Global model runs discussion

[crownweather]

Interesting to see the Canadian & the FIM experimental model latching onto developing the disturbance now near 35 West Longitude. FIM model has it in the 50-55 West Longitude area by Sunday.



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['CaneFreak]

One of the very few good, useful posts in this thread. Thanks for sharing the information from the Miami conference. The ECMWF has been struggling with tropical cyclogenesis for a while now. Hopefully, they will find a way to fix those errors.

The ECMWF does have one of the highest horizontal resolutions at ~25 km (the GFS resolution up to truncation is ~35 km) for the extended range models. The GFDL I believe has a ~10 km resolution and the HWRF has ~5km resolution, but are mainly used for resolving the inner core of systems.

With that said though, there are other revolving issues regarding resolution that creates problems with the ECMWF and cyclogenesis. There was a presentation made at the University of Miami about 3 weeks ago regarding this. Here is an excerpt:

"It is found that errors associated with vorticity, upper-level divergence, low-level convergence, and moisture within and local to easterly waves is a significant source of uncertainty in the genesis forecast. Much of the small-scale error growth and error variance of the ensemble forecast is associated with localized bands of greater vorticity and divergence, likely related to the difficulty in representing convective bands within the tropical wave.. We investigate the degree to which these errors in the mesoscale limit the predictability of genesis forecasts. Lastly, correlations and lag-correlations between errors are presented. ."

You can see the full presentation here: https://ams.confex.com/ams/15MESO/flvgateway.cgi/id/24837?recordingid=24837

[tolakram]

i think the euro has done great in the atlantic this season. if a system of importance were to ever devlop im sure it would show it. the euro has been excellent at seeing the very dry air and it hasnt shown any phantom systems.

What objective measures are you using to say the euro has done great this season? It just missed showing any significant development with Fernand. If only the euro was available every storm that formed this season would have been a surprise. Right now the euro is matching your suspicion of an MDR too dry to support a storm. Are you sure it's not just a coincidence?

[CalmBeforeStorm]

Out of the 6 Atantic systems that have formed has the Euro picked up one of them before it formed? I realize you have an agenda here but I would refrain from using the Euro at 240 Hrs as proof there will not be any Atlantic cyclone genesis during that period.

[dexterlabio]

I just want to butt in to this ECMWF talk....I lost all hopes to Euro when it initialized Supertyphoon Utor as a tropical storm when at that time it was at its peak strength. Then for the rest of the storms, it just catches up when it has already formed.


But if the Euro shows something significant all of a sudden, that's something to watch out for. Euro seldom shows cyclone genesis in their runs nowadays and maybe this one is a hint of something to come...

[ninel conde]

i think the euro has done great in the atlantic this season. if a system of importance were to ever devlop im sure it would show it. the euro has been excellent at seeing the very dry air and it hasnt shown any phantom systems.

What objective measures are you using to say the euro has done great this season? It just missed showing any significant development with Fernand. If only the euro was available every storm that formed this season would have been a surprise. Right now the euro is matching your suspicion of an MDR too dry to support a storm. Are you sure it's not just a coincidence?

i wouldnt call it a suspicion. look at the last wave that just came off that the gfs was developing into a strong cane. the wave dried up. it is too dry. the euro has been great at showing pressures correctly and it hasnt shown a single fantasy storm. not to pat myself on the back but in july when i lowered my numbers to 9/2/0 i said the BOC was the one place in the entire basin to expect development and landfalls. back to the models. gfs shows a well developed storm in 7 days around 35w. euro shows nothing. ill wait till the 12z runs come out. if the euro shows nothing and gfs still has the storm, id put my money on the euro. remeber, with this first storm the gfs developed and euro didnt, the gfs has now dropped.

[caneman]

i think the euro has done great in the atlantic this season. if a system of importance were to ever devlop im sure it would show it. the euro has been excellent at seeing the very dry air and it hasnt shown any phantom systems.

What objective measures are you using to say the euro has done great this season? It just missed showing any significant development with Fernand. If only the euro was available every storm that formed this season would have been a surprise. Right now the euro is matching your suspicion of an MDR too dry to support a storm. Are you sure it's not just a coincidence?

i wouldnt call it a suspicion. look at the last wave that just came off that the gfs was developing into a strong cane. the wave dried up. it is too dry. the euro has been great at showing pressures correctly and it hasnt shown a single fantasy storm. not to pat myself on the back but in july when i lowered my numbers to 9/2/0 i said the BOC was the one place in the entire basin to expect development and landfalls. back to the models. gfs shows a well developed storm in 7 days around 35w. euro shows nothing. ill wait till the 12z runs come out. if the euro shows nothing and gfs still has the storm, id put my money on the euro. remeber, with this first storm the gfs developed and euro didnt, the gfs has now dropped.

