Moines, IA
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617 FXUS63 KDMX 152013 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 313 PM CDT Tue Jul 15 2025 .KEY MESSAGES... - Warm and humid conditions continue today, cooler temperatures in the 70s on Thursday. - Storm chances return to western Iowa late tonight (overnight) into Wednesday morning. A few strong storms possible with gusty winds the primary threat. Conditional threat for additional strong storms later Wednesday into Wednesday night, especially south, but will depend on morning activity. - Drier to end the week before additional storm chances return at times into the weekend. && .DISCUSSION... Issued at 256 PM CDT Tue Jul 15 2025 Another warm and humid afternoon is ongoing with temperatures in the 80s and dew points in the 60s to 70s resulting in heat indicies in the upper 80s to upper 90s across the area. Flow out of the south to southwest will continue to bring in moisture off the Gulf into Wednesday morning ahead of the approaching low-level low which will be moving through southern MN through the daytime Wednesday dragging a cold front with it through the state into Wednesday evening. Attention first is on the developing convection in Nebraska this afternoon into evening which will progress eastward towards the Missouri River into late tonight, maintained in NE by a 30-40 knot LLJ. The overall parameter space into our far western CWA will make it difficult for storms to stay in balance with current thinking in line with previous and recent CAM trends of decaying convection moving into western Iowa near to after midnight before any lingering activity continues to push eastward into early Wednesday morning. Although can`t completely rule out a strong storm as the line initially enters our far western CWA, overall expecting any storms to be sub-severe. For any strong storms that can maintain into western Iowa, strong wind gusts are the primary threat followed by locally heavy rain, though activity should be progressive enough to limit the hydro threat overall, especially after several dry days now. What remains uncertain is the coverage and timing of the decaying storm activity into central Iowa and beyond which has significant implications on the any storm development later in the day Wednesday. The aforementioned cold front will be drifting southward through the area through the day and setting up somewhere near the IA/MO border into Wednesday afternoon. Pending any other lingering outflow boundaries/mesoscale details after the morning activity, this is likely where additional development will occur during the afternoon to evening but this boundary in CAMs is anywhere from south central Iowa into northern Missouri making it difficult to pinpoint at this range where the better storm threat is. As noted yesterday, the better shear lags behind the boundary even though instability blossoms in the warm sector south of the front. There remains enough of a favorable environment for a few strong to severe storms develop in the afternoon to evening, especially over southern Iowa, if not further south, but at this point remains conditional on frontal location, amount of early day clearing, and any other mesoscale details. The primary threat will remain strong wind gusts and locally heavy rainfall once again, though the potential placement of rain over southern Iowa is also the area which can take the most amount of rain given antecedent conditions and continuing maturing crops. The LLJ is not as robust on Wednesday night into Thursday, but may help maintain some rain/storms over far southern Iowa into the night before clearing into Thursday morning. High pressure drifts into and through the area later Thursday into Friday with cooler temperatures moving in behind the frontal passage as well. This will bring some pleasant days to end the week with temperatures in the 70s to low 80s. Active weather returns late Friday into the weekend, however, with multiple additional chances for showers and storms at times. Details remain uncertain at this range, but will continue to monitor trends. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1242 PM CDT Tue Jul 15 2025 VFR conditions ongoing and expected to continue through much of the night. Scattered diurnal cu will diminish tonight but clouds will be on the increase west to east late tonight into early Wednesday. Shower/storm chances also increase in western Iowa near to after 06Z but confidence in showers/storms maintaining to most sites too low at this time to include any precip mentions overnight except at KFOD. Started with shower mentions for KFOD with uncertainty as well in strength of activity as it reaches the terminal. Additional showers/storms possible after the overnight activity into Wednesday morning (and again afternoon/evening) but coverage and timing remain far too uncertain to address at this time. Some gusty winds out of the south this afternoon will decrease tonight with winds shifting to be out of the west to northwest ahead to behind the passing boundary Wednesday. && .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...05 AVIATION...05