New Ivan Forecast... New Orleans

[Derek Ortt]

We had no choice but to make this shift.

forecast by John Cangialosi

http://www.nwhhc.com/atl092004forecast.html

graphics in just a minute or so

[Brent]

[goodlife]

NNNOOOOOOOOOOOOOOOOOOOOOOOO!!!!!!!!!!!!!!

[PurdueWx80]

Great forecast once again. I'm getting a little edgy regarding shear forecasts now. A couple of models I have seen this morning forecast a very favorable outflow environment from 300-200 mb w/ absolutely zero indication of shear as a piece of the ridge actually forms right over the storm. Should be an interesting 3 days ahead.

[LAwxrgal]

NOOOOOOOOOOOOOOOOOOOOOOOOOOO

That's it, I'm leaving now.

Thank you Derek Ortt for your tireless efforts.

[x-y-no]

Oh my ...

[yoda]

I would say you are too far left Derek, but you have more info than I do, so I must say that even though IMO New Orleans will only get a piece of it, your forecast is good.

[Air Force Met]

Derek...why do you think the NHC track has shifted so far to the EAST? They have movd back to Pensacola

[Guest]

Ivan if the first one won't get ya the second one will. Ivan slowing can't put a kink in the forcast right?

[Derek Ortt]

here's the graphic

http://www.nwhhc.com/atl092004graphics.html

stacy wrote the 11 a.m. that should say enough about why there has been a shift to the east

[goodlife]

Derek...who do you work for??

[CFL]

Well now that Ivan has turned NW I assume he's responding to the trough, which I would assume would make New Orleans less likely for a direct hit?

[Air Force Met]

Well now that Ivan has turned NW I assume he's responding to the trough, which I would assume would make New Orleans less likely for a direct hit?

Problem is the trough kicks out today and a high moves into its place. The high is weak...but it means there will be some ridging there.

[yoda]

here's the graphic

http://www.nwhhc.com/atl092004graphics.html

stacy wrote the 11 a.m. that should say enough about why there has been a shift to the east

Well actually no and yes Derek...

This is what the 11 AM DISCUSSION SAYS:

"The NHC model guidance has shifted
slightly westward...and so has the official forecast track. However
...Latest water vapor imagery and 12z upper-air data indicate a 500
mb low over western Tennessee with a sharp north-south oriented
trough extending southward into the north central Gulf of
Mexico...which has eroded the subtropical ridge axis over the
central and eastern Gulf. This has allowed the ridge across Texas
and Louisiana to build eastward over the western Gulf. The
mid-level wind flow across the Florida Peninsula has also veered
from easterly to southerly during the past 24 hours...suggesting
that the ridge has eroded a little farther east than the NOGAPS and
GFDN models have been forecasting. Therefore...the forecast track
remains on the eastern edge of the model guidance envelope."

[Derek Ortt]

I work at the University of Miami at RSMAS

I did <b>not</b> write the nwhhc forecast this morning for ivan. But I do stand by the track from my forecaster

[BayouVenteux]

Well now that Ivan has turned NW I assume he's responding to the trough, which I would assume would make New Orleans less likely for a direct hit?

My thinking as well CFL. I guess the telling sign will be wherever a majority northward component to movement begins. With all respect to Derek and his excellent forecasting skills, I just can't see Ivan's center getting past 86-88W, before moving more easterly

I'm following the NHC's lead ATTM, but I'm beginning to make and store extra ice this morning, just to CMA.

We shall see.

Postscript: Excuse me Derek, as I didn't realize that you did not author the last NWHHC forecast when I posted this message.

[Air Force Met]

here's the graphic

http://www.nwhhc.com/atl092004graphics.html

stacy wrote the 11 a.m. that should say enough about why there has been a shift to the east

Does he stick with the GFS and GFDL solutions usually? Don't understand the 11am discussion. IT states the obvious about the trough...which is where the models put it...but the models also take it out by tomorrow and put a high there. NOt understanding why he has it moving NNE after 48 hours.

[dhweather]

Derek - not to argue here, just trying to understand. I've got a lot of respect for you and your groups forecasts.

The NHC has indicated in great detail they are staying EAST of the models. You seem to be
with WESTERN most guidance.

Is there synoptic reasoning in your forecast that is different from the NHC?

[goodlife]

I don't think the storm is really moving NW...
look at the satellite loop
http://www.ssd.noaa.gov/PS/TROP/DATA/RT/float-vis-loop.html

I think it was more stair stepping...or a wobble.

[caneman]

here's the graphic

http://www.nwhhc.com/atl092004graphics.html

stacy wrote the 11 a.m. that should say enough about why there has been a shift to the east

Does he stick with the GFS and GFDL solutions usually? Don't understand the 11am discussion. IT states the obvious about the trough...which is where the models put it...but the models also take it out by tomorrow and put a high there. NOt understanding why he has it moving NNE after 48 hours.

Read, Yoda's post above.