605 FXUS63 KDMX 111128 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 628 AM CDT Sun Jul 11 2021 ...Updated Aviation... .DISCUSSION.../Today through Saturday/ Issued at 242 AM CDT Sun Jul 11 2021 Early this morning GOES water vapor imagery depicts an upper low centered over southwestern Iowa. The upper low was embedded within a broad trough encompassing the greater region and on the eastern periphery of a western conus ridge. At the surface a few showers remain evident on radar over southwest Iowa, but any thunderstorm activity has subsided as deeper instability is shunted to south of a surface boundary draped across Missouri. The low slowly progresses toward eastern Iowa today. Considerably drier mid level air advecting around the backside of the low should effectively squash precip chances all but maybe the southeastern third of the forecast area. Hi-res models support some slight to lower chance PoPs in south central to southeast Iowa as a mid- level def zone and more appreciable moisture lingers over the area. This may support the redevelopment of some shower and storm activity later this afternoon and evening. Limited instability and weak flow aloft will mitigate any severe weather potential. A few showers may also linger into Monday before a shortwave tracking along the Canadian border finally kicks the upper low out of the area. Dry and warmer conditions for Tuesday as skies clear out and low level southerly flow returns. Steady warm air advection should help push highs back closer to seasonal norms in the mid to upper 80s. A modest mid-level wave begins to drop out of the northern Rockies late Tuesday into Tuesday night which will spark convection across NE and SD. A veering 30+ kt LLJ and persistent theta-e advection may support this convection as it tracks into Iowa overnight into Wednesday morning. Additional convection is likely later in the day as models try to reload the local atmosphere in the wake of early day convection. Much of Iowa resides in the warm sector, south of a frontal boundary stretched across NE to near the IA/MN border. The parameter space is favorable for the development of strong to severe storms later in the day as increasing shear aloft overspreads an unstable airmass. Impacts from morning convection on available instability and boundary locations casts some doubt on the extent of the severe weather threat, but it will need to be closely monitored in the coming days. Upper ridge strengthens again out west late in the week, placing the local region in northwesterly flow aloft. Pattern may remain somewhat active with additional precip windows as models traverse several waves through the mean flow aloft. Confidence is low in the timing/magnitude/placement of individual waves, so slight to low chance PoPs through the extend period will suffice at the present time. && .AVIATION.../For the 12Z TAFS through 12Z Monday morning/ Issued at 624 AM CDT Sun Jul 11 2021 Main concern through the current TAF period is -SHRA/TSRA potential and reduced cigs in southeast Iowa today. KOTM likely holds at MVFR cigs through the day, and possibly lower at times if any more robust precipitation occurs at the terminal. Pockets of fog and reduced visby have also been observed over portions of north central Iowa early this morning. This has included KMCW where visby has dropped below 1sm at times. Vicinity web cam footage suggests fog coverage is sparse and quite shallow, so it should dissipate quickly as the sun rises this morning. A tempo group and KMCW through 13z is appropriate. Elsewhere VFR conditions are expected to prevail through the TAF period. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...Martin AVIATION...Martin