ATL: GASTON - Post-Tropical - Discussion

[Hammy]

BT only has 95kt but it looks much better than when it was 105kt.

[1900hurricane]

BT only has 95kt but it looks much better than when it was 105kt.

Convection has been more shallow for the most part today. However, colder tops have made somewhat of a rebound in the past couple of hours.

[cycloneye]

HURRICANE GASTON DISCUSSION NUMBER 33
NWS NATIONAL HURRICANE CENTER MIAMI FL AL072016
500 PM AST TUE AUG 30 2016

Gaston appears to have strengthened some more. The hurricane has
been maintaining a large and well-defined eye with mesovorticies
within it. In addition, a ring of deep convection surrounds the eye
with little evidence of dry slots. The Dvorak intensity estimates
have increased from both TAFB and SAB, and they support raising the
initial wind speed a little more to 95 kt. Gaston is likely to
maintain this intensity, or perhaps strengthen a little more, in the
short term while it remains in generally favorable environmental
conditions. The global models indicate that westerly shear should
increase over Gaston on Wednesday, and that should promote a gradual
weakening trend. More pronounced weakening is expected when Gaston
moves over cool waters in a couple of days. The NHC intensity
forecast is slightly higher than the previous one at 12 h, based on
the higher initial wind speed, but is otherwise largely unchanged.

The initial motion is now 065/9 kt. A faster east-northeastward
motion is expected during the next couple of days as the cyclone
becomes more embedded in the mid-latitude westerlies. A slower
forward speed is forecast beyond a few days when a large
extratropical low nears Gaston and eventually absorbs it in about
5 days. The NHC track forecast is a little slower than the previous
one, and brings a weaker Gaston near the Azores Islands in about
3 days. Interests in that area should monitor the progress of this
system.

The wind radii were modified based on ASCAT and AMSU data from
earlier today.

FORECAST POSITIONS AND MAX WINDS

INIT 30/2100Z 32.6N 51.9W 95 KT 110 MPH
12H 31/0600Z 33.4N 50.5W 95 KT 110 MPH
24H 31/1800Z 34.9N 47.6W 90 KT 105 MPH
36H 01/0600Z 36.6N 43.7W 85 KT 100 MPH
48H 01/1800Z 37.9N 39.3W 80 KT 90 MPH
72H 02/1800Z 38.8N 31.5W 60 KT 70 MPH
96H 03/1800Z 40.0N 26.5W 40 KT 45 MPH
120H 04/1800Z...DISSIPATED

$$
Forecaster Cangialosi

[Yellow Evan]

Likely nearing Category 4 intensity, with a ring of B and WMG eye.

[1900hurricane]

Visually, Gaston reminds me of Typhoon Champi from last year.

[cycloneye]

 https://twitter.com/EricBlake12/status/770753382273409024

[Kalrany]

[img http://imgur.com/download/ryAgd3v/img]

[imghttp://imgur.com/download/9vBRSJf/img]

ISS captures Hurricane Gaston with a few camera adjustments

Beautiful. Looks like a black hole with the lens flare.

[SouthDadeFish]

Satellite presentation is gorgeous with that huge eye:

[CrazyC83]

I would personally estimate it at 105 kt. Looks like a T6.0 but Dvorak often overdoes large eyes.

[Hammy]

I would personally estimate it at 105 kt. Looks like a T6.0 but Dvorak often overdoes large eyes.

Nailed it--TropicalAtlantic has 105kt for 00z position.

[Kazmit]

It's got that annular look to it.

[Yellow Evan]

B ring not done so likely T5.5 now.

[Yellow Evan]

----- Current Analysis -----
Date : 31 AUG 2016 Time : 001500 UTC
Lat : 32:36:12 N Lon : 51:19:24 W


CI# /Pressure/ Vmax
5.7 / 953.9mb/107.2kt


Final T# Adj T# Raw T#
5.5 5.3 5.3

Estimated radius of max. wind based on IR : 44 km

Center Temp : +15.2C Cloud Region Temp : -60.8C

Scene Type : LARGE EYE

[cycloneye]

HURRICANE GASTON DISCUSSION NUMBER 34
NWS NATIONAL HURRICANE CENTER MIAMI FL AL072016
1100 PM AST TUE AUG 30 2016

Gaston's satellite presentation has continued to improve, with a
large clear eye and cloud tops colder than -60C completely
surrounding the center. Dvorak intensity estimates have risen to
T5.5 from TAFB and SAB and are a little higher from the objective
ADT. The initial intensity is therefore raised to 105 kt, making
Gaston a major hurricane again.

