Tropical Wave over the Western Caribbean

[wxman57]

It'll be running into very strong wind shear in the Caribbean due to its more northward track. No development.

Yep. Model guidance has been showing that since this past weekend.

My motive for posting about this system as frequently as I have is to chronicle the merger of the two waves involved, since the models had been advertising this to occur about a week ahead of time.

I see NHC lowered development chances. It appears that a trof is digging down across the Caribbean in the wake of PTC Two, producing all the shear. Euro keeps it moving west into Central America, the strong shear in its path all the way.

[AJC3]

It'll be running into very strong wind shear in the Caribbean due to its more northward track. No development.

Yep. Model guidance has been showing that since this past weekend.

My motive for posting about this system as frequently as I have is to chronicle the merger of the two waves involved, since the models had been advertising this to occur about a week ahead of time.

I see NHC lowered development chances. It appears that a trof is digging down across the Caribbean in the wake of PTC Two, producing all the shear. Euro keeps it moving west into Central America, the strong shear in its path all the way.

Makes sense. I think there's a small window starting today where this wave's structure will improve as it moves WNW toward the islands, but once it reaches that point the shear will take over. What we'll probably see then is the convection sheared off to the E-NE of the wave axis. Depending on how divergent the shear is, there could be a pretty decent blowup of storms that produces heavy rainfall over the NE islands, however by that time, the wave should be in its death throes, as far as TC potential is concerned.

[cycloneye]

Yep. Model guidance has been showing that since this past weekend.

My motive for posting about this system as frequently as I have is to chronicle the merger of the two waves involved, since the models had been advertising this to occur about a week ahead of time.

I see NHC lowered development chances. It appears that a trof is digging down across the Caribbean in the wake of PTC Two, producing all the shear. Euro keeps it moving west into Central America, the strong shear in its path all the way.

Makes sense. I think there's a small window starting today where this wave's structure will improve as it moves WNW toward the islands, but once it reaches that point the shear will take over. What we'll probably see then is the convection sheared off to the E-NE of the wave axis. Depending on how divergent the shear is, there could be a pretty decent blowup of storms that produces heavy rainfall over the NE islands, however by that time, the wave should be in its death throes, as far as TC potential is concerned.

We expect a good deal of rain from the wave this weekend.

[Kingarabian]

24 hours ago, the GFS had a run where it seemed to split a piece of energy from the wave(s) and managed to hop scotch it around the greater Antilles into the GOM where it later developed and striked eastern Mexico. Today's runs including the Canadian continue to show something similar but on top of the shear it's significant amount of land interaction that hinder it. Could be more rain for a southern state down the line though.

[cycloneye]

2 PM TWO.

Western Tropical Atlantic:
A tropical wave located several hundred miles east of the Windward
Islands is producing disorganized showers and thunderstorms. Any
development of this system should be slow to occur while the wave
moves west-northwestward during the next day or two. The wave is
forecast to move over the Windward Islands on Friday and then over
the eastern Caribbean Sea by the weekend, where further development
is unlikely due to unfavorable environmental conditions.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 5 days...low...10 percent.

[AJC3]

The merging of waves completed earlier today, and the resulting merged wave is already running into increasing westerly shear east of the islands.

I think I see Bones stepping up to the podeum...

30/18Z

A tropical wave is along 52W, from 17N southward over French
Guiana, moving west at 10-15 kt. The two prior tropical waves
analyzed in this region have combined into one feature. Scattered
moderate convection is from 11N to 14N between 47W and 55W.

01/00Z

The axis of a tropical wave is near 55W, from 17N southward,
moving west at 10-15 kt. Scattered moderate isolated strong
convection is from 11N to 16N between 48W and 56W.

[weeniepatrol]

Thanks for showcasing this wave merging process!

[AJC3]

Thanks for showcasing this wave merging process!

I'm glad you liked it. It's not something that happens all too often, but it isn't uber-rare either. This probably wouldn't qualify as a true binary (fujiwhara-type) interaction - while the lead wave slowed for the past couple of days, then basically stopped dead it its tracks as the merger took place, the effect on the track/speed of the trailing wave was negligible. The global model guidance 850 MB vorticity fields were unanimous that this would occur they just disagreed on when it would happen (check out some of my earlier posts that talk about the diffence between the ECM/GFS).

Speaking of which...

The axis of a strong tropical wave is near 56W, from 17N
southward, moving west at 20 kt. A recent scatterometer pass found
a distinct wind shift across the wave with fresh to strong winds
on either side north of 12N. Scattered weak convection is observed
from 10N to 16N between 49W and 59W.

