ATL: ISAAC - Post-Tropical - Discussion

[colbroe]

Totally agree with you , intensification can be seen as it getting into warmer waters .

[Ptarmigan]

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.

True.

[Spacecoast]

12z ensembles.
You can see the stronger Isaac's peel off, weaker Isaac's towards yucatan

[msbee]

Barbara here is the latest infos related to Hurricane Isaac for the Northern Leewards, french version. I let it for you, read it carefully.
For those who are interrested i let the weather forecast for Guadeloupe ( french version).
Gustywind

http://www.meteofrance.gp/integration/s ... eloupe.pdf
http://www.meteofrance.gp/integration/s ... s_nord.pdf

Thanks Gusty

[msbee]

Tonight our local Met Office issued the following special bulletin, stating the following possible impacts for St Maarten:
POTENTIAL IMPACTS:

Based on the above information, the expected impacts on St. Maarten are as follows:

Seas: Sea conditions will begin to deteriorate by Wednesday with waves peaking near 8ft and will further deteriorate Thursday through Friday up to 10 feet or more.



Winds: Winds are expected to increase on Wednesday up 20 kts (25mph) and from Thursday 30kts (35mph) with higher gusts. Based on current information gusts of up to storm force (45mph) could be experienced in St. Maarten late Thursday into Friday morning.

Rainfall: Models are not indicating excessive rainfall over St. Maarten (2 inches). Couple showers will move in on Wednesday and as moisture increases through Thursday rainfall activity will increase further.

Because Isaac is such a small system there are a lot of uncertainties with the forecast. It is likely that as the system draws closer to the islands the track and intensity may change. Therefore it is important to keep updated and alert.

Watches and warnings for the islands may be issued by tomorrow Tuesday.


the full report is here:
http://www.meteosxm.com/tropical-weather-update/

[1900hurricane]

Down to 60 kt for 00Z.

AL, 09, 2018091100, , BEST, 0, 145N, 462W, 60, 997, TS, 34, NEQ, 40, 10, 10, 40, 1010, 150, 10, 0, 0, L, 0, , 0, 0, ISAAC, D, 0, , 0, 0, 0, 0, genesis-num, 021,
AL, 09, 2018091100, , BEST, 0, 145N, 462W, 60, 997, TS, 50, NEQ, 20, 0, 0, 20, 1010, 150, 10, 0, 0, L, 0, , 0, 0, ISAAC, D, 0, , 0, 0, 0, 0, genesis-num, 021,

[Gustywind]

Tonight our local Met Office issued the following special bulletin, stating the following possible impacts for St Maarten:
POTENTIAL IMPACTS:

Based on the above information, the expected impacts on St. Maarten are as follows:

Seas: Sea conditions will begin to deteriorate by Wednesday with waves peaking near 8ft and will further deteriorate Thursday through Friday up to 10 feet or more.



Winds: Winds are expected to increase on Wednesday up 20 kts (25mph) and from Thursday 30kts (35mph) with higher gusts. Based on current information gusts of up to storm force (45mph) could be experienced in St. Maarten late Thursday into Friday morning.

Rainfall: Models are not indicating excessive rainfall over St. Maarten (2 inches). Couple showers will move in on Wednesday and as moisture increases through Thursday rainfall activity will increase further.

Because Isaac is such a small system there are a lot of uncertainties with the forecast. It is likely that as the system draws closer to the islands the track and intensity may change. Therefore it is important to keep updated and alert.

Watches and warnings for the islands may be issued by tomorrow Tuesday.


the full report is here:
http://www.meteosxm.com/tropical-weather-update/

Thanks Barbara.

[colbroe]

Just looked at three satellite pictures of Isaac forty five minutes apart ,this system has expanded and consolidated with some concentrated storm clouds.if this trend continues most of the Carribean will have a big problem

[Gustywind]

Just looked at three satellite pictures of Isaac forty five minutes apart ,this system has expanded and consolidated with some concentrated storm clouds.if this trend continues most of the Carribean will have a big problem

Wow, after a ragged look today, hey hey looks like Isaac is getting bigger and bigger or my eyes are deceiving me? Let's hope that he is not experiencing an RI This little boy is becoming impolite tonight!

[Nimbus]

Isaac seems able to survive from the moisture condensing out of the CDO, guess we will have to look at the mid level moisture ahead tomorrow morning.

[AubreyStorm]

Just looked at three satellite pictures of Isaac forty five minutes apart ,this system has expanded and consolidated with some concentrated storm clouds.if this trend continues most of the Carribean will have a big problem

Wow, after a ragged look today, hey hey looks like Isaac is getting bigger and bigger or my eyes are deceiving me? Let's hope that he is not experiencing an RI This little boy is becoming impolite tonight!

OMG! Bad news!!

[Gustywind]

Hurricane Isaac stays at 4.0/4.0 moving westward at the same latitude...


10/2345 UTC 14.5N 45.4W T4.0/4.0 ISAAC
10/1745 UTC 14.5N 44.1W T4.0/4.0 ISAAC

[Gustywind]

Luis, could you post the latest Best Track please? Thanks? That's very important as Isaac seems to improve a little his structure since the last hour and continues to treck west towards the Lesser Antilles.

