Monday, April 8, 2019

Tonight - Mostly clear skies. Low: 52-56

Tuesday - Clear skies. High: 68-72

Tuesday Night - Skies becoming cloudy. Low: 48-52 

Wednesday - Cloudy Skies. Windy. High: 70-74 

Thursday - Partly cloudy. Windy. High: 64-68

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Above average temperatures and clear skies will stick around for Columbia before the approach of the next system by midweek. A weak cold front passed yesterday that brought strong storms to much of mid-Missouri, but missing the Columbia area. Fortunately the front did not bring down our temperatures much at all overnight. Couds will clear out throughout the day Monday and sunny skies will hep our temperatures rebound back into the mid to upper 70s. We should see much of the same until Tuesday night when clouds approach out ahead of our the next big low pressure system. Wednesday into the latter half of the week will be windy as the system will be very strong coming off of the Rockies and into the Plain states. On Wednesday, temperatures will drop as the low-pressure system begins to make its way into the Midwest due to a decrease in the pressure gradient. Wednesday night shows only a small chance of precipitation with little severity. Thursday will be the aftermath of the low-pressure system with high winds at the surface. Temperatures are still expected to be around the upper 60s.
Forecasters: Danaher and Brown 
Issued: 5:30 p.m., 8 April 2019 

Technical Discussion (The nerdy stuff we are discussing in class!) 
The main issues of this forecast period will be sky conditions and the resulting impacts on surface temperatures throughout the period as well as how an approaching system will impact us Tuesday Night into Wednesday. The WPC model diagnostic discussion suggests using a blend of the GFS and NAM for Monday to Tuesday then use only the GFS for Wednesday to Thursday with slightly above average confidence. The reason is the NAM struggled with the evolution and energy of the next storm system. So, the GFS will be the main model used for this forecast period. 

Heading into Monday night, Columbia will be mostly clear of any frontal system overnight since the exit region of the jet streak is North and a negative cap inversion of the trough. Early Tuesday morning at 3am, the exit region of that jet streak will move more into Missouri due to the jet core on the West coast of the CONUS entering Southern California. By 12Z, the Jet core on the west coast will move further into Southern California and Arizona as the exit region will be over Missouri. Moisture aloft will increase with winds from the NE switching to Easterly (WAA) as the morning progresses. According to GS skew-T's the moisture aloft is from 250mb to 300mb with the Lift Index of about 2C and Lifting Condensation Level of 600-700mb which means the atmosphere is working hard to lift any air parcel. 

By Tuesday night, things will get interesting as the Easterly winds change to South-easterly (WAA) with wind speed increasing from 10 - 25kts. Thickness from 1000 - 500 mb decreases by early Wednesday morning (3am). Throughout Wednesday, the jet core will be past Arizona moving over New Mexico and Texas. The exit region of this jet core will be over KCOU leading to the vertical wind speed profile increasing. For instance, the GFS skew-T it shows the 300 - 700mb layer increasing from 35 - 60kts throughout the day. Surface winds will switch from Southeast to Southwest (WAA) of about 25-40kts. Around noon on Wednesday, the GFS skew-T shows a lift index of - 3 with negative omega values vertically from 700 - 850mb, CAPE of 391 J/kg, but CIN of - 146 J/kg. Winds will stay South-westerly at the surface, but at 700mb - 850mb winds will shift from Westerly to Southwesterly. By Wednesday evening to midnight, CAPE values increase to 794 J/kg but CIN of -223 J/kg and surface wind speeds ranging from 40 - 50kts. So the reason these numbers are thrown out is because the main threat of this storm will be due to the wind speed. The for lightning is very low due to CIN being extremely high on Wednesday. Another thing to note from the GFS skew-T is the vertical dry layer from 850 - 650 mb, but any layer above is saturated. This means that any rain does occure with this system will not reach the ground, but only be aloft (virga).

On Thursday morning, winds will be strong from the South as they range from 40 - 50kts and fall down to 30 - 40 kts by the afternoon after observing the GFS Skew-T.  The same Jet core that was mentioned earlier, continued the path across the CONUS entering the state of Texas. The exit region of this jet streak will become stronger as it moves across the rest of Missouri and this explains why winds will continue to be strong. Using the GFS skew-T, moisture will be over the 700mb layer with CIN of - 75 J/kg and CAPE only 25 J/kg by the afternoon. The overall thing to note for this system is the wind. Future forecast will need to look out for the dry layer on Wednesday evening to night as we end this forecast period.

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