Fair weather for Friday and Saturday as our high temperatures continue to climb back towards normalcy and away from the frigid conditions experienced earlier in the week. The weekend will be more windy than Friday despite the warming temperatures. Clouds will filter into mid-Missouri Sunday and the chance for rain can't be ruled out by noon Sunday though not enough to dampen what should be a warmer weekend than recently felt in the area.
For this forecast period GFS was the model of choice due to close agreement with initial conditions at the start of the forecast period. NAM was running a bit too cold for confidence at this time. Our biggest challenge of this forecast period was accounting for the LLJ Saturday and Sunday and what it means for the temperature forecast as well as the precipitation chances Sunday. The impact of a sudden change to zonal flow also factored into our decision making.
250-mb analysis reveals mid-Missouri in the axis of the amplified trough over the central CONUS. This trough will trek eastward away from the region and we will transition to a zonal flow by Saturday 12Z. Zonal flow persists through early Sunday morning. By Saturday afternoon a jet streak will drape over the Midwest as a new extremely positive tilted trough emerges in the upper level flow from central Canada down into the Rockies and out off the coast of California. This trough will contain Columbia's next weather maker.
Vorticity analysis at 500 mb depicts energy associated with the wraparound portion of the mid-latitude cyclones to our northeast. This vorticity will escape to the east over the course of Friday. As the flow transitions to zonal some shear vorticity will advect into the region but will a lack of significant moisture Saturday not much is expected other than a few passing clouds. Significant vorticity will trek into the Midwest over the course of Sunday as the next system associated with the long wave trough to our west impacts the central CONUS by Sunday afternoon.
The low level moisture profile is fairly dry Friday and Saturday save for a chance for fog Saturday morning. Model soundings reveal a significant radiational inversion at 12Z Saturday with winds at the surface out of the south at 5 knots. Worth is significantly stronger winds above the surface leading to the idea of significant speed shear for much of the weekend. 850-mb analysis builds a LLJ into the southern Plains Saturday afternoon which will advect much warmer temperatures into mid-Missouri. This will help to regulate high temperatures away from the bitter cold experienced this week. However, looking at PWAT values on model soundings the LLJ will not provide sufficient moisture (0.6 by 15Z Sunday) to ramp up precipiation chances Sunday.
What this means for the region is temperatures rebounding to above freezing Saturday and Sunday. Sunday will see clouds move into the region ahead of the advancing system from the west. The chance for rain will exist mainly in the afternoon and evening Sunday though accumulations look light at this time.