Help with Tilt of Storm

[darnalljason]

I am taking an online course through penn state and this weeks Homework wants us to locate a vigorus Mid-latitiude Cyclone and analyse it

I have shosen the upper level low moving through central canada see attached image.

two questions


1st question asks for what tilt the system is in negative, neutral, positive

I believe the storm at the image time was in a neutral tilt or maybe transitiong to negative, But i have read differing AFD;s from local office some say neutral/neg and 2 have it as positive any insight on this would be great

2nd question

How can you tell from the 500mb alone no other data available

state whether this low pressure system will continue to flourish or instead decay, and identify the key process is helping to maintain this low pressure system (or is lacking if you say that your system will decay).

 

[Jim wyman]

darnellj,
I am in the same class....


If you read the section on occulsion and the decaying cycle of the cyclone, it will tell you what you need to look for....

 

[darnalljason]

occulsion and decay

Yeah I have read through that 3 or 4 times, And I believe the upper low was in a neutral tilt at the analysis time of 00z jul 14th

My main question is 2 what the difference was form the various forecast offices with some having it neutral or transitiong to negative and 2 other office showing it as a positive tilt



As far as the later I believe the system would continue to hold its own

 

[CZandbergen]

Take a look at the 250mb (or 200) chart. That will give you a better picture of what the trough looks like. See this link:

http://www.twisterdata.com/index.ph...ding=n&output=image&view=large&archive=false#

As far as "tilt", look at the trough and if it seems to make an upright U shape then it is neutral. If it is tilted to the right it is positive and if it is tilted to the left it is negative.

 

[Jim wyman]

We can ONLY look at the 500 mb chart for the awnsers...

 

[Jim wyman]

Yeah I have read through that 3 or 4 times, And I believe the upper low was in a neutral tilt at the analysis time of 00z jul 14th

My main question is 2 what the difference was form the various forecast offices with some having it neutral or transitiong to negative and 2 other office showing it as a positive tilt



As far as the later I believe the system would continue to hold its own

The 500 mb data is universal - across the board..... IF you go with the chart you captured then use that. It sounds like you have the right train of thought going on ......If it is neutral or "slightly" slanted then the cyclone is still building/maintaining itself....

 

[Jeff Duda]

In my honest opinion it looks like that trough has just a hint of a positive tilt, however, it could be debated that it is just neutral. I don't see negative tilt to the trough.

As far as your second question goes, I think Jim has the right answer, but do you know the reason why?

 

[darnalljason]

I would say with the neutral tilt that the system is jsut enterning into oclussion and thus the system would continue to flourish until it takes on a negative tilt as divergence peaks

 

[Jeff Duda]

I'm kind of surprised you're being asked this question only being able to use one plot at one level, and especially how vorticity is not displayed on the plot.

 

[darnalljason]

question

Yeah it defientely makes it more difficult when you only have the 1 chart to look at to base your answer off of

 

[Jeff Hawkins]

Maybe the teacher is making a point here...you can't determine a mid-level system's status from just 1 plot. I.E. it's an exercise in frustration and mental masturbation.

 

[Greg Blumberg]

My question has to do with the dashed lines on the chart. Are those isotherms or a measurement of height falls? They look like isotherms.

Actually, you can learn a lot from the 500 mb chart about the system's status.

The isotherms could help tell you look forward and see if warm air advection underneath the upper level ridge will continue to build and give the system a negative tilt. This could be done using the isotherms and the height contours using the box method to assess the strength of the warm air advection. The larger the area between the height contours and isotherms, the stronger the temperature advection. You can consider the winds direction too.

You can approximate the location of the vorticity maximum from the wind on the upper air plots. It's a crude method, but you can get a general idea of what you're seeing from it. From there you can assess the cyclonic vorticity advection.

As for me, the tilt looks positive, but I'm looking at the small picture and can't see the picture that well.

 

[John Lavin]

Greg, correct me if I'm wrong, but isn't the size of the contour box inversely proportional to the advection magnitude?

 

[Patrick Marsh]

Greg, correct me if I'm wrong, but isn't the size of the contour box inversely proportional to the advection magnitude?

You are correct. Smaller "boxes" constructed from the height field and the contours of the field in question indicates stronger advection.

EDIT: I do want to add that based on my quick, cursory read of this thread, some questionable meteorology being offered -- if I'm correctly understanding what some people are saying. Negatively tilted troughs tend to promote a deepening system.

 

[Greg Blumberg]

Thank you both Patrick and John. My mistake. I'm happy you're around Patrick to clarify these things...