Tuesday: Mostly cloudy with occasional rain showers. High: 72°F
Tuesday Night: Clouds clearing. Low: 54°F
Wednesday: Party cloudy to start with clouds increasing throughout the day. High: 73°F
Wednesday Night: Clouds clearing. Low 58°F
Thursday: Increasing clouds. High: 79°F
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General Discussion:
Sporadic showers persist through today as a weak cold front moves into Columbia. However, as night falls expect clouds to start clearing bringing cooler temperatures (54°F). Pushing into Wednesday, look for a partly cloudy sky to start with increasing clouds throughout the day. Temperatures will remain below average (81°F) for the remainder of the forecast period.
– Beach
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Forecasters: Alcorn, Beach, Chirpich, John
Date Issued: 09/24/2024 9:00 AM CDT
Technical Discussion:
Key Messages:
- A gloomy week will remain in place with rain chances increasing throughout Tuesday.
- Seasonal temperatures will be the trend throughout the work week (low to mid 70s).
The GFS and NAM models were used for this forecast, in order to compare and contrast differing moisture content and timing.
A positively-tilted trough is moving eastward at 250MB. An upper-level low will move into the area from the north throughout Tuesday and Wednesday. Modest wind divergence will increase tonight into Wednesday morning, though is scattered in nature. The southeastward motion of the low-pressure system will slow down and remain dormant over the Ozark Plateau, eventually being cut off from the aforementioned trough.
Vorticity will be consistent over mid-Missouri throughout the week, as seen at 500MB, though values will increase dramatically throughout the day today. It will decrease by Wednesday morning, but is expected to increase later into the week (Thursday afternoon into Friday). This could provide the forcing necessary for precipitation chances at the end of the forecast period.
Both the GFS and NAM indicates lift at 700MB tonight into early Wednesday morning, though PWAT values are weak (only trace amounts of rain expected). At worst, mid-Missouri will see overcast conditions and possibly sporadic showers. Significant CAA is moving into mid-Missouri by 00Z Wednesday, indicating frontogenesis. This is supported by a temperature gradient at the surface as seen at that same time.
By Wednesday morning, moisture and lift are expected to decrease leading to some possible breaks in the clouds. This is due to the aforementioned cold front stalling out past Missouri, preventing Gulf moisture from reaching the forecast area. Clouds are expected to return Wednesday night, but no rain chances are expected due to the lack of forcing and surface moisture. From Thursday night into Friday, lift and moisture are expected to return to mid-Missouri, thanks to a tropical cyclone making landfall in the Gulf states, moving northward towards the Ohio River Valley. Future forecasters will need to investigate possible increases in lift as well as moisture timing, since the NAM and GFS do not agree on when moisture will fully return into the region.
Moisture is less impressive at 850MB, showing a dry slot most notably around Wednesday night, hampering significant rain chances. Regardless of the ample moisture at higher elevations, lackluster moisture between 850MB and the surface will only produce scattered showers into tonight.
Frontogenesis is best shown at the surface with low temperatures tonight dipping into the low 50s. Dew points Wednesday morning are expected to drop 10 degrees compared to Tuesday night (upper 40s to lower 50s dew points). Although moisture content Wednesday night through Thursday morning is relatively high towards 500MB, dew points are lackluster at the surface, leading to initial cloud cover. However, temporary clearing is expected Thursday morning. Dew points will rebound Thursday afternoon into Thursday night. Given sufficient ingredients in place (lift, vorticity, wind divergence aloft), rain chances increase at that time. Future forecasters will need to pay attention to optimal rain chances by the tail-end of the week.
-Alcorn, Chirpich