National Weather Today: 11/18/15

The dominant feature in the nation’s weather today is still the mid-latitude cyclone and strong, trailing cold front that extends through the south this morning.

The Storm Prediction Center (SPC) has issued a Tornado Watch for Southern Alabama because of this system.

They have also issued a Slight Risk for severe weather:

…and a 2% Tornado Threat ring.

The mid-latitude cyclone itself is centered over Minnesota, as shown by the swirl of clouds on this visible satellite image. It took me a little while to find this, as there is a second low developing over central Missouri. The secondary low is not nearly as strong, but it shows up in the visible satellite imagery.

The enhanced infrared satellite imagery shows the latitudinal extent of the cold front associated with this system. Notice how there is a clearly-defined boundary that runs almost due north from Louisiana. Also notice that this precipitation is out ahead of the system, so perhaps it is beginning to occlude.

The water vapor imagery shows the same boundary, but in terms of moisture instead of cloud cover.

The surface pressure chart shows that the mid-latitude cyclone is over Minnesota, with a central low pressure of 984 mb. This system continues to move northeast, and will continue to occlude.

The RAP shows the system moving out of the country over the next six hours, but continuing to deepen (980 mb) as it enters western Ontario. Also, notice the steep pressure gradient; it will be a windy day across the Dakotas and Minnesota. Even though the occlusion has begun, this system will strengthen a bit before weakening.

The 300 mb NAM chart shows that the trough will continue to push east, and that the line of precipitation we are seeing matches up with the leading edge of this trough.

Overall, this has been a fun system to track, and I wish I had spent more time watching it. This system will strengthen slightly before the occlusion cuts off its energy source. It will be worth watching the secondary low that is occurring over Missouri, as this system may strengthen.

I’m getting into crunch time for the semester’s end, and I’ve let this blog and my predictions slip. However, based on the few observations I’ve made of this system, I think I have a new project. I think I will work on a project this weekend concerning the vertical stacking of mid-latitude cyclones. Stay tuned.

The upper air soundings and mesoscale analysis plots are from the Storm Prediction Center website.
The forecasted upper air soundings are from
The surface observation and upper level charts are from Unisys Weather.
The satellite data is from NASA – MSFC


About highplainschasing

This blog is about my tales in storm chasing. My name is Seth Price and I am an instrumentation instructor at New Mexico Tech. My amateur radio call sign is N3MRA.
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