2020 Global Model Runs Discussion (Out thru day 16)

[crownweather]

For those using the GFS model as a barometer for increased activity as we are heading into September - BE CAREFUL!

It's done horribly this season with tropical cyclone genesis forecasts. Use the ensembles or better yet, use the newer GFS Parallel ensemble guidance (it's done well with genesis forecasts this season - I've been keeping track).

So, what does the GFS parallel ensemble guidance show - There's a signal for a tropical system to form in the Bahamas in about 10 days from now & a signal that shows the SW North Atlantic may be active between the 10th and 16th of September.

[SFLcane]

I don't think we'll get shut out on long trackers this year Just may not be right when we expect.

[aspen]

For those using the GFS model as a barometer for increased activity as we are heading into September - BE CAREFUL!

It's done horribly this season with tropical cyclone genesis forecasts. Use the ensembles or better yet, use the newer GFS Parallel ensemble guidance (it's done well with genesis forecasts this season - I've been keeping track).

So, what does the GFS parallel ensemble guidance show - There's a signal for a tropical system to form in the Bahamas in about 10 days from now & a signal that shows the SW North Atlantic may be active between the 10th and 16th of September.

The GFS-Para has also developed 99L and been consistent about at least a strong TS forming in the MDR sometime within the next 5-10 days. In the long range 06z run, it has a storm in the Gulf and yet another MDR hurricane.

[MarioProtVI]

For those using the GFS model as a barometer for increased activity as we are heading into September - BE CAREFUL!

It's done horribly this season with tropical cyclone genesis forecasts. Use the ensembles or better yet, use the newer GFS Parallel ensemble guidance (it's done well with genesis forecasts this season - I've been keeping track).

So, what does the GFS parallel ensemble guidance show - There's a signal for a tropical system to form in the Bahamas in about 10 days from now & a signal that shows the SW North Atlantic may be active between the 10th and 16th of September.

The GFS-Para has also developed 99L and been consistent about at least a strong TS forming in the MDR sometime within the next 5-10 days. In the long range 06z run, it has a storm in the Gulf and yet another MDR hurricane.

Is it better to trust the GFS-parallel itself then the operational GFS, which has performed horribly this year? Has it done better with genesis then the other? Would like to know.

[crownweather]

For those using the GFS model as a barometer for increased activity as we are heading into September - BE CAREFUL!

It's done horribly this season with tropical cyclone genesis forecasts. Use the ensembles or better yet, use the newer GFS Parallel ensemble guidance (it's done well with genesis forecasts this season - I've been keeping track).

So, what does the GFS parallel ensemble guidance show - There's a signal for a tropical system to form in the Bahamas in about 10 days from now & a signal that shows the SW North Atlantic may be active between the 10th and 16th of September.

The GFS-Para has also developed 99L and been consistent about at least a strong TS forming in the MDR sometime within the next 5-10 days. In the long range 06z run, it has a storm in the Gulf and yet another MDR hurricane.

Is it better to trust the GFS-parallel itself then the operational GFS, which has performed horribly this year? Has it done better with genesis then the other? Would like to know.

For the limited time the GFS-Parallel model has been run (not being run all the time), I think it's done far better with picking out areas to watch out for. The GFS-Parallel ensembles, which seems to be run all the time now has done great with picking out genesis & seems to be doing better than the Euro ensembles!

[chaser1]

The GFS-Para has also developed 99L and been consistent about at least a strong TS forming in the MDR sometime within the next 5-10 days. In the long range 06z run, it has a storm in the Gulf and yet another MDR hurricane.

Is it better to trust the GFS-parallel itself then the operational GFS, which has performed horribly this year? Has it done better with genesis then the other? Would like to know.

For the limited time the GFS-Parallel model has been run (not being run all the time), I think it's done far better with picking out areas to watch out for. The GFS-Parallel ensembles, which seems to be run all the time now has done great with picking out genesis & seems to be doing better than the Euro ensembles!

Odd but true. I've noticed the same thing lately.

