ATL: GABRIELLE - Post-Tropical - Discussion

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Re: ATL: GABRIELLE - Tropical Storm - Discussion

#81 Postby Hammy » Fri Sep 06, 2019 11:43 am

Hurricane Jed wrote:Okayyyyy then. Still looks like a naked swirl to me.


There's associated convection which was lacking overnight (although it was ironically already starting to redevelop at the time it was written off this morning)
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Re: ATL: GABRIELLE - Tropical Storm - Discussion

#82 Postby Hurricane Jed » Fri Sep 06, 2019 1:07 pm

Then they should have A. Not killed it or B. Left it dead.
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Re: ATL: GABRIELLE - Tropical Storm - Discussion

#83 Postby Monsoonjr99 » Fri Sep 06, 2019 3:16 pm

Gabrielle's quick degeneration and regeneration reminds me of Nadine 2012. Like Nadine, Gabrielle is also out in the eastern subtropical Atlantic. Funnily enough, yesterday looking at IR, I was thinking that perhaps Gabrielle was becoming subtropical with the convection far removed from the center, though really it was likely just dry air killing the central convection. The NHC also operationally considered Nadine to briefly be subtropical before degeneration, but in TCR made those points post-tropical. :lol:
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Re: ATL: GABRIELLE - Tropical Storm - Discussion

#84 Postby cycloneye » Fri Sep 06, 2019 3:42 pm

Forecast to become a Hurricane.

Tropical Storm Gabrielle Discussion Number 13
NWS National Hurricane Center Miami FL AL082019
500 PM AST Fri Sep 06 2019

Gabrielle has become somewhat better organized during the past few
hours, with a better-defined surface circulation moving closer to a
large burst of convection in the northern semicircle. There has
been little change in the intensity estimates, so the initial wind
speed will stay 40 kt on this advisory.

The storm continues to move to the northwest at about 15 kt. A
large subtropical ridge to the northeast of Gabrielle is forecast to
build westward, forcing the tropical cyclone to turn west-
northwestward on Saturday. After that time, southwesterly flow
ahead of Hurricane Dorian should turn Gabrielle quickly northward
and northeastward by early next week. Other than some minor speed
differences, the models continue to be tightly packed. The new
NHC track forecast is basically an update of the previous one, and
it lies near the NOAA corrected-consensus model.

Southerly shear currently near Gabrielle is forecast to relax by
late tomorrow, at about the same time that it moves over very warm
waters near 29C. This should promote strengthening, and it is
possible that Gabrielle could intensify quickly near recurvature.
By 96 h, the cyclone should move north of the Gulf Stream, with
increasing shear. These conditions should cause a fast extratropical
transition between 96-120 h. The new NHC prediction is raised at 48
and 72 hours, and it should be noted that quite a few models show
Gabrielle becoming a category 2 hurricane at some point during that
time.


FORECAST POSITIONS AND MAX WINDS

INIT 06/2100Z 27.9N 39.6W 40 KT 45 MPH
12H 07/0600Z 29.3N 41.7W 45 KT 50 MPH
24H 07/1800Z 30.8N 44.5W 50 KT 60 MPH
36H 08/0600Z 32.2N 47.0W 55 KT 65 MPH
48H 08/1800Z 33.9N 48.4W 65 KT 75 MPH
72H 09/1800Z 38.5N 46.0W 80 KT 90 MPH
96H 10/1800Z 44.0N 38.5W 70 KT 80 MPH
120H 11/1800Z 53.0N 23.0W 60 KT 70 MPH...POST-TROP/EXTRATROP

$$
Forecaster Blake
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Re: ATL: GABRIELLE - Tropical Storm - Discussion

#85 Postby EquusStorm » Fri Sep 06, 2019 4:07 pm

It was a hard call, they couldn't declare post-tropical until it was devoid for a long time and by then it was on the verge of re-firing. Surprised they reclassified it so fast in one advisory cycle though, even if it was deserving of it. Note the massive increase in forecast intensity; THAT is a little surprising. Wouldn't be shocked to see that come to pass, but didn't expect such an increase so fast.
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...but still, though, a lot more interesting than the 2013 season.

Not a meteorologist, in fact more of an idiot than anything. You should probably check with the NHC or a local NWS office for official information.

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Re: ATL: GABRIELLE - Tropical Storm - Discussion

#86 Postby Hammy » Fri Sep 06, 2019 4:10 pm

Hurricane Jed wrote:Then they should have A. Not killed it or B. Left it dead.


