Area Forecast Discussion
Issued by NWS Des Moines, IA
Issued by NWS Des Moines, IA
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283 FXUS63 KDMX 052317 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 617 PM CDT Wed Jun 5 2024 ...Updated for the 00z Aviation Discussion... .KEY MESSAGES... - A few showers and storms possible through early evening. Gusty winds are possible with this activity. - Gusty winds expected Thursday. Wind gusts over 40 mph are possible, especially over northern Iowa. && .DISCUSSION... Issued at 342 PM CDT Wed Jun 5 2024 A boundary is currently across southeast Minnesota, northwest Iowa and into Nebraska and will continue to move southeast through the state into this evening. Some surface dew point recovery was ongoing earlier today with a narrow ribbon of upper 50 to near 60 dew points wrapping around the west side of a high to the south and pooling ahead of the boundary. Those dew points have since mixed out some this afternoon into the low to mid 50s. Some modest surface instability has develop ahead of the boundary with around 500 J/kg CAPE. Some light rain has been moving across southern Minnesota and into northwest IA and in the past 15 minutes, some convection is developing into far northwest Iowa. Despite improved effective shear profiles of 25+ kts, not expecting any organized activity to develop. Gusty winds will be possible with any and cannot discount gusts over 50 mph. The shower and storm potential will progress southeast along the boundary into this evening. A wind advisory remains in effect over far northern Iowa. The potential remains for some deeper mixing over the next few hours to result in increased winds and that will remain in effect through 7 pm. The wind will diminish and the skies will clear later this evening and into the overnight. The main weather story on Thursday will again be increasing winds. Despite the potential for 40kts of wind near the top of the mixed layer Thursday, the lack of strong cold advection will limit how much wind does mix to the surface and the lack of a good pressure gradient is also a limit. Therefore, there remains enough uncertainty to remain headline free for Thursday. Two upper lows with one from the northeast CONUS and another over central Alberta along with an upper ridge over the western CONUS, will combine to create a weak upper northwest flow over Iowa from Thursday through much of Saturday. A short wave will rotate south late Saturday into early Sunday which will lead to some cooler temperatures Sunday. With so many strong upper level next weak, there is a lot of noise in the data beyond Monday leading to less confidence in that time period. && .AVIATION /00Z TAFS THROUGH 00Z THURSDAY/... Issued at 613 PM CDT Wed Jun 5 2024 VFR conditions are forecast through the TAF period. A broken band of -shra activity is pushing through central Iowa this evening. Much of this activity is rooted at or above 10k feet with some precipitation not reaching the ground. This makes it difficult to pinpoint if/when precip may occur at a given terminal, and have opted to cover with VCSH although a brief downpour may occur. The shower activity may also be accompanied by sporadic gusty winds. Dry conditions are then forecast by mid to late evening through the remainder of the TAF period. Gusty west-northwest winds return tomorrow morning. The strongest winds reside over northern Iowa where gusts above 30 kts may be common, particularly during the afternoon hours. && .DMX WATCHES/WARNINGS/ADVISORIES... Wind Advisory until 7 PM CDT this evening for IAZ004>007- 015>017. && $$ DISCUSSION...Donavon AVIATION...Martin