ATL: ISAIAS - Post-Tropical - Discussion

[DestinHurricane]

Just a reminder for everyone concerned:

https://twitter.com/iCyclone/status/1287853738988838917

Broken clock is right twice a day.

[caneseddy]

NHC track has a TS landfall in South Florida on Saturday

[wxman57]

NHC track EXACTLY matches mine, to the landfall in FL and even the timing. Can't be right... They keep it a TS because they don't want people to let their guard down as it approaches if they forecast it to weaken to a TD.

[toad strangler]

Here we go!!

Where we going?

[Shell Mound]

Pre-Joaquin (2015):

The depression is expected to be blasted by strong north-northwesterly or northerly winds associated with the tail of an upper-level trough over the central Atlantic beginning on Monday. In fact, global models show the shear being sufficiently strong enough to result in the cyclone either becoming a remnant low or dissipating within a few days. The intensity forecast is below the multi-model consensus through the forecast period, closest to the HWRF solution.

FORECAST POSITIONS AND MAX WINDS

INIT 28/0300Z 27.5N 68.7W 30 KT 35 MPH
12H 28/1200Z 27.7N 69.4W 30 KT 35 MPH
24H 29/0000Z 27.9N 69.9W 30 KT 35 MPH
36H 29/1200Z 28.2N 70.4W 30 KT 35 MPH
48H 30/0000Z 28.8N 70.8W 30 KT 35 MPH
72H 01/0000Z 31.0N 71.6W 30 KT 35 MPH
96H 02/0000Z...DISSIPATED

Pre-Michael (2018):

Strong wind shear is expected to affect the disturbance, and the SHIPS model only show a modest strengthening. This is in contrast to some global models and the HWRF, which are more aggressive in developing this system. Since the environment is marginally favorable, the NHC forecast only gradually strengthens the system at the rate of the intensity consensus IVCN. However, the forecast is highly uncertaingiven the solution of the global models.

FORECAST POSITIONS AND MAX WINDS

INIT 07/0300Z 18.8N 86.6W 25 KT 30 MPH...POTENTIAL TROP CYCLONE
12H 07/1200Z 19.5N 86.5W 30 KT 35 MPH...TROPICAL CYCLONE
24H 08/0000Z 21.0N 86.2W 35 KT 40 MPH
36H 08/1200Z 22.3N 86.1W 40 KT 45 MPH
48H 09/0000Z 23.8N 86.3W 45 KT 50 MPH
72H 10/0000Z 27.4N 87.2W 55 KT 65 MPH
96H 11/0000Z 32.0N 85.0W 30 KT 35 MPH...INLAND
120H 12/0000Z 38.5N 77.5W 30 KT 35 MPH...INLAND

Dorian (2019):

When Dorian approaches Hispaniola in about 3 days, the models show an increase in shear and those stronger environmental winds and the potential interaction with the rugged terrain of Hispaniola suggest that significant weakening is likely. The NHC intensity forecast remains between the dynamical models that show little or no strengthening and the statistical DSHP and LGEM that show significant intensification. It should be noted that the GFS and ECMWF have been very consistent in showing Dorian dissipating over the Caribbean Sea.

FORECAST POSITIONS AND MAX WINDS

INIT 26/0900Z 11.9N 56.4W 50 KT 60 MPH
12H 26/1800Z 12.4N 58.2W 50 KT 60 MPH
24H 27/0600Z 13.2N 60.3W 55 KT 65 MPH
36H 27/1800Z 14.4N 62.4W 55 KT 65 MPH
48H 28/0600Z 15.5N 64.5W 60 KT 70 MPH
72H 29/0600Z 18.0N 68.4W 65 KT 75 MPH
96H 30/0600Z 20.8N 71.6W 30 KT 35 MPH
120H 31/0600Z 23.0N 75.0W 30 KT 35 MPH

Oh, and here’s pre-Hanna:

However, since the depression is still in its formative stage, the rate of strengthening should be gradual. After the storm crosses the coast, steady weakening should commence. The NHC intensity forecast generally follows the IVCN and HCCA guidance.