[EquusStorm]

Might well pull a Beryl, intensifying rapidly east of the islands and weakening rapidly before reaching them. At least, we certainly hope the latter part of that holds. I'd love to see us have three simultaneous majors for the brief photo op and then see Isaac fall apart and bring only breezes and sprinkles to the Lesser Antilles

[OURAGAN]

Best track 14,5 N /46,2 W, 997 MB, 60 Knots, TS, just Below hurrricane strength

[Gustywind]

Best track 14,5 N /46,2 W, 997 MB, 60 Knots, TS, just Below hurrricane strength

Ok thanks. I Wonder if the NHC will downgrad it to a TS tonight?

[MississippiWx]

Best track 14,5 N /46,2 W, 997 MB, 60 Knots, TS, just Below hurrricane strength

Believe that 75mph for this storm has been very generous for a while.

[msbee]

St Maarten is taking no chances with Isaac. Three emergency shelters will open Wednesday. Other emergency procedures are being set in place too.
Full story here:
https://www.thedailyherald.sx/islands/8 ... -requested

[cycloneye]

BULLETIN
Tropical Storm Isaac Advisory Number 14
NWS National Hurricane Center Miami FL AL092018
1100 PM AST Mon Sep 10 2018

...ISAAC A LITTLE WEAKER...
...STILL EXPECTED TO BE AT OR NEAR HURRICANE STRENGTH WHEN IT
APPROACHES THE LEEWARD ISLANDS LATER THIS WEEK...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...14.5N 46.9W
ABOUT 960 MI...1550 KM E OF THE LESSER ANTILLES
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 16 MPH...26 KM/H
MINIMUM CENTRAL PRESSURE...997 MB...29.44 INCHES



Tropical Storm Isaac Discussion Number 14
NWS National Hurricane Center Miami FL AL092018
1100 PM AST Mon Sep 10 2018

Several microwave images that arrived after the issuance of the last
advisory revealed that the low-level center of Isaac has raced ahead
of the main convective mass, and the system is poorly vertically
aligned. The system also recently passed very near NOAA buoy 41041,
which confirmed that the center is on the western side of the
central dense overcast. The maximum winds observed by the buoy were
only about 30 kt, with a minimum pressure of near 1001 mb. Due to
the western adjustment of the center location, the latest Dvorak
classification from TAFB is lower, and a blend of the TAFB final-T
and CI-numbers supports a lower initial intensity of 60 kt. It is
worth noting that this estimate is more uncertain than normal due to
limitations of the Dvorak technique, and most of the other intensity
estimates are higher. Given the high pressure and light winds at the
buoy, I am inclined to favor the lower estimate at this time.

Confidence in the track forecast is slightly higher now, and the
UKMET is the only outlier that does not bring Isaac westward into
the Caribbean within the next 72 h or so. There is still some
disagreement on the speed of Isaac, especially once it crosses the
Leeward Islands, and this seems largely related to the cyclone's
intensity. The ECMWF and GFS depict a weakening storm that simply
continues westward, while the HWRF and CTCI show strengthening as
Isaac slows down and turns more west-northwestward. The NHC track
forecast for now continues to favor the typically more reliable
global models and shows a steady westward motion through day 5. The
updated NHC forecast is a little faster than the previous advisory,
due primarily to the westward adjustment of the initial position,
and remains close to HCCA.

A slight adjustment has been made to the intensity forecast, but
confidence in the intensity forecast remains quite low. Due to the
current structure of Isaac, it seems less likely that the tropical
storm will intensify more than what is shown by the intensity
guidance over the next 24-48 h. The NHC forecast has therefore been
lowered slightly, but it is still near the top end of the guidance,
and calls for Isaac to be a hurricane when it approaches the
Leeward Islands later this week. It is also worth noting that the
small size of Isaac could make it more susceptible to sudden
short-term changes in intensity that are nearly impossible to
forecast. The intensity spread is tremendous by the end of the
forecast period, with multiple models showing Isaac becoming a major
hurricane around day 4 or 5, and others showing outright
dissipation. The NHC forecasts have been favoring a weaker solution
thus far due to an expected increase in shear beginning in a couple
of days, and I see no reason to make a dramatic change at this
point.

Key Messages:

1. Isaac is expected to be at or near hurricane intensity when it
approaches the Lesser Antilles. However, confidence in the forecast
is lower than normal.

2. Interests in the Lesser Antilles should continue to monitor
Isaac during the next few days. Watches will likely be required for
portions of the Lesser Antilles tomorrow.

FORECAST POSITIONS AND MAX WINDS

INIT 11/0300Z 14.5N 46.9W 60 KT 70 MPH
12H 11/1200Z 14.5N 49.0W 60 KT 70 MPH
24H 12/0000Z 14.6N 51.7W 65 KT 75 MPH
36H 12/1200Z 14.8N 54.3W 65 KT 75 MPH
48H 13/0000Z 15.0N 56.9W 65 KT 75 MPH
72H 14/0000Z 15.4N 62.4W 60 KT 70 MPH
96H 15/0000Z 15.5N 68.0W 55 KT 65 MPH
120H 16/0000Z 15.5N 72.5W 50 KT 60 MPH

$$
Forecaster Zelinsky

[Gustywind]

St Maarten is taking no chances with Isaac. Three emergency shelters will open Wednesday. Other emergency procedures are being set in place too.
Full story here:
https://www.thedailyherald.sx/islands/8 ... -requested

OMG