Area Forecast Discussion
Issued by NWS Des Moines, IA
Issued by NWS Des Moines, IA
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233 FXUS63 KDMX 301927 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 227 PM CDT Thu May 30 2024 .KEY MESSAGES... * Showers and thunder slide in from the west late this afternoon, tonight, and through Friday. Very low strong to severe threat. * Additional/periodic shower/storm chances into next week, but model spread continues to make details hazy. Mid-week next week may be next opportunity for stronger storms. * Warming temperatures by late weekend into next week. Highs into the mid 80s at times. && .DISCUSSION... Issued at 226 PM CDT Thu May 30 2024 Conditions early this afternoon remain largely pleasant across the area with temperatures into the mid and upper 70s. It has been notably breezier across western and central areas, gusting into the mid to upper 20s mph at times out of the SE, with the tightening surface pressure gradient. Cloud cover has been slow to move over the area, with largely translucent high level cloud cover streaming across at this time, but will gradually increase as showers/storms continue to encroach from Nebraska. Many may be able to enjoy another fairly pleasant evening before said precipitation chances slide in. Short-term guidance has continued to latch onto the general split and fading of shower/storm activity as they enter and move across the state. This is largely driven by the northern stream trough and southern stream shortwaves being less in-phase and the core of their forcing being centered north and south of the state respectively. That also led to lingering and unusually high variance within overnight (06z) CAM guidance through Friday. The 12z runs showed more consistency, coming closer to extended run HRRR solutions, with weakening convective activity entering western areas of the CWA around/after 03z and struggling mightily to even reach I-35 overnight. By daytime tomorrow, the split forcing becomes more apparent with southern and northern areas most likely to see appreciable precipitation, including thunder as weak boundary slides into northern/northwest Iowa. The risk for strong/severe remains very low with sub-par shear profiles and thermodynamic profiles tending to yield weak MUCAPE of only a couple/few hundred J/kg. Initial storms this afternoon/evening may have a few stronger gusts with dry profiles in place. Overall activity will continue to trend downward Friday night and may be mid-day Saturday before exiting eastern portions of the CWA. Upper level flow pattern becomes more zonal across much of the CONUS by the end of the weekend into next week, allowing multiple shortwaves to potentially initiate periods of showers and non-severe storms. With the subtle nature of the shortwaves, model depictions continue to vary in strength, coverage, and timing. This continues to result in broader PoPs than what will surely occur. The next potential strong/severe threat window continues to look like mid- week next week as a larger trough drops out of the PNW and southern Canada. That would be the time frame to watch for more impactful weather. Temperatures remain slated to warm by late weekend into next week, bringing highs back into the mid 80s, but confidence too is hampered by the discrepancy shortwave handling. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1233 PM CDT Thu May 30 2024 Unusually high uncertainty remains with regards to precipitation and thunder potential during this TAF period. Guidance remains widely spread on evolution across the area, affecting all TAF sites. With the broader trend of greater thunder chances residing north and south of the area, have limited mentions of VCTS to KFOD and entered VCSH at remaining sites. Prevailing MVFR cloud cover will be most likely west during latter portions of the period, but confidence not great enough to have prevailing at KFOD or KDSM at this point. && .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Curtis AVIATION...Curtis