597 FXUS63 KDMX 132017 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 317 PM CDT Tue Oct 13 2026 .KEY MESSAGES... - Showers and storms this afternoon into evening in portions of central to southern Iowa with the highest chances (50-70%) in southern Iowa later tonight into the early overnight where a few strong to severe storms remain possible with large hail, pockets of heavy rain, and isolated gusty winds. - Cloudy and cooler Wednesday with highs in the 60s. - More widespread precipitation expected Wednesday night through Thursday. - Turning much cooler to end the week and start next weekend with frost possible early Saturday. && .SHORT TERM /THROUGH WEDNESDAY/... Issued at 258 PM CDT Tue Oct 13 2026 Stratus was slow to erode this morning with additional clouds/stratus beginning to advect in out of Nebraska. Clouds are expected to continue to increase west/southwest to east/northeast through the rest of the evening with more minimal clearing now expected on Wednesday. The cold front from yesterday did progress a little faster and is further south than thought at this time yesterday with this front found in northern Missouri, arcing back into Kansas and then northeastward into Illinois. As a result storm coverage tonight looks to develop a little further south along this boundary with the LLJ similarly moving a little further southward as well. That said, the elevated boundary remains in the state. Forcing overall remains more limited but does increase slightly into this evening with a push of theta-e advection this afternoon into evening as well. Storms have already started to develop around the boundary in north central Iowa but are not being captured well by the CAMs overall. Instability increases into southern Iowa this evening where values near to over 1000 J/kg of MUCAPE become more common, though greater values remain south of the IA/MO border. These will be paired with around 45-50 knots of bulk shear allowing for a few strong to severe storms to remain possible later this evening into the early overnight period. As noted, the better parameter space and threat is further south, but could see some storm development near the baroclinic zone or develop further south and then leak north/northeastward into the area. Regardless, expect storms to be elevated but could bring a large hail threat and bursts of heavy rain with some isolated stronger wind gusts. Timing overall remains on track with the strongest storms most likely between about 9pm and 4am though as noted previously, non-severe storms may occur before and linger after this time frame. Did shift PoPs overall slightly further south this evening, but then also added some this afternoon further north to account for ongoing activity. Further adjustments are still likely. Temperatures today have been held down in the west where cloud cover has lingered the bulk of the day, warmed decently though still cooler than previous days in the 60s in the clear areas of northern Iowa, and in the 70s to even low 80s further south to southeast with the lingering 80s closest to the surface boundary. Temperatures tonight will not drop off as much with the expected cloud cover. Except for some lingering showers in southern Iowa into early Wednesday morning, coverage and rain/storm chances largely decrease through the later half of the overnight with a period of drier conditions during the earlier daytime Wednesday as surface high pressure nudges into the area before shower chances ramp up again in the later afternoon to evening ahead of the next system. Temperatures Wednesday are expected to be in the 60s and were held down a degree or so with the cloud cover. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Issued at 258 PM CDT Tue Oct 13 2026 Theta-e advection increases later Wednesday afternoon into evening ahead of the upper low coming out of the Four Corners area Wednesday, crossing through the Central Plains Thursday and then being absorbed by the strong upper trough coming out of Canada and swinging through the region Thursday night into Friday. After being shunted to the south during a good portion of the daytime Wednesday, moisture returns late Wednesday night through Thursday. The end result is any showery activity Wednesday evening becomes more widespread rain during the day Thursday with conditions drying out Thursday evening. Windy and much cooler conditions will follow Thursday night into Friday as lows drop into the upper 30s to 40s with highs Friday in the 50s. Temperatures drop further Friday night into Saturday with lows in the low 30s introducing the possibility for some frost to start the weekend. The windy conditions from the daytime will subside by evening as a high pressure moves into the area. This high and an upper ridge overhead will keep conditions dry for Friday through the weekend. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1242 PM CDT Tue Oct 13 2026 MVFR stratus continues to erode becoming FEW-SCT MVFR or even clear ceilings. Additional cloud cover is expected to move in southwest to northeast later this afternoon to evening and lingering well into Wednesday. There are many hints of additional MVFR stratus developing into Wednesday morning with other locations staying low VFR. Have started with mainly low VFR into Wednesday, but adjustments downward and with timing may be needed. Showers and storms are still likely across far southern Iowa and maybe making it into portions of south central Iowa. Have adjusted precip mentions downward or removed them completely at KDSM and KALO respectively, and trimmed the timing at KOTM which still remains the most likely site to see shower/storms, though lowered ceilings/visibilities may be needed depending on shower/storm coverage and intensity. Winds will be light and out of the north to northeast through much of the period. && .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...05 LONG TERM...05 AVIATION...05