FORECAST POSITIONS AND MAX WINDS

INIT 23/0300Z 25.9N 88.2W 25 KT 30 MPH
12H 23/1200Z 26.3N 89.3W 30 KT 35 MPH
24H 24/0000Z 27.0N 90.8W 30 KT 35 MPH
36H 24/1200Z 27.9N 92.4W 35 KT 40 MPH
48H 25/0000Z 28.2N 94.0W 35 KT 40 MPH
60H 25/1200Z 28.5N 95.3W 40 KT 45 MPH
72H 26/0000Z 28.7N 96.8W 35 KT 40 MPH...INLAND
96H 27/0000Z 28.8N 98.1W 25 KT 30 MPH...INLAND
120H 28/0000Z 28.7N 100.5W 20 KT 25 MPH...INLAND

[gatorcane]

Pre-Joaquin (2015):

The depression is expected to be blasted by strong north-northwesterly or northerly winds associated with the tail of an upper-level trough over the central Atlantic beginning on Monday. In fact, global models show the shear being sufficiently strong enough to result in the cyclone either becoming a remnant low or dissipating within a few days. The intensity forecast is below the multi-model consensus through the forecast period, closest to the HWRF solution.

FORECAST POSITIONS AND MAX WINDS

INIT 28/0300Z 27.5N 68.7W 30 KT 35 MPH
12H 28/1200Z 27.7N 69.4W 30 KT 35 MPH
24H 29/0000Z 27.9N 69.9W 30 KT 35 MPH
36H 29/1200Z 28.2N 70.4W 30 KT 35 MPH
48H 30/0000Z 28.8N 70.8W 30 KT 35 MPH
72H 01/0000Z 31.0N 71.6W 30 KT 35 MPH
96H 02/0000Z...DISSIPATED

Pre-Michael (2018):

Strong wind shear is expected to affect the disturbance, and the SHIPS model only show a modest strengthening. This is in contrast to some global models and the HWRF, which are more aggressive in developing this system. Since the environment is marginally favorable, the NHC forecast only gradually strengthens the system at the rate of the intensity consensus IVCN. However, the forecast is highly uncertaingiven the solution of the global models.

FORECAST POSITIONS AND MAX WINDS

INIT 07/0300Z 18.8N 86.6W 25 KT 30 MPH...POTENTIAL TROP CYCLONE
12H 07/1200Z 19.5N 86.5W 30 KT 35 MPH...TROPICAL CYCLONE
24H 08/0000Z 21.0N 86.2W 35 KT 40 MPH
36H 08/1200Z 22.3N 86.1W 40 KT 45 MPH
48H 09/0000Z 23.8N 86.3W 45 KT 50 MPH
72H 10/0000Z 27.4N 87.2W 55 KT 65 MPH
96H 11/0000Z 32.0N 85.0W 30 KT 35 MPH...INLAND
120H 12/0000Z 38.5N 77.5W 30 KT 35 MPH...INLAND

Dorian (2019):

When Dorian approaches Hispaniola in about 3 days, the models show an increase in shear and those stronger environmental winds and the potential interaction with the rugged terrain of Hispaniola suggest that significant weakening is likely. The NHC intensity forecast remains between the dynamical models that show little or no strengthening and the statistical DSHP and LGEM that show significant intensification. It should be noted that the GFS and ECMWF have been very consistent in showing Dorian dissipating over the Caribbean Sea.

FORECAST POSITIONS AND MAX WINDS

INIT 26/0900Z 11.9N 56.4W 50 KT 60 MPH
12H 26/1800Z 12.4N 58.2W 50 KT 60 MPH
24H 27/0600Z 13.2N 60.3W 55 KT 65 MPH
36H 27/1800Z 14.4N 62.4W 55 KT 65 MPH
48H 28/0600Z 15.5N 64.5W 60 KT 70 MPH
72H 29/0600Z 18.0N 68.4W 65 KT 75 MPH
96H 30/0600Z 20.8N 71.6W 30 KT 35 MPH
120H 31/0600Z 23.0N 75.0W 30 KT 35 MPH

Great examples here of how things can change quickly as far as intensity forecasts are concerned

[SFLcane]

Here we go!!

Where we going?

Covid and a TS oh man get ready for major shortages in food and supplies. Can’t even rap my head around it

[DestinHurricane]

Pre-Joaquin (2015):

The depression is expected to be blasted by strong north-northwesterly or northerly winds associated with the tail of an upper-level trough over the central Atlantic beginning on Monday. In fact, global models show the shear being sufficiently strong enough to result in the cyclone either becoming a remnant low or dissipating within a few days. The intensity forecast is below the multi-model consensus through the forecast period, closest to the HWRF solution.

