CPAC: ISELLE - Post-Tropical

[Yellow Evan]

Seems odd there's so little traffic on this thread. Maybe it'll pick up tomorrow as landfall nears.

After all it is the East/Central Pacific which rarely has more than a dozen pages it seems per storm thread.

Yes, but we're talking about possibly making history here.

This is the longest thread for an EPAC storm in the history of Storm2k. It's getting a bit of love.

[WeatherGuesser]

I'm going with 85 kts at the moment, no reason to change it from earlier

That would put it back to a 2.

[Yellow Evan]

The Hawaiian Islands aren't exactly surge prone, except perhaps places like Pearl Harbor from approaches from the south.

Hilo? It is prone to tsunamis.

[Kingarabian]

The Hawaiian Islands aren't exactly surge prone, except perhaps places like Pearl Harbor from approaches from the south.

This right here. Tsunami warnings here almost always call for evacuations in the danger zones.

[dexterlabio]

How often do we see multiple strong hurricanes in the Pacific, crossing from one basin to another, and some of them even threatening Hawaii, during non-El Nino years?

[Kingarabian]

How often do we see multiple strong hurricanes in the Pacific, crossing from one basin to another, and some of them even threatening Hawaii, during non-El Nino years?

It could be that we're in a hidden El-Nino. Honestly I don't know. This seems like Iniki's year.

[tolakram]

I was going to say it appears to be weakening, but looking at the IR it appears a new burst is ongoing.

Live IR: http://wwwghcc.msfc.nasa.gov/cgi-bin/get-goes?satellite=GOES-W%20PACUS&lat=18&lon=-150&info=ir&zoom=1&width=1000&height=1000&type=Animation&quality=95&palette=ir2.pal&numframes=10

[Kingarabian]

Looks like she's running away from south easterly shear.

[CrazyC83]

EPAC storms rarely get 10 pages, let alone 41 (and we aren't at landfall yet).

[Yellow Evan]

How often do we see multiple strong hurricanes in the Pacific, crossing from one basin to another, and some of them even threatening Hawaii, during non-El Nino years?

1985 is the only one that came close, and Hawaii was somewhat speared that year.

[AFWeather]

CPHC must have heard you guys. Update out BEFORE 5PM HST, how about that. Discussion and all. Track bumped north a little.

WTPA43 PHFO 070230
TCDCP3

HURRICANE ISELLE DISCUSSION NUMBER 28
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP092014
500 PM HST WED AUG 06 2014

THE SATELLITE PRESENTATION OF ISELLE HAS DEGRADED SOME OVER THE PAST
FEW HOURS...WITH THE CDO BECOMING RAGGED WITH A PARTIALLY CLOUD
FILLED EYE. AN AIR FORCE RECONAISSANCE AIRCRAFT MADE SEVERAL HELPFUL
PASSES THROUGH THE CYCLONE. MAXIMUM FLIGHT LEVEL WINDS OF 99 KT WERE
RECORDED ON A COUPLE OF EARLIER RECONNASSIANCE PASSES...AND THE
MAXIMUM SFMR WINDS WERE ABOUT 74 KT TO THE NW OF THE CENTER. DVORAK
INTENSITY ESTIMATES WERE A CONSENSUS 4.5 OR 77 KT FROM PHFO...JTWC...
AND SAB. GIVEN ALL OF THIS...WE WILL MAINTAIN A CURRENT INTENSITY OF
80 KT FOR THIS ADVISORY. THE NEXT RECONNAISANCE AIRCRAFT IS
SCHEDULED TO INVESIGATE ISELLE AROUND 0530Z.

ISELLE APPEARS TO BE IN A SMALL REGION OF RELATIVELY WEAK SHEAR TO
THE NORTH OF AN UPPER LEVEL LOW. STRONGER UPPER LEVEL NORTHERLIES
BETWEEN THE BIG ISLAND AND ISELLE ARE EXPECTED TO WEAKEN SOMEWHAT
OVER THE NEXT 36 HOURS. THIS WILL KEEP ONLY WEAK NORTHERLY SHEAR
OVER ISELLE UNTIL IT GETS CLOSE TO HAWAII. SINCE ISELLE IS OVER
MARGINAL SEA SURFACE TEMPERATURES OF ABOUT 26C...AND SHEAR IS
EXPECTED TO REMAIN WEAK...ONLY SLOW WEAKENING WOULD BE EXPECTED
UNTIL THE HURRICANE IS QUITE CLOSE TO THE ISLANDS. IT IS IMPORTANT
TO NOTE THAT WHETHER ISELLE REACHES THE ISLANDS AS A MINIMAL
HURRICANE OR A TROPICAL STORM...SIGNIFICANT IMPACTS FROM WIND...
RAIN...AND SURF CAN BE EXPECTED.

