ATL: JOSEPHINE - Remnants - Discussion

[CyclonicFury]

SCAT SAT ( which the NHC used recently) is showing a bunch of 35kt winds and a few 40 kt winds..

may end up being Josephine at 11pm .. right on the NHC schedule.


https://i.ibb.co/sR8dNJy/Capture.png

So far I haven't really seen NHC use SCATSAT for wind estimates. They seem to primarily use ASCAT.

[cycloneye]

TXNT21 KNES 122358
TCSNTL

A. 11L (NONAME)

B. 12/2330Z

C. 12.0N

D. 46.0W

E. FIVE/GOES-E

F. T1.5/2.5

G. IR/EIR/SWIR

H. REMARKS...A LLCC CHARACTERIZED BY CIRCULARLY DEFINED CLOUD LINES
THAT IS GREATER THAN 1.25 DEGREES REMOVED FROM A LARGE AREA OF ACTIVE
CONVECTION RESULTS IN A DT OF 1.5. THE MET IS 2.0 BASED ON A SIMILAR
APPARENT INTENSITY COMPARED TO 24 HOURS AGO AND THE PT IS 1.5. THE FT
IS BASED ON THE DT.

I. ADDL POSITIONS

NIL

...HOSLEY

Interestingly SAB fixed the center much farther south than the NHC position, resulting in only a T1.5.

Best Track has it more north.

11L ELEVEN 200813 0000 12.7N 46.3W ATL 30 1007

[ozonepete]

Just a couple of things that I see.

It does look like a wave in wxman's annotated satellite image, but it's not.

There may be deathly shear ahead of it, but I have seen 40 knot shear drop to 0 knots in 12 hours and I've seen 0 knots of shear increase to 40 knots in the same time. And 3 to 5 days out? Forget about it. Shear forecasts are still horribly inaccurate.

There is no way of knowing much at all tonight whether this will be a cat3 or a small cumulus deck 5 days from now. That's why I sit out most of these until we have a solid TS with the majority of models showing maintenance or increase going forward. Fun to speculate, but that's about it.

[MarioProtVI]

25 kt maximum on ASCAT - no upgrade tonight and based on the past trend I am beginning to question if it will even get close to 50 kt as predicted - much less get named if it continues to struggle.

[St0rmTh0r]

Just a couple of things that I see.

It does look like a wave in wxman's annotated satellite image, but it's not.

There may be deathly shear ahead of it, but I have seen 40 knot shear drop to 0 knots in 12 hours and I've seen 0 knots of shear increase to 40 knots in the same time. And 3 to 5 days out? Forget about it. Shear forecasts are still horribly inaccurate.

There is no way of knowing much at all tonight whether this will be a cat3 or a small cumulus deck 5 days from now. That's why I sit out most of these until we have a solid TS with the majority of models showing maintenance or increase going forward. Fun to speculate, but that's about it.

Now here's a thinker!

[NDG]

Easterly shear was not supposed to led up until at least late tonight but definitely by tomorrow and Friday as I mentioned yesterday, so I am not surprised that it is still a TD.

[Aric Dunn]

Center exposed again. can be seen here in this loop still heading off to the west.

https://rammb-slider.cira.colostate.edu ... 506&y=8109

[eastcoastFL]

Better hurry up if it wants to be Josephine. Shear is increasing ahead of it and convection is unimpressive at the moment

[eastcoastFL]

Center exposed again. can be seen here in this loop still heading off to the west.

https://rammb-slider.cira.colostate.edu ... 506&y=8109


https://i.ibb.co/q9y2bh2/Capture.png

I’m feeling less confident about it becoming Josephine now. A few hours ago it was almost there but not anymore.

[eastcoastFL]

Easterly shear was not supposed to led up until at least late tonight but definitely by tomorrow and Friday as I mentioned yesterday, so I am not surprised that it is still a TD.

It’ll have another shot at it if it survives the next day or so

[StormTracker]

062
WTNT41 KNHC 130236
TCDAT1

Tropical Depression Eleven Discussion Number 6
NWS National Hurricane Center Miami FL AL112020
1100 PM AST Wed Aug 12 2020

Conventional satellite imagery and a fortuitous ASCAT-B
scatterometer overpass indicate that the center of circulation
is a little farther south than previously estimated and remains
well to the southeast of the deep convective canopy. The latest
UW-CIMSS shear analysis confirms modest east-southeasterly shear
impinging on the cloud pattern. A compromise of the satellite
intensity estimates from TAFB and SAB, and the aforementioned
scatterometer pass retains the initial intensity at 30 kt.

Large-scale models and the statistical-dynamical intensity guidance
still show the shear abating soon which should result in gradual
strengthening with a peak intensity of 50 kt in 2 days. After that
time, the cyclone is forecast to encounter moderate to strong
southwesterly shear associated with a deep-layer trough stretching
over the southwestern Atlantic. This change in the upper wind
pattern should induce steady weakening. A number of the global
models indicate that the cyclone will become a remnant low by day 4
and open up into a trough by day 5 which is certainly possible.
The NHC forecast is similar to the previous advisory but indicates
a more expeditious weakening trend beyond the 48 hour period in
deference to the global model solution.

The initial motion is estimated to be westward, or 275/13 kt, within
the low to mid-tropospheric easterly flow produced by a subtropical
ridge anchored to the north of the depression. The song remains
the same...there is virtually no change to the forecast philosophy
and only a slight shift to the left of the previous track forecast
was made in response to the southward initial position adjustment.


