Wednesday, April 6, 2022

 

 

Current Conditions at Sanborn Field




Wednesday:
Mostly sunny. High: 62


Wednesday Night:
Cloudy. Low: 39
 


Thursday:
Sunny early. Building clouds in the afternoon. High: 52 


Thursday Night:
Overcast. Isolated drizzle possible. Low: 34


Friday:
Overcast. High: 46

 

 

Thanks to IconArchive.com for the icons! 

====================================================================

Discussion:

A warm and sunny beginning to the week has taken a cooler and wetter turn. While the main chances for rain are behind us, there is a small chance of light drizzle Thursday night into Friday. This will not be a washout event by any means, nor will there be any associated severe weather: this is simply just going to be enough rain to wet the ground. Aside from the rain later this week, the main focus will be strong winds and cooler temperatures. Winds will be coming from the northwest ushering colder air that will take our temperatures to near 20 degrees below average by Friday. Breezy conditions are expected throughout Friday with winds gusting up to 35 mph at times. Be sure to secure any lightweight furniture and take caution in high profile vehicles. 

- Kobielusz

=================================================================

Forecasters: Kobielusz, Macko, Bongard

Date Issued: 04/06/2022 10:00AM CDT


Technical Discussion: 
 
With chances of precipitation later this week, it was essential to utilize a deterministic model that accurately depicted the placement of surface features, namely the location of the mature mid-latitude cyclone that will be influencing the weather to come and the location of the cold front that impacted mid-Missouri Tuesday night. While the NAM and the GFS both modeled the strong low-pressure system over Minnesota quite well, the NAM saw more success in its placement of the cold front that moved through the state of Missouri yesterday. Thus, since the NAM has a better grasp on the present environmental conditions, which may impact the weather mid-Missouri will see later in the week, its 06Z run was chosen for the purposes of this forecast.

Upper-level wind and divergence charts depict a ridge-trough-ridge jet pattern stretching across the CONUS. Currently, a east-west oriented jet streak is situated over Missouri. The low-pressure system seen on surface maps over Minnesota is still quite evident, even at 250 mb. As this low-pressure system begins a slow descent to the south-southeast, the initially weak upper-level trough will begin to amplify early Thursday morning. This will result in the jet streak seen over mid-Missouri to move out of the area as the jet axis is pushed further south. As the upper-level low heads south, winds in the upper levels will begin to develop a strong northerly component Friday morning due to the cyclonic rotation around the low. Moreover, the ridge to the west will begin to inch closer to Missouri over the next several days and will reach the Missouri-Kansas border Friday morning.

Vorticity plots at 500 mb imply that two waves of vorticity are to be expected over the next few days. The first "wave" is to be found over mid-Missouri early Wednesday afternoon, where it will persist until early Thursday morning. This first wave is set to be the stronger of the pair as the low-pressure center will begin to weaken later in the week. The second wave of enhanced vorticity will influence the region Thursday evening into Friday as the center of low pressure tracks further south. Circulation will be more widespread but of a lesser  magnitude with the second wave compared to the first band.

Moisture is expected to decrease heading into the mid to late morning hours on Wednesday, bringing a brief end to cloud cover before relative humidity increases Wednesday evening. Moisture will decrease significantly before sunrise on Thursday morning before once again increasing Thursday afternoon. Though moisture is prevalent at multiple time steps during the forecast period, 700-mb plots highlight a lack of negative omega, implying that vertical ascent will be lacking in association with moisture increases. Any considerable precipitation will likely be inhibited by this mechanism. 

A low-level jet extends across Missouri throughout the duration of the forecast period. Northwesterly flow is prominent at this level, but switches to northerly on Friday. This change will bring even cooler temperatures into the region.

As mentioned earlier, significant precipitation is unlikely to be associated with the influence of the low-pressure system to the north. This is due to the lack of negative omega expected between the surface and mid-levels, as well as low PWAT values. K index values are also strikingly low throughout the forecast period. That said, there is potential for trace precipitation just after midnight on Thursday due to a slight increase in negative omega values near the surface as well as K values. However, these changes are not incredibly significant, and PWATs for this time remain low, suggesting that, should precipitation fall, it will be minimal. 

- Macko

No comments:

Post a Comment