Tuesday, February 21, 2023

 

 

 Current Conditions at Sanborn Field




 Tuesday Night: Increasing Clouds. Low: 49.
              
 
Wednesday: Morning rain exiting by early afternoon. Thunder possible. High: 67

 
Wednesday Night: Decreasing clouds overnight. Low: 38

Thursday:
Mostly sunny and breezy. High: 39
 
 
 
Thursday Night: Mostly clear. Low: 18
 
 
 
 

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Discussion:  

Umbrellas will be necessary tomorrow as rain will begin early in the morning and last into the early afternoon hours. High temperatures tomorrow are forecasted to be in the mid 60s before a cold front passes through the area overnight on Wednesday. Thursday will be significantly cooler with high temperatures in the upper 30s and wind gusts up to 35mph possible.

-McCormack

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Forecasters: Smith, McCormack, Peine

Date Issued: 2/21/2023 5:00 PM CST

Technical Discussion:
 

The GFS was favored for this forecast because of its more accurate depiction of the centers of pressure systems and locations of fronts.


Currently there is a jet streak sitting over Kentucky making its way eastward. A trough behind it starts to move into the area, bringing in higher levels of upper level divergence, most specifically around 18Z on Wednesday. In addition to increased divergence, the trough brings in a strong band of vorticity, as seen on the 500 MB vorticity map from 18-21Z on Wednesday. Coming with the trough is another strong jet streak that will sit over Kansas, Nebraska, and Iowa by 15Z Thursday.


A mid level low pressure system will move into the Colorado-Nebraska area. This system will bring moisture with it as seen in the relative humidity maps at both 700 MB and 850 MB. There is also a strong high pressure system off the eastern coast of Florida that is driving a strong low level jet into the southern US where it gets picked up by the LPS from earlier. This allows for strong moisture transfer into the low Midwest. The moisture brought down from the Northwest and brought up by the LLJ will give the area much needed moisture for potential precipitation. The 700MB vertical velocity map shows ample lift for possible storm development at 18Z Wed.


A broad surface low pressure system is going to push its way into the region on Wednesday. The moisture from the NW and the moisture brought up by the LLJ will converge on Mid Missouri. This will give ample moisture for precipitation to start. GFS soundings show a saturation of the entire vertical profile, with precipitation starting at 12Z on Wednesday. Soundings show significant lift at 18Z on Wednesday which lines up with the 700MB vertical velocity map from before. This also lines up with the vorticity band and the upper level divergence timing wise. These ingredients will likely elevate the system from rain showers to thunderstorms. As there is not a lot of energy in the atmosphere with CAPE values being in the 300-400 kj at 18Z Wed, these storms are not expected to become severe. Rain is expected from 12Z Wed to 21Z Wed with the chance for thunderstorms happening at around 18Z on Wed. Throughout the duration, rainfall totals are expected to be between 0.5-0.75 in. Following the rain event will be a cold front moving through the area at approximately 3Z Thurs. This will be most notable in the almost 180 degree shift in the winds from the south to the north. Following the passage of the LPS and the cold front, a high pressure system originating from Alberta will slide into the Northern US states, locking in cold air for a day as it moves east across the north. Our high temperature on Wednesday will be 67F but after the cold front moves through, the forecast high will drop to 39F on Thursday. The lows on Wednesday and Thursday will be 38F and 18F respectively.

 -Smitty

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