ATL: ISAIAS - Post-Tropical - Discussion

[Blown Away]

Well, at 8pm the latitude was 14.2 and now 14.6 at 11pm.

[caneseddy]

New 11:00 pm update they have peak winds now at 65 mph while impacting Miami.

[Dougiefresh]

Rains and thunderstorms have eased up here in Barbados for about two hours thus far hoping for some more showers and thunderstorms later on nothing too serious tho

So feeling any tropical storm force winds? supposedly the LLC is crossing just to your east if not over you.

Nope, quite the opposite, not a leaf twitching.

[HurricaneFrances04]

A key takeaway from the Disco (at least for me):

Assuming the system remains
intact after emerging off the coast of Hispaniola, the slow track
over the very warm waters of the Straits of Florida would result in
more strengthening, assuming the system doesn't interact with the
Cuban landmass. Although the GFS-and ECMWF-based SHIPS intensity
guidance shows considerable southwesterly vertical wind shear of
20-30 kt in the 72-96 h period when the disturbance is over the
Straits, the global model fields show that this is self-induced
shear caused by the SHIPS model incorporating the system's
impressive upper-level outflow winds in its shear calculations. As a
result, this is not being considered a negative intensity factor
compared to land interaction. Due to aforementioned uncertainties,
the new NHC intensity forecast remains on the conservative side, and
lies between the slightly weaker IVCN and stronger NOAA-HCCA
consensus models. Interests in Hispaniola, the Bahamas, Cuba, and
Florida should continue to monitor forecasts as changes to both the
track and intensity are likely.

[tropicwatch]

lol the intensity guidance is the long term actually went UP

FORECAST POSITIONS AND MAX WINDS

INIT 29/0300Z 14.6N 59.4W 35 KT 40 MPH...POTENTIAL TROP CYCLONE
12H 29/1200Z 15.7N 62.3W 40 KT 45 MPH
24H 30/0000Z 17.4N 65.9W 45 KT 50 MPH
36H 30/1200Z 18.7N 69.3W 45 KT 50 MPH...INLAND
48H 31/0000Z 20.1N 72.6W 45 KT 50 MPH...OVER WATER
60H 31/1200Z 21.5N 75.5W 50 KT 60 MPH
72H 01/0000Z 22.8N 77.7W 55 KT 65 MPH
96H 02/0000Z 25.7N 80.7W 55 KT 65 MPH...INLAND
120H 03/0000Z 27.9N 82.0W 45 KT 50 MPH...INLAND

$$
Forecaster Stewart

Gotta love Stewart.

[AutoPenalti]

Impressive really!?

That’s the last word I’d be using to describe PTC-9’s appearance tonight.

https://twitter.com/dylanfedericowx/status/1288302971722358784

I feel like you’re trolling at this point.

You really think this thing looks impressive?

And I’m not trolling, I’m stating the facts.

That’s not a fact...

[Evil Jeremy]

Highlights from the discussion:

"The new NHC track forecast is similar to but a little south of the
previous advisory track, mainly due to the more westward initial
position, and lies along the southern portion of the guidance
envelope near the middle of the consensus models."

"The intensity forecast remains problematic for primarily two
reasons: 1) the lack of a well-defined center and inner-core wind
field and 2) likely land interaction to some degree."

"Assuming the system remains
intact after emerging off the coast of Hispaniola, the slow track
over the very warm waters of the Straits of Florida would result in
more strengthening, assuming the system doesn't interact with the
Cuban landmass. Although the GFS-and ECMWF-based SHIPS intensity
guidance shows considerable southwesterly vertical wind shear of
20-30 kt in the 72-96 h period when the disturbance is over the
Straits, the global model fields show that this is self-induced
shear caused by the SHIPS model incorporating the system's
impressive upper-level outflow winds in its shear calculations. As a
result, this is not being considered a negative intensity factor
compared to land interaction."

[caneseddy]

From the discussion:

Although the GFS-and ECMWF-based SHIPS intensity
guidance shows considerable southwesterly vertical wind shear of
20-30 kt in the 72-96 h period when the disturbance is over the
Straits, the global model fields show that this is self-induced
shear caused by the SHIPS model incorporating the system's
impressive upper-level outflow winds in its shear calculations. As a
result, this is not being considered a negative intensity factor
compared to land interaction.

[Aric Dunn]

From the discussion:

Although the GFS-and ECMWF-based SHIPS intensity
guidance shows considerable southwesterly vertical wind shear of
20-30 kt in the 72-96 h period when the disturbance is over the
Straits, the global model fields show that this is self-induced
shear caused by the SHIPS model incorporating the system's
impressive upper-level outflow winds in its shear calculations. As a
result, this is not being considered a negative intensity factor
compared to land interaction.

was just going to post this.

means the models are messed up on intensity..

[supercane4867]

That was a well-written forecast discussion by Stewart.

[psyclone]

Impressive really!?

That’s the last word I’d be using to describe PTC-9’s appearance tonight.

https://twitter.com/dylanfedericowx/status/1288302971722358784

I feel like you’re trolling at this point.

You really think this thing looks impressive?

And I’m not trolling, I’m stating the facts.

It's a disturbance. A PTC is fancy name for a disturbance expected to become a storm. That's no guarantee it will. We watch disturbances in tropical season. not every one develops but each one is interesting to watch. Constant complaining is becoming increasingly cumbersome and is disrupting my tropical tropospheric chi and i can't be alone. Sit back, enjoy the ride and marvel as nature does nature. Most disturbances don't make it to become TCs...even in active seasons. At least we have something to watch. we're entitled to nothing in latter July.

