ATL: ISAAC - Post-Tropical - Discussion

[SouthFLTropics]

Looks like another hot tower may be firing...I think it's only a matter of time before this consolidates into one center and takes off. He's just stretching his wings right now and gathering his thoughts.

SFT

[Aric Dunn]

Yes, I agree that this far out, a 0.5 or even 1 degree change in location wouldn't make much of a difference in the grand scheme of things.

Given that such a small difference represents either two days over land running up the spine of Florida, or two days running up either the Gulf Stream or the Gulf of Mexico on either side, a minor initialization wobble like this eventually becomes a HUGE difference in the grand scheme of things.


E.g., "Butterfly Effect".

in cases where the system is traveling essentially in a constant path or at a oblique angle to the coast. but right now it wont change much at all because right now the two vorts are rotating around each other which means we take the average distance between them and do to the dynamics of these types of situations the motion averages out and you end up having very little change.

[sandyb]

Florida around 8am Sunday morning. Here's my concern...if you look at the satellite pictures you will see a steady...strong flow of clouds moving from west to east across the Gulf of Mexico and I think that flow is what will push Isaac east of the official forecast track. My concern is that Isaac will stay just east of Florida and eventually make landfall somewhere between Charleston and Myrtle Beach, SC, and then move north.....across east central NC.

this is what is coming from a local met can anyone comment on this I did not copy the whole post

[Portastorm]

Florida around 8am Sunday morning. Here's my concern...if you look at the satellite pictures you will see a steady...strong flow of clouds moving from west to east across the Gulf of Mexico and I think that flow is what will push Isaac east of the official forecast track. My concern is that Isaac will stay just east of Florida and eventually make landfall somewhere between Charleston and Myrtle Beach, SC, and then move north.....across east central NC.

this is what is coming from a local met can anyone comment on this I did not copy the whole post

First of all, we ask folks when quoting sources like this that you also quote the source. Second, without knowing more about this met's reasoning, it appears he/she believes the trough predicted to dig into the central/eastern US will be very strong and will pick up Isaac and shunt him further eastward than what the NHC is predicting.

[wxman57]

Jack was quite generous in keeping Isaac at 40 kts this advisory (as he mentioned). But the NHC can't take chances when a storm is threatening land. My gut is strongly saying west of the peninsula, maybe between Pensacola and Apalachicola. Could be that I'm just hungry. Going home to eat some birthday cake (maybe).

[wxman76]

it is not out of the possibility this thing comes North East of Florida but one of two things or both must happen. The storm will need to strengthen to be picked up by the shortwave and or the shortwave needs to dig more than the models are saying. Considering in the fall the GFS is often to strong with them (when cold air is involved) and it's August don't have a lot of faith in that. I can see how it happens. But Also given the way this storm looks I don't see any rapid strengthening anytime soon, so we will have to see what becomes of the shortwave.

[ozonepete]

Yes, I agree that this far out, a 0.5 or even 1 degree change in location wouldn't make much of a difference in the grand scheme of things.

Given that such a small difference represents either two days over land running up the spine of Florida, or two days running up either the Gulf Stream or the Gulf of Mexico on either side, a minor initialization wobble like this eventually becomes a HUGE difference in the grand scheme of things.

E.g., "Butterfly Effect".

You're still missing the fact that the models can't resolve to that small of an area. They can't "see" a butterfly, or in this case, they can't even see a difference between 15.5 and 16.0 in latitude. It won't produce a different result. The fact that the furthest out point right now could take it to the FL panhandle or North Carolina is a normal distribution that far out. Is that a huge difference? Yes. But it's normal and won't change if the position changes by a degree or less.

[artist]

Jack was quite generous in keeping Isaac at 40 kts this advisory (as he mentioned). But the NHC can't take chances when a storm is threatening land. My gut is strongly saying west of the peninsula, maybe between Pensacola and Apalachicola. Could be that I'm just hungry. Going home to eat some birthday cake (maybe).

HAppy Birthday!

[KWT]

means we take the average distance between them and do to the dynamics of these types of situations the motion averages out and you end up having very little change.

Would that depend alot on the relative strength of the lows, IE if one is much stronger than the other the central point where the systems rotate around will be closer to the bigger low, thats certainly how Baroclinic lows work, not sure that applies for tropics though!

Either way your right, they WILL rotate around, its just to what extent that is in question right now.

[ozonepete]

Jack was quite generous in keeping Isaac at 40 kts this advisory (as he mentioned). But the NHC can't take chances when a storm is threatening land. My gut is strongly saying west of the peninsula, maybe between Pensacola and Apalachicola. Could be that I'm just hungry. Going home to eat some birthday cake (maybe).

Off topic but HAPPY BIRTHDAY wxman57!

[Aric Dunn]

means we take the average distance between them and do to the dynamics of these types of situations the motion averages out and you end up having very little change.

Would that depend alot on the relative strength of the lows, IE if one is much stronger than the other the central point where the systems rotate around will be closer to the bigger low, thats certainly how Baroclinic lows work, not sure that applies for tropics though!

Either way your right, they WILL rotate around, its just to what extent that is in question right now.

exactly.

