ATL: ISAAC - Models

[HurrMark]

Through 24 hrs, nothing really changed from 18Z...perhaps a few miles north.

[wx247]

The 0z GFS should be running soon, correct?

Technically, the GFS had been running for about 20 minutes when you made that post. The images we see posted are only the last portion of the running of the model. First, it has to remove old data files and prep the system for the new run (takes about 10 minutes). Then it needs to make its analysis; that's taking in all the observed station data, radiosondes, satellite data, etc. and creating its best guess at what reality is like within its grids. This takes about another 25 minutes. Then it gets started on running through the forecast. As it gets to the determined times, it will dump out and upload output files, which are then used to generate the maps.

Just thought I'd mention it, since it seems like there's this general sentiment (may be real, I may just be imagining it) that somebody manually puts in some numbers representing "the data", then hits a button and out pops some maps, just like that. Really, its a bunch of scripts and programs that pull in huge batches of data automatically, run through some intense algorithms to try and reproduce the world, then numerically approximate solutions to a ton of equations, which some more scripts then use to make the maps we see. It's a process that, despite using large clusters of extremely powerful computers, still takes quite a while. Hopefully this was helpful to someone, out there. Otherwise, I guess it was a decent way to kill some time.

By the by, if you ever want to see how the NCEP models are progressing, you can visit http://www.nco.ncep.noaa.gov/pmb/nwprod ... index.html. Tonight, we're running a little bit ahead of schedule!

Thanks. That really clears up what I was wondering, but didn't want to ask and clutter the thread with multiple posts. You succinctly answered it.

[bayoubebe]

:uarrow: Yep here is part of long range discussion...

THE ECMWF RECURVES ISAAC AHEAD OF A MID-LATITUDE
TROUGH OVER THE EASTERN UNITED STATES...WHILE THE GFS SLOWS ISAAC
DOWN AS THE TROUGH BYPASSES THE SYSTEM AND THE MODEL THEN TURNS
THE CYCLONE WESTWARD TO THE SOUTH OF A DEVELOPING MID- TO
UPPER-LEVEL RIDGE. THIS BIFURCATION IS ALSO SEEN IN THE MOST RECENT
ECMWF AND GFS ENSEMBLES WITH ABOUT AN EQUAL NUMBER OF MEMBERS
SHOWING RECURVATURE VERSUS A CONTINUE NORTHWESTERLY TRACK TOWARD
THE NORTHERN GULF COAST. SINCE THE UNCERTAINTY IS LARGE AND EITHER
OF THESE SCENARIOS ARE POSSIBLE AT THIS TIME...THE NHC FORECAST IS
LIES BETWEEN THEM. THE UPDATED TRACK IS VERY CLOSE TO THE PREVIOUS
ADVISORY THROUGH 36 HOURS. AFTER THAT TIME...THE TRACK HAS BEEN
ADJUSTED WESTWARD...BUT IT REMAINS EAST OF THE DYNAMICAL MODEL
CONSENSUS TO RETAIN SOME CONTINUITY WITH THE PREVIOUS FORECAST.

This could get very interesting for the N.O. areas and south. Supposed to have 72hr evac plan. They cant sit on this too much longer before begin having to make decisions.

Agreed. The NHC HAS to at least be giving them their best guesses privately tonight to the emergency planners. I'm sitting here watching the Saints pre-season game, wondering how many people in the Superdome known the growing danger that could be coming toward them...

HUH?? When did this all change? Sorry, I did not read through this whole looong thread. I'm one of those people who watched the Saints preseason game without a worry, last I heard Isaac was headed to Destin?

[Jevo]

0z GFS +36

[Blinhart]

GFS initialized over Cuba....might be trash.

Looks to me like it initialized correctly, just off the North Coast of Cuba, right where the center is, might be a little to the East by about 20 to 50 miles, but thats it.

[SouthDadeFish]

GFS initialized over Cuba....might be trash.

I wouldn't call it trash for the whole run, but certainly was odd. Might be trash for how it impacts the Florida Keys. I don't get why they would initialize it there.

[BigB0882]

So far appears on track with the 18z. Next few images will be key.

[HeeBGBz]

When does the next Euro happen?

1:00 AM CDT

Thanks. I need to go to sleep before then, but I need to see what happens too. I probably won't sleep much anyway.

[SeminoleWind]

GFS initialized over Cuba....might be trash.

Nah looks about right, just off the Cuban coast.

