Monday, October 25, 2021

 

Current Conditions at Sanborn Field

 


Monday:
Cloudy, becoming partly cloudy in the late afternoon. High: 54
 

 


Monday Night:
Becoming clear. Low: 39
 

 


Tuesday:
Sunny. High: 63
 

 


Tuesday Night:
Becoming cloudy. Low: 49
 

 


Wednesday:
Cloudy. Rain beginning in the afternoon. High: 59

 
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Discussion:  

A fall-like weather pattern has set up over the much of the United States. For mid-Missouri, that means changing weather this week. Clouds will persist into the afternoon Monday, with some possible peaks of sunshine by late afternoon. Northerly winds behind the cold front that passed Sunday evening will keep our temperatures in the mid 50s. Clearing skies overnight Monday into Tuesday will allow temperatures to bottom out in the upper 30s/lower 40s. The sky clears and winds turn out of the south as high pressure builds into the region making for a warmer Tuesday. A strong low pressure system currently making its way onshore off of the Pacific Northwest will bring back clouds and rain for Wednesday. 

- Travis

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Forecasters: Baker, Travis

Date Issued: 10/25/21 10:00 AM CST

Technical discussion:  

Stormy conditions will hold off... but for how long? The main concern for this period is the amplified meridional flow that will bringing another low pressure system our way late Tuesday into early Wednesday. We will have a little bit of clearing Monday and Tuesday, but get ready for some more rain on Wednesday. Both the GFS and NAM had a good handling on the low pressure system that passed over yesterday; however, we went primarily with GFS guidance, as it seemed to handle the upcoming low and temperature forecasting quite well when compared to satellite imagery and Monday mornings observed temperatures.

The amplified meridional flow visible on the GFS 250-hPa highlights a ridge separating two large low pressure systems. The backside of the low pressure system that moved through Sunday night will lead to clearing sky conditions. Winds switch easterly when the ridges moves in Tuesday; however, it is quickly replaced by a low pressure system building off of The Rockies. This low pressure system will bring with it large amounts of divergence as a jet streak moves in ahead of the tough.

The pattern at 500-hPa is quite similar to the 250-hPa map; however, Tuesday vorticity maxima make its way up across the Mexico border from remnants of Hurricane Rick. This combined with strong circulation coming off of the low pressure system from the west Wednesday morning will give way to turbulent motion and spin.

As the ridge moves across our area it gives way to the clearing of the sky; however, the 700-hPa map shows moisture building into the area ahead of the low pressure system. This combined with positive values of Geometric Vertical Velocity highlights upward motion. This is also evident in our 06Z sounding as the temperature and dew point lines show overcast conditions. The spacing between the two lines progressively gets closer together throughout the night as more moisture builds in. This gives way to rain and showers by Wednesday afternoon.

Winds out of the north will keep our temperatures cooler Monday. As the ridge moves through, there is glimpse of northwest winds that fuel the drying of the of cloud layer; however, winds switch back to southerly ahead of the low pressure system. The low level jet at 30-35 kts is coming straight from the gulf, leading to large amounts of moisture and warm air that will supply the low pressure system. This is also evident at the surface due to WAA solenoids.

- Baker

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