Friday, September 17, 2021


Current Conditions at Sanborn Field



Friday Night:
Mostly clear. Low: 66

 
 

Saturday:
Becoming partly cloudy. High: 90
 
 

Saturday Night:
Partly cloudy. Low: 66
 
 

Sunday:
Becoming cloudy. High: 85
 
 

Sunday Night
: Partly cloudy skies. Low: 67

 
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Discussion:

A continuation of the same fair weather is in store for this weekend. Hot weather will stick around for Saturday's football game. Clouds will be on a gradual increase Saturday afternoon into Saturday night. Sunday, more widespread cloudiness moves in with a low pressure system from the south bringing moisture with it, but likely not enough for widespread rain. However, an isolated shower is not out of the question. Overnight low temperatures will remain comfortable in the mid 60s for the remainder of the weekend.

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 Forecasters: Millsap, Ethridge, Travis

Date Issued: 09/17/21 5:00 PM CST

Technical discussion:

Broken record forecasting has been the story for the past several days and will continue to be into this weekend. The main focus of this period is a low pressure system's slow migration NE and if sufficient moisture to support precipitation will reach mid-Missouri. Both the GFS and NAM had a good handling of the placement of the upper-level low over the TX/OK border and the low-level low near the AR/LA/TX borders when compared to GOES WV channels. That being said, the GFS had a better handling of Friday afternoon's high temperature when compared to the NAM which was cooler by about 5 to 7 degrees Fahrenheit. As such, primarily went with GFS guidance. 

GFS prognosis of the upper-levels show a continuation of zonal flow with a ridge to the southwest evident in the 250- and 500-hPa height fields. By Saturday night and into Sunday, an amplified, positively tilted shortwave trough at 250 hPa digs into Missouri, but lacks significant dynamic traits. Divergence at 250 hPa and circulation at 500 hPa is almost non-existent, but increases to the SE closer to TN and KY. 

At 700 hPa, saturated air from the south works its way to the north, but never quite reaches mid-Missouri, staying off closer to the TN/KY borders. RH values closer to 70 and 80% move overhead, but full saturation is never suggested. More likely is mid-level to upper-level cloudiness spreading out from the LPS will reach the area, but not much beyond that. A look at soundings from the GFS backs this up with moistening of the column, but never does a deep, saturated layer exist before the column clears out Sunday night and into Monday morning. That being said, widely isolated showers, though unlikely, cannot be completely ruled out especially if enough moisture is able to make it far enough north.

The 850-hPa winds further support a struggle in the northward advance of the moisture as a prominent LLJ never sets up where the bulk of the moisture is located. Similarly, MSLP and 1000-500-hPa thickness indicate a largely barotropic environment in and around the weak surface low. As such, temperatures both in the daytime and overnight hours will be on-par with what we've seen these past several days save for Sunday cloudiness keeping the daytime high slightly cooler than Friday's and Saturday's highs.

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