Thursday, May 2, 2019

Tonight - Overcast. Low: 48-52


 Friday - Overcast. High: 58-62.

Friday Night - Overcast with trace amounts of rain. Low: 52-56

Saturday - Mostly Cloudy. High: 62-66.  

Sunday -  Partly Cloudy. High: 72-76

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Showers and thunderstorms in the evening


Dark and gloomy skies hang around into the weekend.  Cloud cover will stick around tonight into tomorrow as the moisture from that system but as high pressure in the low level of the atmosphere builds in, skies will clear up as we move into the weekend.  There is the possibility for patchy fog tomorrow morning as winds are expected to stay calm through the morning.  There is the possibility for a sprinkle or two Friday night but the bulk of that rain will stay to the south of I-70.  Temps will stay on the cooler side for Friday but a warm up is expected for Saturday and Sunday with highs looking to be in the 70s by the end of the weekend.  Clouds will be prevalent for Saturday as we do have the slight chance for rain in the early afternoon.  Sunday looks to see more sunshine and warm temperatures before the next system moves in Monday and brings rain for next week.
Forecasters: Bongard, Doll, and Myers
Issued: 4:10 p.m., 2 May 2019

Technical Discussion (The nerdy stuff we are discussing in class!)
Missouri receives a break in some precipitation tonight as a high pressure system in the lower levels of the atmosphere makes its way into the area. Through tonight however this high pressure infleunces moisture from the gulf keeping cloud cover prominent at the mid to upper levels of the atmosphere. Both the GFS and NAM are in agreement with saturation levels in the upper levels of the atmosphere and near the surface as well as a shift in wind direction at 850-mb from westerly to northerly. Looking ahead to tomorrow morning, originally there was an anticipation for factors developing to create some patchy fog. However with clouds looming overhead through the night and a recent cold front passing, the sounding lacks the warm air advection near the surface and calm conditions to produce fog. Looking at model isobar maps, the GFS and NAM are both in relative agreement of a combination of zonal flow at 500-mb, warm air advection, and disturbance in the upper levels that will create our next look at precipitation Friday afternoon. Looking at the GFS model sounding, flow at 250-mb is consistantly southwesterly while it gradually becomes zonal through the latter of the day. Dropping down to 500-mb, a nice developing low pressure system takes form over eastern Texas that draws in a good combination of moisture, lift, and instability that creates a good potential for severe storm development. Vorticity values hovering around 80mb/s and CAPE values hovering around 800-1000 J/K. Looking at model soundings, GFS has Columbia, MO saturated from 700-mb to 850-mb however a noticeable dry layer near the surface as well as little to no lift. This low pressure system will do its best to create a northwesterly path and extend down into southern Missouri, but will just miss Columbia keeping rain amounts to trace through Friday night. 

Post frontal genesis takes form Saturday as flow becomes zonal at 250-mb with confluence taking shape over Colorado giving head way to Missouri's westerly flow. Sticking with the GFS model, winds stay northerly in the lower levels of the atmosphere through the course of the day until shifting southerly in the later evening. The biggest attention grabber for Saturday is the slight chance for rain in the early afternoon. The 12Z model run of GFS influences in more precipitable water in the early morning Saturday lifting only into the 850-mb layer giving the slight chance for another round of sprinkles early afternoon. The newest 18Z model run of NAM however gives no amount of rain, just missing that saturation with the slight lack of moisture as seen in the GFS. Both models do give the lift with post frontal genesis however, temp differences in the lower and mid levels of the atmosphere as well as the lack of precipitable water doesn't provide the instability or moisture for rain. As the later evening hours ensue, moisture in the mid to lower levels of the atmosphere begin to make its way out of the area giving headway for some sun the following day.

Sunday gives central CONUS a break from the dark gloomy weekend with some southerly warm air advection in the lower levels of the atmosphere bringing in the post frontal genesis dry air from Texas. Slight saturation levels on the GFS sounding trickle down beginning at 250-mb Sunday morning down to 700-mb Sunday evening keeping clouds around but not prominent. Flow at 250-mb zonal through the majority of the day with a low pressure trough development over California Sunday night. 500-mb flow follows suit with westerly winds hovering around 30-40 knots late afternoon through evening while near the surface at 925-mb winds are southwesterly hovering around 15-20 knots. 


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