Current Conditions at Sanborn Field
Clear. Low: 43
Sunny. High: 68
Clear. Low: 43
Pleasant Autumn temperatures are here to stay as a calm and cool weather pattern continues through the rest of the week. A lack of nighttime cloud cover due to a lack of moisture and the presence of high pressure means colder-than-average low temperatures in the lower 40s, so consider bringing plants with poor cold tolerance inside overnight.
Forecasters: Ritsema, Clark, Baker
Date Issued: 09/27/2022 9:00 AM CDT
Our forecast primarily used the GFS due to its better handle on our current temperatures; the NAM was around 10 degrees cooler than our temperatures at the time of forecasting while the GFS was within a couple degrees. However both were used as a guidance while putting together our forecast because both models show the meridional flow that ultimately gives way to the cooler pattern we will see through our forecast period.
Over the past couple of days, mid-Missouri has seen surface wind gusts of over 20 mph. The 250 mb jet stream associated with the trough to our east will move out of our area between 21z today and 06z tomorrow. After it leaves, our flow will become zonal until 21z tomorrow, where we start to transition to a weak meridional flow associated with a shortwave pattern that passes over us. This flow will be around 5-20 kt, leading the forecaster to lead towards calm conditions in the upper levels.
The 500 mb vorticity map tells a similar story to the 250 mb wind map. A lack of significant vorticity values over us for our forecast period will further support the quiet upper-level forecast. The winds take on a similar pattern as 250 mb, with a small area of anticyclonic flow, associated with the same shortwave we saw at 250 mb, in south-central MO developing at 03z Thursday. If lower-level moisture is present, we could see some cloud development over the next couple days.
At 700 mb, we can see that after 21z Tuesday there is no significant amount of moisture to facilitate cloud development for the rest of the forecast period. This is likely due to a high pressure system moving into the area from the west, pushing the little moisture present out to the east. This high pressure system will become our dominant system, helping to ensure a clear sky and stable temperatures for the rest of the forecast period.
There is even less moisture available at 850 mb, ensuring no low-level clouds for the forecast period. The same high pressure system present at 700 mb can be seen moving in at 850 mb and temperatures at this level remain low which further supports the idea of cooler nighttime temperatures, no cloud cover, and daytime highs staying below average. At the surface, the picture is similar to the 850 mb level, with low humidity and nighttime temperatures in the lower 40s.