Area Forecast Discussion
Issued by NWS Des Moines, IA

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429 FXUS63 KDMX 131131 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 631 AM CDT Sun Jul 13 2025 ...Updated for the 12z Aviation Discussion... .KEY MESSAGES... - Departing smoke eastward this morning - <10% chance of showers and storms in northwest Iowa this evening. Low chances again in the northeast on Monday afternoon. - More widespread chances for showers and storms arrives by midweek. && .UPDATE... Issued at 258 AM CDT Sun Jul 13 2025 Another fairly quiet morning across Iowa, though some isolated fog has been occurring on and off over northeast Iowa, which brought visibilities below 2 miles at Mason City early this morning but has since improved. Conditions are expected to remain favorable for on and off isolated areas of patchy fog, which would result in reduced visibilities over northeast Iowa, as the latest HREF indicates through at least sunrise before dissipating. Otherwise, quiet weather is expected across the state today, outside of a very low chance for showers and a possible storm or two in far northwestern Iowa. Compared to model guidance yesterday, CAMS have trended down on any activity even reaching into the CWA as a boundary tracks into eastern South Dakota into far northwestern Iowa and southern Minnesota. Therefore, PoPs have been reduced further over the area to <10%. A look at the parameter space with this boundary overall depicts favorable shear and instability to aid in storm development further west and north of Iowa this evening. However, a Marginal Risk was introduced that does reach into Emmet County, suggesting the potential for at least an isolated severe storm, but the overall potential is very low. Will have to closely watch trends through the day, but given the minimal coverage area and trends limiting development into Iowa, the concern for hazardous weather is very low for the evening at this time. Lingering smoke this morning is also expected to move out of the area over the next several hours as the high pressure over the Midwest tracks away from the region, with the low level flow pattern turning more southwesterly. && .DISCUSSION... Issued at 245 PM CDT Sat Jul 12 2025 The low-level moisture fetch has been shoved to the south and east this morning, leaving little for the passing wave to the northeast to tap into. We`re left with some midlevel cloud debris as well as smoke in the upper levels. Some of this will reach the surface via post-frontal subsidence this afternoon near the IA-MN state line, but much of this will miss much of IA and instead be carried around the high pressure center and back towards the north. There is another weak wave that will dive into the Central Plains from Colorado this afternoon and reinforce the block of Gulf moisture along with the redirection of smoke mentioned earlier. The aforementioned central Plains wave keeps the low-level moisture away from the area for at least the first half of the week, but it will also put the state in northwest flow and open us up to a series of waves from Canada. The LLJ will also reemerge into the Northern Plains later on Monday. It will intersect with a system that is forecasted to impact Minnesota, later dragging its cold front (and the main moisture axis) across Iowa on Tuesday night into Wednesday. This front will then stall somewhere near southern Iowa, hence the broad rain and storm chances for the remainder of the week. && .AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
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Issued at 631 AM CDT Sun Jul 13 2025 Areas of patchy fog may continue to impact the northern terminals at times over the next few hours before dissipating for the day. Otherwise, clouds over the southeast will continue to track out of the state this morning, though cumulus development is possible again late this morning through the afternoon across the state. Winds out of the southwest will increase, with gusts increasing to 15-20 knots over northern Iowa into this afternoon.
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&& .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Bury DISCUSSION...Jimenez AVIATION...Bury