Area Forecast Discussion
Issued by NWS Des Moines, IA
Issued by NWS Des Moines, IA
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567 FXUS63 KDMX 111725 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 1225 PM CDT Sat May 11 2024 ...Updated for the 18z Aviation Discussion... .KEY MESSAGES... * Pleasant day today - mid-upper 70s highs with NW winds and low humidity. * Showers/storms return Sunday PM through at least Monday night - severe chances very low. * Additional shower/storm chances mid-late week - details hard to come by as guidance diverges && .DISCUSSION... Issued at 312 AM CDT Sat May 11 2024 After an ideal evening and overnight for aurora viewing across most of Iowa, today too will be ideal from a Spring weather perspective. Northern stream shortwave trough will continue to glide through the Great Lakes and Ohio Valley regions, leaving in its wake general NW flow and broad subsidence to weak lift. With a substantially dry airmass in place, only a few higher based clouds may be seen as the boundary layer attempts to mix to near 700mb. Aside from some weaker gusts to around 20mph, it will be incredibly difficult to complain about a day filled with sunshine, highs in the 70s, and low humidity. Enjoy it if you can! Sunday will start out quiet enough, but winds will have switched southerly as the western trough begins to slide off the Rockies and exert its influence. Deterministic and ensemble guidance remain in broad agreement on increasing moisture return and chances for precipitation returning by Sunday evening. The GFS/GEFS members have slid towards the Euro suite, meaning the primary change/consequence being lesser opportunity for accumulating precipitation over northern/northwest areas of Iowa. Potential for stronger/severe storms remains low with woeful wind fields expected. There could be a low-end heavy rainfall risk over southern areas with a combination of initial evening MUCAPE values in excess of 1000 J/kg, mean flow under 20kts, and overnight Corfidi vectors suggesting extremely slow to nil propagation. Working against though will be a weak LLJ and by virtue moisture transport. Overall precipitation activity will linger over central to southern areas much of Monday, and possibly into Tuesday over SE areas, before the parent upper low slides eastward across Missouri and into Illinois and the lower Ohio Valley. Guidance continues to consistently signal additional activity by Wednesday into Thursday as shortwave energy slides southeastward out of British Columbia, but this is also where deterministic guidance begins to diverge more substantially in their handling of this energy and beyond. Extremely hard to hang your hat on any details, aside from shower/storm chances in general Wednesday into Thursday, let alone to end the week into next weekend. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1225 PM CDT Sat May 11 2024 VFR conditions will persist through the period. Winds occasionally gust around 20 kts this afternoon, then diminish and shift to southerly after 00z this evening. && .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Curtis AVIATION...Hagenhoff