Thursday, April 25, 2019

Thursday Night Cloudy with trace amounts of rain. Low: 44-48.


Friday - Clouds clearing becoming mostly sunny through the day. High: 64-68.

Friday Night - Clouds build back in. Low: 46-50.

Saturday - Cloudy with trace amounts of rain. High: 68-72.

Sunday -  Mostly sunny with clouds and showers building back in overnight. High: 58-62

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The weather cannot make up its mind this weekend as rain and sun take turns stealing the show. Tonight brings trace amount of rain with a minimal cold front until clouds clear out in the early afternoon hours of Friday. Sun keeps the temps relatively warm and consistant from the past week until clouds make their way back early Saturday morning. Overcast conditions take form Saturday evening as a low pressure system with a cold front sweeps through Saturday night. Trace amounts of rain are highly likely however totals stay under a tenth of an inch. Sunday brings the sun back yet again but keeps temps colder from the two previous cold fronts until clouds build back in Sunday evening. A stronger, more centralized low pressure system makes its way into central Missouri in the late hours of Sunday night. As we get further along in the weekend, rain totals will be more consistant however they average around a quarter of an inch for Sunday night into Monday.
Forecasters:  Bongard, Doll, and Myers

Issued: 4:15 p.m.; 24 April 2019

Technical Discussion (The nerdy stuff we are discussing in class!)
The on and off chances of rain continues tonight through later this weekend with a shortwave ridge moving through the central CONUS this evening. Looking at the NAM model output, a shortwave trough begins to develop later this afternoon on the frontside of this ridge. This results from a jet max development over western MO that speeds up transport of moisture in the higher levels of the atmosphere that eventually cools and sinks due to the northwesterly cold air advection. This trough development deepens through the later hours of the night, paving way for an active weather system over Kentucky/Tennessee. Missouri receives just the nick of the backside of this system through this evening bringing trace amounts of rain. Looking at model soundings NAM shows more instability, placing the trough development closer to Missouri while GFS brings in more moisture from the north giving a bigger rain total at .1" while NAM keeps totals to trace amounts. Looking at the path and development of this short lived system as well as saturation in each atmospheric level, the trace amount seems more likely of a story.

Friday shows some good sun coming through as flow turns zonal throughout the early hours of the day and winds stay northwesterly at the mid to upper levels. Winds stay northwesterly keeping cooler air cycling through central Missouri in the lower levels of the atmosphere. Atmospheric levels dry out through the majority of the day keeping temperatures consitant than the previous 3 days until resaturating in the late nightly hours paving way for the next incoming weather system. A low pressure system develops in the lower levels of the atmosphere over Nebraska as the flow turns meridional and a shortwave trough develops. Looking at the NAM model soundings, the dry layer is smaller at the surface than compared to the GFS models in the later hours of Saturday evening. This is primarily due to GFS keeping the low pressure system in it's later development stages over central Iowa with it tightening and deepening, giving trace amounts of rain to central Missouri. NAM has the system developing a few hours later, creating a bigger but weaker centralized system, expanding further south than GFS giving Columbia around .1" of rain by early Saturday evening. Clouds hang around through the night as we stay saturated near the lower 900-mb level of the atmosphere.

Sunday clear out the clouds with post frontal genesis seen in the morning hours. This brings a dry layer throughout the lower levels of the atmosphere with clouds looming around the 600-mb level. This suggests altocumulus clouds development as through the day southwesterly winds stay true until clouds build back in along with moisture in the mid to lower levels of the atmosphere. Conditions become overcast in the later nightly hours of Sunday as a low pressure system develops over South Dakota bringing yet another chance for rain. As the weekend continues on, a better analysis of the development of this system will be understood as the date approaches. GFS keeps the system calm with minimal amounts of vorticity and instability however with moisture building in all the way from the gulf of CA at the 700-mb level, showers are still a good possibility. Rain totals average out to around a quarter of an inch. The storm prediction center keeps central Missouri just on the edge of the marginal risk for storm development from this system, backing up the observation of good moisture but no instability.


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