Area Forecast Discussion
Issued by NWS Des Moines, IA
Issued by NWS Des Moines, IA
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193 FXUS63 KDMX 261144 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 644 AM CDT Sun May 26 2024 ...Updated for the 12z Aviation Discussion... .KEY MESSAGES... - Showers and storms to continue through the morning with a waning severe weather threat. A few thunderstorms possible southwest this afternoon. - Additional rain chances Monday and Tuesday. Some Monday storms could be strong in the east. - Midweek dry period with seasonal temperatures with rain returning Thursday night. On and off rain through next weekend. && .DISCUSSION... Issued at 225 AM CDT Sun May 26 2024 Convection progressively coated the state overnight, overrunning the surface warm front found in Missouri. 00z upper air analysis placed the nocturnal jet into central Iowa, bringing plenty of upgliding moisture into the state with mostly elevated thunderstorms with sparse hail reports. Expect instability to wane southward through the night as the MCS in Kansas takes over and sinks southeast, which will largely diminish severe weather chances for us. Otherwise, showers and storms will form from the jet-influenced theta-e advection, the passing shortwave, and the left exit region of the upper level jet. Southern Iowa can expect amounts between a half inch to an inch of rain with higher amounts with thunderstorms. The HREF probability matched mean QPF has a max along the H850 warm front between the Highway 20 and Highway 30 corridors where localized amounts nearing 2 inches will be possible. Rain and cloud cover will focus more south through the day Sunday under the influence of the deformation axis and pressure trough, finally exiting after sunset. Enough instability will remain for these to become thunderstorms, but northwesterly winds will inhibit the amount of moisture available. CAA will keep highs in northern Iowa near 70 for the day. Southern Iowa will be in the mid 70s. Additional rain will be possible along passing waves on Monday and Tuesday. CAMs build in an instability axis along the cold front on Monday, bringing thunderstorm chances mostly east. Effective shear at 40kts could organize some of the storms and produce hail and gusty winds. Tuesday`s rain will be focused north. A tightening pressure gradient and dry boundary layer will make for a breezy Monday with 30 mph gusts possible in the west. Upper level ridging will build in by midweek and spare the state from rain until Thursday night when upper level troughing influences the weather pattern again through next weekend. && .AVIATION /12Z TAFS THROUGH 12Z MONDAY/... Issued at 641 AM CDT Sun May 26 2024 MVFR and IFR cigs to build in this morning as rain focuses in the northeast. Cigs will improve to VFR through the morning. Have added low confidence VCTS and VCSH to KDSM and KOTM for this afternoon for low confidence thunderstorms that may impact those terminals after 22z. Light and variable winds to become northerly by 18z. && .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Jimenez AVIATION...Jimenez