ATL: IRMA - Post-Tropical - Discussion

[cycloneye]

100 mph

BULLETIN
Hurricane Irma Advisory Number 5
NWS National Hurricane Center Miami FL AL112017
1100 AM AST Thu Aug 31 2017

...HURRICANE IRMA RAPIDLY INTENSIFYING OVER THE EASTERN ATLANTIC...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...16.9N 33.8W
ABOUT 650 MI...1050 KM W OF THE CABO VERDE ISLANDS
ABOUT 1845 MI...2975 KM E OF THE LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...100 MPH...155 KM/H
PRESENT MOVEMENT...WNW OR 290 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...979 MB...28.91 INCHES
------------------------------------------------------------------------------


Hurricane Irma Discussion Number 5
NWS National Hurricane Center Miami FL AL112017
1100 AM AST Thu Aug 31 2017

Satellite imagines indicate that Irma is rapidly intensifying.
Very deep convection has formed in the central dense overcast,
which is now displaying a small and clearing eye. Dvorak estimates
were up to 77 kt at 1200 UTC, and since the cloud pattern continues
to quickly become more organized, the initial wind speed is set to
85 kt.

Irma has moved somewhat south of and slower than all of the model
guidance since yesterday. Consequently, it stayed longer over the
warmer ocean temperatures away from the drier air to the north,
possibly allowing the rapid strengthening. Irma should move over
cooler waters tomorrow with some increase in mid-level dry air, so
hopefully the hurricane's intensity will level off by then. In a
few days, the hurricane will be moving over warmer waters with light
shear shown by all of the model guidance. This should promote
further strengthening of Irma, and the NHC forecast shows an
extremely dangerous category 4 hurricane next week, similar to the
solutions provided by the HWRF and the ECMWF models. The intensity
forecast is raised considerably from the previous one due to initial
trends, and is on the high end of the guidance at long range.

The hurricane has turned west-northwestward at about 9 kt. This
motion should continue for the next day or so before a ridge builds
over the central Atlantic Ocean. This ridge should force Irma to
turn westward by the weekend, and west-southwestward early next
week. Guidance continues to trend southward, following the trend of
the ECMWF model starting yesterday. Given the strength of the ridge
and depth of the tropical cyclone, there are no obvious reasons to
discount the anomalous west-southwestward motion seen in most of the
guidance. Little change is made to the track forecast in short
range, but the track is shifted southward and westward at long
range, though not as far southwest as the overnight ECMWF and ECMWF
ensemble models.


FORECAST POSITIONS AND MAX WINDS

INIT 31/1500Z 16.9N 33.8W 85 KT 100 MPH
12H 01/0000Z 17.5N 35.2W 100 KT 115 MPH
24H 01/1200Z 18.0N 37.1W 105 KT 120 MPH
36H 02/0000Z 18.2N 39.2W 105 KT 120 MPH
48H 02/1200Z 18.1N 41.6W 105 KT 120 MPH
72H 03/1200Z 17.0N 46.5W 110 KT 125 MPH
96H 04/1200Z 16.0N 51.0W 110 KT 125 MPH
120H 05/1200Z 16.0N 55.5W 115 KT 130 MPH

$$
Forecaster Blake

[TheStormExpert]

Looks like they went with 85kts (100mph).

BULLETIN
Hurricane Irma Advisory Number 5
NWS National Hurricane Center Miami FL AL112017
1100 AM AST Thu Aug 31 2017

...HURRICANE IRMA RAPIDLY INTENSIFYING OVER THE EASTERN ATLANTIC...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...16.9N 33.8W
ABOUT 650 MI...1050 KM W OF THE CABO VERDE ISLANDS
ABOUT 1845 MI...2975 KM E OF THE LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...100 MPH...155 KM/H
PRESENT MOVEMENT...WNW OR 290 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...979 MB...28.91 INCHES

[Gustywind]

Small core tiny pinhole eye well established CDO and outflow.. they are going to very likely sorely under estiamte the strength of it. They will follow their forecast irregardless.

