Hi, long time follower of the site here, though I do not post often. I searched this formu for posts from the last 2 years and did not really see any discussions related specifically to this topic. I've been casually chasing since 2005, sometimes with a friend and sometimes alone. I live in central/northeastern Illinois so the opportunities are limited each year. I only have one tornado to my record (THIS storm (not my picture)) and over the past year, I have decided to take my interest and knowledge to the next level.

I understand the four main ingredients for sever weather are Moisture, Instability, Shear, and the one I have the least grasp on - Lift. I think the reason I am struggling with that is because it's really hard to visualize. I can understand warm fronts and cold fronts, but the other, more subtle areas give me a hard time so I was hoping some of you might be able to help me out with udnerstanding and detecting lift on charts and images.

Vorticity: This is a term I really don't understand, other than it (i think) relates to how much vertical lift goes on in an area?

Height: What do height falls signify? I'm not even sure if this has to do with lift.

mesoscale sources of lift: What charts do you check for these, and how do you recognize them?

Any help in these areas would be greatly appreciated!

Well, lift can come from a variety of sources, as you know.

Cold fronts cause lift when a cold front collides with warm air. When the cold air meets the warm moist air it causes the warm air to try to rise above the cold air and those water molecules cool and condense forming clouds.

Warm fronts can also cause lift in the same manner, basically.

You can also get what is known as orographic lift. This is caused by topography, like mountains. When the air mass reaches the mountains, it causes the air to rise and get cool and after it gets beyond the mountains the air sinks and gets warm.. And voila! Clouds start forming!

Orographic lift would be something you'd just have to know based upon the area.

Sometimes outflow boundaries from old thunderstorms can act as mini-cold fronts. I look for those on visible satellite imagery as well and on radar. They can be very easy to pick out.

Check out this link: en.wikipedia.org/wiki/Outflow_boundary

As for looking for warm fronts and cold fronts on a map. I always go to the SPC and go to the mesoanalysis page. Then I look for the current surface conditions.

There you should be able to find the temperature differences where the cold front, warm front, or both should be.

The temperature below the surface temperature is the dewpoint. Look for the dryline by noticing differences in these temperatures.

The closer together the dewpoint and the surface temperature are, the better off you are. Of course, you don't want them to be the same temperature because then your cloud base is on the ground (i.e. fog). But typically a surface temperature and dewpoint temperature of around ten degrees is ideal for severe weather development.

I hope this helps!!

If you have any questions, just ask!

Hmm, I know that jetstreaks can play a role in lift. I still don't really understand how, but if you are looking down stream at a jetstreak, the back right and forward left quadrants cause lift while the other two cause subsidence? yeah, I don't really get it...

As for vorticity, it has to do with the rotation of air in the atmosphere. I know that positive vorticity advection causes lift, but not exactly why. Then there is omega which is still pretty fuzzy to me. :/

I don't think I helped at all, but I felt like getting my thoughts out on the subject. haha

I get the frontal boundaries, but it's the synoptic scale and mesoscale lifting that i have a hard time figuring out/seeing.

Up here in Illinois, we don't really have drylines either

I can't post much more right now, but look into these 3 things for measuring synoptic scale lift:
Quasigeostrophic Theory
Isentropic Lift
Potential Vorticity

The concepts are math heavy, but try and find something that verbally explains it. These are the 3 main sources of synoptic scale lift.

As far as vorticity, it has very little to do with lift by itself. Vorticity is the measure of spin at a given location with a given wind field. Cyclonic (anti clockwise) vorticity is positive. The reason positive vorticity is associated with upward motion is not because of the vorticity itself, but because cyclones have upward motion.

The real reason, in my opinion, vorticity is important is what happens when you advect it (transport horizontally by the wind field) to a new location. Meteorologists use vorticity advection (among other things) to forecast WHERE that synoptic lift is going to move.

I wish I could help more, but I'm walking out the door.

Incoming!!! (links, that is)


A nice, tried and true basic info source:

www.theweatherprediction.com/

Can't go wrong w/MedEd, either; you'll find graphics demonstrating LFC (Level of Free Convection), LI (Lifted Index), EL (Equilibrium Level), LCL (Lifted Condensation Level), and etc.

www.meted.ucar.edu/training_course.php?id=3

Thanks Jo! I'm pretty sure I knew a lot of this stuff a while back, but I totally forgot now. I totally forgot about those websites too.

I'm back with a link.

From what I'm gathering, you are trying to conceptualize sources of synoptic lift, right?
One of those is called isentropic lift. jeff Duda, a meteorologist with a degree from the University of Oklahoma, did a great job explaining how isentropic lift works. Here's the link: www.stormtrack.org/forum/showthread.php?...-Isentropic-surfaces

Unfortunately I do not have links on QG theory or Potential Vorticity yet.

Thanks for the responses...I'm trying to read them now and see what I can learn! I'll post back with any more questions. Do you also suggest signing up for the stormtrack forum?

chrisbray wrote:
Thanks for the responses...I'm trying to read them now and see what I can learn! I'll post back with any more questions. Do you also suggest signing up for the stormtrack forum?

Well, chris.. that's up to you!

Definitely explore the links and posts we've all given you here.

One more question for you:

Do you have the Storm Chasing Handbook?

www.weathergraphics.com/chasing/

I think that book is a must have for anyone. The explanations of forecasting, etc in that book are simplified and it makes it really easy to understand.