A DIGGING UPPER TROUGH JUST NORTHWEST OF HAWAII IS EXPECTED TO
INDUCE STRONGER SHEAR OVER THE SYSTEM BEYOND 24 HOURS. THERE IS
ALSO THE POSSIBILITY OF SOME DISRUPTION OF THE CYCLONE FROM THE
ISLAND TERRAIN IF THE CYCLONE MOVES OVER THE MOUNTAINOUS TERRAIN OF
THE BIG ISLAND. THE INTENSITY FORECAST CONTINUES TO SHOW A MORE
SIGNIFICANT WEAKENING AFTER 36 HOURS...BUT THE FORECAST CONFIDENCE
IS RATHER LOW. IF ISELLE SURVIVES IT/S INTERACTION WITH THE TROUGH...
THE SHEAR IS EXPECTED TO WEAKEN AGAIN WITH WARMER SSTS AND SO THERE
IS A CHANCE FOR REINTENSIFICATION AGAIN AT THE LONGER TIME RANGES.

THE FORECAST TRACK PHILOSOPHY REMAINS UNCHANGED. ISELLE WILL
CONTINUE TO GRADUALLY GAIN LATITUDE TO THE SOUTH OF A RELATIVELY
WEAK SUBTROPICAL RIDGE SEVERAL HUNDRED MILES NORTH OF THE HAWAIIAN
ISLANDS. THE TRACK GUIDANCE SHIFTED SLIGHTLY NORTH WITH THIS
CYCLE...AND THE FORECAST HAS BEEN ADJUSTED ACCORDINGLY. EVEN THOUGH
THE SHIFT IS SMALL...THE CHANGE REQUIRES AN UPGRADE TO A TROPICAL
STORM WARNING FOR OAHU...AND THE ISSUANCE OF A TROPICAL STORM WATCH
FOR KAUAI AND NIIHAU.


FORECAST POSITIONS AND MAX WINDS

INIT 07/0300Z 17.7N 147.5W 80 KT 90 MPH
12H 07/1200Z 18.2N 149.9W 75 KT 85 MPH
24H 08/0000Z 19.0N 153.2W 70 KT 80 MPH
36H 08/1200Z 19.8N 156.4W 60 KT 70 MPH
48H 09/0000Z 20.6N 159.4W 50 KT 60 MPH
72H 10/0000Z 21.9N 163.7W 45 KT 50 MPH
96H 11/0000Z 23.2N 168.4W 40 KT 45 MPH
120H 12/0000Z 24.7N 173.1W 40 KT 45 MPH

[Yellow Evan]

EPAC storms rarely get 10 pages, let alone 41 (and we aren't at landfall yet).

So far, Amanda, Cristina, Genevieve, and Boris all got 10 pages.

Seasonal thread is 41 pages as well, easily a record.

[Kingarabian]

Tropical Storm warning for Oahu!

AND THE DISCUSSION WAS ON TIME!! YES!!!

[Kingarabian]

HURRICANE ISELLE DISCUSSION NUMBER 28
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP092014
500 PM HST WED AUG 06 2014

THE SATELLITE PRESENTATION OF ISELLE HAS DEGRADED SOME OVER THE PAST
FEW HOURS...WITH THE CDO BECOMING RAGGED WITH A PARTIALLY CLOUD
FILLED EYE. AN AIR FORCE RECONAISSANCE AIRCRAFT MADE SEVERAL HELPFUL
PASSES THROUGH THE CYCLONE. MAXIMUM FLIGHT LEVEL WINDS OF 99 KT WERE
RECORDED ON A COUPLE OF EARLIER RECONNASSIANCE PASSES...AND THE
MAXIMUM SFMR WINDS WERE ABOUT 74 KT TO THE NW OF THE CENTER. DVORAK
INTENSITY ESTIMATES WERE A CONSENSUS 4.5 OR 77 KT FROM PHFO...JTWC...
AND SAB. GIVEN ALL OF THIS...WE WILL MAINTAIN A CURRENT INTENSITY OF
80 KT FOR THIS ADVISORY. THE NEXT RECONNAISANCE AIRCRAFT IS
SCHEDULED TO INVESIGATE ISELLE AROUND 0530Z.

