Monday: Morning clouds, then mostly sunny. High: 68°F
Monday Night: Clear. Low: 50°F
Tuesday: Mostly sunny. High: 78°F
Tuesday Night: Cloudy. Low: 57°F
Wednesday: Mostly cloudy, with afternoon rain possible. High: 77°F
=============================================================================
General Discussion:
Temperatures mid-week will warm into the upper 70s, well above the seasonal high of 69°F. Dry conditions will linger through Wednesday, with precipitation chances picking up Wednesday afternoon. Less than 0.1” of rain is expected, so impacts will be minimal.
- Nobles, Elston, Schifferdecker
=============================================================================
Forecasters: Nobles, Elston, Schifferdecker
Date Issued: 04/21/2025 10:00 AM CST
Technical Discussion:
Key Messages:
- Zonal flow aloft keeps our weather quiet Monday and Tuesday.
- Chance for rain Wednesday evening but little to no impacts expected.
- NAM and GFS models are not in good agreement for Wednesday for moisture.
Current surface analysis shows the cold front that brought us our severe threat yesterday off to our east along the Illinois and Indiana borders down through eastern Tennessee, and back through central Louisiana. This is bringing us westerly winds at the surface at around 10 kts and some cloud cover that will clear by mid-day. Aloft at 300mb there is currently southwesterly winds as we are on the backside of a jet streak. This will move off by 18z today and will shift the winds into a more textbook zonal flow aloft with winds from the WSW at 40-50kts for the rest of Monday. Moving down to 500mb there is much of the same as areas of vorticity moving off to our east leaving zonal flow behind it for the remainder of Monday. 700mb there is no moisture over Missouri, and 850mb shows some splotches of moisture that are currently over Mid-Missouri that will clear out by around 18z today.
Moving into Tuesday zonal flow at 300mb continues with winds aloft between 40-50 kts. At 500mb there is still zonal flow present for Tuesday, but there are some weak areas of vorticity associated with a weak shortwave that move through our area early in the morning (09z). The rest of the day there is zonal flow with another shortwave moving through late Tuesday night (03z). The moisture for Tuesday is minimal as the GFS shows no moisture at 700mb, but the NAM has a line of moisture from central Missouri into Michigan starting around 21z on Tuesday and staying around until Wednesday at 15z. The GFS eventually picks up on the moisture around 06z on Wednesday and has it leaving around the same time as the NAM. At 850mb there is an area of high pressure that moves across southern Missouri in a northeasterly component. This shifts the winds over Columbia from west to south throughout the day on Tuesday. But due to the winds being very weak (10-20 kts) and the high pressure to our south for most of Tuesday the moisture will stay to our south and west.
Wednesday could be a little more active as the GFS has some areas of divergence moving through Missouri Wednesday morning at 300mb. The NAM is almost completely different though as it has just one area of strong divergence aloft over central Kansas all of Wednesday and nothing over Missouri. All of these areas of divergence for Wednesday are associated with shortwaves embedded within the zonal flow aloft. At 500mb there is still apparent zonal flow with shortwave troughs embedded. Both the NAM and the GFS have weak areas of vorticity that move through Wednesday morning, but by Wednesday evening the GFS has pockets of vorticity in southern Missouri down through Louisiana. This is much different than the NAM which has no vorticity in those areas, but instead has a strong pocket in central Kansas. The models disagree greatly for moisture at 700mb on Wednesday with the NAM showing an area of moisture over Kansas while the GFS shows nothing, and the GFS has moisture in southern Missouri through Louisiana. At 850mb the models are in more of an agreement with both of them having moisture to our south for the day on Wednesday. The NAM has a stronger LLJ Tuesday night from western Texas into the panhandle of Oklahoma which is the reason it has more moisture into central Kansas compared to the GFS. This moisture stays off to our west though due to the high pressure just off to our east. As the high pressure keeps moving off to our east into the Ohio river valley, and the LLJ ramps up Wednesday night bringing in more abundant moisture Thursday. Future forecasters should look out for how the moisture builds into Missouri Thursday, and the NAM spinning up an area of low pressure Thursday morning. They should also watch for chances of rain later in the week.
-Elston