[Steve]

ICON has a few systems in the next 10 days. First low forms off the SEUS coast. It's ambiguous what happens with the WCar low as it partially spins down on the Mexican Riviera and partially angles isobars toward Brownsville. It's got some stupid Fujiwara thing going on in the E-Atl with the first two systems before showing 2 systems developing out there.
https://www.tropicaltidbits.com/analysi ... 3112&fh=90


Parallel GFS (06z) has much the same as ICON though less pronounced off the SEUS coast. It also brings a storm out of the Bay of Campeche and hits slightly east of where Laura did as a Cat 2 (or possibly a 3) around 1am 2 weeks from tomorrow. If that verifies I'm not going to eat a hat, but I would be surprised.
https://www.tropicaltidbits.com/analysi ... 83106&fh=6

[gatorcane]

If the GFS trough verifies, and that is a big if, looks like we could see some of the SSTs cool down along the northern Gulf coast with lows in the mid 50s:

[Ivanhater]

If the GFS trough verifies, and that is a big if, looks like we could see some of the SSTs cool down along the northern Gulf coast with lows in the mid 50s:

https://i.postimg.cc/X7KHchxf/gfs-T2m-seus-41.png

Unless there are sustained and multiple cold fronts I doubt anything will cool substantially or for that long. We always have 1 or 2 during the summer like 2018 and we saw a category 5 in October

[cheezyWXguy]

GFS Para seems intent on destroying everything in SW LA that Laura missed, with another major landfall. Along with a strengthening hurricane north of the lesser Antilles of course. If you’re looking for a global model with a decent track record that consistently shows something, this is one of them.

[TheStormExpert]

00z EPS seems to be lighting up again for what it’s worth.

 https://twitter.com/jpkassell/status/1300452851290902535

[gatorcane]

GFS Para seems intent on destroying everything in SW LA that Laura missed, with another major landfall. Along with a strengthening hurricane north of the lesser Antilles of course. If you’re looking for a global model with a decent track record that consistently shows something, this is one of them.

Those storms are way out in the long-range and the GFS para as far as I am concerned seems too eager to develop things. The ensembles could be a better bet and they show some possibilities in the MDR over the Atlantic.

[aspen]

The three most reliable models this year for cyclogenesis — the CMC, ICON, and GFS-Para — as well as the EPS are all showing development in the eastern MDR by late this week. Depending on how this comes out, it could be the long-tracking MDR hurricane we’ve been anticipating. If not, the wave behind it could become one.

[Spacecoast]

The three most reliable models this year for cyclogenesis — the CMC, ICON, and GFS-Para — as well as the EPS are all showing development in the eastern MDR by late this week. Depending on how this comes out, it could be the long-tracking MDR hurricane we’ve been anticipating. If not, the wave behind it could become one.

Is there a metric, (or scorecard) for cyclogenesis reliability amongst these models?

Accurately predicting cyclogenesis 3-5 days prior to actual genesis is one thing, but inaccurately predicting genesis 3-5 days prior when no genesis occurs should be factored in as a 'false positive', and weighed against the overal 'reliability.'

Just as inaccuratey not predicting cyclogenesis 3-5 days prior must be factored in as a 'false negative'.

It appears to me that the GFS / Euro have an unusually high false negative rate.
It also appears to me that CMC / GFS-Para have a fairly high false positive rate.
Both of these errors are equally important.

After genesis, the GFS-Para does seem to predict many rapid blowups, and unusual stalls near the coast. A couple days back it stalled a major just off the N.O coast for a prolonged period of time.

[cheezyWXguy]

The three most reliable models this year for cyclogenesis — the CMC, ICON, and GFS-Para — as well as the EPS are all showing development in the eastern MDR by late this week. Depending on how this comes out, it could be the long-tracking MDR hurricane we’ve been anticipating. If not, the wave behind it could become one.

Is there a metric, (or scorecard) for cyclogenesis reliability amongst these models?

Accurately predicting cyclogenesis 3-5 days prior to actual genesis is one thing, but inaccurately predicting genesis 3-5 days prior when no genesis occurs should be factored in as a 'false positive', and weighed against the overal 'reliability.'

Just as inaccuratey not predicting cyclogenesis 3-5 days prior must be factored in as a 'false negative'.

