Monday, March 20, 2023

 

Current Conditions at Sanborn Field


 

Monday Night:
Increasing Clouds. Low: 39


Tuesday:
Rainy. High: 39

Tuesday Night:
Scattered Showers. Low: 42

Wednesday:
Cloudy, Scattered T-storms Late. High:70

Wednesday Night:
Scattered T-storms. Low: 61
 
  

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Discussion: 

Things just don't want to dry out! Several rounds of showers and rain are expected throughout the next few days bringing a widespread 0.5-0.75" of rain and the potential for thunderstorms! Temperatures will start cool but warm up as we move into the forecast period. 

-Russell

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Forecasters: Russell, Shaw

Date Issued: 03/20/2023 5:00 PM CDT

Technical Discussion:

Rain will continue to dominate the weather headlines. Several rounds of precipitation rounding out with the potential for thunderstorms come Wednesday night is keeping the forecast interesting. The NAM and GFS displayed good agreement on the overall upper air pattern in addition to the track of the low pressure system and thus, are being used in unison when crafting this forecast.

As we move into tonight, upper-level ridging will start to build across the desert southwest, this paired with the weak longwave trough stationed over eastern Canada has us parked in a temporary zonal flow. This west to east is the primary steering mechanism for a stout shortwave that is currently ejecting off the Rockies and will be responsible for the precipitation Tuesday. Low-level moisture advecting into the area thanks to the strengthening LLJ tonight will promote increasing clouds and the eventual development of a shield of light to moderate rainfall come mid-morning. Continued westerly flow will push the disturbance out of the area by Tuesday evening. Precipitation amounts won't be anything ground-breaking with  widespread 0.1-0.3" expected; however modeling has indicated a band of enhanced rainfall rates along the I-70 corridor, which may contribute to a strip of slightly higher totals in the range of 0.5". 

The column briefly drys out Tuesday night before another extremely subtle shortwave propagates through the area. Mid-level moisture looks rather wimpy ahead of this disturbance, however intensification of the LLJ late Tuesday night will coincide nicely with the passage of this SW. With the intensification of the LLJ, we will see increased moisture advection and subsequent saturation of the mid-level profile. This will maintain already cloudy conditions and the possibility for some scattered light rain showers primarily across southern Missouri. Where it is not raining, continued intensification of the LLJ out of the southwest will continue to advect warm air into the region. Due to the overall timing of the strengthening jet, we will hit our low temperature early in the night before temperatures warm rapidly with the approach of dawn. Precipitation will not be near the intensity nor the scale seen on Tuesday, failing to exceed .1" total.

The story of widespread rain luckly doesn't follow us into Wednesday as much of the state including Columbia will see some dry time. The upper-level troughing which is gradually building across the southwest will begin its treck east, removing us from the zonal flow pattern and placing us in a more southwesterly flow regime. As a result, mid-level moisture will stick around on Wednesday, keeping conditions cloudy. Despite the lack of sun, temperatures will be toasty in comparison to the past several days with an expected high of 70 degrees. A warm front associated with a weak surface low situated over Kansas will breifly stall to our north before falling south as a cold front. Further advection of low-level moisture behind the front will push dew points into the mid 60s. Surface based instability in the 300-600 J/kg range will promote the development of scattered thunderstorms along and north of I-70. Steep mid-level lapse rates in conjunction with a powerful mid-level jet will support isolated strong storms which may harbor large hail. Due to the lack of forcing, widespread precipitation is not expected, and many locations may not even see rainfall Wednesday night. Nonetheless, areas which see thunderstorms could have rainfall totals approach .5". Finally, winds will increase heading into Wednesday night, as the pressure gradient tightens across the area with the approach of the deepening trough. 

-Russell

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