Thursday, December 9, 2021


Current Conditions at Sanborn Field

 Sunny. High: 64

Thursday Night:
Mostly Clear. Low: 42

 Cloudy with rain possible late in the afternoon. High: 70

Friday Night :
  Scattered Clouds. Low: 37

: Abundant Sunshine
. High: 47


Thanks to for the icons! 



    Temperatures will begin to recover from the cool weather pattern at the start of the week. A strong southerly wind Thursday and Friday will keep temperatures well above average for this time of year. Clouds will begin to increase ahead of a low pressure system and cold front on Friday, so expect an overcast but warm Reading day as you prepare for finals. The region could see the possibility for showers late Friday afternoon, but rain totals are minimal to none. The rest of the weekend looks to be cooler and drier. 



Forecasters: Aldrich, Duff, McDonald

The 06z GFS was used for our forecast today, as it held a slight advantage over the NAM in terms of temperature initialization

In the upper levels of 250 mb Missouri is just barely outside the path of multiple strong jet streaks, missing the state to the northeast as they flow into Iowa and Wisconsin. The advancement of a trough towards the state at 00z Saturday lines Missouri directly in a section of divergence on the lower right side, indicating an active weather threat Friday night into Saturday morning. Jet streaks look to be stronger at this point, but their magnitude appears to decrease into the later hours of Saturday past 21z. While rain cannot be determined solely from this level, there is reason to believe our sharpest pattern change will occur that day. 

Vorticity is initialized as being active, but will remain quiet at 500 mb until Friday night. At Saturday 06z, vorticity associated with the aforementioned trough will begin to compact and wrap into Kansas and Missouri, covering a large swath of both states. Just slightly ahead of the west moving trough, at least some precipitation would be expected over that timeframe. Winds continue to diverge at this level, indicating that the stacking of the system is fairly even and building confidence in the model output. 

Even as warm air increases, humidity levels at 700 mb will remain low aside from Friday night into Saturday morning. A large swath of humidity will approach alongside the trough’s center to our northwest, situating us on the active side of the system. However, the peak of this humidity does not align with the peaks of vorticity and divergence, indicating that weather produced will contain lighter amounts of rain to generally overcast conditions. Omega values supplement this trend, as values are low during the periods of greatest moisture content in the atmosphere. 

850 mb paints a better picture for temperatures, showing hot air from the southwest extending far into the midwest, keeping the region warm for the next few days. Continuous southwest winds will warm up the region until the trough arrives, where winds shift back to the northwest at 15z Saturday once it departs. The drop in temperature from this strong shift could be substantial, as the model indicates warm air almost immediately receding into the southwest. 

GFS soundings display considerable moisture content increasing each day into Saturday, where heavy cloud cover is certain and rain is a possibility. At the very least, the weekend will feel much more humid and wet in comparison to this past week. 

Future forecasters should pay attention to another trough behind the one anticipated on Satuday, as it looks to bring similar active weather to the mountain west and great plains on Sunday. 

- McDonald

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