Current Conditions at Sanborn Field
Thursday - Overcast with rain likely. High: 50-54.
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At 15 UTC, a surface stationary boundary stretched from the TX panhandle to northeastern IA. A surface low was just beginning to form near Amarillo, TX. This was supported by a well-defined and neutrally-tilted shortwave trof at 500-mb. Conditions in mid-MO as of ~19:30 UTC were quite warm, with middle to upper 60s area-wide. Winds were gusty out of the south. The main challenge in the near term will be to resolve the forecast over the next 24 hours, with the aforementioned sfc low expected to undergo cyclogenesis as the upper-level shortwave ejects out into the Plains.
Visible satellite reveals a large mass of cloud cover extending from mid-MO all the way to the eastern Rockies. As of 19:30 UTC, it is beginning to take on the shape of a baroclinic leaf. These clouds will continue to filter over the area and gradually thicken overnight, with short-range CAMs progging the arrival of precipitation between midnight and 4 AM CDT. It's likely that some of this rain will evaporate before reaching the ground, as the main plume of low-level moisture will likely remain west of mid-MO until near daybreak Tuesday.
Models are sold on a round of rainfall impacting mid-MO from late tonight through the first part of the day on Tuesday. QPF with this looks fairly modest, though some heavier pockets of rain can't be ruled out given a decent (40-50 kt) LLJ and PWATs near 1" around 12 UTC on Tuesday. The SREF means have approximately 0.35" of QPF through mid-morning, with the deterministic GFS just above 0.5". However, the RAP and HRRR both prog QPF at a much more modest 0.1 - 0.25". With all this in mind, I would anticipate anywhere from a quarter to a half inch out of Tuesday morning's rain.
For Tuesday afternoon, attention turns towards the potential for thunderstorms. Insolation looks weak, yet models (especially hi-res CAMs) are very insistent upon the presence of anywhere from 250 - 1000 J/Kg of sfc-based (or near sfc-based) CAPE tomorrow afternoon. Instability looks to maximize between 18 and 21 UTC. This is concerning, since the core of the circulation will be located just about a hundred miles northwest of mid-MO. That leads to 0-1 km SRH values in the 150-250 m^2/s^2 range. Given the dynamics present, even weak updrafts will have the chance to tilt and rotate. Thus, thunderstorms are possible Tuesday afternoon, and a few may be strong to severe. Gusty winds, small hail, and brief spin-up tornadoes will be the primary threats.
The threat will be short-lived, however, as the storm system pulls northward and takes the moisture with it.
For Wednesday, very modest CAA beneath some wrap-around cloud cover will combine to keep temperatures on the cooler side. However, the amount of cloud cover remains difficult to predict. Significant spread exists in the SREF members for highs, so it's possible that - if mid-MO can clear out into some sun - temperatures may hit 60. However, that seems unlikely. Wednesday also currently looks dry.
The active weather pattern will then resume for Thursday, with a couple of shortwaves propagating out into the Midwest. This will cause precipitation chances to increase Wednesday night into Thursday. Heavier overcast and rain present in the area will lead to lower highs on Thursday, making for another rainy and chilly March day in mid-MO.
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