ISELLE APPEARS TO BE IN A SMALL REGION OF RELATIVELY WEAK SHEAR TO
THE NORTH OF AN UPPER LEVEL LOW. STRONGER UPPER LEVEL NORTHERLIES
BETWEEN THE BIG ISLAND AND ISELLE ARE EXPECTED TO WEAKEN SOMEWHAT
OVER THE NEXT 36 HOURS. THIS WILL KEEP ONLY WEAK NORTHERLY SHEAR
OVER ISELLE UNTIL IT GETS CLOSE TO HAWAII. SINCE ISELLE IS OVER
MARGINAL SEA SURFACE TEMPERATURES OF ABOUT 26C...AND SHEAR IS
EXPECTED TO REMAIN WEAK...ONLY SLOW WEAKENING WOULD BE EXPECTED
UNTIL THE HURRICANE IS QUITE CLOSE TO THE ISLANDS. IT IS IMPORTANT
TO NOTE THAT WHETHER ISELLE REACHES THE ISLANDS AS A MINIMAL
HURRICANE OR A TROPICAL STORM...SIGNIFICANT IMPACTS FROM WIND...
RAIN...AND SURF CAN BE EXPECTED.

A DIGGING UPPER TROUGH JUST NORTHWEST OF HAWAII IS EXPECTED TO
INDUCE STRONGER SHEAR OVER THE SYSTEM BEYOND 24 HOURS. THERE IS
ALSO THE POSSIBILITY OF SOME DISRUPTION OF THE CYCLONE FROM THE
ISLAND TERRAIN IF THE CYCLONE MOVES OVER THE MOUNTAINOUS TERRAIN OF
THE BIG ISLAND. THE INTENSITY FORECAST CONTINUES TO SHOW A MORE
SIGNIFICANT WEAKENING AFTER 36 HOURS...BUT THE FORECAST CONFIDENCE
IS RATHER LOW. IF ISELLE SURVIVES IT/S INTERACTION WITH THE TROUGH...
THE SHEAR IS EXPECTED TO WEAKEN AGAIN WITH WARMER SSTS AND SO THERE
IS A CHANCE FOR REINTENSIFICATION AGAIN AT THE LONGER TIME RANGES.

THE FORECAST TRACK PHILOSOPHY REMAINS UNCHANGED. ISELLE WILL
CONTINUE TO GRADUALLY GAIN LATITUDE TO THE SOUTH OF A RELATIVELY
WEAK SUBTROPICAL RIDGE SEVERAL HUNDRED MILES NORTH OF THE HAWAIIAN
ISLANDS. THE TRACK GUIDANCE SHIFTED SLIGHTLY NORTH WITH THIS
CYCLE...AND THE FORECAST HAS BEEN ADJUSTED ACCORDINGLY. EVEN THOUGH
THE SHIFT IS SMALL...THE CHANGE REQUIRES AN UPGRADE TO A TROPICAL
STORM WARNING FOR OAHU...AND THE ISSUANCE OF A TROPICAL STORM WATCH
FOR KAUAI AND NIIHAU.


FORECAST POSITIONS AND MAX WINDS

INIT 07/0300Z 17.7N 147.5W 80 KT 90 MPH
12H 07/1200Z 18.2N 149.9W 75 KT 85 MPH
24H 08/0000Z 19.0N 153.2W 70 KT 80 MPH
36H 08/1200Z 19.8N 156.4W 60 KT 70 MPH
48H 09/0000Z 20.6N 159.4W 50 KT 60 MPH
72H 10/0000Z 21.9N 163.7W 45 KT 50 MPH
96H 11/0000Z 23.2N 168.4W 40 KT 45 MPH
120H 12/0000Z 24.7N 173.1W 40 KT 45 MPH

$$
FORECASTER R BALLARD

[Yellow Evan]

CPHC must have heard you guys. Update out BEFORE 5PM HST, how about that. Discussion and all. Track bumped north a little.