I'd go with A. Given they were forecasting regeneration, it made little sense to issue post-tropical advisory as convection was already starting to redevelop.
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Re: ATL: GABRIELLE - Tropical Storm - Discussion

#87 Postby CyclonicFury » Fri Sep 06, 2019 8:23 pm

00z best track up to 50 kts
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Re: ATL: GABRIELLE - Tropical Storm - Discussion

#88 Postby Abdullah » Fri Sep 06, 2019 8:55 pm

CyclonicFury wrote:00z best track up to 50 kts


That's a large jump if I say so myself. What do you storm experts think this means for the future of the cyclone?
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Re: ATL: GABRIELLE - Tropical Storm - Discussion

#89 Postby CyclonicFury » Fri Sep 06, 2019 8:57 pm

Abdullah wrote:
CyclonicFury wrote:00z best track up to 50 kts


That's a large jump if I say so myself. What do you storm experts think this means for the future of the cyclone?

It's still not well organized yet, I'm guessing NHC will upgrade to 50 kt based on ASCAT. I'm not expecting Gabrielle to intensify significantly until tomorrow night or Sunday when shear relaxes significantly. I honestly wouldn't rule out Gabrielle reaching Category 2 strength.
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Re: ATL: GABRIELLE - Tropical Storm - Discussion

#90 Postby cycloneye » Fri Sep 06, 2019 9:41 pm

Tropical Storm Gabrielle Discussion Number 14
NWS National Hurricane Center Miami FL AL082019
1100 PM AST Fri Sep 06 2019

Deep convection has persisted mainly over the northern semicircle of
Gabrielle since this afternoon, but has been trying to move a little
closer to the low-level center. The subjective intensity estimate
from TAFB suggests slight strengthening has occurred since the
previous advisory, and a recent scatterometer pass measured a
cluster of 45-kt winds. Assuming some slight undersampling in that
area by the scatterometer, the initial advisory intensity has been
increased to 50 kt.

The shear that continues to impact Gabrielle is forecast to decrease
through Saturday morning. Meanwhile, the cyclone will me moving over
waters near 29 C. And, although some dry air will continue to
surround the circulation, the cyclone should be able to gradually
strengthen over the next few days due to the other favorable
environmental conditions. After 72 hours, increasing southwesterly
shear and cooler SSTs will cause the cyclone to weaken. An
approaching mid-latitude trough, courtesy of Dorian, will help
transition Gabrielle to an extratropical cyclone by the end of the
forecast period. The only notable change to the intensity forecast
from the previous advisory was to make Gabrielle a hurricane a
little earlier, and the official advisory is very near the corrected
consensus HCCA.

Gabrielle has been moving to the northwest, or 320/16 kt. A turn to
the west-northwest is expected to occur on Saturday as the
subtropical ridge to the northeast of Gabrielle builds westward. The
aforementioned mid-latitude trough will begin to turn Gabrielle to
the north on Sunday night, then accelerate the cyclone to the
northeast from Monday through the end of the forecast period. The
official forecast is very similar to the previous one, and near the
tightly clustered consensus guidance.


FORECAST POSITIONS AND MAX WINDS

INIT 07/0300Z 29.3N 40.9W 50 KT 60 MPH
12H 07/1200Z 30.9N 42.9W 55 KT 65 MPH
24H 08/0000Z 32.1N 45.6W 60 KT 70 MPH
36H 08/1200Z 33.7N 47.5W 70 KT 80 MPH
48H 09/0000Z 35.7N 48.0W 75 KT 85 MPH
72H 10/0000Z 40.5N 44.0W 80 KT 90 MPH
96H 11/0000Z 47.0N 34.0W 70 KT 80 MPH
120H 12/0000Z 56.1N 16.5W 55 KT 65 MPH...POST-TROP/EXTRATROP

$$
Forecaster Latto
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Re: ATL: GABRIELLE - Tropical Storm - Discussion

#91 Postby cycloneye » Sat Sep 07, 2019 9:54 am

Tropical Storm Gabrielle Discussion Number 16
NWS National Hurricane Center Miami FL AL082019
1100 AM AST Sat Sep 07 2019

Gabrielle's structure does not look healthy this morning. The
low-level circulation appears elongated, and it's difficult from
visible satellite imagery alone to identify a well-defined center.
The initial intensity is held at 45 kt, mainly based on continuity
and satellite estimates from TAFB and the UW-CIMSS SATCON.
We will analyze just-received ASCAT data and make modifications in
the afternoon advisory if necessary.

