ATL: EARL - Remnants - Discussion

[cycloneye]

 https://twitter.com/stormchaserjs/status/759472081692164096

[srainhoutx]

Saturday afternoon briefing from Jeff:

Main focus over the upcoming forecast cycle will be eventual track and intensity of Atlantic tropical wave 97L and its potential movement into the Gulf of Mexico late next week.

Near term forecast will be dominated by general high pressure building aloft over the state and gradually filling the weakness that has been over the region for the last week. Increasing heights aloft will result in warming afternoon temperatures and lessened chances for afternoon thunderstorms. 594dm ridge axis is near the region on Monday and Tuesday and this will be the hottest days with least rain chances with highs likely back into the mid to upper 90’s.

Ridge begins to weaken and shift northward Thursday and Friday which becomes critical in the eventual track of 97L as it enters the Gulf of Mexico. Models want to develop another weakness or “break” in the sub-tropical ridge axis over the NW Gulf coastal areas by next Friday which will at least result in lower afternoon high temperatures and better rain chances along the seabreeze. Main question quickly becomes how does this impact the final track outcome of tropical wave 97L and in what kind of shape will this feature be when it arrives in the Gulf of Mexico. For now any potential impact would be beyond the 5-6 day period, and given the recent model flip-flopping on the system there is little confidence in any one solution.

Now is the time to review your hurricane preparations and make sure you can enact those plans. Make it a point to check the weather at least once a day for the next week to keep update on changes with the tropics!

97L:
Strong tropical wave located 550 miles E of the Leeward Islands continues to race westward at 25-35mph. While showers and thunderstorms have increased in association with this feature this morning and banding features are looking more impressive, there is no evidence of a defined low level circulation from either surface observations of satellite overpasses. 97L is trapped within the strong trade wind flow south of a well defined sub-tropical ridge over the central Atlantic basin and this will bring the system rapidly into and across the Islands tonight and on Sunday and then into the eastern Caribbean Sea on Monday. The fast forward motion should preclude much development in the near term, but as the system reaches the central and western Caribbean Sea and begins to slow down conditions look increasingly favorable for formation of a tropical cyclone. Upper level winds appear favorable, sea surface temperatures are more than warm enough, and dry air should be mitigated. Experience with incoming strong waves into the eastern Caribbean Sea without well developed inner cores usually indicates the system will not develop until it reaches the western Caribbean Sea.

Beyond 4-5 days global models bring 97L as a developed tropical cyclone into the southern Gulf of Mexico with various track and intensity solutions possible. Uncertainty is fairly large at this time range and the global model solutions have been showing large swings from run to run leading to lower than average confidence which is already low. Additionally, without a defined low level center for guidance to ingest into their vortex tracking there really is not much faith in any output at this time.

Analog years strongly support in close development of tropical cyclones this season and 97L deserves close watch once over the western Caribbean Sea and southern Gulf of Mexico late next week.

National Hurricane Center probability of tropical cyclone formation over the next 5 days with 97L is now 60%.

[RL3AO]

Still think this may end up a little further north than the models are indicating right now
just based on where a circulation may be forming.

[Disclaimer]Not a professional Met

I think this as well. This is weather channels spahgetti models which has a couple going more north

This is why spaghetti plots are absurd. The BAM's are not skillful. They are terrible. By showing them, it gives the non-meteorological viewer the idea that these all have equal chances. Look at the GFS, Euro, HWRF, UKMet and maybe the CMC and GFDL or any consensus tracks that use those (like TCVN).

[Hammy]

 https://twitter.com/stormchaserjs/status/759472081692164096

HWRF track looks more realistic but GFDL does on intensity.

[SouthFloridawx]

Mine just say's loading tweet. How do I correct this?

 https://twitter.com/stormchaserjs/status/759472081692164096

[gatorcane]

NAM trending more bullish

[Javlin]

I know it's moving fast but sure does appear that she is trying to close off the W side as far as clouds/convection cover

http://www.ssd.noaa.gov/PS/TROP/floaters/97L/html5-rgb-long.html

[Alyono]

we're really considering the HWRF given its BS initialization?

[ozonepete]

Yes, on the vis and rgb loops it looks like an LLC could very well be developing. The island data tonight should tell us a lot.