Are you taking bets? Now with the CMC and FIM on board - I would feel very confidant and happy to take your money

[weatherwindow]

As Bob Dylan put it .. "Times .. they are a-changin''. I am pretty confident in the consistent prediction of a significant change up coming next week imo. Only thing I would question at this point is whether this extensive lull/long barrier we had will cut the season short (or in half) with less hurr's than expected, or whether mother nature came in late is going to rush to finish her job on time (or go later into the season to make up for lost time). I tend to imagine mother nature this season is a lot like a kid coming in a half hour late for class, and has to finish her assignment (afterschool if need be) before she can go home... interesting analogy, but it was the best I could come up with! This is all just a personal opinion btw.

LOL...Good morning, meri....5*...at the rate this season is going, its looks like "afterschool" and "Saturdays"may be necessary to pull out the numbers many(including myself) were expecting...Grtz from KW, Rich

[tolakram]

i wouldnt call it a suspicion. look at the last wave that just came off that the gfs was developing into a strong cane. the wave dried up. it is too dry. the euro has been great at showing pressures correctly and it hasnt shown a single fantasy storm. not to pat myself on the back but in july when i lowered my numbers to 9/2/0 i said the BOC was the one place in the entire basin to expect development and landfalls. back to the models. gfs shows a well developed storm in 7 days around 35w. euro shows nothing. ill wait till the 12z runs come out. if the euro shows nothing and gfs still has the storm, id put my money on the euro. remeber, with this first storm the gfs developed and euro didnt, the gfs has now dropped.

Don't break your arm patting yourself on the back. I would look into the euro issues with developing storms. It's not a secret, and the model makers are actively looking into the problem. The euro is always mode 'accurate' when a season is slow because it doesn't tend to develop anything, but this is a false positive ... or a false negative ... or something.

This thread works best when we keep back patting and I told you so out of it, and instead figure we really have no idea what's ahead and enjoy the models doing their thing. I would appreciate it if we all resisted posting one liners and other missives that do nothing except to validate an opinion. When looking back at this thread the posts that don't add to the discussion stick out like a sore thumb. Don't be that poster.

So, with that said ...

The 6Z GFS shows the next wave leaving Africa developing quickly and moving NW. This is the fifth run for the GFS showing development of this wave while it's slowly dropped the idea of developing the wave in front of it. It will be interesting to see if this is reality, or if the model is struggling to figure out when conditions will be favorable.



The euro, near the same time, shows no development and very little vorticity.

[blp]

Well the MJO forecast out from the Euro shows the feature starting to exit our region around the September 8th. So if something is going to get going it needs to start happening soon. Normally at this time of the year the MJO does not have such a big influence as in early in the year, but with the lack of instability it's effect is greatly magnified. With the big models pushing back development again, it has me wondering where is the energy going to come from once the mjo has left the region.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ECMF_phase_51m_full.gif

[weatherwindow]

The ECMWF does have one of the highest horizontal resolutions at ~25 km (the GFS resolution up to truncation is ~35 km) for the extended range models. The GFDL I believe has a ~10 km resolution and the HWRF has ~5km resolution, but are mainly used for resolving the inner core of systems.

With that said though, there are other revolving issues regarding resolution that creates problems with the ECMWF and cyclogenesis. There was a presentation made at the University of Miami about 3 weeks ago regarding this. Here is an excerpt:

"It is found that errors associated with vorticity, upper-level divergence, low-level convergence, and moisture within and local to easterly waves is a significant source of uncertainty in the genesis forecast. Much of the small-scale error growth and error variance of the ensemble forecast is associated with localized bands of greater vorticity and divergence, likely related to the difficulty in representing convective bands within the tropical wave.. We investigate the degree to which these errors in the mesoscale limit the predictability of genesis forecasts. Lastly, correlations and lag-correlations between errors are presented. ."

You can see the full presentation here: https://ams.confex.com/ams/15MESO/flvgateway.cgi/id/24837?recordingid=24837

Good morning, USA....Thanks for making this available. A very lucid, common sense approach to the metrics. His choice of techniques was brilliant. The reduction in complexity to accomodate a simple least square regression allowed even the math-challenged such as myself to understand his method and conclusions. I would love to see a similiar analysis done on the GFS and see how they compare with respect to the predictability of the genesis variables. Thanks again...Grtz from KW, Rich

[otowntiger]

with that said ...

The 6Z GFS shows the next wave leaving Africa developing quickly and moving NW. This is the fifth run for the GFS showing development of this wave while it's slowly dropped the idea of developing the wave in front of it. It will be interesting to see if this is reality, or if the model is struggling to figure out when conditions will be favorable.


The euro, near the same time, shows no development and very little vorticity.

So does it seem that currently (and I know its early) that this system is generally forecast to re-curve? I live in central Florida and will be out of the state from 9/4 - 9/12. That's a long time to be gone during hurricane season I know but so far none of the long term models has given me to much reason for concern, unless I'm missing something?? I know things can form closer to home in a short time but I'm liking how this season is going so far. Not having to fret much about pending storm threats. I just hope that continues through September 12 at least.

