


Area Forecast Discussion
Issued by NWS Des Moines, IA
Issued by NWS Des Moines, IA
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078 FXUS63 KDMX 172312 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 612 PM CDT Fri Oct 17 2025 ...Updated for the 00z Aviation Discussion... .KEY MESSAGES... - Breezy west-southwest wind today with gusts of 20-30 mph expected. - A line of showers and storms will slowly pass east/northeast across Iowa, with a low chance for severe weather southeast this evening. A few strong storms however cannot be ruled out. - Saturday will be breezy once again with rain chances (20-50%) returning in the late afternoon and evening. - Cooler Sunday into next week, with breezy conditions common. && .DISCUSSION... Issued at 243 PM CDT Fri Oct 17 2025 Surface map analysis this afternoon depicts a deepening surface low pressure system that is centered over North Dakota into Southern Canada, with a weak front indicated by a southwest to west wind shift that is oriented from roughly Forest City to Audubon. Southerly/southwesterly flow remains established overhead, with warm air advection keeping the warmer temperatures into the state as values reach through the mid 70s to low 80s ahead of the front, and in the upper 60s to low 70s behind it. This increase in flow and a somewhat tighter pressure gradient ahead has brought about continued breezy conditions as well, with gusts around 20-30 mph that will continue into the afternoon before decreasing tonight. Along and ahead of the aforementioned boundary, a line of showers with embedded weak storms have recently developed, moving northeast across central Iowa. Limited instability and forcing this afternoon should keep any storms below severe limits, but storms may continue at times with the shower activity into the remainder of the afternoon, with the front stalling near to just east of I-35. Guidance still indicates that an increase in moisture and better forcing by early evening should allow for additional and more scattered development of showers and storms largely over southern/eastern Iowa. CAM guidance continues to indicate instability increasing up to 500-1000J/kg of MUCAPE, along with shear of 30+ knots ahead of the boundary over southeast Iowa that could result in some stronger storms, though lapse rates are less supportive. Therefore, the severe risk is low but cannot completely rule out a strong storm or two with this evening activity, with small hail and some gusty winds possible. Showers and weak storms are expected to continue but gradually decrease in coverage over south/east Iowa through the morning as the low level jet activity weakens, with a brief period of dry conditions across much if not all of the state into the afternoon. However, the boundary will generally remain over southeast Iowa, which will lead to a noticeable difference in temperatures across the state, with values in the 60s to low 70s over the northwest half of the state, and in the mid to upper 70s further southeast. Winds will be breezy again out of the northwest with gusts up to 20-30 mph. A rather potent lobe of energy within another shortwave trough pivoting into the Upper Midwest from the larger scale circulation is expected to drop into Iowa into Saturday evening, paired with moisture return that is expected to bring additional chances (20-50%) of light shower activity into the state. Storms are not expected given very little instability overhead. The aforementioned trough deepens further as it becomes negatively tilted into Sunday morning, which will develop a rather strong low pressure system into the Ohio Valley, extending a cold front through Missouri where enhanced forcing will lead to a large area of showers and storms in that area. Trends remain in the decreasing potential for this to backbuild into far eastern Iowa per latest guidance, which will lead to drying conditions into Sunday overhead. A notable push in cold air advection and drier air from northwesterly flow will continue Saturday evening into Sunday, with upper level ridging building across the northwestern CONUS that will quickly move across the Midwest. Highs will be more seasonal with values in the 60s across Iowa, along with breezy conditions. Low RHs in the upper 20s to low 30s with the breezy winds could lead to at least some potential for elevated fire weather conditions Sunday. Dry conditions remain into the start of the work week with highs in the upper 60s to low 70s, before the next trough dropping into the Midwest from Canada drops a frontal boundary into the region by Monday evening. Per NAM guidance, weak lift and moisture into eastern Iowa is suggested that would bring another chances for showers, with the GFS indicating activity from this feature mainly over northeast Iowa while the Euro has more widespread coverage across Iowa. These differences are still expected given this is several days out, but seem to agree on at least eastern Iowa seeing rainfall so have left chances (<20%) there at this time and will update as new data comes in. Regardless, the frontal passage will result in cooler temperatures in the upper 50s to low 60s. Upper level northwest flow then seems to settle at least through midweek, keeping conditions generally on the dry side with high pressure over the region as temperatures remain in the 60s through Thursday. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 612 PM CDT Fri Oct 17 2025 A broken line of showers and storms will continue to move across Iowa this evening. FOD and MCW are already behind the line and will be VFR through the period. DSM and ALO have the broken line over them as of TAF issuance time. OTM will see the line move in later this evening. Since this is a broken line, have opted for TEMPO as the rain/lightning will be off and on until the broken line fully passes to the east. When a shower/storm is over the terminal MVFR conditions have been observed. Behind the line, winds will shift to the northwest in VFR conditions. Tomorrow afternoon winds will begin to pick up again with gusts up around 20 knots. && .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Bury AVIATION...NC