Ivan Advisories
Moderator: S2k Moderators
Some thoughts on Ivan
The so called “Miracle track” parallel to the coast by Ivan as he encountered JAMAICA was no coincidence and probably the result of the geographical orientation and topography of the island. If we consider Charley’s track from earlier this year, we saw more or less the same thing happen but a bit further away from the island.
http://www.weather.unisys.com/hurricane ... /track.gif
Now compare that to Ivan.
http://www.weather.unisys.com/hurricane ... /track.gif
Charley actually turned noticeably WSW for a time before resuming the west northwest/NW track after passing by the island. Last night, Ivan took a significant jog west along the Southern Shore of the island and has now resumed the previous motion.
So it is likely that IVAN will maintain a similar track to that of charley with a bit of a westward adjustment at least until reaching Cuba, however it is after he emerges from CUBA is where the differences develop. The synoptic scale set-up which led to Charley’s early NNE/NE turn was easy to pick out w/ a deep trough over the Ohio valley and the axis of which centered between 86 and 88W and the ridge beaten eastward.
http://www.wright-weather.com/archive/d ... 00_500.gif
This was within 10 degrees latitude of charley and easily able to affect its path.
In the case of IVAN there will be no such high amplitude trough centered near 85W, so Ivan’s future movement will be dictated by the orientation of the ridge and to a lesser degree the weakness over the GOM on the synoptic scale.
The majority of the guidance since 0z has been trending west (including the GFS) and is now more in line w/ what the NOGAPS and GGEM had been indicating for many runs. The coherency of the GFS has also improved that we are within 84 hours, as the resolution is down to 55 KM as compared to the lower 77KM resolution between 90 and 180 hrs and then the even more rancid 108 KM thereafter.
The new 12z 9/11 ECMWF is out and even further west than the previous two runs with Ivan’s track as it builds the western edge of the sub-tropical ridge west of 80W longitude. Recall earlier runs were further east as a result of the western edge of the ridge NEVER getting west of 80W.
The implications of such changes are fairly straightforward, and would be consistent with a further west track as advertised by the GGEM and NOGAPS for several prior runs and PERHAPS a panhandle landfall.
Another critical change in the 12z ECMWF in relationship to the 0z run is the course Ivan takes after landfall. Recall the 0z run had it taking a SHARP NE turn after landfall due to a developing bulge in the ridge allowing for a sharper turn as compared to say heading DUE north after the turn occurs. The 12z does not show as significant of a bulge in the ridge which would allow for more meridional movement after landfall. (Strait north at a given longitude for a longer duration as compared to sharp curvature)
The 18z hurricane models—are still indicating more of a sharp-curve than what the 12z ECMWF is. However the key here is how far west Ivan gets before the sharp re-curvature occurs. notice that the majority of the models have IVAN making the turn between 84 and 86 W longitude, w/ the BAMM and BAMD as far west as 87 and 88W
The point at which the Northward trend occurs and the location of western edge of the sub-tropical ridge (and the bulge IF it does infact come to fruition) will ultimately dictate when and were Ivan turns North and then Northeast and where it makes landfall, and its track thereafter. Right now, I would say the eastern and central FL panhandle are most likely to be the landfall position, however depending on later data, this may change.
As far as its intensity is concerned…the further west track would allow Ivan to spend more time over the very warm waters of the eastern gulf where SSTS are over 30 C, enabling enough moisture and heat flux from the ocean to the atmosphere for further intensification to occur. But as usual there is a caveat, that being the expected increase in vertical shear over Ivan once in the GOM. Hard to tell at this juncture how much of an effect it will have on intensity until it actually gets into the GOM, but suffice it to say that anything less than at CAT 3 prior to landfall is unlikely IMO.
Also depending on the track of the h500 low, which if up along the spine of the Appalachians for a time COULD mean another significant severe weather outbreak east of it along the east coast (FL peninsula, GA, SC, NC, VA etc…) in addition to, yes, YET ANOTHER flooding threat.
http://www.weather.unisys.com/hurricane ... /track.gif
Now compare that to Ivan.
http://www.weather.unisys.com/hurricane ... /track.gif
Charley actually turned noticeably WSW for a time before resuming the west northwest/NW track after passing by the island. Last night, Ivan took a significant jog west along the Southern Shore of the island and has now resumed the previous motion.
So it is likely that IVAN will maintain a similar track to that of charley with a bit of a westward adjustment at least until reaching Cuba, however it is after he emerges from CUBA is where the differences develop. The synoptic scale set-up which led to Charley’s early NNE/NE turn was easy to pick out w/ a deep trough over the Ohio valley and the axis of which centered between 86 and 88W and the ridge beaten eastward.
http://www.wright-weather.com/archive/d ... 00_500.gif
This was within 10 degrees latitude of charley and easily able to affect its path.
In the case of IVAN there will be no such high amplitude trough centered near 85W, so Ivan’s future movement will be dictated by the orientation of the ridge and to a lesser degree the weakness over the GOM on the synoptic scale.
The majority of the guidance since 0z has been trending west (including the GFS) and is now more in line w/ what the NOGAPS and GGEM had been indicating for many runs. The coherency of the GFS has also improved that we are within 84 hours, as the resolution is down to 55 KM as compared to the lower 77KM resolution between 90 and 180 hrs and then the even more rancid 108 KM thereafter.
The new 12z 9/11 ECMWF is out and even further west than the previous two runs with Ivan’s track as it builds the western edge of the sub-tropical ridge west of 80W longitude. Recall earlier runs were further east as a result of the western edge of the ridge NEVER getting west of 80W.
