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WxWatcher007

Back From The Dead: Tropical Storm Paulette

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Time to start tracking, though it looks quite a bit north for long term land impacts. A lot of uncertainty with interaction possible with 91L and the coming wave.

A tropical wave and area of low pressure located just west of the 
Cabo Verde Islands is producing a large area of disorganized 
showers and thunderstorms.  Gradual development of this system is 
expected as it moves westward to west-northwestward, and a tropical 
depression is likely to form late this weekend or early next week 
when the system reaches the central tropical Atlantic.
* Formation chance through 48 hours...medium...40 percent. 
* Formation chance through 5 days...high...80 percent.

BP0eg21.png

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Should be a depression shortly if convection continues.

Thunderstorm activity associated with a well-defined low pressure 
system located about midway between the west coast of Africa and the 
northern Leeward Islands continues to get better organized. A 
tropical depression is expected to form later tonight or on Monday 
while the low moves westward or west-northwestward across the 
central tropical Atlantic.
* Formation chance through 48 hours...high...near 100 percent. 
* Formation chance through 5 days...high...near 100 percent.
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NHC will initiate advisories on Tropical Depression Seventeen, the low pressure area over the central tropical Atlantic, at 11 PM AST (0300 UTC).
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Looks like shear trouble in the future

Tropical Depression Seventeen Discussion Number   1
NWS National Hurricane Center Miami FL       AL172020
1100 PM AST Sun Sep 06 2020

The tropical low that the National Hurricane Center has been 
tracking the past few days west of the Cabo Verde Islands has 
developed enough convective banding for the system to be classified 
as a tropical depression. A 06/2345Z ASCAT-B scatterometer pass 
indicated surface wind speeds of 30-31 kt north of the center, which 
are supported by a T2.0/30 kt Dvorak satellite intensity estimate 
from TAFB at 07/0000 UTC.

The initial motion estimate is an uncertain 270/04kt. The center has 
been jumping around somewhat due to small, brief convective bursts 
that then dissipate, leaving small swirls rotating around the mean 
circulation center. However, the latest ASCAT data showed a much 
better defined overall circulation, especially in the inner core 
wind field region, so the forward motion should stabilize fairly 
soon. The depression is expected to remain caught in weak steering 
flow for the next 5 days, so only a slow westward motion is expected 
tonight and Monday, followed by a west-northwestward motion by later 
Monday and Tuesday that will continue through the remainder of the 
120-h forecast period. Possible track forecast complications could 
develop by days 3-5 if binary interaction occurs between the 
depression and the large low (Invest 93L) currently located 
southeast of the Cabo Verde Islands, resulting in TD-17 not gaining 
as much latitude as currently indicated. The NHC forecast track lies 
down the middle of the simple- and corrected-consensus model 
guidance envelope.

The depression is only forecast to slowly strengthen for the next 4 
days or so due to expected intrusions of dry mid-level air. By day 
5, increasing southerly vertical wind shear on the east side of a 
large upper-level low that is forecast to cut off north of Puerto 
Rico is expected to induce gradual weakening. However, both the 
timing of the development of the low and its west-southwestward 
motion will determine if sufficient shear will prevent further 
strengthening after 96 h; a slower formation of the low and/or a 
slower retrograding motion would result in at least less weakening. 
The NHC intensity forecast closely follows an average of the IVCN 
and NOAA-HCCA intensity consensus models.


FORECAST POSITIONS AND MAX WINDS

INIT  07/0300Z 17.0N  41.5W   30 KT  35 MPH
 12H  07/1200Z 17.0N  42.1W   30 KT  35 MPH
 24H  08/0000Z 17.2N  42.7W   35 KT  40 MPH
 36H  08/1200Z 17.5N  43.4W   40 KT  45 MPH
 48H  09/0000Z 18.0N  44.6W   45 KT  50 MPH
 60H  09/1200Z 18.6N  46.3W   50 KT  60 MPH
 72H  10/0000Z 19.2N  48.2W   55 KT  65 MPH
 96H  11/0000Z 20.4N  51.9W   50 KT  60 MPH
120H  12/0000Z 21.2N  55.5W   45 KT  50 MPH

$$
Forecaster Stewart

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BULLETIN
Tropical Depression Seventeen Advisory Number   2
NWS National Hurricane Center Miami FL       AL172020
500 AM AST Mon Sep 07 2020

