Tuesday Night: Brief Thunderstorms possible (30-50%). Low: 60°F
Wednesday: Mostly Sunny. High: 70°F
Wednesday Night: Partly Cloudy. Low: 56°F
Thursday: Thunderstorms possible. (30-50%). High: 73°F
Thursday Night: Decreasing Clouds. Low: 42°F
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General Discussion:
A brief round of thunderstorms is expected to impact portions of Central MO this evening, becoming more severe with northern extent. Main hazards will be small hail (<1 inch), gusty winds (40-50mph), and rumbles of thunder before a cold front shifts through the region. Wednesday will see warm and dry conditions behind the cold front. Another round of thunderstorms is expected Thursday afternoon into the evening, yielding very beneficial rainfall totals between 0.5″ and 1.00″.
-Yost
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Forecasters: Yost. Thee
Date Issued: 04/16/2024 3:00 PM CST
Technical Discussion:
Key Messages:
- Brief round of thunderstorms early this evening with small hail (<1 inch), strong wind gusts (>50 mph) and lightning as main hazards.
- More beneficial rainfall and thunderstorms are expected Thursday afternoon with rain totals between 0.5″ and 1.00″.
Current mid-level water-vapor satellite imagery displays a negatively tilted closed low ejecting through the Upper Great Plains. Latest SPC Mesoanalysis shows a strong belt of enhanced flow (90-100kts) on the southeastern quadrant of the 500MB trough overspreading the mid-level cold pool atop a moist boundary layer in IA and MO. A well-defined surface cyclone (992MB) is meandering across portions of Eastern Nebraska, stretching a warm front eastward through Central Iowa into the Ohio River Valley. A favorable plume of 60s dewpoints and strong WAA ahead of a stalled-out cold front has generated widespread thunderstorms throughout Missouri this morning/afternoon. The linear nature of the morning convection transitioned quickly to an organized, multi-cell structure, surging north-northeastward at 40-50kts and becoming severe early this afternoon. Most of the severe reports were north of the I-70 corridor this afternoon and are expected to continue through Tuesday night.
Continued destabilization across the warm sector associated with surface heating behind this initial wave will potentially generate an all-hazards threat. Confidence is low in the degree of destabilization through the early evening due to ongoing convection. Still, given sufficient surface heating, a favorable plume of 1500-2000J/kg of MLCAPE is forecast to spread into MO and IA, mainly north of the I-70 corridor. Although favorable thermodynamics will be in place — moist boundary layer and steep mid-level lapse rates (>7.0°C/km) — there is only a small window of opportunity for thunderstorms to intensify in Central MO.
Supercell thunderstorms should initiate off the cold front later this afternoon into the early evening with a 40-50kt north-northeast storm motion. This rapid storm motion will limit the window that supercells will intensify in Columbia and decrease the likelihood of receiving impactful weather Tuesday evening. A favorable low-level jet and deep-shear profiles will station just north of the CWA later this afternoon, enabling discrete convection throughout MO. Although Central MO appears to have a glancing blow from the 850MB jet, the short window of opportunity for supercell development will yield little to no tornado/severe risk in the CWA. Extreme northeastern MO, portions of IA, and west-central IL will see a more substantial threat, where more impressive thermodynamics and kinematics will exist. Although severe thunderstorms remain unlikely, rain showers, small hail (<1 inch), strong wind gusts (40-50mph), and lightning will remain possible (30-50%) with any thunderstorms that initiate off the cold front. The post-frontal air mass will shift winds to the southwest overnight on Tuesday, yielding enhanced air mass modification. Model soundings display dominant dry air intrusions and upper-50s surface temperatures after midnight on Tuesday.
Guidance for Wednesday morning shows subtle ridging and an associated surface high that will traverse the CWA throughout the day. Sky conditions are expected to be mostly sunny with temperatures in the 70s as a result. Broad troughing in the Pacific Northwest will gradually overspread the Upper Great Plains region on Thursday. A 700MB shortwave and associated surface low will track along the I-70 corridor Thursday afternoon, pooling a large-swath of 60s dewpoints ahead of a cold front. Model soundings Thursday afternoon display steep mid-level lapse rates atop a moist boundary layer from 18Z – 00Z before substantial capping limits storm coverage. Thunderstorms are possible in this window (30-50%) due to this destabilization with very beneficial rain totals between 0.5” and 1.00”. Most deterministic guidance agrees with the cold front shifting through MO around 06Z Friday, enabling a secondary return to more stable weather conditions on Friday. Future forecast shifts should monitor model trends leading up to Thursday for the potential of severe weather.
-Yost