Yea, credit goes to the CPHC for handling this advisory package well. They have a lot going on.

[somethingfunny]

The Hawaiian Islands aren't exactly surge prone, except perhaps places like Pearl Harbor from approaches from the south.

This is absolutely not true.

Hurricane Iwa brought an 8-foot storm surge to Kauai that reached 900 feet inland in 1982 so you shouldn't think it can't happen along any low-lying coast on any of the islands.

On the big island, Hilo Bay amplifies surges from tsunamis and would amplify storm surge in a storm coming in from this angle. No storm has ever hit at this angle with RFQ onshore winds. You might get false tsunami alarms from earthquakes in Chile or Japan because the angle isn't set up properly, but Hilo frequently has been devastated by tsunamis coming from Alaska, and Iselle/Julio will bring onshore winds at that same angle so there is absolutely a surge threat with these.

that would be determined by how bad Iselle is

If Iselle does not behave... wont matter that much what Julio does because Iselle would have done all of the damage

One other thing to consider, the building codes are not very good in Hawaii. Even a cat 1 Iselle will cause widespread damage, reducing any potential damage for Julio

Lots of houses in Hawaii are old and made out of wood. Our houses here start shaking at the slightest amounts of high winds (15-25mpg gusts). This could be very bad.

I didn't know that about Hawaiian construction practices. This is definitely worth keeping in mind as well, especially since higher elevations will get much higher wind gusts even from what might seem like a weak storm. Hurricane Iwa for example was a Category 1 and aside from the 8-foot surge, it produced gusts of up to 120mph. Even a minimal tropical storm would probably produce hurricane-force gusts in certain locations on the islands.

With all that staying in mind I would still say that I expect Iselle to rapidly weaken before landfall due to wind shear near the Big Island, but that even a minimal tropical storm would potentially cause great damage.

[somethingfunny]

CPHC must have heard you guys. Update out BEFORE 5PM HST, how about that. Discussion and all. Track bumped north a little.

Yea, credit goes to the CPHC for handling this advisory package well. They have a lot going on.

Cut 'em some slack. I've seen folks get impatient even when advisories are on time. Though I do wonder if maybe an NHC forecaster or two caught a flight to Honolulu and is just hanging out in the office there to offer some extra hands. They definitely need some help right now! The CPHC is basically just the same folks who work at the Honolulu NWS office, this is all just extra work and overtime for them in addition to their existing responsibilities as the forecast office for all of Hawaii. Imagine if the NHC was also the Miami NWS office and had to issue Hurricane Local Statements, Point Forecasts, Flood Watches, all that jazz... in addition to being the NHC.

[Alyono]

I don't see anything that will cause this to rapidly weaken to be honest. I do see the shear, but over the Islands. Probably wont be sheared until after landfall

What will rapidly weaken this is crossing 14,000 foot mountains. Dont think it will survive long after crossing the Big Island

[supercane4867]

At 5:00 PM HST, the center of Hurricane Iselle was located at 17.7N 147.5W.

510 miles ESE of Hilo
575 miles ESE of Kailua-Kona
545 miles E of South Point
620 miles ESE of Kahului
675 miles ESE of Kaunakakai
650 miles ESE of Lanai City
720 miles ESE of Honolulu
820 miles ESE of Lihue
870 miles ESE of Niihau

[somethingfunny]

I don't see anything that will cause this to rapidly weaken to be honest. I do see the shear, but over the Islands. Probably wont be sheared until after landfall

What will rapidly weaken this is crossing 14,000 foot mountains. Dont think it will survive long after crossing the Big Island

It would be unprecedented if indeed this doesn't weaken before landfall and a very dangerous situation for a population which is probably viewing these forecasts with an understandable grain of salt...

At 5:00 PM HST, the center of Hurricane Iselle was located at 17.7N 147.5W.

510 miles ESE of Hilo
575 miles ESE of Kailua-Kona
545 miles E of South Point
620 miles ESE of Kahului
675 miles ESE of Kaunakakai
650 miles ESE of Lanai City
720 miles ESE of Honolulu
820 miles ESE of Lihue
870 miles ESE of Niihau

That loop is beautiful! I like that the convergence boundary in the lee of Mauna Kea is so visible. Clearly some northeasterly winds occurring on the Big Island right now.

I wanted to post this too because it is very historic: