826 FXUS63 KDMX 141145 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 645 AM CDT Mon Apr 14 2025 ...Updated for the 12z Aviation Discussion... .KEY MESSAGES... - Elevated sustained winds today, especially in the north this morning and later this evening. Winds will generally remain under 30mph. - Showers and storms likely (>60%) this afternoon and evening. Higher wind gusts upwards of 50mph possible with storms, although a severe gust cannot be ruled out. - Severe storms possible (15% chance of severe) on Thursday. Hail is possible with other threats still in question, at this time. && .DISCUSSION... Issued at 404 AM CDT Mon Apr 14 2025 Objective analysis last night showed the axis of a shortwave trough in Minnesota with wind maximums in the trough base on the approach for today. The surface reflection of the front is well off to the southeast with CAA peaking through the early morning. This is how wind gusts remained overnight. An upper-level jet will deepen a backside feature as it dives over the state this afternoon, maximizing pressure gradients to around 30 ubar/km again late this afternoon. A second boundary will be collocated. While the temperature gradient being advected in won`t be strong, the dryness of the low-level airmass remains so. Even the NAM, which traditionally hangs on to PBL moisture longer, mixes us above 800mb by this afternoon. Even into the cloud layer, lapse rates are dry adiabatic, with superadiabatic lapse rates appearing at the surface. There are some question marks regarding peak synoptic winds today as PBL winds average around 30kts, meaning not a lot of acceleration for gusts will take place; however, these winds being not far from the surface could help drive the sustained winds higher and into Advisory-level. Confidence wasn`t high enough to issue an Advisory overnight due to the lull in CAA and subsidence in between the synoptic features today, as well as the cloud cover potentially inhibiting some of the momentum transfer to the surface. Trends will be monitored with the passage of the next front later today. The focus on winds will be more with the convection moving across the area this afternoon. Have introduced likelies (>60%) across the north this afternoon and evening, although it should be noted that QPF will be low from high-based storms. MUCAPE values are approaching 200 J/kg and is driven mostly by the aforementioned steep lapse rates; this is enough to produce scattered storms. The inverted-v soundings are leading to DCAPE values are actually coming in higher, close to 300 J/kg. This paired with low-level theta-e differences between -2 and -5K imply cold pool acceleration due to dry air entrainment, translating to wind gust potential. Models such as the HRRR and RRFS support this outcome as they have 50kt gusts collocated with simulated storms. Confidence in any one storm having severe winds is around 10%, but at least anticipate strong gusts upwards of 50 mph to accompany showers and storms. The backside northwest flow continues to influence the weather on Tuesday, mostly in the form of lessening breezes and cooler temperatures around 60 degrees. The pattern shifts back to southerly for Wednesday, but this time with more moisture at play. An MCS in northern MO will kick things off Wednesday evening and precipitation will spread into Iowa as the LLJ is pulled northward with the deepening low pressure to our west. A seasonably strong EML will encroach behind the advection wing showers and storms, introducing an unstable airmass for activity later in the day Thursday where convection will fire along the northern gradient. Supporting this is a wave ejecting off a parent upper low in the Four Corners region. Deep layer shear over 50kts is abundant across the state, but some questions remain in how much capping could inhibit surface-based potential. At the very least, the potential is there for severe hail. The shortwave is picked up by the upper low to our north, giving the system a more west-to-east trajectory by late Thursday. The trailing cold front will setup close to the state late Friday, bringing some chance for more convection at least across the southeast. The parent trough then comes more into play at the end of the weekend as it makes its way into the region. The Euro`s faster open wave solution appears to be an outlier compared to the rest of the ensemble suites, which favor a slower and deeper solution. That system will be worth watching for severe weather potential somewhere in the region. && .AVIATION /12Z TAFS THROUGH 12Z TUESDAY/... Issued at 640 AM CDT Mon Apr 14 2025 MVFR to blanket northern sites for a brief window this morning, but lift to MVFR before 18z. Main changes is adjustments to PROB30 groups this afternoon with a gust group introduced to account for increased wind gusts with showers and storms. Have removed thunder from KDSM as confidence is lower in storms reaching site. && .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Jimenez AVIATION...Jimenez