Current Conditions at Sanborn Field
Friday: Clouds increasing throughout the day. High: 81
Friday Night: Cloudy with a slight chance of rain. Low: 52
Saturday: Clear skies. High: 75
Saturday Night: Clear. Low: 57
Sunday: Mostly sunny and hot. High: 90
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Discussion: Increasing clouds as the work week comes to a close will signal the passage of a weak cold front this evening. This cold front will prompt a slight chance of rain before midnight tonight with accumulations less than 0.1 of an inch possible. Skies will clear by morning giving way to a beautiful Fall Saturday. As the weekend progresses high pressure to the south will swing our winds to a more southerly course setting up Sunday to be mostly sunny but unseasonably hot! Chiefs fans attending the game at Arrowhead Sunday will need to hydrate as temperatures in Kansas City could reach the upper 90's during the game.
-Bongard
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Forecasters: Splater, Schneringer, Bongard
Date Issued: 09/24/21 10:00 AM CST
Technical discussion:
For this forecast period the 06Z run of the GFS20 model was used based upon its consistency with observed temperatures and winds Friday morning. The NAM was also fairly consistent but generally colder than what was observed. Additionally, SREF plumes were used to check on model consistency between runs. While, there was consensus regarding temperature the SREF revealed slight inconcistencies regarding precipitation accumulation in the region tonight and therefore pushed forecasters in the direction of the GFS model. Soundings were also used to determine timing of precipitation in the region as well as identifying wind changes both in the short term dealing with fropa tonight as well as the copious amounts of WAA Saturday night into Sunday.
For Friday, upper level 250-mb analysis shows the base of a well-amplified trough in central Canada extending down into the Midwest Friday morning. This trough will bleed to the east over the course of the day advecting some vorticity at 500 mb into Mid-Missouri this evening. This trough is also responsible for dragging the aforementioned weak cold front through the Midwest Friday evening. According to GFS model soundings, fropa looks to occur between 00Z and 03Z Saturday. Zonal flow in the lower levels will help to steer moisture into the region associated with the frontal boundary. The profile moistens from the top down through the evening and winds will shift from a southwesterly course to northerly by 06Z Saturday. Even so, moisture overhead is short-lived prompting only a slight chance of rain locally with accumulations being 0.05 at best. Convection does not look to be a concern at this time as model soundings do not feature any values of CAPE. Worth mentioning were the existence of higher accumulations to the east. Future forecasters may monitor any shifts in precipitation accumulations with future model runs.
By Saturday morning, the profile dries out behind the cold front. The region exists in the downstream flow of the upper level trough escaping to the east while a ridge builds into the CONUS from west to east over the course of the day. Northwesterly flow presides over the region at multiple levels Saturday keeping the atmosphere overhead stable and dry. Surface high pressure builds into northeastern Texas by Saturday afternoon which will helps to dramatically increase temperatures in the region Sunday as the western flank of the high opens the region up to breezy southerly flow and considerable WAA.
Sunday will feature mainly sunny skies with only scant moisture values found in the lower levels but significant warm air advection pushing Sunday high temperatures well above seasonal averages as the surface high treks further east.
-Bongard
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