Area Forecast Discussion
Issued by NWS Des Moines, IA
Issued by NWS Des Moines, IA
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777 FXUS63 KDMX 171728 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 1228 PM CDT Fri May 17 2024 ...Updated for the 18z Aviation Discussion... .KEY MESSAGES... - Warm today into Saturday with highs in the 80s. - Isolated storms remain possible Saturday afternoon. - Several periods with storm chances from late Sunday through Tuesday night and again by late in the week. && .DISCUSSION... Issued at 305 AM CDT Fri May 17 2024 Quiet conditions early this morning across Iowa as surface ridging slides across the state. Warm advection is beginning to strengthen in western Iowa where winds have become southerly. Farther east, winds remain light and variable underneath the ridge axis. The warm advection overspreads the state today as the south to southwest increase. Temperatures should respond with relatively deep mixing and modest dewpoints allowing highs to climb into the 80s in most areas and have gone above NBM for highs this afternoon. Thermal ridging approaches the state overnight with winds remaining decent, particularly in the northwest tonight helping to keep temperatures near 60 in most areas. Broad upper trof across western Canada into the northwest United States will see a shortwave pass through the base and into the Dakotas and northern Minnesota on Saturday. The associated surface boundary slides into Iowa on Saturday with increasing instability ahead of the front by afternoon. Meanwhile, a decent cap is in place into the afternoon which should keep convection at bay. However, sufficient lift along the boundary may be sufficient for a few isolated cells to overcome the cap and have allowed the low PoPs to persist, mainly along and east of the Interstate 35 corridor during the afternoon. The upper pattern evolves through the weekend and by late Sunday into Monday, southwest flow develops across the central United States. This allows ample moisture to stream back north from the Gulf into early next week. The initial surge of moisture into Iowa arrives Sunday into Sunday night with storms spreading from west to east across the state. The unsettled weather remains into Monday and Tuesday as moisture continues to flow into Iowa ahead of a shortwave arriving on Tuesday. Repeated rounds of thunderstorms may eventually lead to hydrologic issues along with some threat of severe weather into the early part of the week. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1225 PM CDT Fri May 17 2024 Breezy southerly winds will persist into this afternoon and increase some through 20z. The mixed layer will decouple this evening, likely after 01z though the wind will remain in the 5 to 8 kt range. The wind will increase mid to late Saturday morning and become more southwesterly. Sct cumulus near 5 kft is expected over southern and eastern IA this afternoon along with passing mid level cloudiness. VFR conditions will persist through the forecast period. && .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Cogil AVIATION...Donavon