FORECAST POSITIONS AND MAX WINDS

INIT 13/0300Z 12.5N 47.1W 30 KT 35 MPH
12H 13/1200Z 13.0N 48.4W 35 KT 40 MPH
24H 14/0000Z 14.2N 51.0W 40 KT 45 MPH
36H 14/1200Z 15.7N 53.7W 45 KT 50 MPH
48H 15/0000Z 17.0N 56.4W 50 KT 60 MPH
60H 15/1200Z 18.3N 58.9W 45 KT 50 MPH
72H 16/0000Z 19.7N 61.4W 40 KT 45 MPH
96H 17/0000Z 22.5N 65.6W 35 KT 40 MPH
120H 18/0000Z 25.6N 67.5W 30 KT 35 MPH

$$
Forecaster Roberts

[TheStormExpert]

Poor guy!

...STRUGGLING DEPRESSION HEADING WESTWARD... ...STILL EXPECTED TO STRENGTHEN INTO A TROPICAL STORM SOON...

[eastcoastFL]

Poor guy!

...STRUGGLING DEPRESSION HEADING WESTWARD... ...STILL EXPECTED TO STRENGTHEN INTO A TROPICAL STORM SOON...

Whatever the long trail of convection is to its east going towards Africa is more impressive than 11 right now.

[abajan]

Wow. All that convection it had just a few hours ago really dried up quickly! Currently, it more resembles a large, well defined tropical wave than a TD. Dry air seems to be taking its toll.

[TheStormExpert]

Poor guy!

...STRUGGLING DEPRESSION HEADING WESTWARD... ...STILL EXPECTED TO STRENGTHEN INTO A TROPICAL STORM SOON...

Whatever the long trail of convection is to its east going towards Africa is more impressive than 11 right now.

At this point it probably won’t even get a name. Definitely underperforming!

[Hammy]

Poor guy!

...STRUGGLING DEPRESSION HEADING WESTWARD... ...STILL EXPECTED TO STRENGTHEN INTO A TROPICAL STORM SOON...

Whatever the long trail of convection is to its east going towards Africa is more impressive than 11 right now.

At this point it probably won’t even get a name. Definitely underperforming!

The MDR seems like it's cursed (or blessed, depending on how you look at it )

Kind of strange that we've had so much dry air and MDR struggles for so many back to back seasons, especially since nothing's really struggled elsewhere.

[CyclonicFury]

Whatever the long trail of convection is to its east going towards Africa is more impressive than 11 right now.

At this point it probably won’t even get a name. Definitely underperforming!

The MDR seems like it's cursed (or blessed, depending on how you look at it )

Kind of strange that we've had so much dry air and MDR struggles for so many back to back seasons, especially since nothing's really struggled elsewhere.

Not sure I agree on that one. 2017 had two Category 5s and a near-Category 5 in the MDR - all after August 30. 2018 had four hurricanes in the MDR despite a much cooler than normal MDR, three of which were in September. 2019 had no hurricanes in the MDR prior to September 18, then it had Jerry (a Category 2) and Lorenzo (a high end Category 4 in the MDR). If anything, the Caribbean has been the part of the basin that has been struggling lately (unless you are referring to the Caribbean as part of the MDR in this case).

I think it's more that the MDR isn't ready yet than a sign of the MDR being unfavorable all season. All 2010 had in the MDR prior to August 20 was a minimal tropical storm. 1998 and 1999, also big MDR years, didn't have much in the MDR yet at this point. 2003 had a weak depression and that's it. 2020 has already had 3 TCs form in the MDR so far.

[Visioen]

Lol just because it looks bad now doesn't mean it will look bad in a few hours. Things change on a whim, especially when shear is forecasted to abate in the short term.

[Hammy]

At this point it probably won’t even get a name. Definitely underperforming!

The MDR seems like it's cursed (or blessed, depending on how you look at it )

Kind of strange that we've had so much dry air and MDR struggles for so many back to back seasons, especially since nothing's really struggled elsewhere.

Not sure I agree on that one. 2017 had two Category 5s and a near-Category 5 in the MDR - all after August 30. 2018 had four hurricanes in the MDR despite a much cooler than normal MDR, three of which were in September. 2019 had no hurricanes in the MDR prior to September 18, then it had Jerry (a Category 2) and Lorenzo (a high end Category 4 in the MDR). If anything, the Caribbean has been the part of the basin that has been struggling lately (unless you are referring to the Caribbean as part of the MDR in this case).

I think it's more that the MDR isn't ready yet than a sign of the MDR being unfavorable all season. All 2010 had in the MDR prior to August 20 was a minimal tropical storm. 1998 and 1999, also big MDR years, didn't have much in the MDR yet at this point. 2003 had a weak depression and that's it. 2020 has already had 3 TCs form in the MDR so far.

The thing is the MDR has been less than ideal pretty much every year as a whole after 2010 with the exception of 2017, seemingly regardless of how active the season as a whole is. It's enough to be noticeable when everything has done a lot better outside of it than the storms that exist there--even this year, literally nothing outside of the MDR has really struggled, and the three storms that we've had there have all faltered and generally under-performed the forecasts. Even Isaias didn't really take off until it reached the Caribbean.

Not at all saying storms won't form there but it's certainly a visible oddity over that particular region of the Atlantic and even the longer range modeling shows the bulk of the stronger activity either over the subtropical Atlantic, or western Atlantic/GoM.

[Chemmers]

Lots off over shooting cloud top near the centre