...DEPRESSION MOVING SLOWLY WEST-NORTHWESTWARD OVER THE CENTRAL
ATLANTIC...
...EXPECTED TO BECOME A TROPICAL STORM LATER TODAY...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...17.3N 42.1W
ABOUT 1200 MI...1930 KM W OF THE CABO VERDE ISLANDS
ABOUT 1380 MI...2225 KM E OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES

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Tropical Depression Seventeen Discussion Number   2
NWS National Hurricane Center Miami FL       AL172020
500 AM AST Mon Sep 07 2020

Tropical Depression Seventeen is a large tropical cyclone, with its
circulation evident several hundred miles from its center. An area
of deep convection has developed tonight just over and to the east
of its center with cloud top temperatures as low as -80 degrees C.
However, there appears to be some dry air in the northwestern
portion of the cyclone's circulation limiting convection there. The
latest Dvorak satellite intensity estimates from TAFB and UW-CIMSS
support keeping the initial intensity at 30 kt.

The depression has been moving west-northwestward at about 5 kt
over the past 12 hours. This general motion is expected to continue 
throughout the 5-day forecast period, with some increase in 
forward speed over the next couple of days as the cyclone is 
steered by a weak mid-level ridge to its north. The overall 
guidance shifted slightly to the north through day 3 and the latest 
NHC forecast lies in between the previous one and the consensus 
track guidance through this time period. For days 3 through 5, the 
forecast track is little changed from the previous one and is in 
good agreement with the fairly tightly clustered track guidance. 

Other than some dry air in the vicinity of the depression, the 
overall environment looks favorable for strengthening over the next 
few days. However, due to the large size of the circulation, 
strengthening may occur more slowly than what might be expected from 
a more compact cyclone. Therefore, only gradual strengthening is 
indicated in the official forecast during that time. By 72 h, 
increasing vertical wind shear should limit further intensification, 
and may cause some weakening to occur. The latest NHC intensity 
forecast is a blend of the previous one and the HFIP corrected 
consensus, HCCA.


FORECAST POSITIONS AND MAX WINDS

INIT  07/0900Z 17.3N  42.1W   30 KT  35 MPH
 12H  07/1800Z 17.5N  42.6W   35 KT  40 MPH
 24H  08/0600Z 17.8N  43.2W   35 KT  40 MPH
 36H  08/1800Z 18.3N  44.1W   40 KT  45 MPH
 48H  09/0600Z 19.1N  45.6W   45 KT  50 MPH
 60H  09/1800Z 19.7N  47.1W   50 KT  60 MPH
 72H  10/0600Z 20.1N  49.0W   50 KT  60 MPH
 96H  11/0600Z 20.6N  52.7W   45 KT  50 MPH
120H  12/0600Z 21.7N  55.5W   45 KT  50 MPH

$$
Forecaster Latto

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27 minutes ago, WxWatcher007 said:

TD 17 doesn't look half bad on visible and IR. It has been able to maintain decent convection. It doesn't look far off from being a TS. Shear still looks to be an issue. 

20111086.gif?0.33588215641988883

Yes definitely some southwesterly shear the low level center is exposed a naked swirl right to the southwest of the convection it is not far off but like all the other storms the mid level circulation is in control. 

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Have to watch if upcoming periodic shear can keep Paulette weaker, shallower and allow it to move further west, or if it becomes stacked/deep enough to slip north into the weakness. There is a possibility that it could remain weak enough to find the WAR and slip under it if future TD18 turns north into the central Atlantic. That could open to door for Paulette to be a threat north of the Antilles. Will just have to see how the pattern evolves and how strong Paulette might become within shear interaction.