The implications of such changes are fairly straightforward, and would be consistent with a further west track as advertised by the GGEM and NOGAPS for several prior runs and PERHAPS a panhandle landfall.
Another critical change in the 12z ECMWF in relationship to the 0z run is the course Ivan takes after landfall. Recall the 0z run had it taking a SHARP NE turn after landfall due to a developing bulge in the ridge allowing for a sharper turn as compared to say heading DUE north after the turn occurs. The 12z does not show as significant of a bulge in the ridge which would allow for more meridional movement after landfall. (Strait north at a given longitude for a longer duration as compared to sharp curvature)
The 18z hurricane models—are still indicating more of a sharp-curve than what the 12z ECMWF is. However the key here is how far west Ivan gets before the sharp re-curvature occurs. notice that the majority of the models have IVAN making the turn between 84 and 86 W longitude, w/ the BAMM and BAMD as far west as 87 and 88W
The point at which the Northward trend occurs and the location of western edge of the sub-tropical ridge (and the bulge IF it does infact come to fruition) will ultimately dictate when and were Ivan turns North and then Northeast and where it makes landfall, and its track thereafter. Right now, I would say the eastern and central FL panhandle are most likely to be the landfall position, however depending on later data, this may change.
As far as its intensity is concerned…the further west track would allow Ivan to spend more time over the very warm waters of the eastern gulf where SSTS are over 30 C, enabling enough moisture and heat flux from the ocean to the atmosphere for further intensification to occur. But as usual there is a caveat, that being the expected increase in vertical shear over Ivan once in the GOM. Hard to tell at this juncture how much of an effect it will have on intensity until it actually gets into the GOM, but suffice it to say that anything less than at CAT 3 prior to landfall is unlikely IMO.
Also depending on the track of the h500 low, which if up along the spine of the Appalachians for a time COULD mean another significant severe weather outbreak east of it along the east coast (FL peninsula, GA, SC, NC, VA etc…) in addition to, yes, YET ANOTHER flooding threat.
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Stormsfury
- Category 5
- Posts: 10549
- Age: 53
- Joined: Wed Feb 05, 2003 6:27 pm
- Location: Summerville, SC
Miamians are used to Channel 7's "Carnival of Carnage" coverage. Watching hurricane coverage with them would be hilarious if it weren't so upsetting. Routine discussion with Max Mayfield: "Where is this hurricane going?" "Either North up to the Carolinas or North to the top of Florida". "Well, what if it doesn't?" "What?" "What if it doesn't do what you're expecting?" "You mean, what if it does something totally different from what we're thinking it'll do?" "Yes. Could it hit Miami then?" "Well, sure, I guess." "Ok, folks. You heard it here first. It could come right to Miami."
Sigh.
Sigh.
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Anonymous
Bottom line: Ivan has missed the trough....
and continues to move around the ridge. There is no other way to put it.
The weakness that was once there, has been noticeably retreating to the north, which tells me Ivan is left on his own, for the time being. The fact that he lsowed, has caused him to be less influenced by the previous trouhg that was hanging over Florida. Look for Ivan to slow even more and possibly sit for 24hrs. while over the western edge of Cuba, before making a move to the north, in a hurry.
The west coast of Florida looks spared, thankful for them, but bad for others.
The weakness that was once there, has been noticeably retreating to the north, which tells me Ivan is left on his own, for the time being. The fact that he lsowed, has caused him to be less influenced by the previous trouhg that was hanging over Florida. Look for Ivan to slow even more and possibly sit for 24hrs. while over the western edge of Cuba, before making a move to the north, in a hurry.
The west coast of Florida looks spared, thankful for them, but bad for others.
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das8929
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gkrangers
Which with the better sattellite rep we have now, and the seemingly dropping pressure...intensification could still be occuring.Stormsfury wrote:gkrangers wrote:Don't these little W/SW wobbles tend to correlate with intensification?
Ironically, with Ivan, seemingly with every westerly wobble, Ivan has undergone, or was undergoing an intensifying phase ...
SF
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NCstateWOLF wrote:Those models are futher west from the last time I check. Whats everyone thoughts about these models right now? Seems a bit too far west to me since the slower movement of Ivan.
Looking at the latest radar loops, those models seem to be looking correct right now, especially the GFDL.
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Opal storm
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Stormsfury
- Category 5
- Posts: 10549
- Age: 53
- Joined: Wed Feb 05, 2003 6:27 pm
- Location: Summerville, SC
Frames 169-172 ... Ivan has been moving WEST ...
(OMIT - Frames 173-180) ...
http://hadar.cira.colostate.edu/ramsdis ... G8vis.html
(OMIT - Frames 173-180) ...
http://hadar.cira.colostate.edu/ramsdis ... G8vis.html
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roostercogburn
-
Rainband
Re: Bottom line: Ivan has missed the trough....
our locals are starting evacuation Monday maybe even tomorrow. Guess they missed your news flashBig EZ wrote:and continues to move around the ridge. There is no other way to put it.
The weakness that was once there, has been noticeably retreating to the north, which tells me Ivan is left on his own, for the time being. The fact that he lsowed, has caused him to be less influenced by the previous trouhg that was hanging over Florida. Look for Ivan to slow even more and possibly sit for 24hrs. while over the western edge of Cuba, before making a move to the north, in a hurry.
The west coast of Florida looks spared, thankful for them, but bad for others.
NO ONE in the GOM is out of the woods at this point 
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Chilly_Water
- Tropical Storm
- Posts: 191
- Joined: Fri Sep 10, 2004 3:59 pm
- Location: Charleston, SC
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