Current Conditions at Sanborn Field
Wednesday Night- Cloudy. Showers and thunderstorms likely throughout the night. Low: 58-62
Thursday - Morning clouds with showers and afternoon clearing. High: 66-70
Thursday Night - Clear. Low: 52-56
Friday - Sunny. High: 68-72
The 12Z NAM was primarily used in the creation of this forecast for the next few days. Our main feature of note is a stationary boundary and associated low pressure system that is currently to our southwest located over the Four Corners region.
As of Wednesday afternoon, our flow at the 250-mb level is more of a meridional pattern with our winds at this level southwesterly. These winds, along with the ridge over the Eastern United States have contributed to our warmer weather over the past couple of days. As Wednesday evening progresses, we will receive several waves of high values (> 1.5 * 106 s-1) of divergence at 250-mb. This divergence corresponds, roughly, to the right entrance region of a jet streak which is sitting over much of the United States spanning from West Texas though the Great Lakes region. The jet will remain over our area through most of Thursday when it will begin to migrate to the east. After the jet leaves, we will find ourselves at the bottom of a trough. Central Missouri will still see some areas of divergence, but nothing as extreme as Wednesday night should be expected on Friday. By Saturday, our flow should become relatively zonal, though the low pressure system will stay parked over West Texas.
Over the course of Wednesday evening, we will see increasing values of vorticity at the 500-mb level originating from the low pressure system near the U.S.-Mexico border. Vorticity maxima (> 3.0 * 10 6 s-1) should be found over Columbia from sundown through about midnight. Another round of vorticity maxima can be expected to go through our area on Thursday morning. Minor values of vorticity will plague the region throughout the day on Thursday. One last significant circulation will go through the area on Friday around 01z. The circulation will correspond with the end of the jet streak moving out of Central Missouri to the North East. Once the 250-mb level jet moves out of the area, the 500-mb level will remain calm for the duration of Friday and Saturday. The trough affecting our weather by that time will cause the winds to shift from a southwest direction on Wednesday afternoon to a northwest direction by Saturday.
At the 700-mb level, we will see values of omega up to -20 mircobars per second indicating UVM through the rest of Wednesday evening, and into the overnight hours of Wednesday. A training line of pockets of vertical motion will stream through the state from southwest to northeast centering on Boone County for most of the night. Gradually, this line will shift south and east toward the boot heel of Missouri. However, we will remain saturated at this level through lunchtime on Thursday. The 700-mb level will remain dry for the remainder of the forecast period.
The 850-mb flow from the low pressure system will cause tropical moisture from the Gulf of Mexico to be advected into our area. A low level jet will be present for most of the evening on Wednesday. Along with the LLJ, there will be more significant vertical motion through Mid-Missouri and southward. The 850-mb level will remain saturated though Thursday afternoon. This level will continue drying out over the course of the day on Friday. By Saturday night, however, we could see the moisture return to the area.
At the surface, our winds will be out of the south for Wednesday night until a cold front passes through our area around midnight. Solenoids can be seen on the 1000-500-mb thickness and MSLP plot. The solenoids can be found ahead of the cold front with winds out of the south, signifying WAA. Behind the cold front winds will be out of the north, signifying CAA. After the cold front moves through, a high pressure system will take its place by overnight Thursday into Friday.
While there is plenty of instability in the atmosphere (CAPE values of over 1600 J/kg), any significant severe development is unexpected due to lack of necessary shear. However, Central Missouri should expect very heavy rain and thunderstorms overnight with the potential of receiving 0.5” to 1” of rain overnight.
Future forecasters should look for the progression of the low pressure system located over Texas.
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