Current Conditions at Sanborn Field 

 

Tuesday: Sunny. High: 97

Tuesday Night: Clear. Low: 71

Wednesday: Sunny with afternoon clouds. High: 90

Wednesday Night: Cloudy with rain. Low: 59

Thursday : Morning rain followed by overcast conditions. High: 67

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Discussion:

Mid Missouri is in for another above average temperature day! Look for a sunshine dominate sky to bring temperatures into the upper 90s. Wednesday looks to start off warm and sunny before clouds start to build in ahead of our cold front. This cold front will move through Wednesday night, giving mid Missouri showers through Thursday morning. High temperatures behind the cold front are looking like our low temperatures we have seen the past couple of nights.

Ritsema

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Forecasters: Baker, Clark, Ritsema

Date Issued: 09/20/2022 9:00 AM CDT

Technical Discussion:

 

As a strong upper level ridge looks to keep most of our forecast period in above average heat, a change in the weather pattern looks to come late in our forecast period. For the forecast period, the GFS was the main model used to guide our forecast as it had a better handling of the frontal passage Wednesday as well as the temperatures waking up this morning. NAM leaned a whole nine degrees cooler. 

 

As the forecast as been pretty quiet lately due to the high pressure system that is dominating the CONUS all the way up to the 250mb level. The jet stream looks to be situated northwest to southeast through Iowa stretching across northeast MO. This placement allowed northern Missouri to be placed under the jet stream flow of 50 knot winds overnight. It does seem to drift north throughout the day today before a shortwave travels through pulling the jet stream over Missouri. Along with the jet stream moving overhead, there are pockets of upper level divergence that moves over starting 18Z Wednesday. The values are not all that impressive, but it looks to dance around MO through the end of our forecast period. 

500mb tells a similar story. The winds have already taken on more of a westerly component, shifting from southwest to west last night. A narrow band looks to move through 12Z today; however, with no lifting mechanism, this leads the forecaster to lead towards circulation due to diurnal heating and energy. The shortwave looks to move through mid Missouri Wednesday 15Z, carrying with it high values of vorticity. This indicates there is some circulation that could promote lower level moisture, if we have it.

 

With some upper level mechanisms hinting at the fact of something is going on Wednesday afternoon through Thursday morning, the 500mb Relative Humidity map is able to tell us if we have substantial moisture to support surface rain. The 70mb map shows a south wind bringing in the moisture that we are already feeling at the surface. As this southerly flow continues throughout the day, it will slowly take on a more westerly component, packing Missouri with high moisture values. These high levels looks to reduce as the front passes, but quickly return after our forecast period. 

The 850mb map tells a similar story, the LLJ sticks around 20 knots throughout the day today. This again contributes to the moisture and record breaking heat Missouri will see. Wednesday 06Z the winds shift to the west allowing for zonal flow. This allows the shortwave to bring in energy and the frontal boundary. 

With all of the winds shift to a westerly component around Wednesday 09Z, the frontal boundary looks to approach. The models have a better agreement in timing, but there is still disagreement. The NAM is pushing the later solution with mid Missouri still reaching 90s through the afternoon hours. GFS has it moving through earlier, which could combat temperatures not reaching the 80s. When closely analyzed in relationship to the high pressure system to the south, the front looks to keep Missouri in another above average heat day Wednesday, before clouds pick up in the afternoon hours, and the rain and showers will pull in that evening. 

 

A sounding was used to confirm these findings with a very dry surface layer sticking around through most of the forecast period. PWAT values around 1.5 are supported, but there is a lack of lift and a saturated profile. Rain amounts overnight Wednesday into Thursday should result no more than half an inch at most. 

Baker