Hi Aric what are you best and latest thoughts on TS IRMA? Do you think that Irma could impact in the EC especially for those in the Leewards/ NE/ PR? Chances are light high or very high?
Second, could we chances to see at least a cat 1 cane in vicinity of the EC? and if it's the case when Irma may be the more close to us next week?
I asked you that because school begin next Monday and throught next week! Thanks for you input.
Regards
Gustywind

[HurricaneBelle]

979 seems a bit high on the pressure for a Cat 2. Are ambient pressures higher than normal?

[TheStormExpert]

979 seems a bit high on the pressure for a Cat 2. Are ambient pressures higher than normal?

It's also a relatively small storm at the moment.

[Aric Dunn]

Thats a good medium for this advisory. they are anticipating the obvious. despite the models.

[TheStormExpert]

Cat.4 intensity in 5-days.

FORECAST POSITIONS AND MAX WINDS

INIT 31/1500Z 16.9N 33.8W 85 KT 100 MPH
12H 01/0000Z 17.5N 35.2W 100 KT 115 MPH
24H 01/1200Z 18.0N 37.1W 105 KT 120 MPH
36H 02/0000Z 18.2N 39.2W 105 KT 120 MPH
48H 02/1200Z 18.1N 41.6W 105 KT 120 MPH
72H 03/1200Z 17.0N 46.5W 110 KT 125 MPH
96H 04/1200Z 16.0N 51.0W 110 KT 125 MPH
120H 05/1200Z 16.0N 55.5W 115 KT 130 MPH

[floridasun78]

I saw a tweet from Joe Bastardi this morning that POTUS needs to have the federal government on a war footing when it comes to the weather over the next two weeks. If the models play out like they are currently showing I think that may be appropriate advice.

It's safe to say that the SE Texas coast could not handle another hit from a major at this time. In addition, the Outer Banks are still trying to recover economically from the power outage earlier this Summer. If you had to choose a location for Irma to strike where they'd be best prepared to handle it, where would it be? We sure don't want it here in East Central/South Florida but in reality we are probably better prepared to handle it than any other location at this time. The Big Bend is still recovering from Hermine last year. At the risk of sounding like I'm -removed- (which I'm not) we may be the best option for the country in terms of being able to deal with this threat. One thing everyone needs to keep in mind is that between the Harvey impacts and potential impacts to Puerto Rico and the US Virgin Islands, FEMA and the federal government is going to be stretched pretty thin.

tell you true south fl not been in cat 4 since Andrew that hit south downtown so not sure city ot country ready for caT4 i dont trust citys and county to have good plan

[tolakram]

Small core tiny pinhole eye well established CDO and outflow.. they are going to very likely sorely under estiamte the strength of it. They will follow their forecast irregardless.

I don't think so.

ZCZC MIATCDAT1 ALL
TTAA00 KNHC DDHHMM

Hurricane Irma Discussion Number 5
NWS National Hurricane Center Miami FL AL112017
1100 AM AST Thu Aug 31 2017

Satellite imagines indicate that Irma is rapidly intensifying.
Very deep convection has formed in the central dense overcast,
which is now displaying a small and clearing eye. Dvorak estimates
were up to 77 kt at 1200 UTC, and since the cloud pattern continues
to quickly become more organized, the initial wind speed is set to
85 kt.

Irma has moved somewhat south of and slower than all of the model
guidance since yesterday. Consequently, it stayed longer over the
warmer ocean temperatures away from the drier air to the north,
possibly allowing the rapid strengthening. Irma should move over
cooler waters tomorrow with some increase in mid-level dry air, so
hopefully the hurricane's intensity will level off by then. In a
few days, the hurricane will be moving over warmer waters with light
shear shown by all of the model guidance. This should promote
further strengthening of Irma, and the NHC forecast shows an
extremely dangerous category 4 hurricane next week, similar to the
solutions provided by the HWRF and the ECMWF models. The intensity
forecast is raised considerably from the previous one due to initial
trends, and is on the high end of the guidance at long range.

