question for experts. why is a big high to the north

[rainstorm]

important for a tropical system to form to its south?

i know why its important, but posters some may not. your explanation is appreciated

[DoctorHurricane2003]

I've got a simple answer for you:

It's not.

[WXBUFFJIM]

We typically have a subtropical high situated over the central Atlantic during the height of the hurricane season, that's totally natural. With the clockwise flow around the high, tropical cyclones forming south of that high tracks from east to west from the Cape Verde Islands through the south central Atlantic.

Also south of the subtropical high, we have the inter tropical convergence zone, or an area of thunderstorms that can form into tropical cyclones if conditions are favorable. As the tropical cyclones track towards the United States, will they move towards Florida, towards the Carolinas, towards New England, or out to sea??


Jim

[Matt-hurricanewatcher]

The high pressure/subtropical high is centered from 20 to 35 north/south. This area of high pressure is counter-clockwise over the northern hem/clockwise over the northern hem. What this do's is push the winds to the south westward on the buttom side of this high.

A break/weakness can pull a storm northward...Which is a trough/low pressure system. On the top side the winds flow to the east.


Also to get into it more the earth spins at the equater at about 1k. While the north/south poles spin none. That makes the winds vear eastward. Which makes the high winds spin outwards while the low spin inwards. Which is a reason why the high has sinking air=removing energy from the location. To low pressure sucking in the energy/rising air which forms clouds.

With this being said the ITCZ is a line between two wind flows. One south of the equater and one north. These to lines merge in this area. While on the backside of the subtropical high makes it move east to west across the tropics.

Also you got the subtropical and polar jet streams for both north and south hems.


I hope that answers your quastions rainstorm.

[rainstorm]

some of us may need a lesson in atmospheric dynamics. maybe this will illustrate my point better. in which situation would a tropical system be more likely to form off florida's east coast?

a- a large non tropical low is sitting just east of new england

b- a 1030 mb high is sitting just east of new england

the answer is clearly, with no room for doubt, b

im asking why that is

[Matt-hurricanewatcher]

Your answer is that the trough would/non area of low pressure would drive the system to the northeast. While the high would block it to the south while pushing it into Florida.

[WXBUFFJIM]

The key is where are sea surface temperatures warmer??? That's obvious, off Florida's east coast. Where are winds aloft lighter??? Off Florida's east coast. In situation b. A high pressure to the north would drive the hurricane further to the west towards the east coast of Florida or the southeast U.S. coast, possibly a stronger hurricane too.


Further north off the coast of New England, sea surface temps are much colder and winds aloft are too strong for a tropical system to form under normal conditions. If a hurricane further to the south interacts with this extratropical low and trailing cold front, the odds are it will get carried out to sea with the front and extratropical system and weaken due to strong winds aloft.

As a result, the answer b. is the most likely answer to choose for a potentially enhanced threat on the United States from a tropical cyclone.
I hope this answers your question.

[gatorcane]

some of us may need a lesson in atmospheric dynamics. maybe this will illustrate my point better. in which situation would a tropical system be more likely to form off florida's east coast?

a- a large non tropical low is sitting just east of new england

b- a 1030 mb high is sitting just east of new england

the answer is clearly, with no room for doubt, b

im asking why that is

Don't you think you are being a bit rude with "some of us may need a lesson in atmospheric dynamics."? I find it condescending. It's a simple question and answer that most of us already know anyway.

[rainstorm]

we are still missing the point. good answers though

[Matt-hurricanewatcher]

Jim she is talking about where the system would be steered if a extratropical low was off at around 40 north. Or a high...In which a hurricane is off Florida. Its where the hurricane go's.

[rainstorm]

some of us may need a lesson in atmospheric dynamics. maybe this will illustrate my point better. in which situation would a tropical system be more likely to form off florida's east coast?

a- a large non tropical low is sitting just east of new england

b- a 1030 mb high is sitting just east of new england

the answer is clearly, with no room for doubt, b

im asking why that is

Don't you think you are being a bit rude with "some of us may need a lesson in atmospheric dynamics."? I find it condescending. It's a simple question and answer that most of us already know anyway.

im not intending to be rude at all and i apologize if it seems that way. i had several posters tell me i was wrong and i wanted some experts to explain it better than i. im soory if i seem rude here

[gatorcane]

okay - no harm

[WXBUFFJIM]

We live and learn?? right???

Ok good deal.

Jim

[weatherwindow]

FWIW, the presence of the high would dictate deep easterly to northeasterly flow. this will minimize shear over a incipient system east of the fla coast. hence, it would be, by far, the most favorable atmospheric setup of the two.....rich

[Air Force Met]

important for a tropical system to form to its south?

i know why its important, but posters some may not. your explanation is appreciated

I guess I'm still not getting the question. A big high to the north is not necessary for a tropical system to form. It's more likley, but not necessary. Generally the reason it happens (speaking of atmospheric dynamics) is that with the subtropical high to the north, you are much more likely to have easterlies aloft and a low shear environment for the tropical system to form...the air column is more likely to be humid and you are more likely to have divergence aloft. You can have all of this with a high to the east or southeast and still get a tropical system to form...but the ingredients necessary for tropical development are much more likely to be present with the subtropical high to the north.

[benny]

important for a tropical system to form to its south?

i know why its important, but posters some may not. your explanation is appreciated

I'd say it isn't important at all. Usually that's just the set-up in the tropical Atlantic. However I would argue if you want a tropical system to form, the low-levels better be cyclonic or trending that way. See Wilma of last year.. no big high there.