New (to me) weather symbol

[bob865]

Was checking the weather today (well a couple of days ago now) and looking at the charts and saw a symbol I don't remember ever seeing in the past.  It's drawn as if it is a front, but it't not a front symbol I know.  It is red dashed line with two red dots.  I've done a quick google search, though admittedly not very thorough, and found nothing.  Does anyone know what these symbols mean?

[carusoam]

I don’t have an answer, I could guess, but...

We know a guy...

@scottd  Scott likes to bring people up to speed on all things weather... even small details...

Scott is aka the Weather Spork guy.  https://weatherspork.com/

This is an invite for Scott, in the event an answer doesn’t arrive soon...

Best regards,

-a-

[lamont337]

Squall line 

 

[carusoam]

Knowing where the cold front technically is, is nice... but the really nasty weather is occurring in front of the cold front...

where the squall line is...

There must be some logic on what causes the squalls to be out front...

Or why the cold front is shown behind where the squall line is...

Cold air flowing in...

Warm air being displaced and pushed aloft...

Adiabatic cooling of high RH air...

Now, that’s some weather making...

Best regards,

-a-

 

[Yetti]

Related thing to search is gust front.   squall's develop preceding a front line due to the interaction of warm and cool air.

[bradp]

I should have taken a screen shot when that big squall line moved through last week (? Fri/Sat).  There were lightening hits in a line that extended from northern Virginia to Guatemala. Yes Guatemala. 

[Scott Dennstaedt, PhD]

Yes, as others have said this is the symbol for a squall line or more precisely a quasi-linear convective system (QLCS).  Notice the formal name doesn't include the word thunderstorm since lightning isn't part of the criteria per se.  Many, many years ago, cold fronts were actually referred to as squall lines. Squall lines usually have a bowing or crescent-shape on NEXRAD which is a good sign for strong straight line winds.  Tornadoes, hail and heavy rains are typically also possible with the passage of a squall line.  

They are typical found in the warm sector (ahead of an advancing cold front) of a major weather system or also can be part of a non-frontal mesoscale convective system (MCS).  They can be found 100+ miles ahead of the surface cold front.  That's because they are usually connected to the dynamics (energy) and instability found in the upper atmosphere eill ahead of the surface cold front.   That's why I like to teach pilots how to read constant pressure charts since what's happening at the surface is like only a small part of the story.  Like reading the jacket of a novel to know who shot the sheriff.   

Remember the surface analysis chart that the OP presented is nearly 90 minutes old by the time you see it, so it's kind of "old news" with respect to a squall line.  

[carusoam]

Great explanation, Scott!

Thanks for the additional details too.

The constant pressure chart overlay with the actual weather is really interesting.

Thanks for sharing the knowledge.

Best regards,

-a-

[Dan208]

Weather is one of my favorite parts of Aviation.  It reminds me I will always be a student. 

[bob865]

Funny to learn that it's a squall line since I was pulling up the chart to see where the front was specifically to find out where the squall line would likely be.    I never expected to see it plotted.  I was looking this particular day because the weather here tends to flow more southwest to northeast, almost matching the direction of the mountains.  Watching the RADAR I could see the movement was almost perfectly south to north.  I was sitting at work which is just east of the squall and never saw more than a little rain.  All this, I thought, unusal so I wanted to see where the front was to see if it was causing the unusual to me flow direction.

 

[Scott Dennstaedt, PhD]

5 hours ago, bob865 said:

I was looking this particular day because the weather here tends to flow more southwest to northeast, almost matching the direction of the mountains.  Watching the RADAR I could see the movement was almost perfectly south to north.  I was sitting at work which is just east of the squall and never saw more than a little rain.  All this, I thought, unusual so I wanted to see where the front was to see if it was causing the unusual to me flow direction.

 

Bob,

I see you are in Greenville.  I'm in Charlotte just "downstream” from you.  This isn't usually taught in primary training, but the movement of a "line" of convection is usually controlled by the overall movement of the air mass.  The individual cells on that line are typically controlled by the upper level flow (say, 500 mb).  The combination of those two "vectors" is the resulting movement of the convection.  So, just imagine a train on tracks.  The train moves along the tracks by the upper level winds and the entire set of tracks are also moving as directed by the air mass.  

In the 500 mb image I posted you can see the wind is generally meridional (south to north) while the upper level trough (that U-shaped pattern) is swinging from west to east.  There's your train on moving tracks.  Hope that helps.

[carusoam]

See how many people can/can’t imagine/picture in their mind’s eye... tracks moving W to E, while the train is moving up the tracks...

approximately one out of 50 people may have difficulty with mind images, so I have been told... 

Thanks again, ScottD

Best regards,

-a-

[Greg Ellis]

I just want to chime in here and say how great it is to have someone lurking and posting on our forums with the weather knowledge that Scott has.  I appreciate that he is willing to chime in with his advice and education on our forum.  Thanks Scott for hanging around here.  I have learned an incredible amount of information from his avwxworkshops website and forums as well as his app WeatherSpork.  I am not trying to plug his stuff.  I am just passing along great information for other fellow Mooney pilots to check out if they did not already know it existed.  If you want to learn more about weather and its affects on your flying check out his website and app.  

[Scott Dennstaedt, PhD]

43 minutes ago, Greg Ellis said:

I just want to chime in here and say how great it is to have someone lurking and posting on our forums with the weather knowledge that Scott has.  I appreciate that he is willing to chime in with his advice and education on our forum.  Thanks Scott for hanging around here.  I have learned an incredible amount of information from his avwxworkshops website and forums as well as his app WeatherSpork.  I am not trying to plug his stuff.  I am just passing along great information for other fellow Mooney pilots to check out if they did not already know it existed.  If you want to learn more about weather and its affects on your flying check out his website and app.  

Greg,

Thanks for the kind words!