It appears to me that the GFS / Euro have an unusually high false negative rate.
It also appears to me that CMC / GFS-Para have a fairly high false positive rate.
Both of these errors are equally important.

After genesis, the GFS-Para does seem to predict many rapid blowups, and unusual stalls near the coast. A couple days back it stalled a major just off the N.O coast for a prolonged period of time.

I remember that, very weird track. However, the system that it showed doing that is still depicted, aka the Bahamas system. Although its handling of the system has varied dramatically, the model has shown the system itself at least semi-consistently, and I’ve seen all the systems it currently depicts on other models at one time or another (wgom on gfs and now on euro ensemble), Bahamas system on gfs and cmc, mdr hurricane on just about all of them). I agree it handles those systems inconsistently, but I have yet to see any model that doesn’t contend with the windshield wiper effect in the long range.

I can’t attest to its false positive rate much, but I don’t recall any extended periods this season where the para was locked onto a system for an extended time that just never panned out. On the other hand, a do recall this on the standard gfs for the phantom cag system it depicted in early August. I definitely can acknowledge that I may be missing some cases so far this season that could be altering my perception though.

[cainjamin]

The 12Z GFS-Para is still showing a slew of systems developing over the next couple weeks:

1. Develops 99L in the Gulf of Honduras
2. Develops the wave about to exit Africa into a hurricane, but dissipates it before it reaches the islands.
3. Develops the following wave into a hurricane with a pretty ominous track approaching the islands at hour 384.
4. Develops a hurricane in the GOM that makes landfall in western Louisiana.
5. Develops what might be the wave currently in the Central Atlantic into a short-lived storm that hits SC.

Doesn't do much with 90L but it looks like we may also get a storm out of that. It's going to be a busy few weeks it looks like.

[shiny-pebble]

The 12Z GFS-Para is still showing a slew of systems developing over the next couple weeks:

1. Develops 99L in the Gulf of Honduras
2. Develops the wave about to exit Africa into a hurricane, but dissipates it before it reaches the islands.
3. Develops the following wave into a hurricane with a pretty ominous track approaching the islands at hour 384.
4. Develops a hurricane in the GOM that makes landfall in western Louisiana.
5. Develops what might be the wave currently in the Central Atlantic into a short-lived storm that hits SC.

Doesn't do much with 90L but it looks like we may also get a storm out of that. It's going to be a busy few weeks it looks like.

That along with 90L would bring us to Teddy with only 2 names left in 16 days...

Sent from my SM-G970U using Tapatalk

[St0rmTh0r]

The 12Z GFS-Para is still showing a slew of systems developing over the next couple weeks:

1. Develops 99L in the Gulf of Honduras
2. Develops the wave about to exit Africa into a hurricane, but dissipates it before it reaches the islands.
3. Develops the following wave into a hurricane with a pretty ominous track approaching the islands at hour 384.
4. Develops a hurricane in the GOM that makes landfall in western Louisiana.
5. Develops what might be the wave currently in the Central Atlantic into a short-lived storm that hits SC.

Doesn't do much with 90L but it looks like we may also get a storm out of that. It's going to be a busy few weeks it looks like.

That along with 90L would bring us to Teddy with only 2 names left in 16 days...

Sent from my SM-G970U using Tapatalk

That's as hyperactive as it gets. With a dangerous landfall pattern it's going to be chaotic

[Hammy]

00z EPS seems to be lighting up again for what it’s worth.

https://twitter.com/jpkassell/status/1300452851290902535

It seems the monsoon gyre being so far north is going to reduce the chances of a long-tracker this year if everything that forms that far east is ending up flung NW over cooler water. But once again the flip side is a much higher chance that those systems either reform or wait to form much further west--leaving no time to miss land.

[St0rmTh0r]

00z EPS seems to be lighting up again for what it’s worth.

https://twitter.com/jpkassell/status/1300452851290902535

It seems the monsoon gyre being so far north is going to reduce the chances of a long-tracker this year if everything that forms that far east is ending up flung NW over cooler water. But once again the flip side is a much higher chance that those systems either reform or wait to form much further west--leaving no time to miss land.

With a monster ridge in place I'm willing to bet everything's heading west