ATL: ISAAC - Post-Tropical - Discussion

[Hammy]

Convection seems like it's expanding very slowly towards the southeast, so it might be trying to wrap around some.

[banksmanforever]

CENTRE of circulation seems to around 14 or is it my imagination

[wx98]

Surprised this thread is not with more comments but I know Florence is the main topic but still people will be affected by whatever Isaac does intensitywise and the track.

becoming very healthy tonight, growing in size with that huge burst of juicy convection. Looks like that we must have to keep a close eye Luis. At this rate, we may see Isaac close to cat 1 before Monday? Hope no!

I think the next advisory might be up to 70 MPH.

Ummm no, not sure why you think that....more like 50 mph most likely.

[cycloneye]

BULLETIN
Tropical Storm Isaac Advisory Number 6
NWS National Hurricane Center Miami FL AL092018
1100 PM AST Sat Sep 08 2018

...ISAAC STRENGTHENING OVER THE EASTERN TROPICAL ATLANTIC...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...14.4N 37.5W
ABOUT 1580 MI...2540 KM E OF THE WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 8 MPH...13 KM/H
MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES




Tropical Storm Isaac Discussion Number 6
NWS National Hurricane Center Miami FL AL092018
1100 PM AST Sat Sep 08 2018

Isaac is strengthening this evening. Satellite images indicate that
the deep convection has been increasing in intensity and coverage
with better defined banding features. The center is not located in
the center of the convection, however, due to some easterly shear.
An ASCAT pass around 00Z showed maximum winds in the 40-45 kt
range. These data are also in line with the latest Dvorak
classifications of 3.0/45 kt from TAFB and SAB. Based on these
estimates, the initial intensity is raised to 45 kt.

Isaac will likely continue to strengthen during the next few days as
the storm remains over warm waters and moves into an environment of
decreasing wind shear. Beyond a few days, the SHIPS model shows a
notable increase in shear, in part due to the outflow from Florence,
which should end the strengthening trend and cause some weakening.
With the exception of the HMON and COAMPS-TC models, the remainder
of the intensity guidance is higher this cycle. The NHC intensity
forecast is raised from the previous one, but it is a little lower
than the HCCA and IVCN guidance.

The storm is moving due westward at 7 kt. The track forecast seems
fairly straightforward. A strengthening subtropical ridge to the
north of the system should cause Isaac to move westward at an
increasing forward speed during the next several days. This
scenario is supported by the usually more reliable GFS and ECMWF
models, and the NHC track forecast is near a blend of those aids.
Based on the current forecast, Isaac will be near the Lesser
Antilles in 4 to 5 days and interests there should monitor the
progress of this system.

FORECAST POSITIONS AND MAX WINDS

INIT 09/0300Z 14.4N 37.5W 45 KT 50 MPH
12H 09/1200Z 14.4N 38.7W 50 KT 60 MPH
24H 10/0000Z 14.5N 40.9W 60 KT 70 MPH
36H 10/1200Z 14.5N 43.5W 70 KT 80 MPH
48H 11/0000Z 14.5N 46.1W 75 KT 85 MPH
72H 12/0000Z 14.5N 51.5W 85 KT 100 MPH
96H 13/0000Z 14.6N 57.0W 80 KT 90 MPH
120H 14/0000Z 15.0N 62.9W 75 KT 85 MPH

$$
Forecaster Cangialosi

[wx98]

becoming very healthy tonight, growing in size with that huge burst of juicy convection. Looks like that we must have to keep a close eye Luis. At this rate, we may see Isaac close to cat 1 before Monday? Hope no!

I think the next advisory might be up to 70 MPH.

Ummm no, not sure why you think that....more like 50 mph most likely.

Up to 50 mph at 0300z, forecast Cat 2 in 72 hours

[USVIKimmie]

Anyone bothered to factor the Sahara dust west of Isaac? Doesn't look like it's going away, and hasn't for the past 2 days. Hope the link works.

Or am I missing something elemental?

http://tropic.ssec.wisc.edu/real-time/s ... plit&time=

[cycloneye]

Peak intensity goes up to 85 kts (Cat 2)

INIT 09/0300Z 14.4N 37.5W 45 KT 50 MPH
12H 09/1200Z 14.4N 38.7W 50 KT 60 MPH
24H 10/0000Z 14.5N 40.9W 60 KT 70 MPH
36H 10/1200Z 14.5N 43.5W 70 KT 80 MPH
48H 11/0000Z 14.5N 46.1W 75 KT 85 MPH
72H 12/0000Z 14.5N 51.5W 85 KT 100 MPH
96H 13/0000Z 14.6N 57.0W 80 KT 90 MPH
120H 14/0000Z 15.0N 62.9W 75 KT 85 MPH

Isaac will be near the Lesser
Antilles in 4 to 5 days and interests there should monitor the
progress of this system.

[HurricaneFrances04]

Amazing, we'll likely have two hurricanes threatening land around the same time.

[cycloneye]

[Gustywind]

[abajan]

Amazing, we'll likely have two hurricanes threatening land around the same time.

And a Tropical Storm (Olivia in Hawaii).
EDIT: Actually, Olivia's ETA is a bit earlier.

