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Ask a Pro Met


am19psu

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  • 2 weeks later...
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  • 2 weeks later...

My dad has asked me this twice now and I don't have an answer for him.

In the winter when it's dry, we tend to get electrical shocks from static electricity more than in the summer when the air is more moist, right? So then how do people in the desert Southwest live? On a humid day their Td might be around the average Td of a Northeast city in winter. Is it like shock city down there? Do people just get used to it? Or does it not happen at all?

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  • 4 weeks later...

Can a more experienced met descibe the significance of OLR anomolies, and importance to weather? Thanks.

OLR anomalies are mainly used as a proxy for the strength of deep convection around the tropics. They are used to gauge the magnitude and movement of the MJO, ENSO patterns other theoretical teleconnection oscillations.

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  • 3 weeks later...

Does anyone have a web site that explains the differences in the models? For example grid spacing, levels, time steps etc between the GFS and ECMWF. Not too detailed but enough to see the differences

Thanks "A retired NWS Met"

http://www.meted.ucar.edu/nwp/pcu2/

There's a ton of great learning material on the met-ed site if you don't already have a (free) account.

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  • 4 weeks later...

I have a quick question regarding the output of the vertical velocities. In the example text output below the graphic shows that the 700mb vv are in negative microbars per second, but other websites have the vertical velocities in mircobars per second (the link below the text output). The question is do I have to negate the sign of the value in the text output to get the correct interpretation of rising and sinking motion? Thanks.

http://68.226.77.253/text/NAM80km/NAM_kisp.txt

http://coolwx.com/cgi-bin/getbufr.cgi?region=NY&stn=KLGA&model=gfs&time=current&field=omeg

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I have a quick question regarding the output of the vertical velocities. In the example text output below the graphic shows that the 700mb vv are in negative microbars per second, but other websites have the vertical velocities in mircobars per second (the link below the text output). The question is do I have to negate the sign of the value in the text output to get the correct interpretation of rising and sinking motion? Thanks.

http://68.226.77.253...km/NAM_kisp.txt

http://coolwx.com/cg...rent&field=omeg

"Omega" (ω) is defined as dp/dt. Since pressure decreases was one moves upward, a negative value of omega indicates upward vertical motion. This has the units of ubar/s. If you are given -ubar/s, or alternatively, negative omega, the signs change so that upward vertical motion is now positive values (with negative units). I think this is just done for convenience since we tend to associate upward motions as positive.

In your links, the first link is given in -ubar/s, so I'm tempted to believe that the positive values indicate upward vertical motion, while the second link has units of ubar/s so negative values indicate upward vertical motion. Hope this makes sense!

Edit: After writing all this I realized you just had a specific question - yes, I'd just switch the sign on the text output to get it to match "traditional" omega sign conventions. I personally think the switch to positive omega --> UVM is more confusing than it is worth.

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What causes lee side cyclogenesis?

Conservation of potential vorticity. As a column of air stretches in the lee of mountains, it must spin faster (like a figure skater pulling in their arms), which increases warm advection ahead of the column and cold advection behind it.

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Conservation of potential vorticity. As a column of air stretches in the lee of mountains, it must spin faster (like a figure skater pulling in their arms), which increases warm advection ahead of the column and cold advection behind it.

thanks

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  • 1 month later...

I have collected some weather observations and do not really know what to make of them. I would appreciate any insight or thoughts you may have on the observations. I have no science or theory to explain the observations, which to me appear to violate the 2nd law of thermodynamics because of their unnatural degree of organization.

They are found as one of several large PDF files archived on the website: askwhy333.minus.com with the title:

Forensic Analysis of the Tornado Outbreak of April 14-15, 2012

Abstract

The weather system producing the tornado outbreak on April 14-15, 2012 is documented using GOES infrared satellite imagery. Sixteen hours of images at half hour intervals are sequentially arranged to show the development and evolution of this system. A forensic analysis is performed using correlation grids, which are highly structured collections of regular geometric shapes spatially correlated to weather features. It is implicitly demonstrated that correlation grids appear to coexist with naturally evolving weather formations. The origin, cause, and actual existence of correlation grids remain unknown.

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I have collected some weather observations and do not really know what to make of them. I would appreciate any insight or thoughts you may have on the observations. I have no science or theory to explain the observations, which to me appear to violate the 2nd law of thermodynamics because of their unnatural degree of organization.

They are found as one of several large PDF files archived on the website: askwhy333.minus.com with the title:

Forensic Analysis of the Tornado Outbreak of April 14-15, 2012

Abstract

The weather system producing the tornado outbreak on April 14-15, 2012 is documented using GOES infrared satellite imagery. Sixteen hours of images at half hour intervals are sequentially arranged to show the development and evolution of this system. A forensic analysis is performed using correlation grids, which are highly structured collections of regular geometric shapes spatially correlated to weather features. It is implicitly demonstrated that correlation grids appear to coexist with naturally evolving weather formations. The origin, cause, and actual existence of correlation grids remain unknown.

I googled that site because it looked like an odd name for a link and came across some of your wunderground posts: http://indonesian.wu...ue=0#commenttop

You're either trying to do something that is way over everyone's head, you're trying too hard to find something that's not there, or you're finding something that is there, known and fairly simplistic and you're trying to make a simplistic thing more complicated than it needs to be.

Reply #598 looks like it may have summed things up nicely (from Neapolitan):

Many of us tried to reason with wxmojo; we often asked very politely for him to explain what it was he was seeing. He'd post one weather map after another atop which he had superimposed dozens of geometric shapes; we'd ask him to explain what it was those shapes were defining or outlining; he'd respond that he didn't know, but it sure was mysterious; we'd again ask him what it was he was showing; he'd become agitated and tell us that a) a person would have to be blind to not see what he was seeing, and b ) if we didn't like it we could just ignore him.

