EPAC: IGNACIO - Post-Tropical

[Kingarabian]

while a miss is the most likely outcome, it is by no means certain. still have to carefully monitor this

If it keeps its large size, we can expect TS warnings to go up.

[Kingarabian]

State of Hawaii:

State officials urged residents to be prepared for the possible arrival of two hurricanes.

On Friday afternoon, Gov. David Ige signed an emergency proclamation ahead of Hurricane Ignacio's expected arrival early next week. The proclamation activates the major disaster fund set aside by the Legislature for disaster relief, allows easier access to emergency resources at the state and federal levels, and allows the suspension of certain laws for emergency purposes, according to Ige's office.

“We understand the public is fatigued from experiencing four major approaching storms so far this season, but we urge people to take the weekend to prepare their homes and families for impacts that could be felt statewide,” said Doug Mayne, Hawaii’s administrator of Emergency Management. “Severe weather associated with Ignacio is expected, and with Jimena not far behind, we need to ready ourselves and our loved ones as much as possible with the time we have."

Hurricane Ignacio continued on a path that could take it over or close to Hawaii at hurricane strength early next week. The National Weather Service forecast for Honolulu says "tropical storm conditions (are) possible" starting Monday night and through Tuesday.

CPHC:

Forecasters are also monitoring the subtropical jet stream near Hawaii, which creates wind shear that has weakened previous storms approaching from the southeast.

"That's the big question," said John Bravender, a meteorologist with the weather service in Honolulu. "What's going to happen when the storm interacts with the jet stream?"

The jet stream, and wind shear, is not as strong as it was when hurricanes Hilda and Guillermo approached the islands. So current forecast models have Ignacio staying at hurricane strength as it nears Hawaii.

However, Bravender said the jet stream, and the chance of stronger wind shear, appear to be strengthening and that could change the path and intensity of Ignacio.

I think there's some overreacting going on. But good to be safe than sorry.

[Yellow Evan]

Also Jimena isn't a Hawaii threat.

[Kingarabian]

[Alyono]

why is CPHC thinking watches as soon as tomorrow? Seems a bit early to me

[Kingarabian]

why is CPHC thinking watches as soon as tomorrow? Seems a bit early to me

Also, they're worried about the jetstream making Ignacio go west when the Euro and GFS have this strengthening as it nears Hawaii.

[Kingarabian]

WTPA43 PHFO 290309
TCDCP3

HURRICANE IGNACIO DISCUSSION NUMBER 17
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP122015
500 PM HST FRI AUG 28 2015

A BANDING EYE FEATURE DEVELOPED IN THE VISIBLE IMAGERY AT 2200
UTC...LENDING ADDITIONAL CONFIDENCE IN THE CENTER POSITION FOR
ADVISORY TIME. THE EYE FEATURE HAS SINCE FILLED IN ONCE AGAIN.
DVORAK INTENSITY ESTIMATES WERE 4.5 FROM PHFO AND SAB AND 5.0 FROM
JTWC...SO THE INTENSITY YET AGAIN WILL BE SET TO 80 KT...UNCHANGED
OVER THE PAST 36 HOURS. AN AIR FORCE RESERVE RECONNAISSANCE UNIT IS
SCHEDULED TO INVESTIGATE IGNACIO AT 0600 UTC...WHICH WILL HELP TO
ASCERTAIN THE ACTUAL SIZE AND INTENSITY OF THE HURRICANE.

THE INITIAL MOTION REMAINS A STEADY 305/7. THE FORECAST PHILOSOPHY
IS UNCHANGED...WITH IGNACIO SLOWLY MARCHING NORTHWEST TOWARD A
WEAKNESS IN A MID-LEVEL RIDGE FOR THE NEXT SEVERAL DAYS. ONCE AGAIN
THE TRACK GUIDANCE REMAINS TIGHTLY CLUSTERED...BUT THERE ARE SOME
NOTEWORTHY OUTLIERS THAT BRING IGNACIO A LITTLE FARTHER TO THE LEFT
THAN THE CONSENSUS. THE LEFT-MOST OUTLIERS ARE CERTAINLY PLAUSIBLE
SOLUTIONS...PARTICULARLY IF WIND SHEAR LATER IN THE FORECAST PERIOD
IMPACTS IGNACIO MORE THAN MOST OF THE DYNAMICAL GUIDANCE IS
INDICATING.

