EPAC: JULIA - Remnants - Discussion

[Aric Dunn]

Interesting...
they probably should have sent the plane.........

[cycloneye]

They added this sentence to the TWO.

While surface observations do suggest broad rotation
and pressures are lower than 24 hours ago, there currently is no
definitive proof that a well-defined circulation exists.

[FireBird]

Hi All from my obs on the ground here in NW Trinidad, I can tell you that this system is quickly developing. The winds started their shift earlier this evening, and though the gusts are still variable, we know down here that when something is strong enough to survive the graveyard, everyone west of us should watch out.
As of now we have had a reported 200mm rainfall, one woman has been swept away without recovery, damage to bridges, roads, homes, and several cars were washed away and destroyed. Riverine alerts remain in effect.
So to my neighbours, prepare for the worst and hope for the best...

[aspen]

I think PTC advisories are warranted now. It’s up to 70% in 48 hours, the NHC has recognized its improved organization, and recon from earlier today found evidence for TS-force surface winds. It’s tracking so close to land that advisories may be needed.

[Aric Dunn]

Interesting...
they probably should have sent the plane.........

https://www.fnmoc.navy.mil/tcweb/dynamic/products/tc22/ATL/91L.INVEST/ssmis/91rgb/20221005.2250.f17.91pct91h91v.91L.INVEST.30kts.1006mb.11.4N.62.8W.075pc.jpg

Cell motion on radar and satellite seems to show the LLC is farther north.. could be multiple vorts I suppose as well.. but definitely something is closed down there.

[cycloneye]

 https://twitter.com/AndyHazelton/status/1577813833904803840

[cycloneye]

AL, 91, 2022100600, , BEST, 0, 114N, 644W, 30, 1006, DB

https://ftp.nhc.noaa.gov/atcf/btk/bal912022.dat

[MarioProtVI]

I think PTC advisories are warranted now. It’s up to 70% in 48 hours, the NHC has recognized its improved organization, and recon from earlier today found evidence for TS-force surface winds. It’s tracking so close to land that advisories may be needed.

It’ll have to wait until 11am tomorrow since they never initiate PTC advisories at night.

[Nuno]

I think PTC advisories are warranted now. It’s up to 70% in 48 hours, the NHC has recognized its improved organization, and recon from earlier today found evidence for TS-force surface winds. It’s tracking so close to land that advisories may be needed.

It’ll have to wait until 11am tomorrow since they never initiate PTC advisories at night.

I hope they initiate them sooner at 5am. Don't need to wait to 11am.

[cycloneye]

 https://twitter.com/AndyHazelton/status/1577827735367565313

[cheezyWXguy]

I think PTC advisories are warranted now. It’s up to 70% in 48 hours, the NHC has recognized its improved organization, and recon from earlier today found evidence for TS-force surface winds. It’s tracking so close to land that advisories may be needed.

It’ll have to wait until 11am tomorrow since they never initiate PTC advisories at night.

I hope they initiate them sooner at 5am. Don't need to wait to 11am.

Advisories were initiated on Ian (as a td) at 5am, could happen again if data is compelling enough. Probably not likely though

[cycloneye]

 https://twitter.com/wxtrackercody/status/1577847720114634753

[Teban54]

https://twitter.com/wxtrackercody/status/1577847720114634753

Could the recent burst of convection to the north (around 11.7N) pull the forming(?) LLC towards it?

[Sciencerocks]

[zzzh]

Center is clear on microwave. Much further north than NHC position.

[Aric Dunn]

https://i.imgur.com/a0BwhjZ.jpg
Center is clear on microwave. Much further north than NHC position.

Yeah I think ASCAT is having issues with all the islands and land nearby. the LLC is pretty apparent on satellite and multiple microwave passes now a good bit north. hopefully, they send a plane tomorrow,.

[AJC3]

https://i.imgur.com/a0BwhjZ.jpg
Center is clear on microwave. Much further north than NHC position.

