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Area Forecast Discussion
Issued by NWS Des Moines, IA
Issued by NWS Des Moines, IA
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861 FXUS63 KDMX 120508 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 1208 AM CDT Mon Aug 12 2024 ...Updated for the 06z Aviation Discussion... .KEY MESSAGES... - Showers and thunderstorms this evening and overnight to Monday morning. Additional precipitation chances Wednesday into Thursday. - Gradual warming back towards seasonal averages this week. && .DISCUSSION... Issued at 231 PM CDT Sun Aug 11 2024 A weak wave off to the west has resulted in increasing cloudiness across the area this afternoon while southeast flow has helped nudge temperatures a degree or two over yesterday. Meanwhile, the primary vorticity lobe across the northern plains will drop southeast this evening and across Iowa overnight and into Monday morning. Instability is quite modest, with HREF mean MUCAPE under 500 J/kg into Iowa and CAM soundings showing the same. While shear is 40-50 kts, it will be difficult for stronger storms to develop in this low instability environment. The primary QPF axis will sweep across southern Iowa with HREF noting a swath of 1-3" possible in this area. Most rain will taper off around 12z Monday morning, however a few CAMs note lingering spotty showers across the area with trailing weak forcing as the system lifts east. Temperatures gradually warm into midweek as the western US thermal ridge gradually rebuilds and influences the area. This will send temperatures back into the low to mid 80s, nearer seasonal averages for this time of year. The pattern becomes more active by the middle of the week as a more robust wave deepens across the central plains and moves across Iowa Wednesday into Thursday. Solutions diverge with the synoptic evolution as the EC remain more progressive while the GFS slows and deepens into a cutoff upper level low over the area that lingers into Friday. As it stands the severe threat is low, however with variability in possible solutions this is low confidence. What is more consistent is the heavy rain potential with weak flow and good moisture transport into the area. Deep warm cloud layers will be in place and models indicate PWATs of 2+" Wednesday into Thursday. High pressure looks to build into next weekend, helping to dry things out. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1205 AM CDT Mon Aug 12 2024 Showers and a few embedded thunderstorms south expected for the next 6-8 hours. MVFR cigs expected to coat southern terminals through the morning, lingering at KOTM until the early afternoon hours. Have removed IFR mentions due to decreasing confidence in this possibility. Have modified VCTS FM groups to reflect times of highest confidence for thunderstorms for KDSM and KOTM. Have left out of KFOD due to low confidence. Prevailing VFR expected after 21z. && .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Hagenhoff AVIATION...Jimenez