Wednesday, November 17, 2021


Current Conditions at Sanborn Field

Wednesday Night:
Clearing sky. Low: 32

Abundant sunshine. High: 46

Thursday Night:
Partly cloudy. Low: 30

Mostly cloudy. High: 48


Friday Night:
Overcast. Low: 37



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 Cooler temperatures are in store for Columbia for the remainder of the week as we look toward a break from our classes for Thanksgiving! These cooler temperatures are brought on by a cold front that moved through earlier on Wednesday. Our sky is expected to clear up through Thursday night, where clouds and slightly warmer temperatures will greet us for the rest of the week as a high pressure system to our south moves eastward. The rest of the week will be dry with no precipitation expected. Keep your winter jackets handy as we head into Thanksgiving break!
- McMullen


Forecasters: McMullen, Noblitt, Cochran

Date Issued: 11/17/21 5:00 PM CST

Technical discussion:     

    The 12Z run of the NAM40 was selected for our forecast. Both the NAM40 and GFS20 were nearly identical with the NWS surface map. However, the NAM40's projection of a high over the Atlantic Ocean and much better temperature plumes via the SREF when compared to the current temperature edged the GFS20 out of the running. Soundings were utilized for cloud cover and temperatures in conjunction with the SREF plumes. A LPS over eastern Canada and its associated trough will be the primary driver of our weather for our forecasting period.

    As we observe the 250-mb plot of heights, winds, and divergence, a trough located over the Plains begins to push east at the time of writing. A jet streak downstream of the trough axis and its associated divergence forces into the Middle Mississippi Valley until Thursday at 18Z when the trough crosses over the Mid-Missouri region. Afterwards an upstream jet streak begins to push in briefly before moving towards the Ohio Valley to connect to the previously mentioned jet streak, leaving Columbia by 3Z Friday. Some upper level divergence can be seen over Missouri at 3Z Saturday as a zonal jet stream flows across the central CONUS, contributing to developing cloud cover at the end of the forecast period.

    Next, the 500-mb plot of heights and vorticity shows very little circulation for the Columbia area as most of the circulation associated with the LPS over Ontario, Canada stays to our north. This remains true until Saturday at 3Z, when a small band of circulation moves with the zonal flow of the atmosphere. This band migrates east at 6Z Saturday, with the remaining time seeing spotty vorticity over the Midwest.

    For the 700-mb plot of heights, RH, and Omega, a strong band of moisture from the LPS over Ontario keeps Mid-Missouri saturated until 8Z Thursday, assisting in keeping our sky cloudy. However, once this band moves out, no significant areas of moisture are seen until 0Z Saturday. The bulk of this moisture is forecasted to remain to our north, east, and southeast over Iowa, Illinois, and the Ozarks.


    Finally, the 850-mb plot of heights, winds, and temperature showcases a shift of the winds over Columbia to the north at 21Z Wednesday. A strong northerly wind cools our area until 12Z Friday when a ridge from a HPS over Texas proceeds over Missouri, giving us a slightly warmer westerly-into-southwesterly wind for the remainder of the forecast period. Looking towards the surface plot of MSLP and 1000-500-mb thickness, strong solenoids indicates CAA already occuring through 15Z Thursday. Beginning 15Z Friday, WAA begins for Missouri, staying strong through the end of the week. No precipitation is anticipated for the forecasting period.


    Future forecasters should pay attention to the zonal jet streak aligned with Missouri for additional divergence and convergence aloft for the weekend.

- Noblitt

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