[Blinhart]

:uarrow: Yep here is part of long range discussion...

THE ECMWF RECURVES ISAAC AHEAD OF A MID-LATITUDE
TROUGH OVER THE EASTERN UNITED STATES...WHILE THE GFS SLOWS ISAAC
DOWN AS THE TROUGH BYPASSES THE SYSTEM AND THE MODEL THEN TURNS
THE CYCLONE WESTWARD TO THE SOUTH OF A DEVELOPING MID- TO
UPPER-LEVEL RIDGE. THIS BIFURCATION IS ALSO SEEN IN THE MOST RECENT
ECMWF AND GFS ENSEMBLES WITH ABOUT AN EQUAL NUMBER OF MEMBERS
SHOWING RECURVATURE VERSUS A CONTINUE NORTHWESTERLY TRACK TOWARD
THE NORTHERN GULF COAST. SINCE THE UNCERTAINTY IS LARGE AND EITHER
OF THESE SCENARIOS ARE POSSIBLE AT THIS TIME...THE NHC FORECAST IS
LIES BETWEEN THEM. THE UPDATED TRACK IS VERY CLOSE TO THE PREVIOUS
ADVISORY THROUGH 36 HOURS. AFTER THAT TIME...THE TRACK HAS BEEN
ADJUSTED WESTWARD...BUT IT REMAINS EAST OF THE DYNAMICAL MODEL
CONSENSUS TO RETAIN SOME CONTINUITY WITH THE PREVIOUS FORECAST.

This could get very interesting for the N.O. areas and south. Supposed to have 72hr evac plan. They cant sit on this too much longer before begin having to make decisions.

Agreed. The NHC HAS to at least be giving them their best guesses privately tonight to the emergency planners. I'm sitting here watching the Saints pre-season game, wondering how many people in the Superdome known the growing danger that could be coming toward them...

HUH?? When did this all change? Sorry, I did not read through this whole looong thread. I'm one of those people who watched the Saints preseason game without a worry, last I heard Isaac was headed to Destin?

The models showed it 6 hours ago, and the NHC is now taking them into effect, and they are starting to let the general public know that things can change in the near future.

[BigB0882]

It doesn't look like it initialized it over Cuba but just offshore which is where the center is. The center is slightly south of the biggest ball of convection. Perhaps you thought the center was further offshore because of that illusion?

[TwisterFanatic]

Comparing the 0z and 18z so far, the 0z appears to be just a tiny, tiny bit west of the 18z.

[Jevo]

The 0z GFS should be running soon, correct?

Technically, the GFS had been running for about 20 minutes when you made that post. The images we see posted are only the last portion of the running of the model. First, it has to remove old data files and prep the system for the new run (takes about 10 minutes). Then it needs to make its analysis; that's taking in all the observed station data, radiosondes, satellite data, etc. and creating its best guess at what reality is like within its grids. This takes about another 25 minutes. Then it gets started on running through the forecast. As it gets to the......

You provide fantastic insight and a general behind the scenes perspective on a bunch of stuff.... But I can't help but find myself reading your posts in the voice of the Character that Phillip Seymour Hoffman played in Twister.. I smile everytime I catch myself doing it

[ROCK]

GFS initialized over Cuba....might be trash.

I wouldn't call it trash for the whole run, but certainly was odd. Might be trash for how it impacts the Florida Keys. I don't get why they would initialize it there.

That is odd..,the center is clearly off the coast ..not by much but still off

[HurrMark]

By 39 hours, it looks NW of 18Z...and the heading is more NW.

BTW...just to make sure, in case you haven't done so, you want to compare similar times. So if 00Z is at 39 hrs, 18Z should be at 45 hrs.

[Jevo]

0z GFS +48

[CYCLONE MIKE]

For those saying run is trash cause it initializes incorrectly, im sorry to say but you are wrong. The center is just off the cost of cuba right about where gfs shows it.

[Houstonia]

It's a process that, despite using large clusters of extremely powerful computers, still takes quite a while (edit - for the GFS, about two hours from start to finish). Hopefully this was interesting to someone out there. Otherwise, I guess it was a decent way to kill some time.

Definitely NOT a waste of time. This was super interesting to me, Thanks!

[BigB0882]

Unless it heads due N from 48 hours on then it isn't visiting the beaches of Florida...

[SeminoleWind]

So im guessing the GFS doesn't bite on the weakness the NAM was showing huh?