Tuesday: Isolated Strong Storm Possible. High: 87
Wednesday: Mostly Sunny. High: 56
Wednesday Night: Mostly Clear. Low: 33
Thursday: Mostly Sunny. High: 57
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Discussion:
There is a possibility of damaging winds, large hail, and an
isolated tornado this afternoon and overnight so make sure you have a way of getting weather warnings. A severe storm setup will be present this afternoon as temperatures reach well into the 80s, however, uncertainty remains on development. With the lack of upper-level moisture, storms may not develop; but if they do, they will be strong to severe. Overnight shows more promise on the development of storms, but less severity. Wednesday and Thursday will usher in calmer and cooler weather with sunny conditions in the 50s.
Forecasters: Simmons, Meier, VanUnnik
Date Issued: 4/4/2023 10:20 AM CDT
A conducive environment for severe weather will be present this afternoon and into overnight. All hazard types are possible with the severe weather which include large hail, damaging winds, and an isolated tornado. There remains a little uncertainty on whether storms will be able to initiate this afternoon due to a strong capping inversion aloft. However, consensus remains that at least a scattered line of convection will move through Missouri overnight tonight with another conditional threat of severe weather.
In the upper levels, a deep longwave trough is situated over the Mountain West. This trough will move into the Great Plains later this evening with the base of the trough rounding through the Southern Plains. As this trough slides eastward, a cyclonically curved jet streak will round the base of the trough putting Missouri in the upper-air divergence zone. Areas of vorticity will approach central and southeastern Missouri from the southeast later today providing forcing for convection. There remains a lack of moisture in the upper-levels which could be difficult for cloud development and storm initiation. However, a very unstable atmosphere will be present with CAPE values exceeding 3000 J due to surface temperatures reaching the 80s and dew points in the mid-60s. As mentioned earlier, a capping inversion will put a lid on the atmosphere here in Mid-Mo at least for most of the afternoon. However, if surface temperatures can warm a little more and the convective temperature is reached, then storm development will become much easier this afternoon which has been hinted at by some convective activity in Eastern MO.
A mid-level low associated with the trough will eject into the Dakotas late tonight with a surface low and extending cold front near the boundary layer over parts of the plains. As the low pressure will move northeast later tonight, the pressure gradient will continue to increase providing a strong southerly wind into Wednesday. This will coincide with the LLJ reaching its maximum strength this evening helping support moisture northward into the warm sector. Model guidance has suggested a broken line of convection emerging well in front of the cold front as it moves east overnight. Linear negative omega values are also present just ahead of the front which would provide some lift for storm development. The vertical wind profile shows veering winds with heights this evening as well as a lifted index values exceeding -10. While the conditional severe threat will remain overnight, the atmosphere will lose some of its instability as daytime heating will be over. Nevertheless, all hazards continue to be present overnight especially from 10pm to 4am which could be problematic for the public to receive warnings.
Once the storms exit the area in the early morning hours of Wednesday, a cold front will still be lagging behind. It is expected that the front will move through around 12Z or so Wednesday morning which will bring temperatures down much cooler compared to today. Wednesday will only see temperatures get into the 50s with a clearing sky as the day goes by. By Thursday, a surface high will move right over Missouri ushering in a calmer and cooler day once again with daytime highs running 5-10 degrees below average.
-Simmons
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