Area Forecast Discussion
Issued by NWS Des Moines, IA
Issued by NWS Des Moines, IA
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008 FXUS63 KDMX 142346 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 646 PM CDT Tue May 14 2024 ...Updated for the 00z Aviation Discussion... .KEY MESSAGES... - Scattered showers in southeast to central Iowa this afternoon taper off this evening. - Warming trend into the end of the week/weekend with additional thunderstorms chances Wednesday evening into Thursday and again this weekend. Severe chances remain low at this time. && .DISCUSSION... Issued at 226 PM CDT Tue May 14 2024 Scattered showers have persisted across southeast Iowa throughout the day as the surface low continues to slowly swirl to our south. Another more isolated, and short-lived, shower has developed towards Boone county with associate more agitated cumulus showing up in GOES imagery. This has mainly been diurnally driven with just enough available moisture for isolated shower development. All of these showers should taper off this evening as the system finally shifts east. Wednesday will see a quieter day to start as the next system swings across the northern Plains towards Iowa. With light winds and lingering moisture, a few high resolution models have indicated chances for patchy fog development in southern Iowa on Wednesday morning though lingering cloud cover may squash this potential. By evening showers and a few thunderstorms will approach the area with a front associated with a trough across the central US. Forcing is weak and focused in the northern and southern streams that split Iowa on either side. Modest MLCAPE less than 500 J/kg and 0-6km shear at or under 30 kts will limit much in the way of severe potential. The boundary continues across Iowa on Thursday with some diurnal restrengthening Thursday afternoon towards eastern iowa. Even so, the parameter space remains similar to Wednesday with very skinny CAPE profiles and a very low severe threat. The unsettled pattern continues this weekend and into next week (along with a warming trend), however model solutions diverge with less confidence in precipitation windows and placement. Broadly, additional chances exist with a shortwave Saturday into Sunday. GFS favors a cutoff low bringing precipitation to southern Iowa Friday night into Saturday, slowing the shortwave into Sunday. Meanwhile the Euro is more progressive and without the cutoff low, pushing the shortwave through on Saturday with less QPF. For now have opted for a middle ground scenario but will need to fine tune as more data is available. Both also indicate another more robust system early next week, though significant differences in timing and placement exist. && .AVIATION /00Z TAFS THROUGH 00Z THURSDAY/... Issued at 646 PM CDT Tue May 14 2024 Confidence is medium or more than VFR conditions will persist across northern Iowa through the period, including KFOD/KMCW/KALO, with generally diurnal cumulus cycles. However MVFR stratus should affect KOTM for at least the next several hours, with at least MVFR conditions due to stratus, and potentially visibilities, affecting other portions of southern Iowa later tonight and into the early morning hours Wednesday, including KDSM and KOTM, with confidence no better than medium. IFR fog is expected across SW Iowa, removed from those sites, however that potential cannot be ruled out in other locations over southern Iowa farther east as well. && .DMX WATCHES/WARNINGS/ADVISORIES...None. && $$ DISCUSSION...Hagenhoff AVIATION...Small