ATL: BRET - Remnants - Discussion

[cycloneye]

AL, 92, 2017061512, , BEST, 0, 50N, 289W, 15, 0, DB, 0, , 0, 0, 0, 0, 0, 0, 0, 0, 0, , 0, , 0, 0, GENESIS004, , 0, , 0, 0, 0, 0, genesis-num, 004,
AL, 92, 2017061518, , BEST, 0, 50N, 301W, 15, 0, DB, 0, , 0, 0, 0, 0, 0, 0, 0, 0, 0, , 0, , 0, 0, GENESIS004, , 0, , 0, 0, 0, 0, genesis-num, 004,
AL, 92, 2017061600, , BEST, 0, 50N, 312W, 15, 0, DB, 0, , 0, 0, 0, 0, 0, 0, 0, 0, 0, , 0, , 0, 0, GENESIS004, , 0, , 0, 0, 0, 0, genesis-num, 004,
AL, 92, 2017061606, , BEST, 0, 50N, 323W, 15, 0, DB, 0, , 0, 0, 0, 0, 0, 0, 0, 0, 0, , 0, , 0, 0, GENESIS004, , 0, , 0, 0, 0, 0, genesis-num, 004,
AL, 92, 2017061612, , BEST, 0, 50N, 333W, 20, 1009, DB, 34, NEQ, 0, 0, 0, 0, 1011, 150, 100, 0, 0, L, 0, , 0, 0, INVEST, S, 0, , 0, 0, 0, 0, genesis-num, 004, SPAWNINVEST, al742017 to al922017,





Thread that was the topic for this wave at Talking Tropics forum.
viewtopic.php?f=31&t=118765

[cycloneye]

[RL3AO]

The obvious question - how crazy does the HWRF go?

[Hurricaneman]

Well here we go, I believe this will be the first deep tropical system of the year of many and first possible tropical storm in the MDR for June in a real long time

[Gustywind]

Here we are with 92L

[Gustywind]

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
715 AM EDT Fri Jun 16 2017

An Atlantic Ocean tropical wave is along 32W from 11N southward,
moving westward 20 knots. A 1011 mb low pressure center is along
the wave near 05N. Scattered moderate to isolated strong from 03N
to 08N between 28W and 36W, and from 01N to 04N between 24W and
28W. Isolated moderate to locally strong rainshowers are elsewhere
from 10N southward between 23W and 40W.

[weathaguyry]

If we are seeing an invest in the MDR in mid-June, it is very scary to think what mid-August will bring

[weathaguyry]

[Hurricane Andrew]

And here...we...go!

I'm still not entirely sold on development, but I think it has a shot at at least becoming a depression...don't systems this far south usually have trouble strengthening due to the reduced Coriolis effect?

[RL3AO]

And here...we...go!

I'm still not entirely sold on development, but I think it has a shot at at least becoming a depression...don't systems this far south usually have trouble strengthening due to the reduced Coriolis effect?

η = ζ + f

η is absolute vorticity
ζ is relative vorticity
f is Coriolis

If relative vorticity is high enough (think 850 mb vorticity map) it can overcome the relative lack of Coriolis. Also, this wave should gain latitude quickly enough to be near 10°N in a few days. The lack of Coriolis won't be an issue.

[Gustywind]

Dr. Jeff Masters · June 15, 2017, 3:05 PM

https://www.wunderground.com/cat6/odds- ... -next-week

Early-season wave continues to bear watching in the eastern Atlantic

A low-latitude tropical wave continued moving at a brisk pace across the remote tropical Atlantic on Thursday. The wave was centered near 5°N, 29°W, with a central pressure of 1012 mb, according to the 7:00 am EDT Thursday tropical discussion from NHC. The wave will likely remain centered south of 10°N as it chugs westward at about 20 knots (23 mph). This is too close to the equator for the system to leverage Earth's spin to help itself get spinning, which will make any development slow to occur. Otherwise, conditions are modestly favorable for development: wind shear should remain light to moderate, dry air is expected to stay just to the north, and SSTs of 27-28°C (81-82°F) will be about 0.5°C above the seasonal norm along the wave’s track. In their 8 am EDT Thursday Tropical Weather Outlook, the National Hurricane Center (NHC) gave this system 2-day and 5-day odds of tropical cyclone development of 10% and 20%, respectively--the same odds given on Wednesday.

