Friday, February 22, 2019





 
Friday Night - Remains cloudy with likely scattered showers. Low 38-42



Saturday - Thunderstorms likely early in the morning. Then lingering isolated storms and showers moving out in the evening. This will leave clouds behind. High: 54-58



 Saturday Night - Cloudy and breezy. Low 28-32



Sunday - Clouds clearing out in the morning leaving sunny skies. High: 38-42


Monday - Mostly sunny. High: 38-42

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Discussion:

Tonight we expect isolated showers with some thunder likely early Saturday morning. These isolated storms and showers should move out Saturday evening, when a cold front moves through. This dries us out and brings in colder temperatures. Saturday night clouds persist with windy conditions. Skies will clear Sunday morning leading us to mostly sunny skies into the beginning of next week.

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Forecasters: Johnston, Rojas, Sumrall, and Hirsch
Issued: 4:58 p.m., February 22, 2019

Technical Discussion (The nerdy stuff we are discussing in class!)
 
Aloft, at 300 mb the trough located southwest of the CONUS is moving northeastward, the jet streak associated with the trough axis will traverse our area in the following hours, this will put Columbia in the middle of two divergence zones which will explain the lower values of precipitation around 0.34 to 0.39'' compared to southeast of MO where near 2" is expected for TN, this is what we will experience late tonight through Saturday. The southwesterly flow will be responsible for the moisture advection that associated with some upward motion will set up the storms and showers for after midnight according to the cross section of GFS and NAM.


Soundings for Saturday morning shows a CAPE of 606 J/kg and a potential unstable conditions in the mid level troposphere, also a maximum 3km shear of 18.9m/s. Severe conditions is not something to be concerned about, because of being in the winter season and the SPC keeps the severe risk in southeast MO. But will expect thunderstorm likely.

South westerly wind and WAA will linger on Saturday. The winds will strengthen as the low pressure system passes and even after that. Despite a model disagreement in the temperature on Saturday, we think that temperatures would slightly increase as the SW flow will bring warm air and the condensation process will release enough latent heat to the atmosphere. As the rain finishes toward late evening, a cold front will pass through dragging dry conditions behind it. The pass of the front will define the clear skies on Sunday and also the decrease in temperatures especially Sunday night as is usual at the first night after the FROPA. The temperature on Monday produces another disagreement in the model as a warm front appears that day, but considering the colder conditions of the night before, we could expect a slightly warming. These conditions need to be monitored toward the next week. We expect zonal flow as we start the next week.