That's not the way a community works, especially one that sometimes discusses science fact and theory at some length. Extraordinary claims require extraordinary evidence; wxmojo failed to provide such evidence.

I'm a frequent contributor to other blogs beside this one; many of them would have not extended wxmojo the same patience and leeway he was granted here, but would have instead laughed him off the forum within minutes of posting his first shape-covered weather map. Just another reason to love WU...

You seem to have a lot of weather questions on wunderground... perhaps instead of asking us about all of these things you see whilst overlaying lines and boxes and trying to theorize some sort of regularity through the language of mathematics and physics, it might be easier just to learn meteorology and see what you can connect yourself. Based on the questions you have raised and the terminology you have used within these questions, you seem like a smart enough person that you could pick up on meteorology if you wanted to.

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You're either trying to do something that is way over everyone's head, you're trying too hard to find something that's not there, or you're finding something that is there, known and fairly simplistic and you're trying to make a simplistic thing more complicated than it needs to be.

You seem to have a lot of weather questions on wunderground... perhaps instead of asking us about all of these things you see whilst overlaying lines and boxes and trying to theorize some sort of regularity through the language of mathematics and physics, it might be easier just to learn meteorology and see what you can connect yourself. Based on the questions you have raised and the terminology you have used within these questions, you seem like a smart enough person that you could pick up on meteorology if you wanted to.

Thanks for your reply, Mark. BTW, I like your USTornadoes blog. My success of getting any useful insight on this topic at the wunderground blog was an experience, to say the least. My solicitations were met from the outset with antagonism and ad hominem attacks (e.g., monkey with an Etch-A-Sketch). It did not take long to realize that any hopes of a productive discussion there were futile.

Regarding your suggestion to pick up some meteorology, I have worked through the introductory textbook Extreme Weather & Climate by Ahrens and Samson. While interesting and informative, I was unable to find any dots connecting the mentioned weather observations. But, one textbook hardly constitutes sufficient training in this area, so this is why I am asking for additional insight. I was most happy to find this "Ask a Pro Met" forum to solicit professional opinions on the observations.

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  • 4 weeks later...
  • 6 months later...

Not sure how often this forum gets checked but I had a pretty basic question which is probably dumb but I'll ask anyways. When it comes to CAD setups can Highs link together to help funnel in cold air? For instance if a 1032 high was sitting in say NW Quebec and a 1028 in NY then a 1024 in PA...would the transport of cold air be better? Basically can highs build essentially a linking roadway of sorts to funnel in cold air? Is that basically what happens anyways? Just curious. Thanks in advance for the answer.

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Not sure how often this forum gets checked but I had a pretty basic question which is probably dumb but I'll ask anyways. When it comes to CAD setups can Highs link together to help funnel in cold air? For instance if a 1032 high was sitting in say NW Quebec and a 1028 in NY then a 1024 in PA...would the transport of cold air be better? Basically can highs build essentially a linking roadway of sorts to funnel in cold air? Is that basically what happens anyways? Just curious. Thanks in advance for the answer.

Yes if the pressure pattern supports it, multiple high centers can reinforce downstream highs with cold air. Such is the case as portrayed in the latest GFS for the x-mas night storm. There isn't great confluence aloft to support a CAD type parent high, but nonetheless, a rather strong (1030 mb) high develops across ern Ontario by 06z wed due to the llvl pattern upstream and downstream blocking.

This mechanism works better across the plains and midwest, while an airmass will become modified if it traverses the glakes region. Llvl theta/e is a good tracer to see how much, if any, the pattern supports a maintenance or possibly a cold reinforcement of Cp/Ca downstream and the generation of a new high center. These aren't true "parent highs" maintained dynamically tho, and they generally make for a lower end CAD setup.

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  • 2 weeks later...

Yes if the pressure pattern supports it, multiple high centers can reinforce downstream highs with cold air. Such is the case as portrayed in the latest GFS for the x-mas night storm. There isn't great confluence aloft to support a CAD type parent high, but nonetheless, a rather strong (1030 mb) high develops across ern Ontario by 06z wed due to the llvl pattern upstream and downstream blocking.

This mechanism works better across the plains and midwest, while an airmass will become modified if it traverses the glakes region. Llvl theta/e is a good tracer to see how much, if any, the pattern supports a maintenance or possibly a cold reinforcement of Cp/Ca downstream and the generation of a new high center. These aren't true "parent highs" maintained dynamically tho, and they generally make for a lower end CAD setup.

Thanks for the answer!

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  • 1 month later...

Dumb question, but what in the world does verbatim mean?  It's everywhere on this site and I have no idea. 

 

In the normal context on this forum, it means reading exactly what the model is showing without any sort of interpretation of the model. It would be like just copying straight off the model for a forecast with no alterations.

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In the normal context on this forum, it means reading exactly what the model is showing without any sort of interpretation of the model. It would be like just copying straight off the model for a forecast with no alterations.

Perfect! Thanks. I know the dctionary definition is something along the lines of copyong something exactly as it originally appeared, but couldnt fit it with meteorology for some reason :P

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Question: The z-time how do you know which model to look at first, my mean time wise like the 0z,12z,18z,06z, i think it's wired how it goes backwards or am i getting confused on it?

 

Thanks,

bobby

 

 

Just go here to see the status of the NCEP models.

http://www.nco.ncep.noaa.gov/pmb/nwprod/prodstat/

Not sure what you mean by "backwards", but Zulu time, in the eastern timezone, is calculated by subtracting 5 in EST and 4 in DST. This leaves you with military time (24 hour clock), which you can then convert to local time. ie: 1300 Hrs = 100 PM.

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