ATL: ISAAC - Post-Tropical - Discussion

[Aric Dunn]

To back up the idea of the center being up there, this is recons latest pass through:

235030 1628N 06803W 8410 01545 0030 +189 +180 273010 011 027 002 00

Wind shift was a touch north of there, strongly agrees with radar and microwave that this is where the strongest circulation is right now...

Not to say that this will be the dominant vortex, but it is the strongest right now.

was jsut about to mention that. the wind field around the northern vort appears to more defined this evening. there is a bunch of missing minob sets that would help but appears to better now. the mid level may die out tonight.

This will be interesting to watch. Recon now headed SE...glancing blow towards what I think is the second center. Winds are already veering back towards the east some instead of staying SW like they should if this was where the LLC was and was all along. Plus the pressure is staying steady. It was 1003 extrap near the light winds to the north and is 1003.3 with 20 kt winds from the SSE.

Update...just passed through another area of light winds: ESE@5 kts and 1002MB at 15.5/67.5. This is lower than the pressure at 16.3/68.9

Yeah I dont think the northern will win out. but also do think there is anything co located with th mid level so either something needs to develop under that or the mid level needs to die.

[Air Force Met]

Pressure dropping yet further closer to the MLC, down to nearly 1000mbs according to the noaa flight. Wind shift much more defined further north, but pressure is lower with the southern area.

That's closer to where I would have put the center...but I think if they fly a little further SW they will find their lowest SLP. The buoy they dropped a couple hours ago gave good indications where the center is...and the satellite presentation is so nice it...it would be a weird turn of events for the eventual LLC not to latch on to where the greatest ML vort is.

[PTrackerLA]

Would not be surprised that the northern circulation is destroyed by the mountain of Hispaniola allowing the southern circulation to become dominate. Just a WAG but that is what I'm thinking......MGC

The above is the opinion of MGC and not an official forecast.

Have been somewhat thinking that myself and I believe that's what the 12z Euro hinted at.

[Kingarabian]

Folks-excuse my back-seat modding, but can we please post what Recon finds in the Recon discussion? That way it's easier for us to look back at informative posts for future or present reference.

Thanks!

Isaac - Recon Discussion

[Zeno8]

2 centers that are fighting it out? this is something you dont see very often...well not like this anyway....

Apparently the King saw it

[Air Force Met]

Yeah I dont think the northern will win out. but also do think there is anything co located with th mid level so either something needs to develop under that or the mid level needs to die.

I think there is...if you look at the recon obs. Go back and extrapolate the data from the dropsonde at 22z and the center matches up close with the satellite. Plus...the latest light wind field near 15.5/67.5 is close to the MLC...and it is the lowest pressure yet found (that I know of). You've almost got a west-Gulf gyre with a better organized MLC on top of it. I think it's just a matter of time before it takes off.

[Air Force Met]

Folks-excuse my back-seat modding, but can we please post what Recon finds in the Recon discussion? That way it's easier for us to look back at informative posts for future or present reference.

Thanks!

Isaac - Recon Discussion

The reason this is pertinent here is it has everything to do with the location of the center...which will determine the track and intensity forecasts of the system. Otherwise I would agree. But if the center is actually 60 miles south: This is the ballgame in terms of who is right...GFS or EURO...SE FL coast or mid Gulf Coast.

Think of it in those terms.

[Shuriken]

Do you think Isaac's centers are finally consolidating, rather than two dueling vorticities?

Generally one of two things happens when a system is decoupled (i.e., has separated surface and mid-level centers):

1) the mid-level center dissipates.

2) a surface center swings over the top of the mid-level center and either then stacks with it, or dissipates (but sometimes with a new surface low forming to take its place -- this is often seen with systems generating outflow boundaries, as Isaac has done during the daylight hours).

-- The dominant circulation is invariably the one with the heaviest associated convection.

[fci]

wow, I must say after being on this site for a few days, you all are very good at analysing isaac.
Do you all keep track of how many times you are right and wrong with your forecasting?
"Great site"

The percentage of "right" would be quite low!!!

