Tuesday Night: Small chance of thunderstorms. Low 53°F
Wednesday: Decreasing clouds. High: 75°F
Wednesday Night: Better chance for thunderstorms. Low: 59°F
Thursday: Partly cloudy. High: 78°F
Thursday Night: Best chance (50-70%) for strong thunderstorms. Low: 45°F
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General Discussion:
Temperatures this week will remain in the 70s and much above average. Additionally, an active week for thunderstorms is expected. The first of which is Tuesday night but we are not expecting very much accumulation. A better chance for severe weather becomes prominent on Wednesday and Thursday, but there is still a lot of uncertainty! Keep an eye out for weather alerts in the coming days.
-Yost
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Forecasters: Yost, Thee
Date Issued: 3/12/2024 6:00 PM CDT
Technical Discussion:
Key Messages:
- Small chance (20-30%) for thunderstorms Tuesday night
- Chance (30-50%) of strong thunderstorms Wednesday night
- Likely chance (50-70%) of strong to severe thunderstorms Thursday evening.
Current mid-level water vapor satellite imagery displays a shortwave pivoting across the Central Plains. The associated surface cyclone lingers in central KS and will track across the IA/MO border overnight tonight. A strong thermal/pressure gradient accompanies the WAA regime ahead of the cyclone, which aided in temperatures reaching mid-70s across the forecast area. Deterministic model guidance (NAM) displays subtle forcing for ascent associated with the shortwave, which will generate a deep moist layer in Central MO tonight. However, the surface cyclone will quickly dissipate as it traverses the Mid-Mississippi Valley. Enhanced air mass modification was noted between 03Z to 09Z tonight on model soundings, but only suggest 2-3 hours of precipitation. The potential for any thunderstorms is low (20-30%) considering the lack of moisture and MUCAPE values remaining >500 J/kg (via HREF ensemble mean).
Wednesday morning, subtle ridging will build in behind the aforementioned shortwave and induce a little sunshine. At the same time, renewed cyclogenesis on the Rockies will be induced by a potent upper-level trough upstream, which will take aim at the Midwest Wednesday evening. A lee-shortwave will track ahead of the main long-wave through portions of KS/MO/IA. Broad, southwesterly mid-level flow will accompany this feature and induce forcing for ascent in Mid-Missouri starting Wednesday evening. The main forcing will be relegated to KS and IA but will still be sufficient for lift. The surface cyclone will intensify throughout Wednesday evening and generate a tight pressure gradient across the CWA, inducing strong WAA. An associated warm front will retreat north throughout Wednesday night and is expected to generate thunderstorms through the overnight hours. The main caveats to thunderstorm initiation is moisture quality, and the capping inversion. An unstable atmosphere will be in place with HREF ensemble mean depicting 1000-1500 J/kg of MUCAPE, and surface dewpoints across the forecast area in the 60s. However, model soundings suggest a lot of dry air entrainment in the Planetary Boundary Layer (PBL), and a substantial capping inversion. The best chance for thunderstorm activity is before 00Z Thursday, after-which the capping inversion becomes too strong for any parcels to break. If any parcels are able to break the capping inversion along the warm front in the overnight hours, elevated severe thunderstorms are possible across Central MO. With that said, there is a good chance (30-50%) for thunderstorm development in the evening hours Wednesday. The main severe threat will be confined to western MO, into eastern KS.
For Thursdays impactful weather, the main long-wave trough will be the synoptic forcing mechanism for storm initiation. Strong WAA will continue into Thursday and temperatures are expected to remain in the mid-to-upper 70s. A crashing cold front behind the aforementioned surface cyclone will sweep through the CWA Thursday evening. Strong prefrontal thunderstorms are expected as a strong LLJ (50kts) interacts with an unstable warm sector. A large swath of 60s dew points will disseminate throughout the mid-Mississippi Valley, along with 1000-2000 J/kg of CAPE (via NBM CAPE probabilities). There is higher confidence (50-70%) in convective initiation for Thursday compared to Wednesday. The main reasoning is there will be less capping across the entire severe threat. Second, there will be stronger forcing for ascent. Severe threats will be mainly damaging winds and large hail. However, elongated hodographs may be supportive for some discrete supercells, with a very conditional chance of tornadoes. The post-frontal air mass will quickly advect a cooler, more stable air mass into the region. Expect a seasonal temperature trend for this weekend.
-Yost