ATL: ISAAC - Post-Tropical - Discussion

[Hammy]

According to 00Z Best Track we now have three simultaneous hurricanes in the Atlantic Ocean.

09L ISAAC 180910 0000 14.6N 41.0W ATL 65 993

Looks like I should've waited another hour before posting...

[Kazmit]

According to 00Z Best Track we now have three simultaneous hurricanes in the Atlantic Ocean.

09L ISAAC 180910 0000 14.6N 41.0W ATL 65 993

The same thing happened one year ago from yesterday.

[cycloneye]

00z Best Track up to Hurricane.

AL, 09, 2018091000, , BEST, 0, 146N, 410W, 65, 993, HU

[supercane4867]

According to 00Z Best Track we now have three simultaneous hurricanes in the Atlantic Ocean.

09L ISAAC 180910 0000 14.6N 41.0W ATL 65 993

The same thing happened one year ago from yesterday.

9/8/2017



9/9/2018

[MississippiWx]

Looks to me like Isaac is rapidly intensifying. This is bad news for the Northern islands who received so much damage last year. A stronger storm is more than likely going to trend north. Crossing my fingers for shear to do its job.

[AubreyStorm]

WOOWWWWWW!

According to 00Z Best Track we now have three simultaneous hurricanes in the Atlantic Ocean.

09L ISAAC 180910 0000 14.6N 41.0W ATL 65 993

The same thing happened one year ago from yesterday.

9/8/2017



9/9/2018

[MississippiWx]

Just maybe the powers that be are on to something when they say September 10 is the average peak of the season?

[SoupBone]

Just maybe the powers that be are on to something when they say September 10 is the average peak of the season?

Always the case. Season canceled?

[Gustywind]

According to 00Z Best Track we now have three simultaneous hurricanes in the Atlantic Ocean.

09L ISAAC 180910 0000 14.6N 41.0W ATL 65 993

Waouw here we are! That was fast 24 hours later this tiny boy is in a hurry, where do you go little newbie Isaac.

[cycloneye]

BULLETIN
Hurricane Isaac Advisory Number 10
NWS National Hurricane Center Miami FL AL092018
1100 PM AST Sun Sep 09 2018

...ISAAC BECOMES THE FIFTH HURRICANE OF THE 2018 ATLANTIC SEASON...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...14.5N 41.6W
ABOUT 1305 MI...2100 KM E OF THE WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...W OR 275 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...993 MB...29.33 INCHES

WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.

Interests in the Lesser Antilles should monitor the progress of
Isaac.

[cycloneye]

BULLETIN
Hurricane Isaac Advisory Number 10
NWS National Hurricane Center Miami FL AL092018
1100 PM AST Sun Sep 09 2018

...ISAAC BECOMES THE FIFTH HURRICANE OF THE 2018 ATLANTIC SEASON...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...14.5N 41.6W
ABOUT 1305 MI...2100 KM E OF THE WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...W OR 275 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...993 MB...29.33 INCHES


WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.

Interests in the Lesser Antilles should monitor the progress of
Isaac.


Hurricane Isaac Discussion Number 10
NWS National Hurricane Center Miami FL AL092018
1100 PM AST Sun Sep 09 2018

Isaac's IR satellite presentation has generally improved since the
last advisory. While there is no evidence of an eye in conventional
satellite imagery, the most recent microwave imagery around 2100 UTC
indicated the presence of a pinhole eye. Dvorak intensity estimates
are T4.0 from both TAFB and SAB, and on this basis Isaac has been
upgraded to a hurricane, the 5th of the 2018 Atlantic season and 3rd
in the past few days.

I must stress that all aspects of the forecast are highly uncertain
at this time. The dynamical track model spread is nearly 1000 miles
at day 5, while the intensity guidance spread is nearly 100 kt.
Although the NHC track and intensity forecasts have not been changed
very much, this should not be interpreted as increasing confidence
in the forecast.

With regard to track, there is a clear split in the model guidance
regarding the speed of Isaac. The GFS and ECMWF models forecast that
a mid-level ridge to the north will accelerate the hurricane
westward for the next 36 h, with a westward motion continuing
through day 5 as the ridge is reinforced in the wake of Florence. On
the other hand, the UKMET and HWRF models show a weakness developing
in the ridge which causes Isaac to move much slower, and eventually
turn northward. The NHC forecast has been favoring the former
solution, and continues to do so with this advisory since I see no
reason to make a drastic change to the forecast at this point.

