ATL: ISAAC - Post-Tropical - Discussion

[MississippiWx]

Makes sense. It is definitlely better organized, and firing intense convection. I don’t see this being less than a hurricane before the islands. After the islands, I’m not sure.

[KAlexPR]

Looks like we have Isaac:

AL, 09, 2018090818, , BEST, 0, 145N, 363W, 35, 1005, TS

Any link? please. Thanks

Here's the link for the ATCF best track:
ftp://ftp.nhc.noaa.gov/atcf/btk/bal092018.dat

[NotoSans]

...TROPICAL DEPRESSION NINE BECOMES TROPICAL STORM ISAAC...
5:00 PM AST Sat Sep 8
Location: 14.5°N 36.6°W
Moving: W at 7 mph
Min pressure: 1005 mb
Max sustained: 40 mph

[cycloneye]

BULLETIN
Tropical Storm Isaac Advisory Number 5
NWS National Hurricane Center Miami FL AL092018
500 PM AST Sat Sep 08 2018

...TROPICAL DEPRESSION NINE BECOMES TROPICAL STORM ISAAC...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...14.5N 36.6W
ABOUT 1640 MI...2640 KM E OF THE WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...W OR 275 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...1005 MB...29.68 INCHES



Tropical Storm Isaac Discussion Number 5
NWS National Hurricane Center Miami FL AL092018
500 PM AST Sat Sep 08 2018

The structure of the cyclone, while still a shear pattern, is
improving, with the low-level center now near the convective
overcast and improved outflow in the eastern semicircle. Satellite
intensity estimates have increased to the 30-45 kt range, with the
CIMSS satellite consensus technique now suggesting winds near 35
kt. Based on these estimates, the initial intensity is increased to
35 kt and the depression is upgraded to Tropical Storm Isaac.

Isaac is now moving slowly westward, with the initial motion 275/6.
The subtropical ridge to the north of Isaac is forecast to steer the
system westward with an increasing forward speed for at least the
next 2-3 days. After that time, there is some uncertainty in the
track forecast due to the formation of a mid- to upper-level trough
over the central Atlantic, with some of the track guidance showing a
decrease in forward speed and a more northerly motion near the end
of the forecast period. The GFS and ECMWF models show a continued
westerly motion through that time, and the official forecast follows
that scenario, although with a slower forward speed than in the
previous forecast. The new forecast is again similar to the
earlier forecast and lies near the various consensus models.

Conditions appear favorable for gradual strengthening during the
next 72 h as Isaac moves westward across the warm waters of the
tropical Atlantic. In best agreement with the SHIPS model for the
next three days, the new intensity forecast is raised from the
previous forecast during this time. From 72-120 h, the system is
expected to encounter westerly wind shear, which is expected to
cause some weakening.


FORECAST POSITIONS AND MAX WINDS

INIT 08/2100Z 14.5N 36.6W 35 KT 40 MPH
12H 09/0600Z 14.6N 37.7W 40 KT 45 MPH
24H 09/1800Z 14.7N 39.5W 50 KT 60 MPH
36H 10/0600Z 14.7N 42.0W 60 KT 70 MPH
48H 10/1800Z 14.7N 44.6W 65 KT 75 MPH
72H 11/1800Z 14.5N 50.0W 75 KT 85 MPH
96H 12/1800Z 14.5N 55.5W 75 KT 85 MPH
120H 13/1800Z 15.0N 61.0W 70 KT 80 MPH

$$
Forecaster Beven

[cycloneye]

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.

[cjrciadt]

Might double its windspeed by tomorrow!!

[SoupBone]

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.

I'm here! I've been mostly in the models thread. I think because Caribbean shear is supposed to weaken it, it's getting a lot less attention. I'm hoping for you it takes the wind out of its sails, then it continues weak on west.

[MacTavish]

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.

Because you have CONUS threat from a major hurricane.

[Blinhart]

Been coming in here but can't really said much about this one. The runs for Isaac reminds me too much of Harvey last year.

[La Sirena]

I’ve been lurking! I’ll be in New Orleans next week for work so I’m paying extra attention to see if he’ll pan out as a CONUS threat.

[cjrciadt]

https://imgflip.com/i/2hiwhs

[msbee]

I am watching this one, Luis

[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.

[cycloneye]

SAB up to 3.0.

08/2345 UTC 14.5N 36.9W T3.0/3.0 ISAAC -- Atlantic

[Gustywind]

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!

[Gustywind]

SAB up to 3.0.

08/2345 UTC 14.5N 36.9W T3.0/3.0 ISAAC -- Atlantic

Increasing system for sure, waouw not so far from Helene 3.5/3.5...

[Blinhart]

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.

[1900hurricane]

It's still getting backsheared with the center near the eastern side of the convection. 3.0 with the shear pattern looks good to me, which is about 45 kt.

[cycloneye]

And that value is what the 00z Best Track has.

AL, 09, 2018090900, , BEST, 0, 144N, 371W, 45, 1005, TS

[USVIKimmie]

What base are they coming from?

ST Croix.

They sent the gulfstream. Will need long legs to get info on Isaac. It just landed about 20 minutes ago.