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GFS 96-120 different this run.  Paulette appears to reform further west and split the tutt in half. Restrengthening after that, possibly into a major.

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It means little at this point, but the signal for Paulette has been further west as it fails to find the weakness between ridging. You can see it on the latest GFS. There’s enormous uncertainty in the steering pattern. 

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3 hours ago, WxWatcher007 said:

It means little at this point, but the signal for Paulette has been further west as it fails to find the weakness between ridging. You can see it on the latest GFS. There’s enormous uncertainty in the steering pattern. 

That last trough comes in and kicks out pretty quick but I that trough is flatter or weaker that could keep it interesting but recurve still looks likely.

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30 minutes ago, shaggy said:

That last trough comes in and kicks out pretty quick but I that trough is flatter or weaker that could keep it interesting but recurve still looks likely.

Yeah I’d favor recurve at this point given how many opportunities there seem to be for weaknesses in ridging to develop, but I think it’s far from a lock for Paulette, especially if it stays weak. 

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BULLETIN
Tropical Storm Paulette Advisory Number   5
NWS National Hurricane Center Miami FL       AL172020
1100 PM AST Mon Sep 07 2020

...A SLIGHTLY STRONGER PAULETTE DRIFTING NORTH-NORTHWESTWARD...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...17.8N 42.5W
ABOUT 1230 MI...1975 KM W OF THE CABO VERDE ISLANDS
ABOUT 1350 MI...2175 KM E OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...NNW OR 330 DEGREES AT 5 MPH...7 KM/H
MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES

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Tropical Storm Paulette Discussion Number   5
NWS National Hurricane Center Miami FL       AL172020
1100 PM AST Mon Sep 07 2020

Satellite images show that Paulette continues to become better 
organized, with a more symmetric presentation and very deep 
convection near or just north of the center. The initial wind speed 
is increased to 40 kt, a little higher than recent subjective Dvorak 
estimates, but close to the objective estimates and the UW-CIMSS 
satellite consensus.  Further strengthening is expected during the 
next day or so while the storm remains in a warm SST and 
low-to-moderate shear environment.  By midweek, some weakening is 
forecast due to an increase in shear from an enhanced mid-oceanic 
upper-level trough.  There's a fair amount of uncertainty on how 
quickly the tropical cyclone moves across the trough axis, which 
would then allow Paulette to find an area of lighter shear, plus 
very warm water, by the end of the forecast period.  The intensity 
forecast is slightly higher in the short-term, and lower in the 
day-4 period just before the environment is forecast to improve.

Paulette appears to be moving slowly north-northwestward this 
evening.  A mid-level ridge is likely to build over the western and 
central North Atlantic in a day or two, and this pattern should 
cause Paulette to move faster toward the northwest tomorrow, and  
west-northwestward or westward through late week.  A turn back 
toward the west-northwest or northwest is possible over the weekend 
as the cyclone reaches the western periphery of the ridge.  This is 
not a particularly certain forecast because the track models aren't 
in good agreement, perhaps linked to the strength of Paulette, and 
there is significant spread in the various ensemble guidance.  With 
no clear trends to rely on, and since the new model consensus came 
in very close to the previous NHC forecast, the new NHC track 
prediction is basically unchanged from the previous one.


FORECAST POSITIONS AND MAX WINDS

INIT  08/0300Z 17.8N  42.5W   40 KT  45 MPH
 12H  08/1200Z 18.4N  42.9W   45 KT  50 MPH
 24H  09/0000Z 19.2N  44.1W   50 KT  60 MPH
 36H  09/1200Z 19.9N  45.9W   55 KT  65 MPH
 48H  10/0000Z 20.5N  47.9W   55 KT  65 MPH
 60H  10/1200Z 20.9N  49.9W   50 KT  60 MPH
 72H  11/0000Z 21.3N  51.8W   50 KT  60 MPH
 96H  12/0000Z 22.5N  55.0W   45 KT  50 MPH
120H  13/0000Z 25.0N  58.0W   50 KT  60 MPH

$$
Forecaster Blake

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BULLETIN
Tropical Storm Paulette Advisory Number   6
NWS National Hurricane Center Miami FL       AL172020
500 AM AST Tue Sep 08 2020

