Monday, November 29, 2021

 

Current Conditions at Sanborn Field




Monday Night:
Clear. Low: 35



Tuesday:
Increasing clouds. High: 54


Tuesday Night:
Partly cloudy. Isolated showers. Low: 39

 


Wednesday: Becoming clear. High: 59



Wednesday Night:
Increasing clouds. Low: 47


 

 

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Discussion:
As November comes to an end with December quickly approaching, temperatures will stay above average for this week. Tonight, the sky will clear out with light winds coming from the southwest and lows dropping into the mid 30s for the mid-Missouri region. However, clouds will return as we head into Tuesday with highs reaching the mid 50s, but rain chances return Tuesday night. This event will not be a complete washout for the region; only trace amounts up to 0.05 of an inch are expected. Lows will drop into the upper 30s and low 40s Tuesday night and Columbia will see the possibility of showers. Tuesday night looks to stay partly cloudy. As the Mid-Missouri region clears out by Wednesday, temperatures will climb into the upper 50s for a mild day and night with lows in the upper 40s and increasing cloud cover. 

-Gromada

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Forecasters: Alexander, Gromada, Gotsch

Date Issued: 11/29/21 5:00 PM CST

Technical Discussion:    

After a very temperate Thanksgiving, a ridge has settled on the western half of the CONUS causing the sky to clear and diurnal temperature to fluctuate greatly.  While the sky will remain clear for the next 12 hours, clouds are expected to begin filtering into the area on Tuesday due to a 250mb shortwave trough ahead of a slightly stronger shortwave trough that will traverse the region late Tuesday night into early Wednesday. There is not a lot of active weather expected in this forecasting period, but nonetheless the NAM and GFS both were used. We needed to use both models this shift because the GFS was doing better with the upper level winds and surface temperatures while putting a lot of moisture into the atmosphere that we felt did not belong. The NAM was missing accuracy with the surface temperature, but we felt its moisture amounts were much more reasonable. 

Currently, the jet stream is flowing north of the Rockies, zonally over Montana, then gently turning into a northwesterly wind over South Dakota and Nebraska. From there it maintains a fairly straight path, flying over points such as Missouri and northern Gerogia. As mentioned before, there are two shortwave troughs expected to pass over Missouri before Wednesday morning. The first shortwave is expected to enter the region around noon on Tuesday and exit later that evening. This is a mild shortwave and is likely to only bring a few more clouds to the area. The second shortwave, entering Missouri around 12AM Wednesday is a bit stronger and positively tilted. There is some upper-level divergence and mid-level negative omega associated with this shortwave. Mid to upper-level precipitation could occur with this system, but with a large dry layer beneath it, most of the precipitation will likely turn into virga. That being said, there is a chunk of mid to lower-level moisture in Iowa and if that moisture were to make its way into Mid-Missouri, we could see slightly higher precipitation amounts. All in all, we expect total precipitation accumulation amounts to be less than .05 inch.

Once the second shortwave exits Wednesday morning, the sky should begin clearing up again creating a day similar to Monday, albeit with a few more clouds. Wednesday night the sky will become a bit more cloudy, and with light winds from the southwest, the temperature should be warmer than the preceding nights.

The next shift should pay attention to the shortwaves' passage and where areas of moisture are located. Otherwise, there is not a lot of action expected in the next few days.

-Alexander

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