ATL: ELEVEN - Post-Tropical - Discussion

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Re: ATL: INVEST 97L - Discussion

#61 Postby Hammy » Fri Sep 21, 2018 9:19 pm

:uarrow: TS intensity, why only a depression on upgrade?
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Re: ATL: INVEST 97L - Discussion

#62 Postby CyclonicFury » Fri Sep 21, 2018 9:22 pm

Hammy wrote::uarrow: TS intensity, why only a depression on upgrade?

SCATSAT is often unreliable from what I have seen. It seems to show a closed circulation in every disturbance and its wind estimates are often high. ASCAT is much better.
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Re: ATL: ELEVEN - Tropical Depression - Discussion

#63 Postby Hugo1989 » Fri Sep 21, 2018 9:32 pm

TD for how long? The Shear is just killing it right now.
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Re: ATL: ELEVEN - Tropical Depression - Discussion

#64 Postby Sciencerocks » Fri Sep 21, 2018 9:39 pm

Hugo1989 wrote:TD for how long? The Shear is just killing it right now.


I fully expect post season that this will be extended back 24 hours.
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Re: ATL: ELEVEN - Tropical Depression - Discussion

#65 Postby Ptarmigan » Fri Sep 21, 2018 9:48 pm

Kirk?
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ATL: ELEVEN - Advisories

#66 Postby cycloneye » Fri Sep 21, 2018 9:49 pm

BULLETIN
Tropical Depression Eleven Advisory Number 1
NWS National Hurricane Center Miami FL AL112018
1100 PM AST Fri Sep 21 2018

...TROPICAL DEPRESSION FORMS EAST OF THE WINDWARD ISLANDS...
...FORECAST TO DISSIPATE WITHIN A FEW DAYS...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...13.1N 53.4W
ABOUT 510 MI...825 KM E OF THE WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...WNW OR 290 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...1007 MB...29.74 INCHES


WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.


DISCUSSION AND OUTLOOK
----------------------
At 1100 PM AST (0300 UTC), the center of Tropical Depression Eleven
was located near latitude 13.1 North, longitude 53.4 West. The
depression is moving toward the west-northwest near 6 mph (9 km/h),
and this general motion will likely continue for the next couple
of days.

Maximum sustained winds are near 35 mph (55 km/h) with higher gusts.
Little change in strength is expected for the next day or two. The
depression is forecast to dissipate late this weekend or early next
week before it reaches the Lesser Antilles.

The estimated minimum central pressure is 1007 mb (29.74 inches).


HAZARDS AFFECTING LAND
----------------------
None


NEXT ADVISORY
-------------
Next complete advisory at 500 AM AST.

$$
Forecaster Zelinsky




Tropical Depression Eleven Discussion Number 1
NWS National Hurricane Center Miami FL AL112018
1100 PM AST Fri Sep 21 2018

The small, but well-defined, low pressure system located about 500
miles east of the Lesser Antilles has been producing steady
convection for the past several hours. Although this convection is
displaced to the south and east of the exposed low-level center due
to strong westerly wind shear, it has persisted long enough to meet
the NHC definition of a tropical cyclone. On this basis, advisories
are being initiated on Tropical Depression Eleven.

The initial intensity is set at 30 kt based on ASCAT data from
earlier today which showed a couple of 25-30 kt wind vectors in the
northeast quadrant of the circulation. The intensity guidance is in
extremely good agreement that the depression is unlikely to
strengthen. All of the global models forecast an increase in
upper-level winds over the small cyclone during the next 24 h. In
fact, SHIPS diagnostics indicate that the 850-200 mb shear could
exceed 30 kt by tomorrow morning, and will be near 40 kt within 48
h. As a result of this shear and some dry air also in the vicinity,
the dynamical models unanimously forecast dissipation within 72 h,
and most show that the depression will open into a trough of low
pressure sooner than that. The NHC forecast conservatively maintains
the tropical cyclone for 48 h, but it could weaken and dissipate
sooner than currently indicated.

The depression has recently been moving almost due west, but a
longer-term motion yields an initial motion of 290/5 kt. A break in
the subtropical ridge to the north of the depression should result
in fairly weak steering flow for the next day or two, and only a
slow west-northwestward to westward motion is anticipated. All of
the typically-reliable track models are in fairly good agreement on
this scenario. The NHC forecast is very close to HCCA at all
forecast hours, and lies near the south edge of the tight guidance
envelope.


