Current Conditions at Sanborn Field
Thursday Night - Clear. Low: 32-36
Friday - Partly cloudy early. Mostly clear in the afternoon. High: 56-60
Friday Night - Mostly clear skies. Low: 40-44
Saturday - Increasing clouds becoming mostly cloudy. High: 68-72
Sunday - Cloudy. Morning showers. High: 52-56
Clear skies after the cold front last night will allow for colder temperatures Thursday night leading to the first frost advisory of the season. Clouds will begin to roll in early Friday morning, but clear up by the afternoon. Friday is expected to be cooler than Thursday, and temperatures won't warm up until Saturday. After a clear Friday night, clouds will begin to accumulate as Saturday evening approaches. The clouds will stick around into Sunday. A cold front early Sunday morning will bring rain that tapers off before noon.
After a prolonged period of quiet weather and above average temperatures, the pattern looks to finally be shifting to more continuous meridional flow typical of this time of the year. The main issue we are focusing on this period is yet another cold front that will be approaching the region Sunday morning and the effects that come with it. The GFS was used in constructing this forecast with consultation of SREF and GEFS plumes for temperatures. Less emphasis was placed on the GEFS by Sunday due to extremely poor agreement between the members.
As mentioned above, upper-level flow at 250 hPa has turned meriodional with a LW trough parked right over the central CONUS into south-central Canada. The polar jet sits just to the south of Columbia as of 21z and GFS shows that the wave will continue to dig further south Thursday night. Little moisture and a whole lot of surface dry air will keep skies clear into Thursday night. Seeing as Thursday night is the first clear night post cold frontal passage, expect temperatures to dip down quite lower than what we have seen thus far this season. The NWS has issued a frost advisory for mid-Missouri (KCOU included) with freeze warnings over SE Missouri. In the lower levels, the 850-hPa 0C isotherm moves just to the south of Boone County Thursday night, and the 1000-500-hPa 540 thickness isopleth reaches well south of Columbia reaching the MO-AR border by morning. The result will be temperatures in the low to mid 30s by Friday morning.
By friday, the LW begins to progress off to the NE and the cold air with it. GFS 500-hPa heights show flow turning zonal in between the NE propagating LW and the SE propagating SW. Winds throughout all levels in the column persist out of the WNW turning more westerly by evening. Friday will look much like Thursday with similar day-time highs and mostly clear skies. Surface high pressure will remain to the south of Missouri keeping us in westerly flow.
By Saturday upper-level flow looks much the same out ahead of the SW that will cause headaches for forecasters Sunday. The GFS shows ridging that had developed over the SE CONUS and a sfc anticyclone associated with it will move off to the east putting the Midwest in SSW flow in the lower levels. The approaching low pressure system associated with the mid-level wave will reinforce south-westerly flow resulting in strong WAA Saturday. Temperatures will be on the rise potentially reaching into the mid 70s.
By Saturday night into Sunday morning a prominent cold front seen on GFS MSL maps will pass Columbia between 06z and 09z. Winds will take a hard shift from SSW to the NNW. This front is less likely to knock temperatures as low as Thursday night as MSLP overlaid with 1000-500-hPa thickness show looser gradients and smaller solenoids (weaker CAA) than seen Thursday. GFS 700-hPa RH shows increased moisture moving into Midwest associated with the strong south-westerly flow in the mid to lower levels. GFS Skew T's show a rapid saturating of the column Sunday morning and with moderate UVM will likely see rain that tapers off by noon. GFS Skew Ts indicate a mostly cloudy sky persisting into Sunday evening.
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