Friday, February 17, 2023

 

 Current Conditions at Sanborn Field



 

Friday: Sunny. High: 37





Friday Night: Clear. Low: 28





Saturday: Increasing clouds. High: 52



 

Saturday Night: Chance for light rain, then clear. Low: 34

 
 
Sunday: Increasing clouds. High: 59

 

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Discussion: 


Following the passage of a cold front overnight, temperatures are expected to remain in the 30s today. But the cold is not here to stay; this weekend will warm up into the 50s, brought to us by southerly winds. This is a great weekend to get outside, full of sunshine and a clear sky, with the exception of Saturday night, as clouds roll in along with the chance for light rain. This precipitation will be very light with little to no impacts as it falls late Saturday evening. We'll even get a hint of spring as temperatures reach 59 degrees on Sunday!


Sallot

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Forecasters: Sallot, Allen, McGuire

Date Issued: 2/17/2023 10:30 AM CST

Technical Discussion:
 

The main weather activity we’re looking at this weekend are temperature shifts that are above average for this time of year and a chance of light rain Saturday night. The NAM and GFS were both used for the bulk of this forecast however, the GFS was more in line with the prediction of light rain on Saturday night.

At 250mb there is a positively tilted trough that moves out of MO throughout Friday afternoon, with a ridge with meridional flow moving into MO. There is also a jet streak that moves into MO at about Sunday 3z that reaches 150kt that trails behind some increased wind divergence. At the end of the forecast period at Mon 0z the jet streak over MO reaches as high as 185kt.

While the positively tilted trough moves out of MO at 500mb, it takes with it 2 large bands of vorticity that reach from northern TX to the Great Lakes at about Friday 21z. The meridional flow that we saw at 250mb continues to move through MO until about 0z on Sunday, which is when we see a short wave, along with increased vorticity, come in from KS and OK.

At 700mb the atmosphere is dry over MO until Sunday 3z when we see some moisture move throughout the state until about Sunday 9z. After this time period this layer of the atmosphere is dry until the end of the forecast period. From Friday 15z until Saturday 21z there is WAA that will help to increase our Saturday high, and again Sunday 3z to 12z to get us in the upper 50’s.

At 850mb there is some WAA moving across MO Friday 18z. This, along with the southerly wind from  large high pressure system over the Gulf of Mexico and the southern states, will help to increase our temperatures to above freezing Friday afternoon and into the 50’s Saturday and Sunday. The atmosphere is dry until Sunday 3z when moisture quickly moves into our region and then quickly moves to the northeast. This, along with the moisture at 700mb at this same time, indicates a chance of light rain early Sunday morning.

At the surface, there is a change in wind direction on Friday 21z in MO from the northwest to the southwest. This is due to the high-pressure system over the TX, AR, LA region that creates a return flow from the Gulf. At Sunday 3z the GFS indicates some light rain over the forecast region, this is supported by the short wave seen at 500mb at this time and the moisture at 700mb and 850mb at this time. However, due to the atmosphere being dry besides short time period from 3z to about 6z it is likely that only trace amounts will reach the surface.


-Allen 






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