DESPITE BEING IN AN ENVIRONMENT OF WEAK SHEAR AND WARM OCEAN
TEMPERATURES...IGNACIO HAS BEEN STUBBORN TO INTENSIFY THUS FAR.
ALTHOUGH IT IS DIFFICULT TO BE CERTAIN WHY...THE CIMSS MIMIC-TOTAL
PRECIPITABLE WATER AS WELL AS VISIBLE SATELLITE IMAGERY SHOWED A
RIBBON OF DRY AIR THAT APPEARS TO HAVE BEEN PULLED INTO THE CORE
CIRCULATION OF THE CYCLONE. IF IGNACIO CAN OVERCOME THIS...THE
ENVIRONMENT STILL SEEMS TO FAVOR SOME INTENSIFICATION OVER THE
NEXT 24-36 HOURS BEFORE SOUTHWESTERLY SHEAR STARTS TO INCREASE.
THERE IS GOOD AGREEMENT IN THE GLOBAL MODELS REGARDING THIS
SHEAR...WHICH SHOULD INDUCE STEADY WEAKENING AFTER 48 HOURS. THE
STATISTICAL GUIDANCE SHOWS A MORE RAPID WEAKENING TREND AND SHIPS
HAS NOW COME INTO BETTER AGREEMENT WITH OUR OFFICIAL FORECAST. THE
DYNAMICAL MODELS HOLD IGNACIO STRONGER...BUT THIS SEEMS UNLIKELY
GIVEN THE SHEAR THEY ARE DEPICTING.


FORECAST POSITIONS AND MAX WINDS

INIT 29/0300Z 15.2N 145.2W 80 KT 90 MPH
12H 29/1200Z 15.9N 146.3W 85 KT 100 MPH
24H 30/0000Z 16.8N 147.8W 90 KT 105 MPH
36H 30/1200Z 17.7N 149.3W 90 KT 105 MPH
48H 31/0000Z 18.6N 150.6W 85 KT 100 MPH
72H 01/0000Z 20.5N 153.4W 75 KT 85 MPH
96H 02/0000Z 22.6N 155.9W 70 KT 80 MPH
120H 03/0000Z 24.7N 158.3W 60 KT 70 MPH

$$
FORECASTER R BALLARD

[Yellow Evan]

WTPA43 PHFO 290309
TCDCP3

HURRICANE IGNACIO DISCUSSION NUMBER 17
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP122015
500 PM HST FRI AUG 28 2015

A BANDING EYE FEATURE DEVELOPED IN THE VISIBLE IMAGERY AT 2200
UTC...LENDING ADDITIONAL CONFIDENCE IN THE CENTER POSITION FOR
ADVISORY TIME. THE EYE FEATURE HAS SINCE FILLED IN ONCE AGAIN.
DVORAK INTENSITY ESTIMATES WERE 4.5 FROM PHFO AND SAB AND 5.0 FROM
JTWC...SO THE INTENSITY YET AGAIN WILL BE SET TO 80 KT...UNCHANGED
OVER THE PAST 36 HOURS. AN AIR FORCE RESERVE RECONNAISSANCE UNIT IS
SCHEDULED TO INVESTIGATE IGNACIO AT 0600 UTC...WHICH WILL HELP TO
ASCERTAIN THE ACTUAL SIZE AND INTENSITY OF THE HURRICANE.

THE INITIAL MOTION REMAINS A STEADY 305/7. THE FORECAST PHILOSOPHY
IS UNCHANGED...WITH IGNACIO SLOWLY MARCHING NORTHWEST TOWARD A
WEAKNESS IN A MID-LEVEL RIDGE FOR THE NEXT SEVERAL DAYS. ONCE AGAIN
THE TRACK GUIDANCE REMAINS TIGHTLY CLUSTERED...BUT THERE ARE SOME
NOTEWORTHY OUTLIERS THAT BRING IGNACIO A LITTLE FARTHER TO THE LEFT
THAN THE CONSENSUS. THE LEFT-MOST OUTLIERS ARE CERTAINLY PLAUSIBLE
SOLUTIONS...PARTICULARLY IF WIND SHEAR LATER IN THE FORECAST PERIOD
IMPACTS IGNACIO MORE THAN MOST OF THE DYNAMICAL GUIDANCE IS
INDICATING.

