ATL: KAREN - Remnants - Discussion

[northjaxpro]

Some really heavy precipitation is starting to fire on the north side of PR on radar!!!
https://www.ar15.com/media/mediaFiles/437928/09252019-0048-Radar_JPG-1101643.jpg

This is a terrible developing situation currently going on there. Rain bands really converging and dumping loads of rain on the north side of the island.

[WeatherEmperor]

Pretty clear the new circ is coming together. old circ has no convection and will die..


https://i.ibb.co/QkFy0xb/14.gif

Is it your position that ultimately we should be tracking the mid level center currently exiting PR as opposed to the low level center that's already out in the Atlantic?

I ask because won't the 0z models most likely be initialized with the much further NE center?

its not just in the mid levels. surface obs ( in the loop ) and earlier recon pass showed it developing..

it is just becoming more defined deeper in the atmosphere. low levle and mid level convergence as well.

yeah models are going to be all wacky until probably at least 6z or 12z

What are the implications? Will the models shift more west towards Florida as a result of center reformation?


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[Aric Dunn]

Is it your position that ultimately we should be tracking the mid level center currently exiting PR as opposed to the low level center that's already out in the Atlantic?

I ask because won't the 0z models most likely be initialized with the much further NE center?

its not just in the mid levels. surface obs ( in the loop ) and earlier recon pass showed it developing..

it is just becoming more defined deeper in the atmosphere. low levle and mid level convergence as well.

yeah models are going to be all wacky until probably at least 6z or 12z

What are the implications? Will the models shift more west towards Florida as a result of center reformation?


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the million-dollar question..

I can say that logically it would get trapped sooner and not as far north so that would in theory lead to a farther west track.

[gatorcane]

probably stronger too since Karen would get right underneath the big upper-high that will set up rather than being on the edge and slightly sheared as the GFS shows.

[StormTracker]

Okay with all that being said though, doesn't the MLC normally follow the LLC???

[Aric Dunn]

Okay with all that being said though, doesn't the MLC normally follow the LLC???

There is a llc under the MLC already..

[NDG]

I am sure tonight the whole process will begin all over again of the LLC relocating or reforming further west like it did this morning.

[Blown Away]

Big convection blowup far to the west of my approximate Karen location of 18.7N/65.3W...

[StruThiO]

Old LLC definitely weakening/becoming diffuse now

[StormTracker]

Okay with all that being said though, doesn't the MLC normally follow the LLC???

There is a llc under the MLC already..

Correct/understood, but most of the time the MLC just follows the old LLC right? Another one of these intelligent storms that know exactly what to do to survive!

[gatorcane]

I find it hard to believe the old LLC is going to last much longer way off to the NE now of the big blowup of convection, Think we will see a reformation under the deep convection and that means some west adjustments with the models.

[Aric Dunn]

Old LLC definitely weakening/becoming diffuse now

https://i.imgur.com/eD8ldgm.png

yep and starting to rotate around the larger new one with all the convergence. it will soon elongate out and die.

[HDGator]

The heavy convection on radar seems to be compressing towards the center and it looks like a center is starting to emerge off the coast.
Meanwhile the low level vortex emerging NNE off Viequez Is. seems to start rotating NW or ccw around the new center emerging NNW of San Juan.
ETA: this is after too many looks at the current radar out of PR

[Aric Dunn]

I find it hard to believe the old LLC is going to last much longer way off to the NE now of the big blowup of convection, Think we will see a reformation under the deep convection and that means some west adjustments with the models.

you mean this llc ?

[abajan]

Some really heavy precipitation is starting to fire on the north side of PR on radar!!!
https://www.ar15.com/media/mediaFiles/437928/09252019-0048-Radar_JPG-1101643.jpg

That convection has really exploded within the last hour or so.

[StruThiO]

[GeneratorPower]

Land interaction isn’t all bad for storms.

[South Texas Storms]

The aircraft data supports a well defined center to the east of the convection. I don't see that center dying out anytime soon.

The big blow up of convection north of Puerto Rico this evening is likely due to orographic lifting from the mountains. I don't think Puerto Rico helped out the system today.

[Hammy]

Puerto Rico tends to do strange things to weaker tropical storms, especially if they go around the edge of it. Karen appears that it's doing the same as Gabrielle did in 2013--MLC gets hung up on the mountains, aided by shear, and the LLC goes shooting off to the north separately.

[StruThiO]

Thanks, Avila!

Tropical Storm Karen Discussion Number 12
NWS National Hurricane Center Miami FL AL122019
1100 PM AST Tue Sep 24 2019

During the afternoon and early evening hours, satellite images
indicated that the cloud pattern associated with Karen was
becoming a little better organized. Then, surface observations from
the area just east of Puerto Rico indicated that the pressures
were falling, and a center was apparently becoming better defined.
The presence of this center was confirmed by a reconnaissance
plane which was able to fix a tight small circulation of about 1002
or 1003 mb. This, by no means, indicates that the overall
circulation of the cyclone is well organized. Winds are still swirly
on the western portion of the circulation and are responding to an
elongated trough of low pressure north of Puerto Rico. In fact, I
would not be surprised if another center reforms father to west
within the trough or the large cyclonic envelope, and the center we
are tracking dissipates. In any case, preliminary analysis indicates
that the center of Karen that we were tracking moved very near or
over Vieques around 2100 UTC and then over Culebra a little bit
later. This small center could also have been a meso-vortex within
the larger circulation.

Data from the reconnaissance plane and satellite intensity estimates
yield an initial intensity of 40 kt. These winds are occurring
primarily to the southeast of the center. Karen is heading toward a
shear environment that is not ideal at all for significant
intensification. As previously indicated, the NHC forecast calls for
a very modest increase in intensity during the next 3 to 5 days as
indicated by the HCCA model. However, some of the statistical
guidance brings Karen to hurricane status by the end of the
forecast period.

Satellite and reconnaissance fixes indicate that Karen is moving
toward the north-northeast or 015 degrees at 12 kt. This motion
however, is highly uncertain because it includes the reformation of
the center. The circulation of Karen is trapped between a
subtropical high over the Atlantic and a mid-level trough over the
Bahamas. This flow pattern will continue to steer Karen in this same
generaldirection for the next 3 days. After that time, the steering
flow is forecast to collapse, and Karen, if it is still a cyclone,
will begin to meander. This would allow another ridge to develop
north of the cyclone and force it to move westward. This is the
solution provided by most of the global models.


Key Messages:

1. Karen will continue to bring heavy rainfall, flash floods and
mudslides to Puerto Rico, Vieques and the U.S. and British Virgin
Islands into Wednesday even as the center moves away from the
region.

FORECAST POSITIONS AND MAX WINDS

INIT 25/0300Z 19.1N 65.0W 40 KT 45 MPH
12H 25/1200Z 20.8N 64.6W 45 KT 50 MPH
24H 26/0000Z 23.2N 64.0W 45 KT 50 MPH
36H 26/1200Z 25.5N 63.4W 50 KT 60 MPH
48H 27/0000Z 27.0N 62.5W 55 KT 65 MPH
72H 28/0000Z 26.8N 61.5W 55 KT 65 MPH
96H 29/0000Z 26.5N 61.5W 55 KT 65 MPH
120H 30/0000Z 26.0N 65.5W 55 KT 65 MPH

$$
Forecaster Avila