


Area Forecast Discussion
Issued by NWS Des Moines, IA
Issued by NWS Des Moines, IA
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120 FXUS63 KDMX 140336 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 1036 PM CDT Sun Jul 13 2025 ...Updated for the 06z Aviation Discussion... .KEY MESSAGES... - Patchy fog possible in far southern Iowa late tonight & early Monday - Muggy conditions return to start the week with dew point temperatures rising back to near 70F - Next widespread chance (40-60%) of rain returns to the region beginning late Tuesday night and continuing into Thursday. && .DISCUSSION... Issued at 240 PM CDT Sun Jul 13 2025 The anomalously dry air mass (PWAT of 0.71" on OAX`s 00z sounding puts it in just the 10th percentile per SPC`s sounding`s climatology) that made a brief appearance yesterday and today disappears quickly tonight as moisture advection and typical mid-summer Iowa humidity returns to begin the week. As this begins, short-range CAMs consistently depict a decaying low-level boundary and weak convection initiating & dropping thru S MN late this evening and overnight. However, unable to sustain moisture enough to overcome the drier air mass, no solutions sustain this activity into northern sections of the CWA. So for now - will keep silent precip chances across the far north. Additionally, added patchy fog mention in far southern Iowa late tonight & early Monday as clear skies combine with light winds to narrow dew point depressions to near saturation. Flow turns zonal for Monday & southwesterly for Tuesday as the pattern buckles ahead of the next wave moving into the Pacific Northwest. Continued low-level warm-air thermal advection both days will push afternoon highs back into the upper 80s to near 90F. In the absence of any forcing the bulk of both days will remain dry. However, it`ll feel noticeably muggier both days as surface dew points return back to around 70F. By Tuesday night, the first shortwave kicks out into the region, bringing perhaps a MCS and next shot of moisture into the state late. The boundary will remain in the vicinity for Wednesday and into Thursday. This will be our best window of the week for widespread precipitation. Another week, another shot at several inches of rainfall. Deep layer shear makes a return as well during this period as right entrance of upper-level jet moves across the state. This will aid convective organization through the period. Any severe potential will be refined in the coming days as the mesoscale details can be resolved. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1036 PM CDT Sun Jul 13 2025 Haze remains across parts of Iowa but continues to diminish. At the same time, patchy light fog has begun to develop this evening. Have included MVFR mention at KOTM when restrictions are most likely in southeast Iowa, however expansion to other sites is possible overnight. Fog will diminish with sunrise and VFR conditions will follow for the rest of Monday. && .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Hahn AVIATION...Hagenhoff