Hey Barometer Bob (or anybody)

[coriolis]

Do you remember the one night on your show, I had submitted a question asking what happens to the rising air in a Low? I've been looking at the CONUS models and have a tentative answer.

Right now, there's a low sitting over NE Iowa, with occluded and warm fronts extending east to west virginia, and a cold front extending south to texas.

The 1000 mb plot shows the air in front (north) of the warm front flowing west to the low, and the air in front (east) of the cold front flowing north to the low. Behind this low there's a circular pattern, that with just a little imagination, appears to be spiraling into the low. We all know that air rises in the low, so all that air that flowed into the low goes up once it gets there. Then what? That was the crux of my question.

By the time you get up to the 700 mb plot you can see that the warm front boundary (change in wind direction) is way up in Michigan and along the PA/NY border. You can also start to see cirulation around the low on the east side starting to break away and continue north.

In the 500 mb plot, there is no hint of the east to west flow ascociated with the warm front and all circulation around the low continues north on the east side of the low.

And then in the 300 mb plot, you see that the low is just a dip in the high level flow - a trough.

So my conclusion is that the rising air in the low gets swept away in the upper level flow and disappears into the jet stream.

One other observation- the east to west flow in front of the warm front is removing air ahead of that front allowing the front to advance.

Is this an accurate assessment of the situation? This may be real basic stuff, but it's no less fascinating to me. I am not to the point of making forecasts, but am working to understand what the heck is going on.

A last question: Is this a "surface low" because the flow is completely circular at the surface?

I'd appreciate any input on this.

Ed

[Guest]

Well yes, it's s urface low pressure. Now remember, a barclonic low is different then a tropical low. A tropical low allows for the rising air to create a high pressure aloft. As the air rushes in to replace the air at the surface that is lifted up in the low, this creates teh winds at the surface.
Now, being this is a barclonic low, and the air is limited to it's height, yes the upper level winds take over in the form of shear. With shear in advance of the trough, frontal boundry, ect, this helps to create the unstable atmosphere in turn severe weather.
Those winds you see at 700-850MB are shear related winds. from south to north! Severe Weather.
If I am wrong, someone please correct me, but this is my understanding of barclonic low pressure systems.