FORECAST POSITIONS AND MAX WINDS

INIT 22/0300Z 13.1N 53.4W 30 KT 35 MPH
12H 22/1200Z 13.5N 54.2W 30 KT 35 MPH
24H 23/0000Z 13.8N 55.0W 30 KT 35 MPH
36H 23/1200Z 14.2N 56.3W 30 KT 35 MPH
48H 24/0000Z 14.5N 58.0W 25 KT 30 MPH
72H 25/0000Z...DISSIPATED

$$
Forecaster Zelinsky
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Re: ATL: ELEVEN - Tropical Depression - Discussion

#67 Postby cycloneye » Fri Sep 21, 2018 9:52 pm

Ptarmigan wrote:Kirk?


Not forecast to be Kirk.

INIT 22/0300Z 13.1N 53.4W 30 KT 35 MPH
12H 22/1200Z 13.5N 54.2W 30 KT 35 MPH
24H 23/0000Z 13.8N 55.0W 30 KT 35 MPH
36H 23/1200Z 14.2N 56.3W 30 KT 35 MPH
48H 24/0000Z 14.5N 58.0W 25 KT 30 MPH
72H 25/0000Z...DISSIPATED
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Re: ATL: ELEVEN - Tropical Depression - Discussion

#68 Postby AnnularCane » Fri Sep 21, 2018 9:56 pm

cycloneye wrote:
Ptarmigan wrote:Kirk?


Not forecast to be Kirk.

INIT 22/0300Z 13.1N 53.4W 30 KT 35 MPH
12H 22/1200Z 13.5N 54.2W 30 KT 35 MPH
24H 23/0000Z 13.8N 55.0W 30 KT 35 MPH
36H 23/1200Z 14.2N 56.3W 30 KT 35 MPH
48H 24/0000Z 14.5N 58.0W 25 KT 30 MPH
72H 25/0000Z...DISSIPATED



Probably wasn't forecast to be a TD either, though, so you never know.
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Re: ATL: ELEVEN - Tropical Depression - Discussion

#69 Postby floridasun78 » Fri Sep 21, 2018 9:59 pm

could be tropical wave by 6am
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Re: ATL: ELEVEN - Tropical Depression - Discussion

#70 Postby Fego » Fri Sep 21, 2018 10:13 pm

Anyone has the link for the SHIPS data? Thanks in advance.
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Re: ATL: ELEVEN - Tropical Depression - Discussion

#71 Postby bob rulz » Sat Sep 22, 2018 4:40 am

What is the shortest-lived system ever in the Atlantic?
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Re: ATL: ELEVEN - Tropical Depression - Discussion

#72 Postby TheStormExpert » Sat Sep 22, 2018 4:53 am

bob rulz wrote:What is the shortest-lived system ever in the Atlantic?

My guess is TS Philippe from last year.
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Re: ATL: ELEVEN - Advisories

#73 Postby cycloneye » Sat Sep 22, 2018 6:32 am

BULLETIN
Tropical Depression Eleven Advisory Number 2
NWS National Hurricane Center Miami FL AL112018
500 AM AST Sat Sep 22 2018

...TROPICAL DEPRESSION NOT MOVING VERY MUCH...
...EXPECTED TO DISSIPATE IN A DAY OR TWO...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...13.0N 53.5W
ABOUT 505 MI...810 KM E OF THE WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 5 MPH...7 KM/H
MINIMUM CENTRAL PRESSURE...1007 MB...29.74 INCHES


Tropical Depression Eleven Discussion Number 2
NWS National Hurricane Center Miami FL AL112018
500 AM AST Sat Sep 22 2018

Deep convection remains displaced to the east of the depression's
center due to 30-40 kt of westerly shear. Although Dvorak final-T
numbers from TAFB and SAB have decreased since yesterday--now a
consensus T1.0--the initial intensity is held, perhaps generously,
at 30 kt. Strong westerly shear is expected to persist for several
days, which at the very least will prevent the depression from
getting any better organized. Since the global models show the
depression opening up into a trough in about 24 hours, the new NHC
intensity forecast brings down the winds a little faster, shows the
system becoming a remnant low by 36 hours, and dissipates the low
entirely by 48 hours well east of the Windward Islands. This
evolution could certainly occur more quickly than indicated by the
official forecast.