The hurricane has turned west-northwestward at about 9 kt. This
motion should continue for the next day or so before a ridge builds
over the central Atlantic Ocean. This ridge should force Irma to
turn westward by the weekend, and west-southwestward early next
week. Guidance continues to trend southward, following the trend of
the ECMWF model starting yesterday. Given the strength of the ridge
and depth of the tropical cyclone, there are no obvious reasons to
discount the anomalous west-southwestward motion seen in most of the
guidance. Little change is made to the track forecast in short
range, but the track is shifted southward and westward at long
range, though not as far southwest as the overnight ECMWF and ECMWF
ensemble models.


FORECAST POSITIONS AND MAX WINDS

INIT 31/1500Z 16.9N 33.8W 85 KT 100 MPH
12H 01/0000Z 17.5N 35.2W 100 KT 115 MPH
24H 01/1200Z 18.0N 37.1W 105 KT 120 MPH
36H 02/0000Z 18.2N 39.2W 105 KT 120 MPH
48H 02/1200Z 18.1N 41.6W 105 KT 120 MPH
72H 03/1200Z 17.0N 46.5W 110 KT 125 MPH
96H 04/1200Z 16.0N 51.0W 110 KT 125 MPH
120H 05/1200Z 16.0N 55.5W 115 KT 130 MPH

$$
Forecaster Blake

NNNN

[Kingarabian]

Very tight and compact core:



Flattening/sharpening of the outflow to the NW suggests some shear and dry air is still there. So I wouldn't be surprised to see an EWRC initiate quicker than normal.

[Exalt]

Small core tiny pinhole eye well established CDO and outflow.. they are going to very likely sorely under estiamte the strength of it. They will follow their forecast irregardless.

Hi Aric what are you best and latest thoughts on TS IRMA? Do you think that Irma could impact in the EC especially for those in the Leewards/ NE/ PR? Chances are light high or very high?
Second, could we chances to see at least a cat 1 cane in vicinity of the EC? and if it's the case when Irma may be the more close to us next week?
I asked you that because school begin next Monday and throught next week! Thanks for you input.
Regards
Gustywind

I'm not Aric, but conditions look sufficient enough to support a major up the coast.

[txwatcher91]

979 seems a bit high on the pressure for a Cat 2. Are ambient pressures higher than normal?

Looks like my guess of 95-100mph was right on the money Due to the strong HP to the north creating a stronger pressure gradient and the small size of the storm, that's probably why they went with the higher pressure. This thing will become much larger when it starts and finishes an eyewall replacement cycle though.

[Gustywind]

 https://twitter.com/webberweather/status/903246174034984960

The only difference is this is quite abit further north than this system, other then that the track is certainly one of the closer of the models.

Isabel and Ike both show us that even if this does end up curving to the NW like the GFS ensembles expect it could still be a threat to the states.

dont forget hugo !

That could be a great analog.
Don't speak about HUGO in 1989! The latest awfull one in Guadeloupe.

[tolakram]

 https://twitter.com/philklotzbach/status/903269143952015360



Philip Klotzbach ✔ @philklotzbach
#Irma is 7th Cat. 2+ hurricane east of 35°W in tropical Atlantic (S of 23.5°N) in the satellite era (since 1966) & first since Julia (2010).
10:52 AM - Aug 31, 2017

[Exalt]

Very tight and compact core:



Flattening/sharpening of the outflow to the NW suggests some shear and dry air is still air. So I wouldn't be surprised to see an EWRC initiate quicker than normal.

This looks like a compact Andrew-esque buzzsaw in the making

[Aric Dunn]

Small core tiny pinhole eye well established CDO and outflow.. they are going to very likely sorely under estiamte the strength of it. They will follow their forecast irregardless.