2. Western Tropical Atlantic:
A tropical wave located a few hundred miles east of the Windward
Islands is producing disorganized showers and thunderstorms. Any
development of this system should be slow to occur while the wave
moves west-northwestward during the next day or two. The wave is
forecast to move over the Windward Islands today and then over the
eastern Caribbean Sea by the weekend, where further development is
unlikely due to unfavorable environmental conditions.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 5 days...low...10 percent.

Here's the ASCAT pass they mentioned. you can see a well-defined wind shift along the preimary wave axis, but you can also see that, as of the time of the pass, the waves hadn't quite merged 100 percent just yet. There were still two wave crests about 1.5 to 2 degrees apart.

[cycloneye]

Hi Tony. Great job of explaining about the merging of the waves. It will not develop, but for some islands including PR, beneficial rains will fall as drought conditions prevail.

[AtlanticWind]

The system is better organised today , although still strongly sheared.
The models dont show anything but I wonder if there is
any possibilities down the road.

[AtlanticWind]

https://cdn.star.nesdis.noaa.gov/GOES16 ... 0x1000.jpg

Pretty impressive this afternoon.

[AtlanticWind]

Looking at water vapor I think shear may have lessened but I dont know if it enough to allow
any further development.

[NXStumpy_Robothing]

Wave has been much more convectively active than I think most models were anticipating, and there's hints we may end up having the energy of the wave split by Hispaniola. Conditions seems to be overall unfavorable, but areas of convection and rotation have been spinning up today near the wave axis. I'm still in the "no development" camp for now, but if the convection manages to maintain itself around an area of vorticity, I see no reason why it couldn't take advantage of slightly more favorable conditions further down the road.

There's even a pretty decent hot tower attempting to work down vorticity to the surface SSW of Puerto Rico, which has been affecting low-level flow. Worth watching as we move past dmin.

[cycloneye]

8:05 PM discussion.

A robust Caribbean tropical wave extends along roughly 67W/68W from
near the Mona Passage to central Venezuela, and moving to the west
at 15 kt. Scattered showers to isolated strong convection is
found along the trough axis, mainly from 15N to 17N between 67W
and 69W. Earlier this afternoon, this pattern was also
interacting with local sea breezes to enhance convection over
Puerto Rico and the Virgin Islands. An earlier scatterometer
satellite pass show strong to near gale- force winds to the east
of the trough axis. Seas are 6-9 ft in the eastern Caribbean Sea.

[cycloneye]

8:05 AM Discussion:

A strong Caribbean tropical wave extends from 21N70W to 06N74W
and is moving W at 15-20 kt. Scattered moderate isolated strong
convection is observed from 17N to 23N between 65W and 73W.
Scatterometer data from 0100 to 0200 UTC tonight showed strong to
gale force winds occurring south of the Dominican Republic in
strong convection, which has since diminishing considerably.
However strong winds to near 30 kt and seas to 11 ft are assumed
to continue to the south of Hispaniola early this morning. Localized
winds to gale force are still possible in the vicinity of
thunderstorms. Fresh to strong winds associated with this wave are
also occurring across the Atlantic waters from offshore of
eastern Cuba to north of Hispaniola.

[cycloneye]

8:05 PM discussion.

A robust Caribbean tropical wave has its axis from 25N72W to
09N81W, moving W around 10-15 kt. Scattered moderate convection
is occurring from 15N-24N between 67W-78W. The strongest
convection is affecting Hispaniola and the offshore waters. A
recent scatterometer satellite pass depict fresh to strong winds
N of 13N between 66W and 76W. Seas of 7-10 ft are expected in
the described waters.

[cycloneye]

8:05 AM discussion.

A strong tropical wave extends across the western Caribbean along
80W south of 22N. Scattered moderate convection is observed from
11N to 13N between 81W and 83.5W, and from 17N to 20N between 78W
and 82W. Fresh to strong winds are observed behind the wave
between 67W and 77W in the central Caribbean, where seas are 8-11
ft

[Nimbus]

So the circulation in the western Caribbean isn't an upper low?
Not much convection near the center so thought it looked cold core.

[cycloneye]

8:05 AM discussion.

A western Caribbean tropical wave extends along 85W from 08N to
22N, moving W at 10 kt. Scattered moderate to strong convection
is noted from 10.5N to 20N between 83W and 87.5W.