Gaston is expected to remain over waters warmer than 26C for at
least the next 36 hours. In addition, vertical shear is not
expected to increase any further than what is already affecting the
system. Therefore, Gaston should be able to at least maintain its
intensity in the short term, but weakening is likely to commence by
24 hours. Due to cooler waters, a rather fast weakening trend
is expected after 36 hours, with Gaston likely to weaken to a
tropical storm between 48 and 72 hours. The cyclone is now
expected to become post-tropical by day 4 since it will be
difficult for it to maintain organized, deep convection over cold
water, and it should become absorbed by another extratropical
cyclone by day 5. The NHC intensity forecast closely follows the
ICON intensity consensus for the entire forecast period.

The initial motion is 070/9 kt. Gaston is becoming embedded in the
mid-latitude westerlies, which should cause it to accelerate
toward the east-northeast during the next couple of days. Some
reduction in speed is then forecast to start by day 3 once Gaston
begins to interact with the separate extratropical cyclone. The
track guidance is tightly clustered, and no significant changes
were needed from the previous NHC track forecast. The updated NHC
forecast continues to show a threat to the Azores in about 3 days.

FORECAST POSITIONS AND MAX WINDS

INIT 31/0300Z 32.9N 50.9W 105 KT 120 MPH
12H 31/1200Z 33.7N 49.2W 105 KT 120 MPH
24H 01/0000Z 35.4N 46.0W 95 KT 110 MPH
36H 01/1200Z 36.9N 41.7W 85 KT 100 MPH
48H 02/0000Z 37.9N 36.9W 75 KT 85 MPH
72H 03/0000Z 38.7N 29.5W 50 KT 60 MPH
96H 04/0000Z 40.5N 23.5W 35 KT 40 MPH...POST-TROPICAL
120H 05/0000Z...DISSIPATED

$$
Forecaster Berg

[cycloneye]

Major again.

...GASTON ONCE AGAIN REACHES MAJOR HURRICANE STRENGTH...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...32.9N 50.9W
ABOUT 810 MI...1300 KM E OF BERMUDA
ABOUT 1385 MI...2230 KM W OF THE AZORES
MAXIMUM SUSTAINED WINDS...120 MPH...195 KM/H
PRESENT MOVEMENT...ENE OR 70 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...956 MB...28.23 INCHES

[Darvince]

Satellite presentation is gorgeous with that huge eye:

It's got a hexagonal eye!

[cycloneye]

HURRICANE GASTON DISCUSSION NUMBER 35
NWS NATIONAL HURRICANE CENTER MIAMI FL AL072016
500 AM AST WED AUG 31 2016

Gaston's satellite presentation continues to be outstanding. It
consists of a large and clear eye surrounded by rings of very deep
convection. Dvorak intensity estimates have remained steady and
still support and initial intensity of 105 kt.

Gaston is over warm waters and the shear is expected to increase
just a little during the next day or two. Consequently, only a
slight weakening is anticipated during the the day or so. After
that time, Gaston should encounter cooler waters resulting in a
faster weakening. By the end of the forecast period, Gaston should
become absorbed by another extratropical cyclone. The NHC intensity
forecast is very similar to the previous one.

The initial motion is 050/8 kt. Gaston is already embedded in the
mid-latitude westerlies, and this pattern should steer the hurricane
toward the northeast and east-northeast with a gradual increase in
forward speed. By day 3, the cyclone should reduce its forward
speed once it begins to interact with a separate extratropical
cyclone. No significant adjustments were made to the previous NHC
track forecast and it continues to be close to the multi-model
consensus TVCN. Gaston continues to move in the direction of the
Azores, and all interests in these islands should monitor the
progress of this cyclone.


FORECAST POSITIONS AND MAX WINDS

INIT 31/0900Z 33.4N 50.2W 105 KT 120 MPH
12H 31/1800Z 34.5N 48.2W 105 KT 120 MPH
24H 01/0600Z 36.3N 44.5W 95 KT 110 MPH
36H 01/1800Z 37.5N 40.0W 85 KT 100 MPH
48H 02/0600Z 38.5N 35.0W 70 KT 80 MPH
72H 03/0600Z 39.5N 28.0W 45 KT 50 MPH
96H 04/0600Z 41.5N 22.0W 30 KT 35 MPH...POST-TROPICAL
120H 05/0600Z...DISSIPATED

$$
Forecaster Avila

[Kazmit]

It's interesting to see powerful, annular hurricanes at such a high latitude.

[tolakram]

No mention of annular by the NHC.

Go Gaston Go

http://weather.msfc.nasa.gov/cgi-bin/get-goes?satellite=GOES-E%20HURRICANE&lat=34&lon=-49&info=vis&zoom=1&width=1024&height=768&type=Animation&quality=92&palette=ir1.pal&numframes=5&mapcolor=gray&map=none

[Ntxw]

Gaston has put on almost 19 units of ACE! Putting the Atlantic near average to slightly above for this date. Not only was it a major but it lasted for a decent amount of time as a major which helps

http://tropical.atmos.colostate.edu/Includes/Documents/Realtime/northatlanticstormstats.html