[chaser1]

I'm equally impressed with 97L, and fully anticipate it developing into a tropical depression as it approaches a point south of HIspanola. This system appears to have quite a large overall sized envelope which might also inhibit any quick spin up, but also likely negate any minimal inflow impact as a result of the relative close proximity to Hispanola as it approaches from the ESE. Where I'd rarely anticipate that any one particular disturbance might actually develop into a Cat. 4 or 5 hurricane, I do think that this system has the capacity to develop, "potentially" encounter RI conditions south of Cuba, and possibly turn into a fairly formidable hurricane. I would NOT go so far as to predict that, but that is largely a cause of my own bias based on climatology and overall conditions this season leading up to now. To be honest though, I typically lean way toward the dynamic conditions in place and take into consideration any particularly detrimental or unusually conducive conditions that may be at play. If this system can maintain a strong upper anticyclone over itself, and then move into a position to tap into some very very warm Caribbean water, than I see no reason that 97L should outright not develop into a hurricane. Lets wait and see of course how closely it tracks toward (or over land).

[Nimbus]

NAM looks like it is still expecting some shear from the south in the western Caribbean this run.
The recent evolution to a stronger system is interesting though.

[Nimbus]

Doesn't look like it has a well developed inflow yet just mid level rotation.
Hopefully we won't see an explosive burst of convection signaling it has reached the surface before the islands.

[chaser1]

Still think this may end up a little further north than the models are indicating right now
just based on where a circulation may be forming.

[Disclaimer]Not a professional Met

I think this as well. This is weather channels spahgetti models which has a couple going more north

This is why spaghetti plots are absurd. The BAM's are not skillful. They are terrible. By showing them, it gives the non-meteorological viewer the idea that these all have equal chances. Look at the GFS, Euro, HWRF, UKMet and maybe the CMC and GFDL or any consensus tracks that use those (like TCVN).

To a general extent I agree with you, especially regarding my faith in the EURO with the larger overall picture. Not here though. I don't see 97L burying itself that far south as Belize (or just north of that point). Problem with the EURO here is I don't believe it is very well initializing the system. I'd be curious if we had a distinct surface low in proximity to the parent mid-level center, whether this would provide the EURO something a bit better to bite onto and potentially impact the systems forward motion?

[BobHarlem]

Some of it is starting to show up on Barbados Radar.

Barbados Radars: http://www.barbadosweather.org/

link Long term Barbados radar recording.

[tarheelprogrammer]

GFS might be overdoing the shear this system will face but I am no MET.

[stormlover2013]

Depends on what the high pressure looks looks like over Texas or se us, if it's strong its south Texas or Mexico

[RL3AO]

So far in the East Pacific the Euro has been terrible. Only the GFDL has been worse of the consensus models (GFS, UKMET, HWRF, GFDL, Euro, and maybe one more). Just something to keep in mind as we move into August.

[Alyono]

So far in the East Pacific the Euro has been terrible. Only the GFDL has been worse of the consensus models (GFS, UKMET, HWRF, GFDL, Euro, and maybe one more). Just something to keep in mind as we move into August.

which is exactly what I said would happen due to it using a horrible resolution for TCs. The resolution is too fine for paramaterized convection, not too coarse for explicit convection

[RL3AO]

So far in the East Pacific the Euro has been terrible. Only the GFDL has been worse of the consensus models (GFS, UKMET, HWRF, GFDL, Euro, and maybe one more). Just something to keep in mind as we move into August.

which is exactly what I said would happen due to it using a horrible resolution for TCs. The resolution is too fine for paramaterized convection, not too coarse for explicit convection

I still remember thinking that when taking NWP last spring and seeing the info about the Euro update. That 6 to 10 km zone is kinda no mans zone for convection.

[Hammy]

So far in the East Pacific the Euro has been terrible. Only the GFDL has been worse of the consensus models (GFS, UKMET, HWRF, GFDL, Euro, and maybe one more). Just something to keep in mind as we move into August.

which is exactly what I said would happen due to it using a horrible resolution for TCs. The resolution is too fine for paramaterized convection, not too coarse for explicit convection

Has it been under or overdoing genesis/intensity?