Isaac is a very small hurricane, which makes the intensity forecast
particularly tricky since small storms are susceptible to rapid
changes of intensity, up and down. Since the wind shear is expected
to remain low, and Isaac is forecast to remain over fairly warm SSTs
for the next 48 h, the current forecast of further intensification
seems reasonable, and the NHC forecast is still at the top end of
the guidance envelope. From 72 h onward, there could be a sudden,
and substantial increase in wind shear associated first with an
upper-level trough to the north, and later with the outflow of
Hurricane Florence. Assuming this shear affects Isaac as expected,
the tiny hurricane would likely weaken quickly, perhaps even faster
than currently shown in the forecast. By the end of the forecast
period, the NHC forecast remains a fair amount below the intensity
consensus, closer to the weakening solutions of the GFS and ECMWF.

Key Messages:
1. Isaac is a small hurricane and uncertainty in the forecast is
higher than normal. Although Isaac is forecast to begin weakening
by Tuesday when it approaches the Lesser Antilles, it is still
expected to be at or near hurricane intensity when it reaches the
islands.

2. Interests in the Lesser Antilles should continue to monitor Isaac
during the next few days.

FORECAST POSITIONS AND MAX WINDS

INIT 10/0300Z 14.5N 41.6W 65 KT 75 MPH
12H 10/1200Z 14.7N 43.5W 75 KT 85 MPH
24H 11/0000Z 14.9N 46.3W 80 KT 90 MPH
36H 11/1200Z 15.0N 49.3W 85 KT 100 MPH
48H 12/0000Z 15.0N 52.0W 85 KT 100 MPH
72H 13/0000Z 15.2N 57.3W 75 KT 85 MPH
96H 14/0000Z 15.5N 63.5W 60 KT 70 MPH
120H 15/0000Z 15.5N 70.0W 50 KT 60 MPH

$$
Forecaster Zelinsky

[Blinhart]

From the latest advisory: I must stress that all aspects of the forecast are highly uncertain at this time. The dynamical track model spread is nearly 1000 miles at day 5, while the intensity guidance spread is nearly 100 kt. Although the NHC track and intensity forecasts have not been changed very much, this should not be interpreted as increasing confidence
in the forecast.

This isn't good that there is so much uncertainty in this system..

[BobHarlem]

From the latest advisory: I must stress that all aspects of the forecast are highly uncertain at this time. The dynamical track model spread is nearly 1000 miles at day 5, while the intensity guidance spread is nearly 100 kt. Although the NHC track and intensity forecasts have not been changed very much, this should not be interpreted as increasing confidence in the forecast.

This isn't good that there is so much uncertainty in this system..

This is as close to "We don't know." as I've ever read in an NHC dicussion.

[eastcoastFL]

From the latest advisory: I must stress that all aspects of the forecast are highly uncertain at this time. The dynamical track model spread is nearly 1000 miles at day 5, while the intensity guidance spread is nearly 100 kt. Although the NHC track and intensity forecasts have not been changed very much, this should not be interpreted as increasing confidence in the forecast.

This isn't good that there is so much uncertainty in this system..

This is as close to "We don't know." as I've ever read in an NHC dicussion.

I've never seen anything like that before.

[Sciencerocks]

[Ptarmigan]

I would not be surprised if Isaac and Helene become major hurricanes.

[Gustywind]

I would not be surprised if Isaac and Helene become major hurricanes.

Hope not especially for those you lived in the EC like me and Luis, Msbee and others friends...

[La Breeze]

8-)

Hurricane Isaac ??? Sorry, I thought that I saw you made a comment about Isaac having a 90% chance of heading to the Carolinas. My mistake, I presume.

[Ptarmigan]

I would not be surprised if Isaac and Helene become major hurricanes.

Hope not especially for those you lived in the EC like me and Luis, Msbee and others friends...

Helene at this point looks like a fish storm. Isaac is a bit concerning.

[Blinhart]

I would not be surprised if Isaac and Helene become major hurricanes.

Hope not especially for those you lived in the EC like me and Luis, Msbee and others friends...

Helene at this point looks like a fish storm. Isaac is a bit concerning.

Already affected the CV Islands, so technically not a Fish.