FORECAST POSITIONS AND MAX WINDS

INIT 28/0300Z 27.5N 68.7W 30 KT 35 MPH
12H 28/1200Z 27.7N 69.4W 30 KT 35 MPH
24H 29/0000Z 27.9N 69.9W 30 KT 35 MPH
36H 29/1200Z 28.2N 70.4W 30 KT 35 MPH
48H 30/0000Z 28.8N 70.8W 30 KT 35 MPH
72H 01/0000Z 31.0N 71.6W 30 KT 35 MPH
96H 02/0000Z...DISSIPATED

Pre-Michael (2018):

Strong wind shear is expected to affect the disturbance, and the SHIPS model only show a modest strengthening. This is in contrast to some global models and the HWRF, which are more aggressive in developing this system. Since the environment is marginally favorable, the NHC forecast only gradually strengthens the system at the rate of the intensity consensus IVCN. However, the forecast is highly uncertaingiven the solution of the global models.

FORECAST POSITIONS AND MAX WINDS

INIT 07/0300Z 18.8N 86.6W 25 KT 30 MPH...POTENTIAL TROP CYCLONE
12H 07/1200Z 19.5N 86.5W 30 KT 35 MPH...TROPICAL CYCLONE
24H 08/0000Z 21.0N 86.2W 35 KT 40 MPH
36H 08/1200Z 22.3N 86.1W 40 KT 45 MPH
48H 09/0000Z 23.8N 86.3W 45 KT 50 MPH
72H 10/0000Z 27.4N 87.2W 55 KT 65 MPH
96H 11/0000Z 32.0N 85.0W 30 KT 35 MPH...INLAND
120H 12/0000Z 38.5N 77.5W 30 KT 35 MPH...INLAND

Dorian (2019):

When Dorian approaches Hispaniola in about 3 days, the models show an increase in shear and those stronger environmental winds and the potential interaction with the rugged terrain of Hispaniola suggest that significant weakening is likely. The NHC intensity forecast remains between the dynamical models that show little or no strengthening and the statistical DSHP and LGEM that show significant intensification. It should be noted that the GFS and ECMWF have been very consistent in showing Dorian dissipating over the Caribbean Sea.

FORECAST POSITIONS AND MAX WINDS

INIT 26/0900Z 11.9N 56.4W 50 KT 60 MPH
12H 26/1800Z 12.4N 58.2W 50 KT 60 MPH
24H 27/0600Z 13.2N 60.3W 55 KT 65 MPH
36H 27/1800Z 14.4N 62.4W 55 KT 65 MPH
48H 28/0600Z 15.5N 64.5W 60 KT 70 MPH
72H 29/0600Z 18.0N 68.4W 65 KT 75 MPH
96H 30/0600Z 20.8N 71.6W 30 KT 35 MPH
120H 31/0600Z 23.0N 75.0W 30 KT 35 MPH

Oh, and here’s pre-Hanna:

However, since the depression is still in its formative stage, the rate of strengthening should be gradual. After the storm crosses the coast, steady weakening should commence. The NHC intensity forecast generally follows the IVCN and HCCA guidance.

FORECAST POSITIONS AND MAX WINDS

INIT 23/0300Z 25.9N 88.2W 25 KT 30 MPH
12H 23/1200Z 26.3N 89.3W 30 KT 35 MPH
24H 24/0000Z 27.0N 90.8W 30 KT 35 MPH
36H 24/1200Z 27.9N 92.4W 35 KT 40 MPH
48H 25/0000Z 28.2N 94.0W 35 KT 40 MPH
60H 25/1200Z 28.5N 95.3W 40 KT 45 MPH
72H 26/0000Z 28.7N 96.8W 35 KT 40 MPH...INLAND
96H 27/0000Z 28.8N 98.1W 25 KT 30 MPH...INLAND
120H 28/0000Z 28.7N 100.5W 20 KT 25 MPH...INLAND

Those were in August, Sept, and October. This is July. Much more of a chance of another Gonzalo than a Dorian.
Also Hannah and Michael were in the Gulf. Gulf is usually more conductive for that type of thing than this part of the Atlantic.

