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After our first taste of summer storms made its way through Columbia last night, conditions will begin to clear out through the weekend. High pressure takes full control over Missouri beginning early Friday afternoon and continues through the remainder of the weekend. Temps warm as breezy winds come through Friday but die out by the early morning hours of Saturday. Sunny skies ensue Saturday and temps warm even more through the day. Conditions remain clear into Sunday morning as clouds begin to roll in through the day and take full control of the sky Sunday evening. We find ourselves caught in between a high and low pressure system Sunday. This brings a good chance of rain Sunday night with a very small chance of storm development into Monday morning with rain totals coming under a quarter of an inch.
Forecasters: Bongard, Doll, and Myers
Issued: 4:31 p.m., 18 April 2019
Technical Discussion (The nerdy stuff we are discussing in class!)
Looking at the 250-mb GFS model output, tonight ushers in a deep trough that makes its presence in the eastern Texas area. Continuing looking upstairs, Missouri will find itself in the axis of this trough, shifting winds from southwesterly to northerly as we get into the morning hours of Friday. Continuing with the GFS model, 500-mb vorticity is present through mid-Missouri however we have no moisture influx at this level keeping the talk of rain off the table. Stepping down to 700-mb, we do have a presence of slight moisture through the night as well as frontogenesis occuring in southwestern Missouri. This keeps cloud presence through the night until clearing out Friday morning when this deep trough scurries out of the Midwest clearing our conditions. At the surface level in the GFS sounding, conditions will remain calm through tonight with colder, northerly winds finding its way into mid-Missouri Friday morning. Overall, we stayed with the GFS model because of the recommended blend model output from the SBC model guidance with an emphasis on the low pressure system track with GFS in the southern US.
As this deep trough moves out of the central CONUS, central Missouri begins drying out through all levels of the atmosphere when looking at the GFS model soundings. This is due to Missouri receiving the southerly portion of confluence at the 500-mb and 700-mb levels drawing in the dry, cooler air from the northwest CONUS. Comparing the NAM and GFS models at 250-mb, GFS keeps the low pressure system over Indiana with a much stronger source of warm air advection and a larger upper level jet max with stronger negative tilt of this trough over West Virginia. Going with this model, this will show conditions clearing out fast with Missouri on the backside of the trough with cool breezy conditions through tomorrow night.
An incoming ridge pushes the deep trough seen previously to Missouri's east out of sight and out of mind. With this ridge comes some slight veering at the surface level on the GFS sounding model as a high presure system begins to develop through the later afternoon hours of Saturday over northern Louisiana. This high pressure system is most present at the 850-mb level with Missouri's moisture flow coming from the dry air of western Texas. This promotes dry, stable conditions throughout the atmosphere warming temps down to the surface. Warm air adevection is seen present from the 700-mb to 925-mb levels on the GFS model output with warm air coming from the general area of western Texas. This warm air advection is the icing on the cake of Missouri's warmer, sunny day on Saturday.
Conditions at the 250mb level on the GFS model show flow becomes very zonal and relatively calm, however a lot more activity coming from the mid-lower atmosphere levels. At the 500mb-level, vorticity does become present coming off of a small low pressure system that develops over western Kansas Sunday night. With moisture coming in at the 500-mb through the 925-mb level later in the evening hours of Sunday, the low level atmosphere high pressure system takes full form and develops over Mississippi. As Sunday begins to draw to a close, the combination of the low pressure system to Missouri's west, high pressure system to Missouri's southeast, and vorticity present at 500-mb promotes good conditions for a single cell convection development over mid-Missouri Sunday night. Looking at GFS model soundings 80 plus hours out, CAPE is shown at values of 1400 J/K however there is a significant dry layer at the lower-surface pressure levels. As moisture finally rolls in at the surface levels from the high pressure system over Louisiana, cape values begins to dwindle but present promoting small storm chances going into Sunday. With rain totals staying under a quarter of an inch according to GFS this rain will be short lived through the night, promoting the single cell development.