...PAULETTE STRENGTHENS A LITTLE MORE OVER THE OPEN CENTRAL
TROPICAL ATLANTIC...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...18.1N 42.8W
ABOUT 1250 MI...2010 KM W OF THE CABO VERDE ISLANDS
ABOUT 1330 MI...2140 KM E OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...NW OR 325 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...1000 MB...29.53 INCHES

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Tropical Storm Paulette Discussion Number   6
NWS National Hurricane Center Miami FL       AL172020
500 AM AST Tue Sep 08 2020

GOES-16 Proxy-VIS and enhanced BD-curve infrared imagery reveals 
that Paulette's cloud pattern has continued to improve during the 
past several hours.  Specifically, the developing inner core is 
much more symmetric with new bursts of deep convection (-76C cloud 
tops) near the surface circulation center.  Subsequently, subjective 
and objective satellite intensity estimates support an initial 
intensity of 45 kt.

The global models and the statistical-dynamical intensity guidance 
indicate increasing southwesterly shear commencing later today. 
So, only modest strengthening is shown in the NHC foreast during 
next 24 hours.  On Friday, the shear stiffens and becomes less 
diffluent as the cyclone approaches the high amplitude mid-Atlantic 
TUTT.  Therefore, Gradual weakening is expected to occur at that 
time.  Beyond day 3, there are some mixed signals, specifically in 
the GFS/FV3 and ECMWF SHIPS output.  The GFS/FV3 continues to 
indicate strong southwesterly shear through day 5 further weakening 
Paulette to a depression around day 4.  The ECMWF SHIPS, however, 
shows a more southerly and diffluent upper wind pattern supporting 
reintensification after day 4.  The intensity forecast sides with 
that latter solution and also agrees with the HCCA intensity 
multi-model indicating the same intensity trend.   

The initial motion is estimated to be northwestward, or 325/5 kt.  
The rather weak synoptic steering pattern consists of a large mid-
to upper-level low just west of the Canary Islands and ridging to
the northwest of the cyclone.  During the next couple of days, the
large-scale models show the upper low filling and lifting
northeastward, allowing the subtropical ridge to build in behind
the departing upper low from the western Atlantic.  This change 
in the pattern should cause Paulette to turn west-northwestward on 
Wednesday and continue moving in this general motion through early 
Saturday.  Through the remaining portion of the period, the global 
models indicate a major shortwave trough moving off of the 
northeast coast of the U.S. and breaking down the western extent of 
the subtropical ridge/Bermuda high.  This growing weakness in the 
ridge should cause Paulette to turn toward the northwest early 
Sunday.  The official track forecast is a little bit slower and to 
the right of the previous forecast after day 3, and is close to the 
various consensus aids.



FORECAST POSITIONS AND MAX WINDS

INIT  08/0900Z 18.1N  42.8W   45 KT  50 MPH
 12H  08/1800Z 18.6N  43.6W   50 KT  60 MPH
 24H  09/0600Z 19.5N  45.0W   55 KT  65 MPH
 36H  09/1800Z 20.2N  46.9W   55 KT  65 MPH
 48H  10/0600Z 20.5N  48.9W   55 KT  65 MPH
 60H  10/1800Z 20.8N  50.4W   50 KT  60 MPH
 72H  11/0600Z 21.3N  51.9W   50 KT  60 MPH
 96H  12/0600Z 22.9N  54.9W   45 KT  50 MPH
120H  13/0600Z 25.4N  57.8W   50 KT  60 MPH

