Current Conditions at Sanborn Field
Monday Night: Partly cloudy. Low: 56-60.
Tuesday: Partly sunny. High: 76-80.
Tuesday Night: Showers and thunderstorms possible late. Low: 58-62.
Wednesday: Showers and thunderstorms likely. A few may be strong. High: 68-72.
Thursday: Mostly cloudy with rain possible. High: 54-58.
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Discussion:
The warm weather we've enjoyed today will continue into Tuesday. Temperatures Tuesday will likely be in the upper 70s to near 80, with breezy south winds and increasing clouds. Tuesday night into Wednesday morning, showers and storms are possible. One or two may be on the strong side. Another round of thunderstorms is possible Wednesday afternoon as a cold front swings through mid-MO. These too could be on the strong to severe side, but how strong they get will depend upon when the front arrives and how much dry time we can get during the day on Wednesday. Wednesday night looks dry and cooler, and Thursday will see the return of rain chances as moisture wraps around on the backside of the storm system. Look for things to be cooler on Thursday, with highs only in the middle to upper 50s.
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Forecaster: Vanderpool
Issued: 5:00 PM CDT 5 April 2021
Technical Discussion (The nerdy stuff we are discussing in class):
As advertised by the previous shift, temperatures as of 20 UTC have climbed into the upper 70s across mid-MO. RAP upper air analysis reveals a fairly zonal pattern aloft at 500-mb, with just a slight indication of ridging over the central CONUS. This too is in line with the previous shift, so only slight modifications of this forecast will be needed.
Overnight and into Tuesday, the primary focus will remain on very warm temperatures, with highs Tuesday likely once again making a run at 80 and beating seasonal averages by nearly 15 degrees. Short range hi-res models indicate the continuance of southerly flow over the central and southern CONUS; therefore, expect surface dew point values to remain in the low to mid 50s over the next ~24 hours. The primary difference between today and Tuesday will be in terms of sky conditions; models are in agreement in advertising increased moisture advection in the upper levels of the atmosphere. That will lead to increasing clouds Tuesday afternoon, though filtered sunlight and intense WAA throughout the column will still drive surface temperatures into the upper 70s to near 80 degrees.
Tuesday night into Wednesday, a closed circulation aloft will drop into the Midwest, with the track of the 500-mb circulation likely passing near or just north of COU Wednesday night into Thursday. As this happens, WAA and moisture advection will intensify out ahead of a developing surface low in KS. A round of convection is likely to fire over central Kansas late Tuesday evening as the cold front pushes into a warm and humid air mass. Favorable dynamics indicate the potential of severe weather there, with a small MCS potentially developing and moving eastward into the Kansas City area after 06 UTC Wednesday. This MCS (or a weakening remnant) may push as far east as mid-MO by sunrise Wednesday, giving Columbia its first chance of showers and storms. One or two may contain gusty winds or small hail, though the severe threat will remain low.
Throughout the day Wednesday, the aforementioned sfc low will continue to progress eastward. It will also start to slow down and occlude as the upper-level trough takes on a deeply negative tilt. What happens in mid-MO at the surface Wednesday afternoon will depend upon how quickly convective debris can clear the area. Insolation will be limited, so SBCAPE values should be limited as well. Never the less, the cold frontal boundary will be passing through Wednesday afternoon, providing a focal point for convective initiation. Another wildcard in the mix will be the timing of the front. The 12 UTC GFS pegs the FROPA at circa 18 UTC, which would mean less time for morning rain to clear and thus lower storm/severe chances. The 18 UTC NAM and extended HRRR, however, both concur with a significantly later FROPA - likely between 21 UTC and 00 UTC. Given the tendency for models to rush these events (and the fact that this system will be in the early stages of occlusion), I foresee the NAM/HRRR as having a better grasp on this system. That will lead to a second chance of showers and storms Wednesday afternoon, a few of which may be strong to severe. Interested parties should monitor this situation closely, as increased sunshine could create favorable conditions for discreet cells or even a fast-moving QLCS, as is currently advertised by the 18 UTC NAM-nest.
After the front progresses through mid-MO, mid-MO should see the dry slot of the system and thus a quick end to ongoing rain Wednesday evening. A few hours of drytime look likely Wednesday night before wrap-around rain from the occluded low in IA enters the picture for Thursday. Due to clouds, rain, and strong CAA on Thursday, highs will trend much lower.
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