Clouds will move back into central Missouri today preceding some light showers this afternoon. This cloudiness will continue overnight with another round of showers moving through the area. The rain will clear before sunrise Saturday morning, but cloud cover will persist throughout the day. A cold front will push storms through Mid-Missouri Saturday night into early Sunday morning. Light winds and soggy ground conditions lead to a chance for morning fog Sunday morning. No chance of precipitation on Sunday, but the cloudiness will remain throughout the duration of the forecast period. Total rainfall amounts will reach 0.4"-0.6" by Sunday morning.
-Splater & Schneringer
Forecasters: Splater, Schneringer, Bongard
Date Issued: 10/1/21 10:00 AM CST
GFS was the model of choice for this forecast period as it was optimal in handling initial conditions as well as precipitation accumulations for the forecast period. SREF and GEFS plumes were also used in determining the quality of the model run. SREF revealed inconsistencies with the NAM run especially in precipitation accumulations where NAM dProg/dt showed a diminishing accumulation even though chart analysis tells a different story. Model soundings from the 06Z GFS run were also utilized in the areas of timing and accumulations of rainfall as well as thunderstorm probability.
At 250 mb the flow continues to be well amplified and meridional across the CONUS. The well established trough to the west that has slowly made its way across the Rockies features a closed low over the Four Corners region Friday morning that will slowly migrate to the northeast by Friday night pushing the upper level ridge currently residing over the Midwest to the east. Strong southwesterly flow in the transitional zone between trough and ridge over the region will persist aloft until Saturday night when the trough and associated frontal system move through the region. By Sunday a post frontal weather regime will preside over the Midwest backing winds around to the northwest and ultimately helping to dry the region out by the end of the period.
The 500 mb upper level model chart again features southwest flow in the upstream region of the trough to the west. Some vorticity exists to the northwest of Missouri Friday but should not influence the region. Copious amounts of vorticity will begin to advect into the central CONUS by 12Z Saturday as the low pressure center associated with the trough pushes into Kansas at that time. Vorticity will push into Missouri by Saturday evening as expected just ahead of the cold front. Frontal passage looks to occur between 03Z and 06Z Sunday which is when we expect highest probabilities of rain and convection for the period.
In the lower levels moisture values continue to maintain high PWAT values as the region resides in the warm sector of the encroaching mid-lat cyclone. Model soundings for Friday afternoon have any CIN available in the morning eroding away by 18Z opening the atmosphere up to CAPE values of 1200 J/kg. Some question exists as to whether this will lead to convective development as a lack of LLJ or any real dynamical forcing may diminish convective chances. That being said convection cannot be entirely ruled out Friday afternoon. The profile remains moist and promotes scattered showers and rain chances through Saturday evening. Heavy rain will be possible just ahead of the frontal passage Saturday night. After 06Z the profile begins to dry out and a post frontal weather regime builds into the region by Sunday morning as the forecast period comes to a close.