CAUSES IN THE TURN DUE NORTH

[CYCLONE MIKE]

Can anyone explain why the models are showing a due north motion into Florida. What is supposed to happen to cause Ivan to recurve in a couple of days. Thanks

[x-y-no]

It's following a forecast weakness between ridges in the Atlantic and over CONUS. The question is, where will that weakness be (if it lasts at all) and how pronounced will it be?

[LowMug]

Look at the water vapor loop links I have provided:

In the top middle of the screen you can see the remnants of Frances lifting out over the northeastern US into Canada...now follow the white outflow down the eastern seaboard - this is a residual trough due to Frances...this feature is dividing the Bermuda High to the right (the dark area over the Atlantic Ocean) and the Continental High to the left (the dark area over the US)...

Now look at the counter-clockwise motion to the east of the Bermuda High around latitude 30N - this feature is helping push the high pressure to the Southwest which helps reinforce the ridge steering Hurricane Ivan...

Now look to the top left and you can see a front coming from the northwest...

These are the players in Ivan's movement...

The synoptic reasoning goes like this...the Bermuda High is shifting SW, however the trough left over from Frances will help erode the eastern edge of it thus weakening the ridge thus allowing Ivan to move in a more WNW to NW direction over the next couple of days...by this time the front coming from the west is expected to pull Ivan due north over the Florida peninsula...once again all is dependent upon the western edge of the Bermuda High and the strength of it.


http://www.ssd.noaa.gov/PS/TROP/DATA/RT/nwatl-wv-loop.html

http://www.ssd.noaa.gov/PS/TROP/DATA/RT/watl-wv-loop.html

[vbhoutex]

Good explanation!! But didn't you mean Western where you said Eastern in reference to eroding the ridge?

[LowMug]

Good explanation!! But didn't you mean Western where you said Eastern in reference to eroding the ridge?

Yea ... you are right I did mean to say western...thanks for catching that

[TyphoonTim]

Looks to me like the Bermuda high is winning the battle, pushing the trough back. So far I see no sign of weakening.

[FloridaDiver]

Look at the water vapor loop links I have provided:

-- snip -- ]

That was a great explanation of the weather patterns that are steering Ivan, excellent job!

[chadtm80]

Look at the water vapor loop links I have provided:

In the top middle of the screen you can see the remnants of Frances lifting out over the northeastern US into Canada...now follow the white outflow down the eastern seaboard - this is a residual trough due to Frances...this feature is dividing the Bermuda High to the right (the dark area over the Atlantic Ocean) and the Continental High to the left (the dark area over the US)...

Now look at the counter-clockwise motion to the east of the Bermuda High around latitude 30N - this feature is helping push the high pressure to the Southwest which helps reinforce the ridge steering Hurricane Ivan...

Now look to the top left and you can see a front coming from the northwest...

These are the players in Ivan's movement...

The synoptic reasoning goes like this...the Bermuda High is shifting SW, however the trough left over from Frances will help erode the eastern edge of it thus weakening the ridge thus allowing Ivan to move in a more WNW to NW direction over the next couple of days...by this time the front coming from the west is expected to pull Ivan due north over the Florida peninsula...once again all is dependent upon the western edge of the Bermuda High and the strength of it.


http://www.ssd.noaa.gov/PS/TROP/DATA/RT/nwatl-wv-loop.html

http://www.ssd.noaa.gov/PS/TROP/DATA/RT/watl-wv-loop.html

Good Explanation thanks for breaking it down for everyone.. I plan on making a graphic showing just that later on tonight for everyone if I get a chance

[Josephine96]

My question is how much the storm may weaken if at all :eek;

[CYCLONE MIKE]

Thanks for the rundown. That helps me a lot. Do you think the ridge will hold or possibly combine with the one over the US or is the trough left by frances too strong and will weaken the Bermuda High?

[Ixolib]

Looks to me like the Bermuda high is winning the battle, pushing the trough back. So far I see no sign of weakening.

...which begs the question - Since this seems to be the overwhelming factor, is it posible at this point to nail down any specifics on whether the ridge will or will not weaken?

[LowMug]

Looks to me like the Bermuda high is winning the battle, pushing the trough back. So far I see no sign of weakening.

...which begs the question - Since this seems to be the overwhelming factor, is it posible at this point to nail down any specifics on whether the ridge will or will not weaken?

It is the overwhelming factor at least in the near term...this is why forecasting is so difficult at time and why models are so relied upon...only time will tell...IMO (and many others) the GFS will not verify...

The ridge does appear to be digging further SW and putting the squeeze on the remnants of Francis