[Gustywind]

Peak intensity goes up to 85 kts (Cat 2)

INIT 09/0300Z 14.4N 37.5W 45 KT 50 MPH
12H 09/1200Z 14.4N 38.7W 50 KT 60 MPH
24H 10/0000Z 14.5N 40.9W 60 KT 70 MPH
36H 10/1200Z 14.5N 43.5W 70 KT 80 MPH
48H 11/0000Z 14.5N 46.1W 75 KT 85 MPH
72H 12/0000Z 14.5N 51.5W 85 KT 100 MPH
96H 13/0000Z 14.6N 57.0W 80 KT 90 MPH
120H 14/0000Z 15.0N 62.9W 75 KT 85 MPH

Isaac will be near the Lesser
Antilles in 4 to 5 days and interests there should monitor the
progress of this system.

Waouw, let's hope that neither RI occurs with Isaac during the next 4 days. Curious to imagine that he will race straight west even the subtropical ridge is expected to be strong enough to steer it on a Westerly course till its cruise towards the Leewards. Something to keep a real eye all the islanders! Do not let your guard dow, we saw what happens last year, let's monitor it carefully in case of.

[StruThiO]

Raw adt is going up

[Blinhart]

Shear ahead of Isaac is only very slightly on the increase, with that sweet spot for development right ahead of the islands. After the islands, 25-40kts shear.

If he can stay in the lower shear areas, I can see him getting up to Cat 3 before the Islands.

[SoupBone]

Shear ahead of Isaac is only very slightly on the increase, with that sweet spot for development right ahead of the islands. After the islands, 25-40kts shear.

If he can stay in the lower shear areas, I can see him getting up to Cat 3 before the Islands.

My paid for meteorology services call for a peak intensity of 90 mph (high end Cat 1), with a possible slight weakening before it reaches the islands.

[Blinhart]

Shear ahead of Isaac is only very slightly on the increase, with that sweet spot for development right ahead of the islands. After the islands, 25-40kts shear.

If he can stay in the lower shear areas, I can see him getting up to Cat 3 before the Islands.

My paid for meteorology services call for a peak intensity of 90 mph (high end Cat 1), with a possible slight weakening before it reaches the islands.

Sure hope so, but RI is still very likely I'm sure haven't seen the models that show the percentages for RI but I'm sure it says in 36 to 48 hours it should have a good chance.

[colbroe]

Looks like an eye has formed at 14 N

[cycloneye]

BULLETIN
Tropical Storm Isaac Advisory Number 7
NWS National Hurricane Center Miami FL AL092018
500 AM AST Sun Sep 09 2018

...ISAAC EXPECTED TO STRENGTHEN DURING THE NEXT FEW DAYS...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...14.5N 38.1W
ABOUT 1540 MI...2475 KM E OF THE WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...1001 MB...29.56 INCHES



Tropical Storm Isaac Discussion Number 7
NWS National Hurricane Center Miami FL AL092018
500 AM AST Sun Sep 09 2018

The cloud pattern of Isaac has changed significantly during the past
several hours. The storm no longer has a sheared appearance, and
instead microwave images reveal a well-defined curved band that
wraps a little more than halfway around the center. Despite the
change in the storm's structure, the Dvorak classifications are
unchanged at 3.0/45 kt. Based on that data, the initial intensity
is held at 45 kt for this advisory.

Now that the shear has lessened, Isaac should steadily strengthen
during the next few days as the storm remains over warm waters and
in a low wind shear environment. Beyond a few days, however, the
SHIPS model shows a notable increase in shear, in part due to the
outflow from Florence, which should end the strengthening trend and
induce some weakening. There was no significant change in the
intensity guidance this cycle, so the official forecast is largely
an update of the previous one. This prediction lies fairly
close to the IVCN and HCCA models.

Isaac remains on the forecast track and the initial motion is the
same as before, 270/7. A strengthening subtropical ridge to the
north of the system should cause Isaac to move westward at an
increasing forward speed during the next several days. Although
there is some spread in the models, the usually more reliable GFS
and ECMWF models have been consistent in showing a due westward
motion through the forecast period. The NHC track forecast leans
toward those models, and it is fairly similar to the previous
prediction. Based on the current forecast, Isaac will be near the
Lesser Antilles in 4 to 5 days and interests there should monitor
the progress of this system.

FORECAST POSITIONS AND MAX WINDS

INIT 09/0900Z 14.5N 38.1W 45 KT 50 MPH
12H 09/1800Z 14.6N 39.6W 55 KT 65 MPH
24H 10/0600Z 14.7N 41.9W 60 KT 70 MPH
36H 10/1800Z 14.7N 44.6W 70 KT 80 MPH
48H 11/0600Z 14.7N 47.5W 80 KT 90 MPH
72H 12/0600Z 14.7N 53.1W 85 KT 100 MPH
96H 13/0600Z 14.9N 58.9W 80 KT 90 MPH
120H 14/0600Z 15.3N 64.5W 70 KT 80 MPH

$$
Forecaster Cangialosi

[AubreyStorm]

This is an eye????

[Sciencerocks]

Oh wow! This thing has great outflow in nearly all quads and poleward and equatorward outflow channels.

That 85h and 37h microwave image shows a tight eye! This thing is probably a hurricane right now.

With this structure the hwrf predictions are very possible.