[Alyono]

Looked at some velocity potentials this morning

The East Atlantic may NOT be favorable through the next 16 days.

However, what does look favorable are areas west of 50W. Could see waves not developing until they near the islands of the eastern Caribbean or within the Caribbean itself

[Blown Away]

Looked at some velocity potentials this morning

The East Atlantic may NOT be favorable through the next 16 days.

However, what does look favorable are areas west of 50W. Could see waves not developing until they near the islands of the eastern Caribbean or within the Caribbean itself

Historically developing after 50W is where most of the landfalling legends started...

[jconsor]

Strongly agree with this. It will likely be a case of "delayed, but denied" for development of next few waves.

Looked at some velocity potentials this morning

The East Atlantic may NOT be favorable through the next 16 days.

However, what does look favorable are areas west of 50W. Could see waves not developing until they near the islands of the eastern Caribbean or within the Caribbean itself

[CrazyC83]

Agreed the MDR is still quite stable and unfavorable. But as we saw with Fernand, things can blow up quickly farther west. The W Gulf and W Caribbean are highly favorable right now as the MJO creeps in.

['CaneFreak]

Strongly agree. This is going to wreak havoc on weather weenies who want a TC to track in the modeling because typically models have a hard time resolving weak tropical waves. And as you well know, any errors in initialization often get carried over into the rest of the model forecast. So, if everyone will be PATIENT, we might have something to track in a week to 10 days.

Looked at some velocity potentials this morning

The East Atlantic may NOT be favorable through the next 16 days.

However, what does look favorable are areas west of 50W. Could see waves not developing until they near the islands of the eastern Caribbean or within the Caribbean itself

[TreasureIslandFLGal]

yes, concern more for the local home brew storms this year. GFS, and actually (surprisingly) the CMC tend to pick out early compared to some of the other models.

Euro may not predict storms well, but if it is used along with the GFS to look at what it does with the synoptic setup, that can give better hints as to when/if something could develop in an area, and where we should watch for potential down the road. tail ends of fronts deep in the tropics can spin up and head north or northeast (what tampa bay should most be concerned with happening) late in the season.

Some very big storms formed further west and in the deep tropics, and those monsters form most often in the peak of the season and after.

[ronjon]

Jeff Masters blog from this am on future development:

It's been an unusually quiet August for hurricane activity in the Atlantic, and if we finish the month without a hurricane, it will mark the first year since 2002 without an August hurricane. However, the quiet weather pattern we've been blessed with is about to come to an end, as conditions favorable for hurricane formation move into place for the last few days of August and the first week of September. The big guns of the African Monsoon are firing off a salvo of African tropical waves over the next two weeks that will find the most favorable conditions for development that we've seen this year. While there is currently a new outbreak of dry air and dust from the Saharan Air Layer (SAL) over the Eastern Atlantic, the latest European model forecast calls for a reduction in dry air and dust over the Tropical Atlantic during the 7 - 14 day period, accompanied by low wind shear. The Madden Julian Oscillation (MJO), a pattern of increased thunderstorm activity near the Equator that moves around the globe in 30 - 60 days, has begun a new active phase. The most active part of the MJO has not yet crossed into the Atlantic, but is expected to do so during the period 7 - 14 days from now. The MJO will bring rising air that will aid strong thunderstorm updrafts and thus tropical storms--and their subsequent intensification into hurricanes. According to Dr. Michael Ventrice, an MJO expert at WSI, Inc., the latest run of the GFS model predicts that this MJO event will be the 3rd strongest in the Western Hemisphere since 1989. During the last four comparable strong MJO events, 68% of all the tropical depressions that formed during these events (21 out of 31 storms) intensified into hurricanes. The MJO will likely continue to support Atlantic hurricane activity through September 15. The MJO is then expected to progress into the Western Pacific for the last half of September, which would likely bring sinking air over the Atlantic and a quieter portion of hurricane season.

[ninel conde]

Agreed the MDR is still quite stable and unfavorable. But as we saw with Fernand, things can blow up quickly farther west. The W Gulf and W Caribbean are highly favorable right now as the MJO creeps in.

this is where i disagree vociferously. yes the MDR is dried up and most likely the MJO wont ever get into the atlantic. where i disagree is the w gulf and w carib being favorable. the BOC is favorable but otherwise the nw flow over the east coast and west atlantic and the persistent east coast trough is going to make things very difficult in the carib and gom north of 25n. for in close development of anything significant you need a strong STATIONARY high over new england. there is now talk of a subtropical storm forming later in the week at 38n 70w. that is not a sign of an active season south of there. at some points the models were showing that the texas ridge would break down. it really hasnt. look at this past weekend. we had a strong disturbance moving west toward texas, a tropical storm south of texas, and we had ivo in the pacific sending moisture into the southwest, but today texas is almost completely dry. if the ridge were to break down and the nw flow end over the east coast then the models would light up.