Hi Aric what are you best and latest thoughts on TS IRMA? Do you think that Irma could impact in the EC especially for those in the Leewards/ NE/ PR? Chances are light high or very high?
Second, could we chances to see at least a cat 1 cane in vicinity of the EC? and if it's the case when Irma may be the more close to us next week?
I asked you that because school begin next Monday and throught next week! Thanks for you input.
Regards
Gustywind

Well it is still to early to say even for the Islands. once the wsw to sw turn starts we will have a better idea. right now set up seems to favor the Euro, however you cant rule out the other models just yet either so a multi model average is best for the time being which would still bring it very close to the islands. so its better to be prepared then not. just give it a few more days.

[cycloneye]

[Kingarabian]

Very tight and compact core:

[img]http://i.imgur.com/GNHqdHF.gif[/mg]

Flattening/sharpening of the outflow to the NW suggests some shear and dry air is still air. So I wouldn't be surprised to see an EWRC initiate quicker than normal.

This looks like a compact Andrew-esque buzzsaw in the making

Hopefully a combination of an EWRC + dry air + cooler SSTs will combine to do a number on it and the GFS/Euro major forecasts do not verify.

[AdamFirst]

This looks like a compact Andrew-esque buzzsaw in the making

This has a lot of ground to cover. ERCs will happen, and the windfield will expand. This storm is going to be huge.

[Aric Dunn]

Small core tiny pinhole eye well established CDO and outflow.. they are going to very likely sorely under estiamte the strength of it. They will follow their forecast irregardless.

I don't think so.

ZCZC MIATCDAT1 ALL
TTAA00 KNHC DDHHMM

Hurricane Irma Discussion Number 5
NWS National Hurricane Center Miami FL AL112017
1100 AM AST Thu Aug 31 2017

Satellite imagines indicate that Irma is rapidly intensifying.
Very deep convection has formed in the central dense overcast,
which is now displaying a small and clearing eye. Dvorak estimates
were up to 77 kt at 1200 UTC, and since the cloud pattern continues
to quickly become more organized, the initial wind speed is set to
85 kt.

Irma has moved somewhat south of and slower than all of the model
guidance since yesterday. Consequently, it stayed longer over the
warmer ocean temperatures away from the drier air to the north,
possibly allowing the rapid strengthening. Irma should move over
cooler waters tomorrow with some increase in mid-level dry air, so
hopefully the hurricane's intensity will level off by then. In a
few days, the hurricane will be moving over warmer waters with light
shear shown by all of the model guidance. This should promote
further strengthening of Irma, and the NHC forecast shows an
extremely dangerous category 4 hurricane next week, similar to the
solutions provided by the HWRF and the ECMWF models. The intensity
forecast is raised considerably from the previous one due to initial
trends, and is on the high end of the guidance at long range.

The hurricane has turned west-northwestward at about 9 kt. This
motion should continue for the next day or so before a ridge builds
over the central Atlantic Ocean. This ridge should force Irma to
turn westward by the weekend, and west-southwestward early next
week. Guidance continues to trend southward, following the trend of
the ECMWF model starting yesterday. Given the strength of the ridge
and depth of the tropical cyclone, there are no obvious reasons to
discount the anomalous west-southwestward motion seen in most of the
guidance. Little change is made to the track forecast in short
range, but the track is shifted southward and westward at long
range, though not as far southwest as the overnight ECMWF and ECMWF
ensemble models.


FORECAST POSITIONS AND MAX WINDS

INIT 31/1500Z 16.9N 33.8W 85 KT 100 MPH
12H 01/0000Z 17.5N 35.2W 100 KT 115 MPH
24H 01/1200Z 18.0N 37.1W 105 KT 120 MPH
36H 02/0000Z 18.2N 39.2W 105 KT 120 MPH
48H 02/1200Z 18.1N 41.6W 105 KT 120 MPH
72H 03/1200Z 17.0N 46.5W 110 KT 125 MPH
96H 04/1200Z 16.0N 51.0W 110 KT 125 MPH
120H 05/1200Z 16.0N 55.5W 115 KT 130 MPH

$$
Forecaster Blake

NNNN

haha im glad ! though at some point when a system starts looking like this you kind of have to take notice..