[TheStormExpert]

First advisory forecast track. I’m hopeful this changes as it usually does some considering it’s the first advisory, because no one needs anymore excitement this year!

[Do_For_Love]

NHC has this as Isaias (never heard that one before this storm lol) by tomorrow which would make it the 5th named storm of July. I know most of them haven't been very strong but that's pretty crazy regardless.

[Hypercane_Kyle]

IMO, I think this'll become a minimal hurricane in the Bahamas. Perhaps something similar to Erin in 1995. I think the global models are struggling to consolidate this one correctly, given its broad and generally speaking disorganized state.

[curtadams]

It's still an unholy mess. Two separate MLCs, each literally hundreds of miles from the LLC, with the weaker (trailing) MLC closer. I assume they're calling it a tropical cyclone because it's going to bring TS conditions to the Lesser Antilles in spite of epic misorganization. I suppose you could view it as a bizarre subtropical storm, since MLC and LLC don't have to be aligned for those.

[HurricaneAndre2008]

Recon is having communication issues this morning. Hopefully they get those issues resolved soon.

[chaser1]

NHC track EXACTLY matches mine, to the landfall in FL and even the timing. Can't be right... They keep it a TS because they don't want people to let their guard down as it approaches if they forecast it to weaken to a TD.

Very very sensible forecast and thought process given what we've got right now.

[TheStormExpert]

IMO, I think this'll become a minimal hurricane in the Bahamas. Perhaps something similar to Erin in 1995. I think the global models are struggling to consolidate this one correctly, given its broad and generally speaking disorganized state.

Erin 1995 could be an analog but does anyone remember how they were forecasting Erika in 2015 to strike the East Coast of Florida as a minimal hurricane and it failed to do so? Similar location, track, and speed.

[Nuno]

Pre-Joaquin (2015):

The depression is expected to be blasted by strong north-northwesterly or northerly winds associated with the tail of an upper-level trough over the central Atlantic beginning on Monday. In fact, global models show the shear being sufficiently strong enough to result in the cyclone either becoming a remnant low or dissipating within a few days. The intensity forecast is below the multi-model consensus through the forecast period, closest to the HWRF solution.

FORECAST POSITIONS AND MAX WINDS

INIT 28/0300Z 27.5N 68.7W 30 KT 35 MPH
12H 28/1200Z 27.7N 69.4W 30 KT 35 MPH
24H 29/0000Z 27.9N 69.9W 30 KT 35 MPH
36H 29/1200Z 28.2N 70.4W 30 KT 35 MPH
48H 30/0000Z 28.8N 70.8W 30 KT 35 MPH
72H 01/0000Z 31.0N 71.6W 30 KT 35 MPH
96H 02/0000Z...DISSIPATED

Pre-Michael (2018):

Strong wind shear is expected to affect the disturbance, and the SHIPS model only show a modest strengthening. This is in contrast to some global models and the HWRF, which are more aggressive in developing this system. Since the environment is marginally favorable, the NHC forecast only gradually strengthens the system at the rate of the intensity consensus IVCN. However, the forecast is highly uncertaingiven the solution of the global models.

FORECAST POSITIONS AND MAX WINDS

INIT 07/0300Z 18.8N 86.6W 25 KT 30 MPH...POTENTIAL TROP CYCLONE
12H 07/1200Z 19.5N 86.5W 30 KT 35 MPH...TROPICAL CYCLONE
24H 08/0000Z 21.0N 86.2W 35 KT 40 MPH
36H 08/1200Z 22.3N 86.1W 40 KT 45 MPH
48H 09/0000Z 23.8N 86.3W 45 KT 50 MPH
72H 10/0000Z 27.4N 87.2W 55 KT 65 MPH
96H 11/0000Z 32.0N 85.0W 30 KT 35 MPH...INLAND
120H 12/0000Z 38.5N 77.5W 30 KT 35 MPH...INLAND

Dorian (2019):

When Dorian approaches Hispaniola in about 3 days, the models show an increase in shear and those stronger environmental winds and the potential interaction with the rugged terrain of Hispaniola suggest that significant weakening is likely. The NHC intensity forecast remains between the dynamical models that show little or no strengthening and the statistical DSHP and LGEM that show significant intensification. It should be noted that the GFS and ECMWF have been very consistent in showing Dorian dissipating over the Caribbean Sea.

