CPAC: ISELLE - Post-Tropical

[JonathanBelles]

Anyone understand the AHI? What does a 3 mean?

This looks like it is pretty much Annular, which means RI isn't likely.

[supercane]

As always, Google is your friend. See this presentation by Schumacher et al: OPERATIONAL IMPLEMENTATION OF AN OBJECTIVE ANNULAR HURRICANE INDEX at http://www.ofcm.gov/ihc07/Presentations/s6-04schumacher.ppt or ftp://rammftp.cira.colostate.edu/schumacher/IHC/s6-04schumacher.ppt.ppt or the later Knaff et al paper "Objective Identification of Annular Hurricanes" at http://www.ssec.wisc.edu/~kossin/articles/Knaff_et_al_WaF_2008.pdf

From this presentation, 3 would still be a pretty low number. I suspect the trailing southern band is sufficient to prevent this from being annular, and have not strictly evaluated all the environmental parameters they used.

Edited to change links and add link to paper.

[supercane4867]

The overall structure is certainly improving and I belive Iselle possess the most annular characteristics since Adrian in 2011

[Kingarabian]

SAB now back to 5.5. All three agencies now support at least 100kts, but I'd go with 105kts.

[Kingarabian]

110kts. Stronger than I thought.

000 WTPZ44 KNHC 040559 TCDEP4 HURRICANE ISELLE SPECIAL DISCUSSION NUMBER 15 NWS NATIONAL HURRICANE CENTER MIAMI FL EP092014 1100 PM PDT SUN AUG 03 2014

The satellite presentation of Iselle has become much better organized over the past few hours with a warm, well-defined eye and strong convection in the eyewall. A special 0500 UTC Dvorak classification from TAFB had a Data-T value of 6.0, or 115 kt, with constraints suggesting a slightly lower final wind speed. CIMSS ADT values have been running near 110 kt for the past six hours, and this will be used as the initial intensity. With Iselle's current annular structure, little change in intensity is foreseen in the near-term. A slow weakening could begin by late Monday due to the hurricane encountering a somewhat less favorable thermodynamic environment.

The official NHC wind speed prediction has been raised significantly from the previous one through 36 hours due to the stronger initial intensity. No changes have been made to the intensity forecast beyond 72 hours at this time. No changes have been made to the previous forecast track in this advisory.

FORECAST POSITIONS AND MAX WINDS
INIT 04/0600Z 16.0N 135.2W 110 KT 125 MPH
12H 04/1200Z 16.0N 136.2W 110 KT 125 MPH
24H 05/0000Z 16.0N 137.8W 105 KT 120 MPH
36H 05/1200Z 16.0N 139.3W 95 KT 110 MPH
48H 06/0000Z 16.5N 141.3W 85 KT 100 MPH
72H 07/0000Z 18.1N 146.8W 65 KT 75 MPH
96H 08/0000Z 20.1N 153.1W 45 KT 50 MPH
120H 09/0000Z 22.3N 159.2W 40 KT 45 MPH
$$ Forecaster Blake

[supercane4867]

...POWERFUL ISELLE CONTINUES MOVING WESTWARD...

2:00 AM PDT Mon Aug 4
Location: 16.0°N 135.6°W
Moving: W at 9 mph
Min pressure: 958 mb
Max sustained: 125 mph




CI# /Pressure/ Vmax
6.0 / 952.3mb/115.0kt
Final T# Adj T# Raw T#
6.0 6.2 6.2

Center Temp : +15.0C Cloud Region Temp : -65.9C

Cat.4 likely

[cycloneye]

HURRICANE ISELLE DISCUSSION NUMBER 16
NWS NATIONAL HURRICANE CENTER MIAMI FL EP092014
200 AM PDT MON AUG 04 2014

Iselle continues to show an annular hurricane structure with no
outer banding around a symmetric inner core. Satellite
classifications are about the same as a few hours ago, so the
initial wind speed will remain 110 kt. Little change in intensity
is likely today while a low-shear environment remains near the
hurricane. Iselle is likely to experience some shear on Tuesday,
which should start a more consistent weakening. As the cyclone
moves deeper into the central Pacific basin, a combination of dry
air aloft, westerly shear and marginal SSTs should continue the
weakening process. The latest NHC forecast is somewhat above the
model consensus early on due to the annular structure, but ends up
below the consensus at long range due to the unfavorable
environment described above.

