Disturbance in the SW Caribbean Sea (Is Invest 91L)

[Teban54]

Isn't this... where we began?

Seeing predictions of this being a Mexico/CA storm is giving me vibes of early Ida as a model storm, which was thought to be Grace 2.0 at that time.

[toad strangler]

I'm not very concerned about this system. Most likely, it'll track west into Central America and southern Mexico as a disturbance or depression. The Canadian is not the model to look at for such systems. The only thing it'll have going for it is that we're coming up to the Labor Day weekend, and the tropics are quite aware of holidays.

Dry. Very DRY humor.

[Zonacane]

Isn't this... where we began?

Seeing predictions of this being a Mexico/CA storm is giving me vibes of early Ida as a model storm, which was thought to be Grace 2.0 at that time.

It was a Pink Floyd reference.

[Frank P]

Last night sat images of SW Caribbean disturbance

[cycloneye]

A broad area of low pressure is forecast to develop over the
southwestern Caribbean Sea during the next couple of days. Some
slow development of this system is possible by the end of the week,
if the system remains over water. This system is expected to move
gradually west-northwestward or northwestward at 5 to 10 mph toward
Central America.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...20 percent.

[xironman]

https://www.fnmoc.navy.mil/tcweb/cgi-bi ... 99L.INVEST,

[ouragans]

https://www.fnmoc.navy.mil/tcweb/cgi-bin/tc_home.cgi?YEAR=2021&MO=Aug&BASIN=ATL&STORM_NAME=99L.INVEST&PROD=track_vis&TYPE=ssmi&PHOT=yes&ARCHIVE=Latest&NAV=tc&DISPLAY=Active&ACTIVES=21-ATL-09L.IDA,21-ATL-10L.KATE,21-ATL-90L.INVEST,21-ATL-99L.INVEST,

99L? It was Ida... If this area becomes an Invest, it should be numbered 91L

[xironman]

https://www.fnmoc.navy.mil/tcweb/cgi-bin/tc_home.cgi?YEAR=2021&MO=Aug&BASIN=ATL&STORM_NAME=99L.INVEST&PROD=track_vis&TYPE=ssmi&PHOT=yes&ARCHIVE=Latest&NAV=tc&DISPLAY=Active&ACTIVES=21-ATL-09L.IDA,21-ATL-10L.KATE,21-ATL-90L.INVEST,21-ATL-99L.INVEST,

99L? It was Ida... If this area becomes an Invest, it should be numbered 91L

Sorry about that, I was on NRL looking for 90l and noticed they posted it. NRL has nice links to microwave. 12N 76W

[Javlin]

Looks like we have a little mid-level rotation but also a lot of shear.

https://www.tropicaltidbits.com/sat/sat ... =truecolor

[Tampa Bay Hurricane]

There is a new cluster with rotation forming further northeast on the northern part of the disturbance- this could get into the GOm

[tropicwatch]

Not really seeing anything on the vorticity map.

http://tropic.ssec.wisc.edu/real-time/windmain.php?&basin=atlantic&sat=wg8&prod=vor&zoom=&time=

[IcyTundra]

12Z CMC ends up forming this in the BOC. Don't think that solution is very realistic, but I'll still keep an eye on it

[LadyBug72]

Newbie here so I'm still learning....

1. Is the CMC not a very reliable model?

2. Didn't this model pick up this possible development last week too?

Thank you!!

[Wampadawg]

Newbie here so I'm still learning....

1. Is the CMC not a very reliable model?

2. Didn't this model pick up this possible development last week too?

Thank you!!

Also can anyone explain what the CMC and GFS might be seeing in the BoC that is driving their models?

[IcyTundra]

Newbie here so I'm still learning....

1. Is the CMC not a very reliable model?

2. Didn't this model pick up this possible development last week too?

Thank you!!

CMC is pretty reliable but is usually seen as a worse model than the GFS (American model) and the ECMWF (European model). Usually it is better to look at the ensemble members from the GFS ensemble and Euro ensemble this far out because they show a wide range of different outcomes compared to one singular model run.

To answer your 2nd question yes the CMC has been showing development in this area for over a week now, but it is really the only major model showing substantial development so I wouldn't really worry about it at the moment. The GFS and Euro ensemble members aren't showing much of anything either so I think it is safe to say that nothing will probably come of this. People should still keep half an eye on it though as we still don't know how exactly this going to play out.

[IcyTundra]

Newbie here so I'm still learning....

1. Is the CMC not a very reliable model?

2. Didn't this model pick up this possible development last week too?

Thank you!!

Also can anyone explain what the CMC and GFS might be seeing in the BoC that is driving their models?

I think the CMC and GFS are actually showing two different systems. The CMC develops the 0/20 area of interest in the SW Caribbean Sea in the Bay of Campeche while the GFS doesn't really do anything with the current area of interest instead it develops a seperate area of low pressure in the Bay of Campeche in about 10 days. To my untrained amateur eyes it looks like the CMC has a tropical wave interact with the monsoon trough in the Carribean while the storm the GFS is showing later on looks like it comes from the Central American Gyre.

[tolakram]

Newbie here so I'm still learning....

1. Is the CMC not a very reliable model?

2. Didn't this model pick up this possible development last week too?

Thank you!!

5 days, or 120 hours, is generally the longest timeframe any model can be trusted. Beyond that you might infer that a model is finding favorable conditions but the track or location can't be trusted. Under 120 hours you look for model agreement. The CMC might show a well defined low, the GFS might show nothing, the euro might show a slight red area of vorticity. That would be something to keep an eye on to see if agreement continues. For Ida, the CMC actually beat out the other two models by a half a day. All models showed something beyond 120 hours, but way down in the southern Gulf.

So in short, don't focus on a model saying you are going to get hit if it's just one model or past 120 hours. The NHC uses something call a super ensemble and will tag / warn way ahead of us guessing where something might go. If they see a strong agreement in development and track we'll know it.

[LadyBug72]

Thank you everyone!

[Javlin]

Not really seeing anything on the vorticity map.

http://tropic.ssec.wisc.edu/real-time/windmain.php?&basin=atlantic&sat=wg8&prod=vor&zoom=&time=

I was looking at mids 500mb http://tropic.ssec.wisc.edu/real-time/w ... oom=&time=

[edu2703]

 https://twitter.com/pppapin/status/1432816862182748165