FORECAST POSITIONS AND MAX WINDS

INIT 26/0900Z 11.9N 56.4W 50 KT 60 MPH
12H 26/1800Z 12.4N 58.2W 50 KT 60 MPH
24H 27/0600Z 13.2N 60.3W 55 KT 65 MPH
36H 27/1800Z 14.4N 62.4W 55 KT 65 MPH
48H 28/0600Z 15.5N 64.5W 60 KT 70 MPH
72H 29/0600Z 18.0N 68.4W 65 KT 75 MPH
96H 30/0600Z 20.8N 71.6W 30 KT 35 MPH
120H 31/0600Z 23.0N 75.0W 30 KT 35 MPH

Oh, and here’s pre-Hanna:

However, since the depression is still in its formative stage, the rate of strengthening should be gradual. After the storm crosses the coast, steady weakening should commence. The NHC intensity forecast generally follows the IVCN and HCCA guidance.

FORECAST POSITIONS AND MAX WINDS

INIT 23/0300Z 25.9N 88.2W 25 KT 30 MPH
12H 23/1200Z 26.3N 89.3W 30 KT 35 MPH
24H 24/0000Z 27.0N 90.8W 30 KT 35 MPH
36H 24/1200Z 27.9N 92.4W 35 KT 40 MPH
48H 25/0000Z 28.2N 94.0W 35 KT 40 MPH
60H 25/1200Z 28.5N 95.3W 40 KT 45 MPH
72H 26/0000Z 28.7N 96.8W 35 KT 40 MPH...INLAND
96H 27/0000Z 28.8N 98.1W 25 KT 30 MPH...INLAND
120H 28/0000Z 28.7N 100.5W 20 KT 25 MPH...INLAND

Those were in August, Sept, and October. This is July. Much more of a chance of another Gonzalo than a Dorian.
Also Hannah and Michael were in the Gulf. Gulf is usually more conductive for that type of thing than this part of the Atlantic.

We're like days away from August. It is irrelevant. Conducive conditions to even have a storm like this forming shows you not to cling to much to historical precedent. It's here now.

And the Atlantic has had plenty of rapidly intensifying cyclones...

[Shell Mound]

Actually, Joaquin became the strongest hurricane of non-tropical origin observed over the subtropical Atlantic, specifically the Sargasso Sea, since the satellite era began in 1961, while Michael was by far the strongest and most intense landfalling U.S. hurricane in October, being the only Category-5 cyclone to strike the Florida Panhandle on record. The fact is that these kinds of scenarios are dangerous because they are poorly forecast and unusual, with only a small change in the variables meaning the difference between a dissipating wave and a landfalling, intensifying, even record-breaking Cat-5. One of these days we will see that worst-case scenario: a system that is expected to be only a moderate tropical storm (or even dissipate) yet ends up rapidly intensifying into a Cat-5 on short order, is handled badly by the global and/or other model guidance, and strikes a densely populated part of the mainland U.S. It is rare, a “black swan” of sorts, but it will happen, and it will happen when we least expect it. This system may or may not be that one, but that one will come one day, and we’ve already seen enough over just the past three seasons to know the answer.

[Dean4Storms]

If this wasn't so large I'd bet on a much deeper system but we all know these large TW's that are elongated need concentrated convection, low shear and slower forward speed in most instances, throw in the Greater Antilles and the mountains and I can see why NHC is skeptical for this reaching much organization. If this can pop out on the other side of the trough as a surface reflection it might pop, but then we're talking the GOM as the lower level flow would likely take it there.

[HurricaneAndre2008]

Recon is back live.

[Nuno]

IMO, I think this'll become a minimal hurricane in the Bahamas. Perhaps something similar to Erin in 1995. I think the global models are struggling to consolidate this one correctly, given its broad and generally speaking disorganized state.

Erin 1995 could be an analog but does anyone remember how they were forecasting Erika in 2015 to strike the East Coast of Florida as a minimal hurricane and it failed to do so? Similar location, track, and speed.

https://i.ibb.co/QMdhgsH/D0-FFBF8-F-7-B42-4182-9790-73-DFF22-ED413.jpg

I really do miss the old map and color scheme.