Current Conditions at Sanborn Field
Monday Night: Showers and thunderstorms early. Low: 38-42.
Tuesday: Mostly cloudy. High: 52-56.
Tuesday Night: Mostly cloudy with rain late. Low: 42-46.
Wednesday: Rain and thunder likely. High: 54-58.
Thursday: Overcast with rain. Breezy. High: 42-46.
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Discussion:
Scattered thunderstorms are possible this evening and overnight. A couple may be on the strong to severe side, with gusty winds and hail the main threats. However, a brief and isolated tornado cannot be ruled out. Showers and storms will end later on tonight, leaving things mostly cloudy and dry. Tuesday looks to be the driest day of the next few, though cloud cover will still help to keep temperatures down in the 50s. Our next storm system then arrives Wednesday, yielding a chance of rain and a few thunderstorms just in time for St. Patrick's Day. Some of the showers and storms may be on the heavy side. The storm system will then pass by and move off to our east for Thursday, bringing colder conditions and wrap-around rain. Thursday looks like quite a raw day, with gusty winds and highs only in the lower to middle 40s.
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Forecaster: Vanderpool
Issued: 5:00 PM CDT 15 March 2021
Technical Discussion (The nerdy stuff we are discussing in class):
WPC sfc analysis from 15 UTC indicated an occluded surface low centered over Kansas. An occluded front extended between the center of this low and the center of another developing low in western Kentucky. 18 UTC RAP analysis showed that this low was vertically-stacked throughout the lower and middle layers of the atmosphere, with the placement of the 500-mb center of circulation almost directly above the circulation at the surface.
In the near term, this decaying low will make for some interesting weather in mid-MO. The aforementioned occluded boundary is progged to slowly push northward before likely stalling out just south of I-70 around 22 or 23 UTC. As it does so, the region near and south of the front will develop surface-based CAPE on the order of 250-750 J/kg due to insolation (areas north of the front will remain cloudy). Thus, the occluded boundary will act as a pseudo-warm front in the near term. 0-6 km bulk shear will also be quite significant along and just south of this front, leading to a setup for isolated severe storms. The focus for convective initiation will be along the occluded boundary between ~20 and 23 UTC, where (given mean cloud layer winds of 40-60 kt out of the southwest) storms will quickly move northeast. They will progress into a much less favorable environment for convective maintenance, so the focus area of concern this afternoon and evening will be in a relatively narrow stripe extending from about 75 miles south of I-70 to 20 miles north of it.
Primary threats look to be small to marginally-severe hail and gusty winds, although (given HRRR-progged 0-3 km SRH of 200 - 350 m^2/s^2, a brief tornado cannot be ruled out. The window for severe weather will last only a couple hours from the formation of the cells before they progress northward into an unfavorable environment. Leftover showers and storms may continue into the early overnight hours.
For Tuesday, the surface low will dissolve and leave mid-MO in a bit of an in-between pattern. The next storm system will be forming in the southern Rockies, though it won't affect the weather in Columbia to a great degree (at least not until Wednesday). GFS model soundings indicate modest CAA beneath mostly cloudy skies for Tuesday, with the GEFS and HRRR backing this up. With no real lift present in the atmosphere, Tuesday should stay dry, with highs in the lower to middle 50s.
Tuesday night into Wednesday, the developing surface low will deepen and move out into the southern Plains. Ahead of it, PWATs may approach or even exceed 1 inch over mid-MO. Given ample lift coinciding with this Wednesday and Wednesday night, heavy rain is possible. There will also be at least some CAPE present, with SREF mean MUCAPE peaking at ~450 J/kg early Wednesday morning. Thunder will therefore also be a possibility throughout the day on Wednesday. Severe weather currently looks unlikely, though heavy downpours and lightning may still be a bit of a concern for St. Patrick's Day.
For Thursday, the surface cyclone will push off to the east. Northerly flow on the back end of this maturing cyclone will allow for strong CAA. Additionally, wrap-around moisture will ensure heavy cloud cover and the potential for cold rain throughout the day. Given stiff northerly winds and precipitation, highs Thursday should be kept down in the 40s, with upper 30s possible by the evening. Overall, Thursday will be rainy and raw, more reminiscent of early February than mid-March. Despite the fairly cold temperatures, this storm system lacks access to any real cold air. Therefore, precipitation is expected to remain as rain. After rain departs Thursday evening, total QPF from the entire event will likely range from 0.5 - 1.5 inches.
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