Ok Ok...Pattern Pop Quiz

[Brent]

Hint...look in the box between 20 and 40N...60 and 90W.

My answer may not be 100% because I could be missing something synoptically...but I will give it a bit later on....

MW

I see it. The dark blue east of Frances(Upper level low?) moved SW closer to Ivan.

[marc21688]

Is that enough to support a dramatic northward turn?

[AL Chili Pepper]

Low pressure the GFS was predicting?

[GalvestonDuck]

Hint...look in the box between 20 and 40N...60 and 90W.

My answer may not be 100% because I could be missing something synoptically...but I will give it a bit later on....

MW

I don't know what it means or if I'm seeing the right thing...but the dry air to the west and east side of that box are closer together and the channel of moist air in between is narrower.

[Brent]

Low pressure the GFS was predicting?

Hmmmmm.... I don't know.

[Harbormaster]

I would have to say that what you are looking at is the atlantic ridge building S and W. Correct?????? Seems like the most dramatic feature.

I know where you are going with this if this is the case.... less possibility of a poleward motion???

[Brent]

I would have to say that what you are looking at is the atlantic ridge building S and W. Correct?????? Seems like the most dramatic feature.

I know where you are going with this if this is the case.... less possibility of a poleward motion???

If that's it... it would prevent a northward turn(certainly one as sharp as the models indicate)

I knew it.

[Greg]

Newby guess. A high pressure zone has developed off the Eastern US coast, steering the tradewinds to a SouthEasternly direction.

[MWatkins]

Aw OK...again this is not the 100% TRUTH because there are a lot of inferences that have to be made because this is water vapor imagery only...but here goes:

1. The ridge axis centered near 30/75 or so yesterday is a shell of it's former self today. Frances is nosing it down pretty good.

2. Note the clouds in the 24 hour ago photo...near 20N. Yesterday...they were clearly moving NE to SW under the ridging...tonight...that flow has relaxed considerably.

3. There is a low cutting off in the central Atlantic that the models have picked up on.

4. Partially due to Frances' tail...the flow north of 20N to 30N...70 to 90W has switched from WSW to ENE to more of a tilt toward the SW to NE...again indicative of the flow weakening up there.

I cannon completely rule out enough ridging to keep Ivan moving due w...but the pattern is changing as we speak...we are losing the ridging we had.

MW

[MWatkins]

I think innotech was closest to my analysis. This doesnt mean he's right...just means he was closest to my analysis.

MW

[charleston_hugo_veteran]

o.k...so which way will it go....fla/texas/sc/nc..........what?

[Ziplock48]

to HEll
Let me sing it again,
A highway to Hell...

The low trough between the highs is like a highway, complete with roadmaps, gasoline, and highspeed lanes right up the FLorida penninsula.

Maybe more like Europe's Autobahn.

Very scary, indeed.
Zip

ps thanks Mike for making learning about the tropics so darn fun. Even in the face of Ivan...

[MBryant]

If Ivan had gone North sooner, I could agree with you, but I think Ivan is too far South of the narrowing ridge to be affected by it.

[AL Chili Pepper]

Went back and looked at the latest models and this is how I'm gonna play it. It depends on how much is left of the Atlantic ridge when Ivan starts gaining latitude. Looks like most of the models taking it eastward have Ivan moving north of Jamaica, while the Canadian is to the south. Therefore, it is my unprofessional opionion that if Ivan moves south of Jamaica, it's a GOM threat. To the north, more of a SE FL threat.

[tronbunny]

The way these newbie eyes see it...
that atlantic ridge (now forecast to continue retrograde west in the 8:05pm tropical weather discussion) COULD block Ivan from moving north and eastward toward SW FL, if the ridge continues its current trend. The trough will continue to be squeezed between the central CONUS ridge.
IF and only IF Ivan reaches that funnel, he'll be guided right up into the big bend.
But the good news for FL seems to be that an ULL in the W Carib. is retrograding west and could draw Ivan with it.

All of the above is to be taken with a grain of margarita salt, as I've not been doing tropical analysis for any time at all, and have no historical data at hand to verify my hunch.
(or it could be wishful thinking based on PTSD from Charley and Frances)
:-p

[Biloxi]

Ridge building back.

[dougjp]

Thanks Mike, that's what is usually missing for those of us trying to learn! Graphic indicators in addition to text explaining the factors which might cause, or have caused a hurricane to change direction.

I wish this thread could keep going tomorrow with a larger number of graphic sequences. It will be interesting to see what 75W & 19-25N looks like, and if it makes any difference.

It would also be interesting to have a graphical post analysis of direction changes, plus the flip side to that, atmospheric changes which were thought should, but didn't, cause a change in direction.

Furthermore, post analysis on the various models' medium and long term forecasting accuracy or lack thereof would also be interesting, with the distances of the inaccuracies in miles. If a database existed for that, then the models could be ranked by performance, much the same as other things are......

[charleston_hugo_veteran]

Thanks Mike, that's what is usually missing for those of us trying to learn! Graphic indicators in addition to text explaining the factors which might cause, or have caused a hurricane to change direction.

I wish this thread could keep going tomorrow with a larger number of graphic sequences. It will be interesting to see what 75W & 19-25N looks like, and if it makes any difference.

It would also be interesting to have a graphical post analysis of direction changes, plus the flip side to that, atmospheric changes which were thought should, but didn't, cause a change in direction.

Furthermore, post analysis on the various models' medium and long term forecasting accuracy or lack thereof would also be interesting, with the distances of the inaccuracies in miles. If a database existed for that, then the models could be ranked by performance, much the same as other things are......

you know...when your ignorant to these type of post it's like listening to the adults in a peanuts cartoon...wawawa....wawa...wawawawa..why can't someone talk in layman terms sometimes...thanks!!

[MBryant]

I understood that perfectly.

[Okibeach]

Great way to post Mike, Having the graphics and everyone giving their analysis of them helped this newbie understand the threads and thinking a lot better.