Area Forecast Discussion
Issued by NWS Des Moines, IA
Issued by NWS Des Moines, IA
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402 FXUS63 KDMX 242330 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 630 PM CDT Tue Sep 24 2024 ...Updated for the 00z Aviation Discussion... .KEY MESSAGES... - Shower activity dissipates this evening with cool temperatures overnight. - Milder temperatures return Wednesday through Monday. - Impacts from Helene appear to remain mostly south and east of forecast area. && .DISCUSSION... Issued at 337 PM CDT Tue Sep 24 2024 Have had a few isolated strong storms develop in instability axis in the far southwest forecast area this afternoon. There have been a couple of reports of quarter to half dollar sized hail with the strongest storm but the activity seems to be slowly waning. Anticipate this convection to persist over the next few hours but any of the activity in the forecast area is likely to diminish as sunset approaches and daytime instability subsides. The widespread cumulus is also expected to dissipate into the evening with generally clear skies overnight across the forecast area. Have undercut guidance in favored cool spots including the Nishna valleys in the west given a very good raditional cooling setup. Some patchy sunrise fog may also develop in places as well. Much of the upcoming forecast is dominated by the upper low currently crossing the state and its eventual interaction with Helene. This low drops southeast of the state into Wednesday and eventually absorbs the remnants of Helene into this weekend. The bulk of the moisture, forcing and activity is not expected to remain mostly south and east of the forecast area through the weekend and PoPs have been lowered over much of the area except in the southeast forecast area. Otherwise, the polar jet remains well north of the state into Canada, therefore above normal temperatures are expected to prevail for the next several days with any cooler air remaining well to the north. The jet begins to buckle into early next week with a decent shortwave dropping into the Midwest by Monday. This sweeps a cold front across the state but with very limited moisture, little chance for precipitation is expected. However, cooler temperatures are likely to arrive by the end of the forecast period. && .AVIATION /00Z TAFS THROUGH 00Z THURSDAY/... Issued at 628 PM CDT Tue Sep 24 2024 A few showers are lingering in vicinity of KDSM/KOTM early in the period though should not reach either site. Note though an outflow boundary may go through KDSM in the next hour or so and bring a brief increase in wind. Otherwise VFR with light winds into Wednesday. There is the potential for fog late tonight. At this time confidence at any location remains low so it is not mentioned in the forecast. && .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Cogil AVIATION...Donavon