Thursday, October 1, 2020


 Current Conditions at Sanborn Field




Thursday Night -
Mostly Clear. Low: 36-40
 
 

Friday -
Partly cloudy. Becoming mostly cloudy by evening. High: 58-62

Friday Night -
Becoming cloudy. Low: 44-48

Saturday
- Cloudy. Scattered showers in the morning. High: 56-60
 
 

Sunday -
Partly cloudy. High: 56-60

 
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Discussion: 
On Thursday night, Columbia will experience calm skies with lower temperatures than the previous nights. Moving into Friday, expect to see clouds increasing as the day continues and reaching cloudy skies by nighttime. Friday's daytime temperatures will be slightly cooler than Thursday's, but will stay warmer throughout the night. Clouds from Friday are expected to continue into Saturday, where light rain can be anticipated in the morning, but tapering off by afternoon. Early Sunday, a cold front passes through Columbia, keeping temperatures steady.
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Forecaster: Lamb, Cochran, Travis
Issued:  5 PM CDT 1 October 2020
 
Technical Discussion (The nerdy stuff we are discussing in class)


The main concern for this forecast period is the potential first frost of the season as temperatures will continue to plummet to end off the week. Attention then turns to the next system that will drop out of the north into the Midwest that will bring with it chances for rain into Saturday. The GFS was used for overall pattern recognition while GEFS and SREF were consulted for temperature patterns.

Much of south-central Canada and the Upper Midwest remain on the poleward side of LW trough for the entire forecast period so suggests GFS plots of 250-hPa heights and wind. This will allow cold air to surge south. GFS 700-hPa RH plots are in good agreement that moisture associated with the parent LW trough will stay confined to the Upper Great Lakes Region. Winds at 850 hPa will stay out of the NNW, allowing the cold air to penetrate further south into the Mid Mississippi Valley. The GFS wants to keep the 850 hPa 0-C isotherm to the north of Columbia. Temperatures could very well dip into the upper 30s and possibly lower. Would not be surprised to see the potential for frost early Friday morning as skies will remain clear and winds relatively calm. 

Attention turns to a SW seen in 500-hPa heights and vorticity that both models want propagating along the parent LW mentioned earlier. As the aforementioned high pressure at 850 hPa and the surface slides to the east over the Middle Mississippi Valley, winds will see a shift from northwest to southwest coinciding with the wave's arrival. The LLJ originating from the Gulf sets up over the Southern Plains that will advect plenty of moisture into the Middle Mississippi Valley during the day on Friday. The moisture, combined with the dynamically primed SW will result in high chances for precip Friday evening into Saturday. GFS soundings show a moistening of the lower levels with a closing "zipper" at the surface occurring around 09 to 12z Saturday. GFS continuity has been pretty poor with this system as yesterday's 12z GFS had full saturation occurring Friday afternoon around 21z. Regardless, seems more likely that precip will begin early Saturday morning in the form of scattered showers throughout mid-Missouri. 

GFS soundings indicate a drying out of the column by 18z Saturday, so showers should taper off by then. However, soundings do not fully dry out so clouds will remain into the evening on Saturday until potential FROPA Saturday night into Sunday. Around 06z on Sunday winds take a hard shift from southeasterly to northwesterly hinting at the passage of a cold front. The column dries out almost completely (save for likely fair weather cumulus clouds) during the day on Sunday. Sunday soundings from the GFS show straight northerly winds at the surface and northwesterly winds aloft will keep temperatures from rising significantly on Sunday and thus will likely see similar temps to Saturday highs.

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