Friday, March 18, 2022

Current Conditions at Sanborn Field




Friday:
Rain all day. High: 54




Friday Night:
Rain ending after midnight. Low: 38




Saturday:
Clearing sky by morning. Sunny. High: 56

 



Saturday Night:
Clear and cold. Low: 38



Sunday:
Partly cloudy and warmer. High: 70


Thanks to IconArchive.com for the icons! 

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Discussion: 

 

Don't forget your umbrella today! A low pressure system brings clouds and rain to mid-Missouri Friday morning, which will stick around throughout the day and night. Rainfall accumulation with this storm will range from 0.75 to 1 inch. As the system moves east, the sky will clear in the early hours Saturday morning, with a cool and clear day in store for the start of the weekend. Southerly winds will lead to a warmer and partly cloudy day on Sunday as the weekend comes to a close.

-VanUnnik
 

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Forecasters: VanUnnik, Bongard

Date Issued: 3/18/2022 10:00AM CDT

Technical Discussion: 
 

The impact of the system currently over the Midwest will be the main issue for this forecast period. While both models handled positioning of the LPS fairly well, the GFS was a bit more accurate in its rendering of current temperatures as the NAM was slightly colder than was is being observed. Therefore, the GFS will be utilized for this forecast period. NBM data will be used to pin down temperatures through the weekend as well as precipitation accumulation associated with the Friday system pushing through the Midwest.

At 250 mb, the upper level shortwave responsible for the low pressure system over the Central Plains is well amplified stretching from central Canada down through the Dakotas into the Southern Plains. This shortwave is embedded in a much broader longwave trough over the entirety of the western CONUS with ridging over the eastern half of the country. A the entrance region of a south-north oriented jet streak is draped over east central Missouri as the jet wraps itself in the axis of the ridge to the east over the Great Lakes. This trough pushes through the Midwest today and by 06Z tonight the meriodional flow over the CONUS morphs into a more ridge-trough-ridge pattern. The axis of the trough pushes through the central CONUS by 00Z on Sunday. Upper level flow that was zonal as the axis of the longwave trough pushed through the Midwest will veer to a shorter northwest flow as a jet streak develops there over the northern Plains by 06Z Sunday. The ridge pushing this trough east will transition into the Plains through the day on Sunday.

Copious amounts of vorticity will preside over central Missouri associated with the energetic shortwave trough stationed in the Midwest Friday. This activity will remain in place over the region until 00Z on Sunday as the upper level trough slides to the east and the aforementioned ridge builds into the Central Plains. The ridge keeps the central CONUS vorticity free for the remainder of the period though the next shortwave that will impact the area early next week is evident carrying large amounts of vorticity over an area from the Baja of California up through western Montana. 

The lower levels are saturated at both 700 and 850 mb's thanks to the LPS over the Midwest on Friday. Though the LLJ at 850 mb associated with the system is modest at best, the center of low pressure currently over Tulsa, OK will drift slowly to the northeast over southern Missouri today. This places the forecast area in the moisture rich precipitation shield of the system lending to higher precipitation amounts today. GFS model soundings eradicate moisture from the sounding dramatically between 09Z and 12Z Saturday morning. While some CAPE is present Friday morning and early afternoon the sounding also sports CIN values that inhibit convection as this looks to mainly be a rain event for the mid-Missouri region. Rainfall accumulations for Friday and Friday night will range from 0.75 to 1 inch. The profile stabilizes as the ridge to the west moves in promoting a fair weather weekend Saturday and Sunday. As the forecast period comes to an end Sunday afternoon the profile begins to saturate from the top down and lift is present as the next system to impact the region begins to impact the Midwest.

Future forecasters should monitor this new system out west for rainfall impacts and the chance for convective development early next week.

 -Bongard

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