Current Conditions at Sanborn Field
Thursday: Mostly cloudy. High: 72
Friday: Mostly cloudy with light rain throughout the day. High:65
Friday Night: Mostly cloudy with rain stop. Low: 57
Saturday: Chance of showers and thunderstorm development. High: 83
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Discussion:
After the long period of continuous dry and sunny days, some much needed precipitation is expected to make its way to Columbia. Light rainfall will occur for much of Friday. Additionally, Saturday afternoon has a decent chance of showers and thunderstorms.
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Forecasters: Hefner, Samson, Macko
Date Issued: 5/04/2023 10:00 AM CDT
Technical Discussion:
The focus of the forecasting period was on incoming precipitation expected Thursday night, as well as the potential for thunderstorm development Saturday afternoon. The GFS was selected as the primary model for this forecast period as it had better handling of initial moisture within the upper levels. It is important to note the NAM and GFS were under large model disagreement specially when handling the potential thunderstorm development on Saturday afternoon. Future forecasters should be aware of the sizable uncertainty within the models and should proceed with careful analysis of multiple model outputs.
In the upper levels, the Omega blocking pattern which has dominated our recent weather has begun to release its grip due to the decaying low-pressure system over the East Coast. We are currently under the effects of an upper-level ridge centered over the Central Plains, however we will be quickly transitioning to meridional flow.
Our region will lack moisture until Friday 00Z. At this time, the low-level jet will begin to transport an abundance of moisture both in the 700 and 850mb levels into mid-Missouri. Additionally, measurable vorticity will be present for Thursday night and Friday morning providing the required forcing for precipitation. Much needed rainfall is expected around Friday at 06Z and will persist for much of the day Friday. Accumulation totals will be on the lighter end and remain under 0.10 inches.
Saturday afternoon poses the threat of thunderstorm development occurring over mid-Missouri. For Saturday at 21Z GFS model soundings output surface CAPE values over 3000 J/kg, -9 Lifted Index, directional wind shear, non-existent CINH, and a total totals of 52. Currently there is still much uncertainty with this event as is shown in NAM soundings with far less bullish thunderstorm indices. The main source of the uncertainty is due to determining the amount of diurnal heating that will occur Saturday. GFS soundings output a surface temperature in the high 80s, while the NAM outputs a much cooler surface temperature in the mid 70s.
Both models agree that timing for thunderstorm development will be a short window of opportunity around Saturday 21Z. Additionally, there is strong consensus between the models outputting precipitation totals over 0.5 inches of rainfall for this event.
-Hefner
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