Gabrielle is swinging around the northeastern side of a mid- to
upper-level low, which has imparted a rather fast northwestward
motion of 310/15 kt. A generally northwestward trajectory should
continue for the next 24 hours while Gabrielle remains positioned
between the deep-layer low and high pressure to its northeast.
After that time, Gabrielle should recurve around the high and then
become embedded in the mid-latitude westerlies beginning in 48
hours. That steering regime should induce a northeastward
acceleration over the north Atlantic. Despite the cyclone's
uncertain initial position, the track models are tightly clustered,
and the NHC track forecast was placed close to a consensus of the
GFS and ECMWF models. This new forecast largely lies right on top
of the previous one.

Gabrielle's environment never really becomes ideal for
strengthening. For the next 24 hours, upper-level divergence and
moderate easterly shear should continue over the system. By
48 hours, vertical shear is expected to increase further, and
Gabrielle will be moving over sub-26C waters as it heads toward the
north Atlantic. Based on these conditions, some strengthening is
still shown in the official forecast, but it has been lowered from
the previous advisory to match the latest intensity guidance.
Based on the global model fields and phase-space diagrams,
Gabrielle is forecast to be fully extratropical by day 4, if not
sooner, and the system is likely to dissipate in the westerlies as
it heads toward the British Isles.


FORECAST POSITIONS AND MAX WINDS

INIT 07/1500Z 31.4N 43.7W 45 KT 50 MPH
12H 08/0000Z 32.4N 45.7W 45 KT 50 MPH
24H 08/1200Z 34.1N 47.6W 50 KT 60 MPH
36H 09/0000Z 36.5N 47.9W 55 KT 65 MPH
48H 09/1200Z 39.4N 46.3W 60 KT 70 MPH
72H 10/1200Z 45.0N 37.0W 65 KT 75 MPH
96H 11/1200Z 51.5N 22.5W 55 KT 65 MPH...POST-TROP/EXTRATROP
120H 12/1200Z...DISSIPATED

$$
Forecaster Berg
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Re: ATL: GABRIELLE - Tropical Storm - Discussion

#92 Postby Buck » Sat Sep 07, 2019 10:42 am

This storm....

Image
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Re: ATL: GABRIELLE - Tropical Storm - Discussion

#93 Postby AnnularCane » Sat Sep 07, 2019 12:33 pm



She just relocated. Does that count? :lol:
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Re: ATL: GABRIELLE - Tropical Storm - Discussion

#94 Postby Buck » Sat Sep 07, 2019 1:16 pm

AnnularCane wrote:


She just relocated. Does that count? :lol:


We will see. :roll:
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Re: ATL: GABRIELLE - Tropical Storm - Discussion

#95 Postby galaxy401 » Sat Sep 07, 2019 1:29 pm

Well Dorian's reformation helped it, maybe the same will happen for Gabby.
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I don't get hurricanes here but I do get their remnants.

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Re: ATL: GABRIELLE - Tropical Storm - Discussion

#96 Postby cycloneye » Sat Sep 07, 2019 9:46 pm

Tropical Storm Gabrielle Discussion Number 19
NWS National Hurricane Center Miami FL AL082019
1100 PM AST Sat Sep 07 2019

Microwave data indicate that Gabrielle has a well-organized central
core. However, the convection isn't very deep, perhaps because of
dry air entrainment, with most of the convection in a band southeast
of the center. The initial intensity is kept at 45 kt, which
agrees well with an ASCAT-B pass of 40-45 kt and the latest TAFB
fix.

The storm is moving steadily west-northwestward around the
southwestern side of a mid-level high over the eastern Atlantic.
This high is forecast to slide eastward as the westerlies intensify
due to flow around Gabrielle's southern flank in the far north
Atlantic. Models are in very good agreement overall, but there
continues to be some speed differences. The NHC forecast is on the
faster side of the guidance, near the NOAA corrected-consensus
guidance and the previous forecast, since the typical error in the
higher latitudes is to be too slow.