[Aric Dunn]

Yeah I dont think the northern will win out. but also do think there is anything co located with th mid level so either something needs to develop under that or the mid level needs to die.

I think there is...if you look at the recon obs. Go back and extrapolate the data from the dropsonde at 22z and the center matches up close with the satellite. Plus...the latest light wind field near 15.5/67.5 is close to the MLC...and it is the lowest pressure yet found (that I know of). You've almost got a west-Gulf gyre with a better organized MLC on top of it. I think it's just a matter of time before it takes off.

I think eventually something will. but if you remember last night and earlier the MLC had been spitting out vorts. each time it would appear to be getting better defined near the mlc then it would just spit the vort out. its happened multiple times. figure eventually it will stop.

[TwisterFanatic]

Best track going with the northern center, but I really like the southern one. It's looking way better right now.

Personal Forecast Disclaimer:
The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

[hurricanes1234]

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

Yeah, I agree with AFM, conditions remain favorable for a good bit of intensification, it just needs to get a better defined circulation and it would take off from there.

[Shuriken]

Would not be surprised that the northern circulation is destroyed by the mountain of Hispaniola allowing the southern circulation to become dominate. Just a WAG but that is what I'm thinking......MGC

The above is the opinion of MGC and not an official forecast.

Have been somewhat thinking that myself and I believe that's what the 12z Euro hinted at.

I remember a dumbbelling Hurricane Gilbert strengthening very quickly after scraping off northern lobes over Haiti.

[Hurricaneman]

Would not be surprised that the northern circulation is destroyed by the mountain of Hispaniola allowing the southern circulation to become dominate. Just a WAG but that is what I'm thinking......MGC

The above is the opinion of MGC and not an official forecast.

Have been somewhat thinking that myself and I believe that's what the 12z Euro hinted at.

I remember a dumbbelling Hurricane Gilbert strengthening very quickly after scraping off northern lobes over Haiti.

So you're saying that Hispaniola could end up helping Isaac, if some of the northern vortmaxes go over Hispaniola I could believe that

[wxman76]

On the satellite I see the northern Vort but looks like it is detatching headed for Hispanola. However just to it's west is another and it is folding into the large area of convection. My thoughts are the center is still outside the convection but just to the SW of the folding vort. Thought earlier that the mountains of haiti might actually help this storm by weeding down some of those vorts. I really like that theory and am excited to see if it holds.

[Portastorm]

Would not be surprised that the northern circulation is destroyed by the mountain of Hispaniola allowing the southern circulation to become dominate. Just a WAG but that is what I'm thinking......MGC

The above is the opinion of MGC and not an official forecast.

Have been somewhat thinking that myself and I believe that's what the 12z Euro hinted at.

I remember a dumbbelling Hurricane Gilbert strengthening very quickly after scraping off northern lobes over Haiti.

Don't think so ... Gilbert was in a steady state of strengthening at that point and rolled south of Haiti.

[stormhunter7]

#NOAA42: Doppler analysis from first pass in #Isaac shows circulation doesn't extend above 8 km altitude. Easterly winds above that height.

Not going to do much until that easterly calms down... Especially at 5 miles above surface.

[ozonepete]

The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org. For Official Information please refer to the NHC and NWS products.


This is the first time I really see a consolidation that might stick. And it looks to me like the northern vort is going to win out. Just what I see from watching these for decades and what I see as the balance point between the competing centers and the 2 convective concentrations on the east and west sides. JMHO.

[ozonepete]

#NOAA42: Doppler analysis from first pass in #Isaac shows circulation doesn't extend above 8 km altitude. Easterly winds above that height.

Not going to do much until that easterly calms down... Especially at 5 miles above surface.

You're saying they sampled the whole storm already?!

[CronkPSU]

Cantore and Postel both thought the Northern eye was going to win and they think this is finally ready to start getting its act together but say the South American dry spot is still going to inhibit strength