DESPITE BEING IN AN ENVIRONMENT OF WEAK SHEAR AND WARM OCEAN
TEMPERATURES...IGNACIO HAS BEEN STUBBORN TO INTENSIFY THUS FAR.
ALTHOUGH IT IS DIFFICULT TO BE CERTAIN WHY...THE CIMSS MIMIC-TOTAL
PRECIPITABLE WATER AS WELL AS VISIBLE SATELLITE IMAGERY SHOWED A
RIBBON OF DRY AIR THAT APPEARS TO HAVE BEEN PULLED INTO THE CORE
CIRCULATION OF THE CYCLONE. IF IGNACIO CAN OVERCOME THIS...THE
ENVIRONMENT STILL SEEMS TO FAVOR SOME INTENSIFICATION OVER THE
NEXT 24-36 HOURS BEFORE SOUTHWESTERLY SHEAR STARTS TO INCREASE.
THERE IS GOOD AGREEMENT IN THE GLOBAL MODELS REGARDING THIS
SHEAR...WHICH SHOULD INDUCE STEADY WEAKENING AFTER 48 HOURS. THE
STATISTICAL GUIDANCE SHOWS A MORE RAPID WEAKENING TREND AND SHIPS
HAS NOW COME INTO BETTER AGREEMENT WITH OUR OFFICIAL FORECAST. THE
DYNAMICAL MODELS HOLD IGNACIO STRONGER...BUT THIS SEEMS UNLIKELY
GIVEN THE SHEAR THEY ARE DEPICTING.


FORECAST POSITIONS AND MAX WINDS

INIT 29/0300Z 15.2N 145.2W 80 KT 90 MPH
12H 29/1200Z 15.9N 146.3W 85 KT 100 MPH
24H 30/0000Z 16.8N 147.8W 90 KT 105 MPH
36H 30/1200Z 17.7N 149.3W 90 KT 105 MPH
48H 31/0000Z 18.6N 150.6W 85 KT 100 MPH
72H 01/0000Z 20.5N 153.4W 75 KT 85 MPH
96H 02/0000Z 22.6N 155.9W 70 KT 80 MPH
120H 03/0000Z 24.7N 158.3W 60 KT 70 MPH

$$
FORECASTER R BALLARD

[Kingarabian]

981mb found so far. 80kts is justifiable.

[Alyono]

surface winds are greater than flight level winds. May be a sign of intensification ongoing

[Yellow Evan]

surface winds are greater than flight level winds. May be a sign of intensification ongoing

Something seems fishy about that.

[Alyono]

surface winds are greater than flight level winds. May be a sign of intensification ongoing

Something seems fishy about that.

seemed legit. It is possible, especially when flying at 700mb

[Kingarabian]

00z GFS south of 18z run. Really close to the big island.

It has Ignacio weaker near the big Island compared to the 18z. Maybe the CPHC is right about the shear

[Alyono]

00z GFS south of 18z run. Really close to the big island.

It has Ignacio weaker near the big Island compared to the 18z. Maybe the CPHC is right about the shear

it is still quite strong!

[Kingarabian]

00z GFS south of 18z run. Really close to the big island.

It has Ignacio weaker near the big Island compared to the 18z. Maybe the CPHC is right about the shear

it is still quite strong!

I don't understand the steering. Why would a slight variation in mb cause the track to shift?

[Alyono]

looks like a 75 kt hurricane with a pressure maybe around 976mb

[Kingarabian]

looks like a 75 kt hurricane with a pressure maybe around 976mb

Even though 972mb was found?

[Alyono]

southwest quad is the most intense. winds close to 80 kts at the surface there

[Kingarabian]

southwest quad is the most intense. winds close to 80 kts at the surface there

Not good for Hawaii.

Maybe TS watches should be initiated tomorrow.

[Kingarabian]

00z HWRF closer south.