[Gustywind]

000
WTNT34 KNHC 222038
TCPAT4

BULLETIN
TROPICAL STORM ISAAC ADVISORY NUMBER 7
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012
500 PM AST WED AUG 22 2012

...CENTER OF ISAAC MOVING THROUGH THE LEEWARD ISLANDS...NEW WARNINGS
AND WATCHES ISSUED...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...16.0N 61.2W
ABOUT 25 MI...40 KM SSE OF GUADELOUPE
ABOUT 365 MI...585 KM ESE OF SAN JUAN PUERTO RICO
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...W OR 280 DEGREES AT 22 MPH...35 KM/H
MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES

[wxman76]

FOR THE NHC 5 PM DISCUSSION
"ATELLITE...AIRCRAFT...RADAR...AND SURFACE OBSERVATIONS INDICATE
THAT ISAAC HAS A BROAD CENTRAL AREA OF LIGHT WINDS WITH MULTIPLE
VORTICITY MAXIMA EMBEDDED. THE LOWEST PRESSURES ARE IN AN AREA
NEAR GUADELOUPE...WHICH IS USED AS THE CURRENT CENTER SINCE IT HAS
SOME CONTINUITY WITH THE CENTER PREVIOUSLY BEING TRACKED.
HOWEVER...THE MEAN CENTER IS LIKELY TO THE SOUTHEAST OF THE
ADVISORY POSITION. SOME ADJUSTMENT OF THE CENTER POSITION MAY BE
NECESSARY WHEN THE CENTRAL CORE AGAIN CONSOLIDATES. THE INITIAL
INTENSITY IS HELD AT 40 KT...ALTHOUGH THE HURRICANE HUNTER AIRCRAFT
DATA SUGGESTS THIS COULD BE GENEROUS."

[tropicwatch]

Jack was quite generous in keeping Isaac at 40 kts this advisory (as he mentioned). But the NHC can't take chances when a storm is threatening land. My gut is strongly saying west of the peninsula, maybe between Pensacola and Apalachicola. Could be that I'm just hungry. Going home to eat some birthday cake (maybe).

Gee thanks, put us in the bullseye. Well never the less it is becoming more and more likely that Isaac will be a GOM storm.

[jabman98]

Jack was quite generous in keeping Isaac at 40 kts this advisory (as he mentioned). But the NHC can't take chances when a storm is threatening land. My gut is strongly saying west of the peninsula, maybe between Pensacola and Apalachicola. Could be that I'm just hungry. Going home to eat some birthday cake (maybe).

Happy Birthday! Wouldn't that put the dirty side of the storm nearer to Tampa than the RNC would wish?

[KWT]

Jack was quite generous in keeping Isaac at 40 kts this advisory (as he mentioned). But the NHC can't take chances when a storm is threatening land. My gut is strongly saying west of the peninsula, maybe between Pensacola and Apalachicola. Could be that I'm just hungry. Going home to eat some birthday cake (maybe).

Yep, I can see the logic behind it. I think really 35kts is probably a more fair reflection of this systems current strength given the 40-43kts found earlier on, but either way its not in the best of shape in terms of current low level set-up. As said on the advisory, the mean center is SE of that circulation as you can see by the northern center rotating to the WSW.

[CaneCurious]

FOR THE NHC 5 PM DISCUSSION
"ATELLITE...AIRCRAFT...RADAR...AND SURFACE OBSERVATIONS INDICATE
THAT ISAAC HAS A BROAD CENTRAL AREA OF LIGHT WINDS WITH MULTIPLE
VORTICITY MAXIMA EMBEDDED. THE LOWEST PRESSURES ARE IN AN AREA
NEAR GUADELOUPE...WHICH IS USED AS THE CURRENT CENTER SINCE IT HAS
SOME CONTINUITY WITH THE CENTER PREVIOUSLY BEING TRACKED.
HOWEVER...THE MEAN CENTER IS LIKELY TO THE SOUTHEAST OF THE
ADVISORY POSITION. SOME ADJUSTMENT OF THE CENTER POSITION MAY BE
NECESSARY WHEN THE CENTRAL CORE AGAIN CONSOLIDATES. THE INITIAL
INTENSITY IS HELD AT 40 KT...ALTHOUGH THE HURRICANE HUNTER AIRCRAFT
DATA SUGGESTS THIS COULD BE GENEROUS."

Well to my amateur self, this means that until they adjust the center position, all of the models will be wrong. So its just a wait and see game.

[LaBreeze]

FOR THE NHC 5 PM DISCUSSION
"ATELLITE...AIRCRAFT...RADAR...AND SURFACE OBSERVATIONS INDICATE
THAT ISAAC HAS A BROAD CENTRAL AREA OF LIGHT WINDS WITH MULTIPLE
VORTICITY MAXIMA EMBEDDED. THE LOWEST PRESSURES ARE IN AN AREA
NEAR GUADELOUPE...WHICH IS USED AS THE CURRENT CENTER SINCE IT HAS
SOME CONTINUITY WITH THE CENTER PREVIOUSLY BEING TRACKED.
HOWEVER...THE MEAN CENTER IS LIKELY TO THE SOUTHEAST OF THE
ADVISORY POSITION. SOME ADJUSTMENT OF THE CENTER POSITION MAY BE
NECESSARY WHEN THE CENTRAL CORE AGAIN CONSOLIDATES. THE INITIAL
INTENSITY IS HELD AT 40 KT...ALTHOUGH THE HURRICANE HUNTER AIRCRAFT
DATA SUGGESTS THIS COULD BE GENEROUS."

Well to my amateur self, this means that until they adjust the center position, all of the models will be wrong. So its just a wait and see game.

Seems like it's always a "hurry up and wait" situation. Interesting thoughts and inputs on here as usual.

[Aric Dunn]

Dont think recon is going to find much left of that vort where its heading. wind direction where its at indicate the to its nne or so .

[Ivanhater]

Very nice