Yeah I think ASCAT is having issues with all the islands and land nearby. the LLC is pretty apparent on satellite and multiple microwave passes now a good bit north. hopefully, they send a plane tomorrow,.

https://i.ibb.co/zhd3YxH/91l.png

It's not the instrument. When a formative system is embedded in the easterly trades, the surface LLC shown in scatterometer data is always going to be displaced south of the LL vort center you see in M/I because of the translational forward speed. Take an idealized (uniform) LLVC, vectorially add 15kt across its environment, and watch what happens to the center. A great example of this is cyclone Agni in 2004. All of the M/I passes as well as conventional satellite data showed the apparent center remaining north of the equator, however QS clearly showed the surface center dipped south of it.

I made a post about this on here several years ago. I'll see if I can find it...

[cheezyWXguy]

https://i.imgur.com/a0BwhjZ.jpg
Center is clear on microwave. Much further north than NHC position.

Yeah I think ASCAT is having issues with all the islands and land nearby. the LLC is pretty apparent on satellite and multiple microwave passes now a good bit north. hopefully, they send a plane tomorrow,.

https://i.ibb.co/zhd3YxH/91l.png

It's not the instrument. When a formative system is embedded in the easterly trades, the surface LLC shown in scatterometer data is always going to be displaced south of the LL vort center you see in M/I because of the translational forward speed. Take an idealized (uniform) LLVC, vectorially add 15kt across its environment, and watch what happens to the center. A great example of this is cyclone Agni in 2004. All of the M/I passes as well as conventional satellite data showed the apparent formative vort center remaining north of the equator, however QS clearly showed the surface wind center dipped south of it.

I made a post about this on here several years ago. I'll see if I can find it...

This is interesting but a bit over my head. Is ascat too far south with the center, or is microwave too far north?

[AJC3]

Yeah I think ASCAT is having issues with all the islands and land nearby. the LLC is pretty apparent on satellite and multiple microwave passes now a good bit north. hopefully, they send a plane tomorrow,.

https://i.ibb.co/zhd3YxH/91l.png

It's not the instrument. When a formative system is embedded in the easterly trades, the surface LLC shown in scatterometer data is always going to be displaced south of the LL vort center you see in M/I because of the translational forward speed. Take an idealized (uniform) LLVC, vectorially add 15kt across its environment, and watch what happens to the center. A great example of this is cyclone Agni in 2004. All of the M/I passes as well as conventional satellite data showed the apparent formative vort center remaining north of the equator, however QS clearly showed the surface wind center dipped south of it.

I made a post about this on here several years ago. I'll see if I can find it...

This is interesting but a bit over my head. Is ascat too far south with the center, or is microwave too far north?

The storm-relative LL vort center is where M/I puts it. The ground-relative LL wind center is where ASCAT puts it. Going by the strict definition of a TC, the LLC is where the surface wind center is.

[ElectricStorm]

Southeastern Caribbean Sea:
An area of low pressure located over the far southeastern Caribbean
Sea is producing a large area of showers and thunderstorms over the
southern Windward Islands, northern South America, and adjacent
waters. Satellite-derived wind data indicate that this system does
not yet have a well-defined center of circulation. While land
interaction with the northern coast of South America may hinder
significant development during the next day or so, environmental
conditions are expected to be mostly conducive for development as
the system moves generally westward, and a tropical depression is
likely to form in the next couple of days by the time the system
enters the south-central Caribbean Sea.

1. Regardless of development, heavy rainfall with localized flooding,
as well as gusty winds to gale force, are expected over portions of
the Windward Islands, northern portions of Venezuela including
Isla Margarita, and the ABC Islands during the next day or two.
Interests in those locations, in addition to those in Central
America, should continue to monitor the progress of this system.
* Formation chance through 48 hours...high...80 percent.
* Formation chance through 5 days...high...90 percent.