• After witnessing the continued decrease of involvement in the SpotterNetwork staff in serving SN members with troubleshooting issues recently, I have unilaterally decided to terminate the relationship between SpotterNetwork's support and Stormtrack. I have witnessed multiple users unable to receive support weeks after initiating help threads on the forum. I find this lack of response from SpotterNetwork officials disappointing and a failure to hold up their end of the agreement that was made years ago, before I took over management of this site. In my opinion, having Stormtrack users sit and wait for so long to receive help on SpotterNetwork issues on the Stormtrack forums reflects poorly not only on SpotterNetwork, but on Stormtrack and (by association) me as well. Since the issue has not been satisfactorily addressed, I no longer wish for the Stormtrack forum to be associated with SpotterNetwork.

    I apologize to those who continue to have issues with the service and continue to see their issues left unaddressed. Please understand that the connection between ST and SN was put in place long before I had any say over it. But now that I am the "captain of this ship," it is within my right (nay, duty) to make adjustments as I see necessary. Ending this relationship is such an adjustment.

    For those who continue to need help, I recommend navigating a web browswer to SpotterNetwork's About page, and seeking the individuals listed on that page for all further inquiries about SpotterNetwork.

    From this moment forward, the SpotterNetwork sub-forum has been hidden/deleted and there will be no assurance that any SpotterNetwork issues brought up in any of Stormtrack's other sub-forums will be addressed. Do not rely on Stormtrack for help with SpotterNetwork issues.

    Sincerely, Jeff D.

Closed Lows & cut-off Lows

Joined
Sep 25, 2006
Messages
156
I wanted to ask in the advanced so I could get a more advanced topic going.

What is the difference between a Closed upper level low and a normal low? Whats the significance there? In other words when a low closes off whats happening, and what should one expect? From a Meteorology perspective and a chasing, severe weather perspective.

The other part of my question is cut-off lows. Same goes.
 
So are closed upper level lows always vertically stacked? And it mentions its basically an occluded low, which suggests upper level cold air being wrapped all the way around it. Whats that mean from a chasing stand point? Haby suggests its a bad thing for severe weather. Can anyone go into detail?
 
Closed lows are not always vertically stacked. Last weekend's blizzard in the southern Plains was a good example of that. It was baroclinic and exhibited significant tilt, but the upper low was closed.

Tim
 
As Tim already stated closed lows do not necessarily mean vertically stacked but there is a tendency for them to move in that direction. In fact many extratropical cyclones reach their strongest intensity, lowest pressure, shortly after the 500 mb low closes off, prior to the system becoming stacked.

From a chasing standpoint the occlusion process means the best surface based instability will be shifted into the narrowing warm sector. Convection along the occlusion will have a tendency to be elevated in nature. The tendency for the low to become vertically stacked will also decrease shear, especially directional shear.


So are closed upper level lows always vertically stacked? And it mentions its basically an occluded low, which suggests upper level cold air being wrapped all the way around it. Whats that mean from a chasing stand point? Haby suggests its a bad thing for severe weather. Can anyone go into detail?
 
As Tim already stated closed lows do not necessarily mean vertically stacked but there is a tendency for them to move in that direction. In fact many extratropical cyclones reach their strongest intensity, lowest pressure, shortly after the 500 mb low closes off, prior to the system becoming stacked.

From a chasing standpoint the occlusion process means the best surface based instability will be shifted into the narrowing warm sector. Convection along the occlusion will have a tendency to be elevated in nature. The tendency for the low to become vertically stacked will also decrease shear, especially directional shear.

When you say the occlusion process and narrowing warm sector, it sounds like your talking about the occlusion process of a surface low.

What mechanisms are responsible for closing the low off? Is it just the fact cold air is being pulled in around the low. And correct me if I am wrong but low tilt is a function of baroclinicity is it not. Larger temp contrasts in and around the lows causes the tilting with height towards the colder air. Barotropic systems have less of a temp contrast in and around them? That would explain why tropical systems are mostly barotropic. And Cold core setups are for the most part barotropic?
 
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