$$
Forecaster Roberts

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Tropical Storm Paulette Discussion Number   6NWS National Hurricane Center Miami FL       AL172020500 AM AST Tue Sep 08 2020GOES-16 Proxy-VIS and enhanced BD-curve infrared imagery reveals that Paulette's cloud pattern has continued to improve during the past several hours.  Specifically, the developing inner core is much more symmetric with new bursts of deep convection (-76C cloud tops) near the surface circulation center.  Subsequently, subjective and objective satellite intensity estimates support an initial intensity of 45 kt.The global models and the statistical-dynamical intensity guidance indicate increasing southwesterly shear commencing later today. So, only modest strengthening is shown in the NHC foreast during next 24 hours.  On Friday, the shear stiffens and becomes less diffluent as the cyclone approaches the high amplitude mid-Atlantic TUTT.  Therefore, Gradual weakening is expected to occur at that time.  Beyond day 3, there are some mixed signals, specifically in the GFS/FV3 and ECMWF SHIPS output.  The GFS/FV3 continues to indicate strong southwesterly shear through day 5 further weakening Paulette to a depression around day 4.  The ECMWF SHIPS, however, shows a more southerly and diffluent upper wind pattern supporting reintensification after day 4.  The intensity forecast sides with that latter solution and also agrees with the HCCA intensity multi-model indicating the same intensity trend.   The initial motion is estimated to be northwestward, or 325/5 kt.  The rather weak synoptic steering pattern consists of a large mid-to upper-level low just west of the Canary Islands and ridging tothe northwest of the cyclone.  During the next couple of days, thelarge-scale models show the upper low filling and liftingnortheastward, allowing the subtropical ridge to build in behindthe departing upper low from the western Atlantic.  This change in the pattern should cause Paulette to turn west-northwestward on Wednesday and continue moving in this general motion through early Saturday.  Through the remaining portion of the period, the global models indicate a major shortwave trough moving off of the northeast coast of the U.S. and breaking down the western extent of the subtropical ridge/Bermuda high.  This growing weakness in the ridge should cause Paulette to turn toward the northwest early Sunday.  The official track forecast is a little bit slower and to the right of the previous forecast after day 3, and is close to the various consensus aids.FORECAST POSITIONS AND MAX WINDSINIT  08/0900Z 18.1N  42.8W   45 KT  50 MPH12H  08/1800Z 18.6N  43.6W   50 KT  60 MPH24H  09/0600Z 19.5N  45.0W   55 KT  65 MPH36H  09/1800Z 20.2N  46.9W   55 KT  65 MPH48H  10/0600Z 20.5N  48.9W   55 KT  65 MPH60H  10/1800Z 20.8N  50.4W   50 KT  60 MPH72H  11/0600Z 21.3N  51.9W   50 KT  60 MPH96H  12/0600Z 22.9N  54.9W   45 KT  50 MPH120H  13/0600Z 25.4N  57.8W   50 KT  60 MPH$$Forecaster Roberts

How many times have we seen the terms "major trough" and that be a damn lie...

Sent from my LML212VL using Tapatalk

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Honestly, Paulette is looking pretty darn good at the moment. Perhaps it reaches hurricane intensity prior to getting walloped by shear?

2e57084587b85d169ad5f9e039914c74.gif

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ADT currently supports a meager 51 kts. Paulette doesn't have a lot of time before conditions become less favorable. It would need to really crank convection and wrap the core ASAP. I suppose a 15 kt gain isn't out of the question but it likely remains a TS into weakening trend.

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06 GFS says it falls apart and  is  nothing. Euro says  major  near  bermuda.

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2 hours ago, ldub23 said:

06 GFS says it falls apart and  is  nothing. Euro says  major  near  bermuda.

Follow the ensembles 

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Follow the ensembles 

With a TC fully developed IRL, you can put more weight on the operationals to see how they play out run-to-run. Certainly the ensembles are still important, as pre-TCG, I definitely put more weight on them. They have no doubt performed better with genesis this year. The ops have been horrible. Obviously nothing beats the super ensemble for track forecasting, especially into the ~96-120 mid-range hours. Intensity guidance should of course always be more reliant upon the actual TC models.

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29 minutes ago, Random Chaos said:

The ensemble doesn’t help :flood:

 

590918E3-E775-47AD-B629-5EA9E2D3D875.png

Dang, hard to figure out what kind of fish it will be. I’d hate to be a forecaster working the central Atlantic Ocean. 

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