Iselle is moving westward at roughly 8 kt. This general motion
should continue for a day or so with some acceleration after that
time due to a restrengthening of a ridge over the central Pacific.
Iselle should move more to the west-northwest in a few days due to
the cyclone moving around the southwestern portion of the ridge.
Model guidance has not changed much during the past 6 hours, and
the latest NHC forecast is very close to the previous forecast and
the dynamical model consensus.

FORECAST POSITIONS AND MAX WINDS

INIT 04/0900Z 16.0N 135.6W 110 KT 125 MPH
12H 04/1800Z 16.1N 136.9W 110 KT 125 MPH
24H 05/0600Z 16.1N 138.5W 105 KT 120 MPH
36H 05/1800Z 16.3N 140.2W 90 KT 105 MPH
48H 06/0600Z 16.9N 142.6W 80 KT 90 MPH
72H 07/0600Z 18.5N 148.5W 60 KT 70 MPH
96H 08/0600Z 20.6N 155.0W 50 KT 60 MPH
120H 09/0600Z 22.7N 160.4W 45 KT 50 MPH

$$
Forecaster Blake

[Kingarabian]

Cat 4?

[Yellow Evan]

110 knts? Iselle surprises us again.

[Alyono]

the MPI for this water temp is near a cat 5. Thus, in a zero shear environment, we shouldn't be surprised at this

[Yellow Evan]

the MPI for this water temp is near a cat 5. Thus, in a zero shear environment, we shouldn't be surprised at this

Storms very rarely reach their MPI.

[Yellow Evan]

3rd Cat 4 of the season

EP, 09, 2014080412, , BEST, 0, 161N, 1361W, 115, 952, HU, 34, NEQ, 90, 90, 50, 70, 1010, 180, 20, 0, 20, E, 0, , 0, 0, ISELLE, D,
EP, 09, 2014080412, , BEST, 0, 161N, 1361W, 115, 952, HU, 50, NEQ, 50, 40, 30, 40, 1010, 180, 20, 0, 20, E, 0, , 0, 0, ISELLE, D,
EP, 09, 2014080412, , BEST, 0, 161N, 1361W, 115, 952, HU, 64, NEQ, 30, 25, 20, 25, 1010, 180, 20, 0, 20, E, 0, , 0, 0, ISELLE, D,

[Ntxw]

Cat 4? Wow, she's definitely been an overachiever against the forecast much of her life.

[Siker]

Cat 4? Wow, she's definitely been an overachiever against the forecast much of her life.

Just like her early season sisters .

[Yellow Evan]

48 hours ago, this was Iselle's projected intensity


48H 04/1200Z 16.0N 135.9W 75 KT 85 MPH

Someone was off

[Alyono]

has clearly intensified overnight and is now near cat 3.

Shear according to SHIPS may drop to 1 kt in 24 hours. I could see this making a run at cat 4

And I can also see Julio making a run at cat 4

we have a chance for 2 hurricanes to strike Hawaii in 3 days

[Yellow Evan]

has clearly intensified overnight and is now near cat 3.

Shear according to SHIPS may drop to 1 kt in 24 hours. I could see this making a run at cat 4

And I can also see Julio making a run at cat 4

we have a chance for 2 hurricanes to strike Hawaii in 3 days

That would be a disaster to the islands.

It could leave the island paralyzed for weeks.

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

[Yellow Evan]

[tolakram]

Live IR: http://wwwghcc.msfc.nasa.gov/cgi-bin/get-goes?satellite=GOES-W%20PACUS&lat=16&lon=-137&info=ir&zoom=2&width=1024&height=768&type=Animation&quality=95&palette=ir1.pal&numframes=10

Color, Zoomed: http://wwwghcc.msfc.nasa.gov/cgi-bin/get-goes?satellite=GOES-W%20PACUS&lat=16&lon=-137&info=ir&zoom=1&width=1024&height=768&type=Animation&quality=95&palette=ir2.pal&numframes=10

[xtyphooncyclonex]

The storm had so much improvements over the past 24 hours, and it underwent some intensification. Iselle is the most impressive since Cristina (obviously) and I would not be surprised if it nears the latter hurricane's intensity. Also, I see some improvements also in its satellite presentation, as this looks almost annular and its convection is cooling especially over western quadrant of the CDO, and its eye has warmed a lot. This is the first fun EPAC storm IMO that I have tracked since Cristina, after a streak of some unimpressive weak storms and one short-lived hurricane earlier this year.