Climatology does not favor a tropical cyclone forming in the Main Development Region east of the Antilles so early in the year. As we discussed in Wednesday’s post, only one tropical storm and one hurricane have been known to develop in this area during June in records going back to 1851. Of our three most reliable models for predicting tropical cyclone formation several days in advance, the UKMET fails to develop this wave in its 00Z Thursday run. Less than a third of the 50 ECWMF ensemble members from 00Z Thursday develop the wave into a tropical depression by Saturday, with only a couple bringing it to tropical storm strength. The GFS is more supportive, with about half of its 20 ensemble members producing a tropical storm and a couple of members even generating a hurricane over the next five days.

The GFS and ECMWF ensembles agree on a track that would take the wave into the coast of Venezuela or Guyana or perhaps into the southernmost Lesser Antilles early next week. The GFS ensemble tracks are clustered slightly further north, with most members bringing the system into the southeast Caribbean. However, any system entering the Caribbean is likely to encounter progressively stronger wind shear, and none of the GFS and ECMWF ensemble members bring the system fully through the Caribbean. The eastern Caribbean is a notorious “graveyard” for tropical cyclones, especially early in the season, because of persistent divergence at low levels that tends to weaken showers and thunderstorms.

[Gustywind]

Eastern Atlantic Disturbance
https://weather.com/storms/hurricane/ne ... -june-2017

A tropical wave in the far eastern Atlantic Ocean is also being monitored for development by the NHC.
The system is producing some shower and thunderstorm activity and as of Friday morning it has become better organized.
The NHC has given this system a medium chance of development during the next five days. Given the increase chance for development, this system has been dubbed Invest 92L.
The good news is that it is far from any land areas and there is plenty of time to monitor its progress in the days ahead.

[Gustywind]

From accuweater.com
http://www.accuweather.com/en/videos/ex ... 7uhvc8is0n

[SEASON_CANCELED]

Well here we go, I believe this will be the first deep tropical system of the year of many and first possible tropical storm in the MDR for June in a real long time

That means nothing. 2006 started off early with alberto on June 8th but was pretty much a non season when it came to threats and system longevity

[abajan]

It's such a low rider that its identification isn't being shown on the S2K map!

[weathaguyry]

If the 06z GFS were to verify, this would be a 70MPH tropical storm at it's peak

http://www.tropicaltidbits.com/analysis/models/gfs/2017061606/gfs_mslp_wind_92L_17.png

[Hypercane_Kyle]

Well here we go, I believe this will be the first deep tropical system of the year of many and first possible tropical storm in the MDR for June in a real long time

That means nothing. 2006 started off early with alberto on June 8th but was pretty much a non season when it came to threats and system longevity

Alberto was just your average GOMEX rainmaker. Pretty much ever year has one. Even 2013 had Andrea. MDR development June is a much more significant signal, IMO.

[Alyono]

And here...we...go!

I'm still not entirely sold on development, but I think it has a shot at at least becoming a depression...don't systems this far south usually have trouble strengthening due to the reduced Coriolis effect?

η = ζ + f

η is absolute vorticity
ζ is relative vorticity
f is Coriolis

If relative vorticity is high enough (think 850 mb vorticity map) it can overcome the relative lack of Coriolis. Also, this wave should gain latitude quickly enough to be near 10°N in a few days. The lack of Coriolis won't be an issue.

too many talk about lack of coriolis because they do not understand the equation you discussed. You can get something slightly south of the equator even if the relative vorticity is strong enough. Nearly had an equator crosser in the CPAC in January of last year during the el niño. Gave Tarawa a major scare

[tolakram]

latest saved



from: http://tropic.ssec.wisc.edu/#

[RL3AO]

Latest ASCAT pass caught the system on the right side. Clear circulation with impressive convergence along the ITCZ.