Friday, April 12, 2019

Friday Night - Partly Cloudy. Low: 34 - 38.

Saturday - Overcast. High 54 - 58.


Saturday Night - Cloudy with rain begining after midnight. Low: 36-40.

Sunday - Overcast with rain ending in the evening. Clouds begin to move out over night. High 44 - 48.

Monday - Mostly sunny. High: 64 - 68.

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Colder and cloudy conditions will prevail this weekend. The only likely time for precipitation will be early Sunday morning lasting through out the day. Clouds will move out Sunday night allowing a sunny start for the work week on Monday.
Forecasters: Johnston, Rojas, and Sumrall 
Issued: 5:00 p.m., 12 April 2019 

Technical Discussion (The nerdy stuff we are discussing in class!) 
Weather Prediction Center Model Diagnostics has an average confidence of a general model blend with less weight on the 12Z GFS and excluding the CMC. So due to NAM and GFS being the easist to access and with what WPC said we leaned on the NAM the most.

The clear skies and breezy conditions experienced during the day will change later today due to the high pressure over our area. This will bring calm winds, the moisture will increase in the mid troposphere which will help to increase the cloudiness toward Saturday morning. The upper level trough located over west Texas will arrive to the area by Saturday morning, the probability of rain will increase toward late Saturday. We can see at 16Z maximum vorticity at 500mb-height as the trough is passing, an increase in moisture is noticeable at 700 mb too but the lower troposphere is still dry. As we move forward, during 22Z and 23Z a maximum vorticity spots are over us at 500 mb-height, the column become saturated and the values of omega are around –12 ub/s at 700mb-height but we will have precipitation after midnight because of the drier conditions at surface. The warm convection starts to appear at surface due to the southerly flow producing the moisture convergence required. The rain will remain overnight into Sunday evening. 

As the system is moving out on Sunday, we will experience a decrease in temperatures due to the cold advection. The upper and mid troposphere will be still moist, the 540 dam thickness contour expands southward during the morning on Sunday. Although NAM shows snow during Sunday this is getting less probable as the humidity aloft is slowly being diminished and the surface temperature remain above freezing level. This still depends on surface temperature that we will see in the following model runs. There is less confidence in snow at this moment, as the soundings at 12Z show warmer conditions aloft that could melt any snow aloft also the surface temperatures do not reach the freezing level. The models have a big disagreement in maximum temperature on Sunday too, GFS indicates warmer temperatures, NAM colder, SREF does not show consensus on this. Thus, the forecast is based more on an average of all of them. Finally, the system will leave the area after Sunday midnight, this will bring post frontal conditions, clear skies, cold temperatures leading Monday morning.