[aspen]

The NHC’s 11pm update was not what I was expecting. PTC-9 is forecast to turn north and go through the Greater Antilles. However, it passes right over the DR, and the NHC bumps its peak intensity to 55 kt.

I was anticipating either death by DR or a Caribbean Crusier, potentially trying to make landfall in Cuba.

[caneseddy]

That was a well-written forecast discussion by Stewart.

I’ve always loved Stacy”s discussions. He is very particular about everything and goes into detail of everything

[CyclonicFury]

lol the intensity guidance is the long term actually went UP

FORECAST POSITIONS AND MAX WINDS

INIT 29/0300Z 14.6N 59.4W 35 KT 40 MPH...POTENTIAL TROP CYCLONE
12H 29/1200Z 15.7N 62.3W 40 KT 45 MPH
24H 30/0000Z 17.4N 65.9W 45 KT 50 MPH
36H 30/1200Z 18.7N 69.3W 45 KT 50 MPH...INLAND
48H 31/0000Z 20.1N 72.6W 45 KT 50 MPH...OVER WATER
60H 31/1200Z 21.5N 75.5W 50 KT 60 MPH
72H 01/0000Z 22.8N 77.7W 55 KT 65 MPH
96H 02/0000Z 25.7N 80.7W 55 KT 65 MPH...INLAND
120H 03/0000Z 27.9N 82.0W 45 KT 50 MPH...INLAND

$$
Forecaster Stewart

Gotta love Stewart.

Stewart is by far the most bullish at NHC, it seems.

[caneseddy]

From the discussion:

Although the GFS-and ECMWF-based SHIPS intensity
guidance shows considerable southwesterly vertical wind shear of
20-30 kt in the 72-96 h period when the disturbance is over the
Straits, the global model fields show that this is self-induced
shear caused by the SHIPS model incorporating the system's
impressive upper-level outflow winds in its shear calculations. As a
result, this is not being considered a negative intensity factor
compared to land interaction.

was just going to post this.

means the models are messed up on intensity..

He also posted a center could form tonight because of friction with the islands

Also everything is land interaction because according to the discussion, shear won’t be that big of a factor

[tropicwatch]

lol the intensity guidance is the long term actually went UP

FORECAST POSITIONS AND MAX WINDS

INIT 29/0300Z 14.6N 59.4W 35 KT 40 MPH...POTENTIAL TROP CYCLONE
12H 29/1200Z 15.7N 62.3W 40 KT 45 MPH
24H 30/0000Z 17.4N 65.9W 45 KT 50 MPH
36H 30/1200Z 18.7N 69.3W 45 KT 50 MPH...INLAND
48H 31/0000Z 20.1N 72.6W 45 KT 50 MPH...OVER WATER
60H 31/1200Z 21.5N 75.5W 50 KT 60 MPH
72H 01/0000Z 22.8N 77.7W 55 KT 65 MPH
96H 02/0000Z 25.7N 80.7W 55 KT 65 MPH...INLAND
120H 03/0000Z 27.9N 82.0W 45 KT 50 MPH...INLAND

$$
Forecaster Stewart

Gotta love Stewart.

Stewart is by far the most bullish at NHC, it seems.

He is also one of the most experienced at the NHC.

[GeneratorPower]

Ah! Stewart!

[DestinHurricane]

lol the intensity guidance is the long term actually went UP

FORECAST POSITIONS AND MAX WINDS

INIT 29/0300Z 14.6N 59.4W 35 KT 40 MPH...POTENTIAL TROP CYCLONE
12H 29/1200Z 15.7N 62.3W 40 KT 45 MPH
24H 30/0000Z 17.4N 65.9W 45 KT 50 MPH
36H 30/1200Z 18.7N 69.3W 45 KT 50 MPH...INLAND
48H 31/0000Z 20.1N 72.6W 45 KT 50 MPH...OVER WATER
60H 31/1200Z 21.5N 75.5W 50 KT 60 MPH
72H 01/0000Z 22.8N 77.7W 55 KT 65 MPH
96H 02/0000Z 25.7N 80.7W 55 KT 65 MPH...INLAND
120H 03/0000Z 27.9N 82.0W 45 KT 50 MPH...INLAND

$$
Forecaster Stewart

Gotta love Stewart.

Stewart is by far the most bullish at NHC, it seems.

That would explain his forecast. How can it survive the shredder?? This thing is all but certain to die before it reaches 20N.

[Craters]

Rains and thunderstorms have eased up here in Barbados for about two hours thus far hoping for some more showers and thunderstorms later on nothing too serious tho

So feeling any tropical storm force winds? supposedly the LLC is crossing just to your east if not over you.

Nope, quite the opposite, not a leaf twitching.

You must be in the mighty eye!!!

[WxEp]

From the discussion:

Although the GFS-and ECMWF-based SHIPS intensity
guidance shows considerable southwesterly vertical wind shear of
20-30 kt in the 72-96 h period when the disturbance is over the
Straits, the global model fields show that this is self-induced
shear caused by the SHIPS model incorporating the system's
impressive upper-level outflow winds in its shear calculations. As a
result, this is not being considered a negative intensity factor
compared to land interaction.

was just going to post this.

means the models are messed up on intensity..

Is this something that happens frequently? I've been paying close attention to the tropics (including on this forum) for 16 years now and I can't remember hearing that SHIPS or any intensity guidance was incorporating "self-induced" shear.