ATL: NANA - Remnants - Discussion

[Hammy]

Is there some dry air in the Caribbean that is responsible for the models weakening or not developing 99L?

They don't seem to develop anything this year without a plane being in there first. I'm pretty sure the storms they're currently developing will vanish once the incipient wave is actually present only for them to later develop as well.

[Extratropical94]

A westward-moving tropical wave accompanied by a broad low pressure
area is located over the eastern Caribbean Sea just west of the
Windward Islands. Associated shower and thunderstorm activity
continues to show signs of organization, and environmental
conditions are expected to gradually become more conducive for
development. A tropical depression is likely to form during the
next day or two while the system moves moves westward at about 15
mph across the central Caribbean Sea. Interests in Jamaica,
Honduras, Belize, Guatemala and Yucatan should monitor the progress
of this disturbance.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 5 days...high...80 percent.

[MarioProtVI]

A westward-moving tropical wave accompanied by a broad low pressure
area is located over the eastern Caribbean Sea just west of the
Windward Islands. Associated shower and thunderstorm activity
continues to show signs of organization, and environmental
conditions are expected to gradually become more conducive for
development. A tropical depression is likely to form during the
next day or two while the system moves moves westward at about 15
mph across the central Caribbean Sea. Interests in Jamaica,
Honduras, Belize, Guatemala and Yucatan should monitor the progress
of this disturbance.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 5 days...high...80 percent.

This is a lock for Nana at this point.

[MississippiWx]

A westward-moving tropical wave accompanied by a broad low pressure
area is located over the eastern Caribbean Sea just west of the
Windward Islands. Associated shower and thunderstorm activity
continues to show signs of organization, and environmental
conditions are expected to gradually become more conducive for
development. A tropical depression is likely to form during the
next day or two while the system moves moves westward at about 15
mph across the central Caribbean Sea. Interests in Jamaica,
Honduras, Belize, Guatemala and Yucatan should monitor the progress
of this disturbance.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 5 days...high...80 percent.

Well then.

[aspen]

Water vapor imagery shows a large plume of dry air and shear in the Caribbean. However, if 99L’s anticyclone remains on top of it, that should act like a protective bubble to help it develop. The GFS/Euro must be showing 99L and the anticyclone drifting apart.

[Aric Dunn]

weird they issued a special TWO at 12..

then at 2pm upped the chances even more..

[MississippiWx]

Water vapor imagery shows a large plume of dry air and shear in the Caribbean. However, if 99L’s anticyclone remains on top of it, that should act like a protective bubble to help it develop. The GFS/Euro must be showing 99L and the anticyclone drifting apart.

The GFS and Euro don’t even know why they don’t show development. Their ability to predict TCG this season has been embarrassing.

[RL3AO]

The only things that have changed over the last year or two in terms of data are the new GOES satellites and fewer ACARS obs due to COVID.

[Aric Dunn]

hmmm tower popping right under the MLC..

lets see if that sustains.

[Nimbus]

weird they issued a special TWO at 12..

then at 2pm upped the chances even more..

Weird but functionally acceptable no watches or warnings to be issued today, probably cut backs at the NHC and its Sunday. Are you waiting for model output for the track?

[Aric Dunn]

weird they issued a special TWO at 12..

then at 2pm upped the chances even more..

Weird but functionally acceptable no watches or warnings to be issued today, probably cut backs at the NHC and its Sunday. Are you waiting for model output for the track?

Track is very straightforward. farthest north would possible be the southern BOC>

[hipshot]

AL, 99, 2020083012, , BEST, 0, 120N, 625W, 25, 1008, LO, 34, NEQ, 0, 0, 0, 0, 1010, 150, 100, 0, 0, L, 0, , 0, 0, INVEST, S, 0, , 0, 0, 0, 0, genesis-num, 033, SPAWNINVEST, al762020 to al992020,

Thread at Talking Tropics forum that was for this wave.

viewtopic.php?f=31&t=121254

How do they determine the alpha-numeric naming system for these invests. I've been monitoring these boards for years and always
thought to ask and never have.

[RL3AO]

AL, 99, 2020083012, , BEST, 0, 120N, 625W, 25, 1008, LO, 34, NEQ, 0, 0, 0, 0, 1010, 150, 100, 0, 0, L, 0, , 0, 0, INVEST, S, 0, , 0, 0, 0, 0, genesis-num, 033, SPAWNINVEST, al762020 to al992020,

Thread at Talking Tropics forum that was for this wave.

viewtopic.php?f=31&t=121254

How do they determine the alpha-numeric naming system for these invests. I've been monitoring these boards for years and always
thought to ask and never have.

AL (or L) is for the Atlantic. And it goes from 90 to 99 and then repeats.

[toad strangler]

 http://twitter.com/pppapin/status/1300132627786145792

[Nimbus]

weird they issued a special TWO at 12..

then at 2pm upped the chances even more..

Weird but functionally acceptable no watches or warnings to be issued today, probably cut backs at the NHC and its Sunday. Are you waiting for model output for the track?

Track is very straightforward. farthest north would possible be the southern BOC>

There is a little coastal Mexican town named Moron just south of the tropic?

Recon is tasking an investigation flight at 15.5 degrees south of Kingston for Tuesday and Wednesday the ridge is going to start receding.
Maybe the 18z models will show something?

[SouthDadeFish]

Invest 99L looks pretty darn good for a system with minimal model support for genesis. In my opinion, it's not that far off right now. I think a sustained convective burst near the MLC over the next few hours could put it over the edge. I'd keep a close eye on this system if I lived in Jamaica, the Cayman Islands, and the Yucatan.

[Aric Dunn]

Invest 99L looks pretty darn good for a system with minimal model support for genesis. In my opinion, it's not that far off right now. I think a sustained convective burst near the MLC over the next few hours could put it over the edge. I'd keep a close eye on this system if I lived in Jamaica, the Cayman Islands, and the Yucatan.

https://i.imgur.com/6nKzcts.gif

Yeah, kind of been the going theme this year with the models.

and its those few towers popping up now under that MLC that are most intriguing ...

[Nimbus]

A single lightning flash just south of 15N and we all jump LOL.

[tailgater]

Well we are just past D max, let’s see if the convection wanes over the next 8 hrs.
https://i.imgur.com/9ITCnFZ.png

Diurnal maximum happens at sunrise since this is when thunderstorm activity is maximized due to a strong temperature decrease with height. When the sun rises, the middle and upper troposphere warms, and reduces this temperature decrease with height. Temperatures close to the surface do not change very much because of the ocean surface temperatures being relatively constant throughout the day.

So we are actually pretty close to diurnal minimum, since we are close to the middle of the day.

Yes that is what I was saying,

[Do_For_Love]

Pretty good looking disturbance. Agree with others that the NHC numbers should be looked at over models...they had trouble developing a lot of storms this year. Maybe it will sneak in and develop by tomorrow night to give August it's 5th named storm.