The low-shear area that was supposed to materialize in the
subtropical Atlantic near Gabrielle this weekend did not occur, and
as a result there is very little guidance suggesting that the
cyclone will become a hurricane. The storm still has a day or two
to strengthen over relatively warm waters before shear increases
markedly, and water temperatures plummet north of the Gulf Stream.
The intensity forecast is reduced about 5 kt from the previous one
at 36-48 h, although still above the model consensus, and is similar
thereafter. All models still show extratropical transition by 72 h
and dissipation by day 5.


FORECAST POSITIONS AND MAX WINDS

INIT 08/0300Z 32.0N 48.0W 45 KT 50 MPH
12H 08/1200Z 33.4N 49.3W 50 KT 60 MPH
24H 09/0000Z 35.8N 49.4W 55 KT 65 MPH
36H 09/1200Z 38.8N 47.6W 55 KT 65 MPH
48H 10/0000Z 41.7N 43.6W 55 KT 65 MPH
72H 11/0000Z 47.0N 31.0W 50 KT 60 MPH...POST-TROP/EXTRATROP
96H 12/0000Z 54.5N 13.0W 40 KT 45 MPH...POST-TROP/EXTRATROP
120H 13/0000Z...DISSIPATED

$$
Forecaster Blake
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Re: ATL: GABRIELLE - Tropical Storm - Discussion

#97 Postby AnnularCane » Sat Sep 07, 2019 10:19 pm

cycloneye wrote:The low-shear area that was supposed to materialize in the
subtropical Atlantic near Gabrielle this weekend did not occur



Somehow I'm not surprised. :roll: Sometimes it seems like shear is harder to forecast than hurricanes.
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Re: ATL: GABRIELLE - Tropical Storm - Discussion

#98 Postby cycloneye » Sun Sep 08, 2019 6:52 am

Tropical Storm Gabrielle Discussion Number 20
NWS National Hurricane Center Miami FL AL082019
500 AM AST Sun Sep 08 2019

Gabrielle has become a little better organized overnight. The
storm now has well-defined curved bands, especially to the south
of the center, with some evidence of an inner core trying to form.
The initial intensity is nudged upward to 50 kt, which is between
the Dvorak classification from TAFB and the latest satellite
consensus estimate from the CIMSS at the University of Wisconsin.
Earlier ASCAT data revealed that Gabrielle is a compact storm with
its tropical-storm-force winds only extending out to about 60 n mi
from the center.

The tropical storm is gradually turning to the right, with the
initial motion estimated to be northwestward at 11 kt. The system
is located near the southwestern periphery of a mid-level ridge
centered near the Azores, and it should be moving around the
western side of that ridge later today and tonight. This should
cause Gabrielle to turn northward with some increase in forward
speed during that time. An even faster northeastward motion is
expected on Monday and Tuesday as Gabrielle, or its post-tropical
remnants, become embedded in the mid-latitude westerlies. The
track models are in fairly good agreement, and only minor
adjustments were made to the previous forecast.

Gabrielle could strengthen a little more today while it remains
over warm water and in generally favorable atmospheric conditions.
However, the combined influences of increasing southerly shear and
cooler waters should end the chances of intensification on Monday.
The global models are in agreement that Gabrielle should become
extratropical when it merges with a cold front that is associated
with Post-Tropical Cyclone Dorian in a little more than 2 days.
The extratropical low is expected to gradually weaken and
ultimately dissipate in 4 to 5 days. The NHC intensity forecast is
largely an update of the previous one and in line with the majority
of the intensity guidance.


FORECAST POSITIONS AND MAX WINDS

INIT 08/0900Z 32.7N 48.6W 50 KT 60 MPH
12H 08/1800Z 34.3N 49.2W 55 KT 65 MPH
24H 09/0600Z 37.1N 48.5W 55 KT 65 MPH
36H 09/1800Z 40.1N 45.7W 55 KT 65 MPH
48H 10/0600Z 42.7N 41.0W 55 KT 65 MPH
72H 11/0600Z 48.1N 28.6W 45 KT 50 MPH...POST-TROP/EXTRATROP
96H 12/0600Z 56.0N 10.0W 35 KT 40 MPH...POST-TROP/EXTRATROP
120H 13/0600Z...DISSIPATED

$$
Forecaster Cangialosi
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Re: ATL: GABRIELLE - Tropical Storm - Discussion

#99 Postby jconsor » Sun Sep 08, 2019 9:09 am

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Re: ATL: GABRIELLE - Tropical Storm - Discussion

#100 Postby AnnularCane » Sun Sep 08, 2019 9:27 am

I think Gabbie wants some attention too. :lol:
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