The center of the depression has not been moving much, and it's
possible the sheared convection is trying to pull it back toward
the east. However, the average motion over the past 12 hours is
westward, or 270/4 kt. The track guidance insists that the
depression should move slowly west-northwestward over the next
couple of days, but given that the system has not made any
northward progress, I elected to skirt the southern edge of the
guidance envelope. This new forecast is a little south of the
previous NHC track prediction.


FORECAST POSITIONS AND MAX WINDS

INIT 22/0900Z 13.0N 53.5W 30 KT 35 MPH
12H 22/1800Z 13.3N 54.3W 30 KT 35 MPH
24H 23/0600Z 13.6N 55.4W 25 KT 30 MPH
36H 23/1800Z 13.8N 56.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 24/0600Z...DISSIPATED

$$
Forecaster Berg
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Re: ATL: ELEVEN - Tropical Depression - Discussion

#74 Postby wxman57 » Sat Sep 22, 2018 7:53 am

Looking at visible satellite, it's already dissipated. Could well have been a TS 2-3 days ago, but it's no TD now.
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Re: ATL: ELEVEN - Tropical Depression - Discussion

#75 Postby EquusStorm » Sat Sep 22, 2018 8:12 am

I understand that persistence is a key factor in deciding to upgrade to a TC, but, they waited too long to upgrade the one.
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Re: ATL: ELEVEN - Advisories

#76 Postby cycloneye » Sat Sep 22, 2018 9:48 am

BULLETIN
Tropical Depression Eleven Advisory Number 3
NWS National Hurricane Center Miami FL AL112018
1100 AM AST Sat Sep 22 2018

...TROPICAL DEPRESSION EXPECTED TO DISSIPATE IN A DAY OR TWO...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...13.2N 53.8W
ABOUT 485 MI...780 KM E OF THE WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS...30 MPH...45 KM/H
PRESENT MOVEMENT...W OR 280 DEGREES AT 3 MPH...6 KM/H
MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES




Tropical Depression Eleven Discussion Number 3
NWS National Hurricane Center Miami FL AL112018
1100 AM AST Sat Sep 22 2018

It appears that the depression's best day is behind it, as the
cloud pattern has become less organized this morning. The low-level
center is becoming increasingly separated from the warming cloud
tops in what remains of the deep convection, which is displaced to
the east by nearly 40 kt of west-southwesterly shear as analyzed by
UW-CIMSS. The initial intensity has been lowered to 25 kt,
consistent with a T1.0 classification from TAFB. Given that the
strong shear is expected to continue and the depression will be
moving through a relatively dry environment, the cyclone should
gradually spin down and become a remnant low by 24 hours and
dissipate by 48 hours. However, I would not be surprised if either
or both of these occurred sooner.

The center of the depression hasn't moved much during the past few
hours, but a long-term initial motion estimate is 280/03. The
weakening cyclone should be steered westward to west-northwestward
by a low-level ridge. The new NHC track forecast is north of the
previous one but remains along the southern edge of the guidance
envelope given doubts about how much latitude such a shallow system
will gain prior to dissipation.

FORECAST POSITIONS AND MAX WINDS

INIT 22/1500Z 13.2N 53.8W 25 KT 30 MPH
12H 23/0000Z 13.6N 54.5W 25 KT 30 MPH
24H 23/1200Z 14.0N 55.7W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 24/0000Z 14.4N 56.8W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 24/1200Z...DISSIPATED

$$
Forecaster Brennan
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Re: ATL: ELEVEN - Tropical Depression - Discussion

#77 Postby wxman57 » Sat Sep 22, 2018 1:45 pm

Bones has three words for Isaac:

Image

Image
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Re: ATL: ELEVEN - Advisories

#78 Postby cycloneye » Sat Sep 22, 2018 3:38 pm

BULLETIN
Tropical Depression Eleven Advisory Number 4
NWS National Hurricane Center Miami FL AL112018
500 PM AST Sat Sep 22 2018

...TROPICAL DEPRESSION EXPECTED TO BECOME A REMNANT LOW TONIGHT OR
SUNDAY...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...13.6N 53.9W
ABOUT 480 MI...770 KM E OF THE WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS...30 MPH...45 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 3 MPH...6 KM/H
MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES



Tropical Depression Eleven Discussion Number 4
NWS National Hurricane Center Miami FL AL112018
500 PM AST Sat Sep 22 2018

Since the last advisory was issued, deep convection decreased in
association with the depression to the point that it was not
classifiable with the Dvorak technique at 18Z. However, there are a
couple of patches of thunderstorms that have developed recently,
and if they persist they could help the system hold on to tropical
cyclone status a bit longer. The low-level center remains exposed
with UW-CIMSS now analyzing nearly 45 kt of westerly shear over the
cyclone. Gradual spin down is expected during the next 12 to 24
hours, and the cyclone should become a remnant low by Sunday. Global
model fields show the surface circulation dissipating by 36 hours
and that is indicated in the official forecast.

The low-level center has been moving erratically today, with a
recent northward jog seen, but the long-term initial motion estimate
is 305/03. The weakening cyclone should be steered west-
northwestward by a weak low-level ridge through dissipation, and
the NHC track forecast has been nudged northward toward the latest
multi-model consensus.


FORECAST POSITIONS AND MAX WINDS

INIT 22/2100Z 13.6N 53.9W 25 KT 30 MPH
12H 23/0600Z 13.9N 54.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
24H 23/1800Z 14.4N 56.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
36H 24/0600Z...DISSIPATED

$$
Forecaster Brennan
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Re: ATL: ELEVEN - Advisories

#79 Postby cycloneye » Sat Sep 22, 2018 9:37 pm

BULLETIN
Tropical Depression Eleven Advisory Number 5
NWS National Hurricane Center Miami FL AL112018
1100 PM AST Sat Sep 22 2018

...POORLY ORGANIZED TROPICAL DEPRESSION CREEPING NORTHWESTWARD...
...COULD DISSIPATE AS SOON AS SUNDAY...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...13.8N 54.5W
ABOUT 440 MI...710 KM E OF THE WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS...30 MPH...45 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 3 MPH...6 KM/H
MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES


Tropical Depression Eleven Discussion Number 5
NWS National Hurricane Center Miami FL AL112018
1100 PM AST Sat Sep 22 2018

Although deep convection has increased since earlier today, it has
become increasingly difficult to identify a well-defined center
associated with the depression. After moving erratically during the
afternoon, the center of the depression appears to have become
disrupted by convection to its east, and it is unclear at this point
if a closed surface circulation still exists. Since visible imagery
is not currently available and recent ASCAT data from around 0000Z
was inconclusive, at least one more advisory will be issued under
the assumption that the depression has not quite yet dissipated.

The initial motion is highly uncertain, but it is assumed that the
system is still moving generally northwestward, or 310/3 kt. No
substantial changes were made to the NHC intensity or track
forecasts. All available guidance indicates that the depression will
continue to move slowly west-northwestward or northwestward for the
next day or two while it gradually weakens due to continued strong
wind shear. Given the recent increase in convection, it no longer
seems likely that the system will become a remnant low prior to
dissipating. Therefore, the NHC forecast now keeps the system as a
tropical depression until dissipation occurs in 36 h, if not sooner.

FORECAST POSITIONS AND MAX WINDS

INIT 23/0300Z 13.8N 54.5W 25 KT 30 MPH
12H 23/1200Z 14.2N 55.3W 25 KT 30 MPH
24H 24/0000Z 14.5N 56.6W 20 KT 25 MPH
36H 24/1200Z...DISSIPATED

$$
Forecaster Zelinsky
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Re: ATL: ELEVEN - Advisories

#80 Postby cycloneye » Sun Sep 23, 2018 5:10 am

Tropical Depression Eleven Discussion Number 6
NWS National Hurricane Center Miami FL AL112018
500 AM AST Sun Sep 23 2018

Satellite images indicate that the depression is poorly organized.
The circulation is becoming increasingly elongated, and it seems
likely that a closed circulation may no longer exist. However, we
are maintaining advisories for now to wait for visible imagery to
better assess the low-level circulation. The depression continues
to produce a few patches of deep convection, but these are confined
to the east and northeast portions of the circulation due to about
35 kt of westerly shear. The initial intensity remains 25 kt based
on the earlier ASCAT data.

The system is moving into an environment of even stronger westerly
wind shear. These hostile winds and dry air should cause the
depression to dissipate, if it has not already, later today or
tonight. The depression, or its remnants, are expected to move
slowly west-northwestward for another day or so.

FORECAST POSITIONS AND MAX WINDS

INIT 23/0900Z 14.5N 55.0W 25 KT 30 MPH
12H 23/1800Z 15.0N 56.0W 25 KT 30 MPH
24H 24/0600Z...DISSIPATED

$$
Forecaster Cangialosi
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