CPAC: ISELLE - Post-Tropical

[tallywx]

Looks like it won't be a hurricane at landfall after all according to latest advisory.

It could if convection increases a little

Interestingly, last few frames show that.

Outflow on its western semicircle appears ever-so-slightly better too.

[Yellow Evan]

Looks like it won't be a hurricane at landfall after all according to latest advisory.

It could if convection increases a little

Interestingly, last few frames show that.

Yea. Looks a little more organzied. Storms tend to re-fire when they near Hawaii, so I give it a decent shot to hit Hawaii as a cane.

[tallywx]

Winds at Kona International Airport (leeward side of the island) are currently north at 31 mph, gusting to 38, with nary a drop of rain and a temp of 91 (warmest temperature recorded so far this year and first reading above 90). Makes me think some downsloping is going on. It's really going to be fascinating to see how local terrain effects enhance winds locally as this thing comes in.

[Kingarabian]

Funny how the strongest part of the eyewall is from E/NE, yet the deepest convection is to the NW/SW.

[supercane4867]

Pressure seems to be holding steady on this pass

[Yellow Evan]

CPHC still yet to release a discussion.

[tallywx]

CPHC still yet to release a discussion.

HURRICANE ISELLE DISCUSSION NUMBER 31
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP092014
1100 AM HST THU AUG 07 2014

ISELLE CONTINUES TO GRADUALLY WEAKEN. THE EYE IS NO LONGER EVIDENT
IN SATELLITE IMAGERY...AND THE RECONNASIANCE AIRCRAFT FOUND THE
SURFACE PRESSURE AT THE CENTER HAD RISEN A COUPLE OF MILLIBARS.
MAXIMUM FLIGHT LEVEL WINDS ON THE NORTHEAST SIDE OF THE CYCLONE WERE
69 KT...WHICH SUGGESTS MAXIMUM SURFACE WINDS NEAR 60 KT. OTHER
REDUCTION FACTOR TECHNIQUES WERE SUGGESTING 60 TO 65 KT MAXIMUM
SUSTAINED SURFACE WINDS. THUS THE INTENSITY FOR THIS ADVISORY IS
BEING LOWERED TO 65 KNOTS...AND THIS COULD BE A LITTLE GENEROUS.

ISELLE IS STILL LOCATED IN A REGION OF RELATIVELY WEAK SHEAR BETWEEN
TWO UPPER LEVEL ANTICYCLONES...TO ITS EAST AND WEST. THE HURRICANE
HAS BEEN MOVING SLIGHTLY FASTER THAN THIS WEAKNESS...AND WILL START
TO FEEL INCREASING NORTHERLY SHEAR OVER THE NEXT 12 HOURS WHICH WILL
MAINTAIN A WEAKENING TREND DESPITE GRADUALLY INCREASING SEA SURFACE
TEMPERATURES. EVEN IF ISELLE REACHES THE BIG ISLAND AS A TROPICAL
STORM...SIGNIFICANT IMPACTS WILL STILL BE FELT FROM WIND...RAIN...
AND SURF.

BEYOND 12 HOURS...THE COMBINATION OF MUCH STRONGER NORTHERLY SHEAR
AND INTERACTION WITH THE BIG ISLAND TERRAIN IS EXPECTED TO WEAKEN
ISELLE FURTHER. THE TRACK GUIDANCE SHOWED A LITTLE MORE SPREAD FOR
THIS CYCLE...AND SHIFTED SOMEWHAT TO THE SOUTH BEYOND 24 HOURS...
LIKELY DUE TO UNCERTAINTIES WITH THE INTENSITY OF A WEAKER ISELLE.
THE OFFICIAL FORECAST THUS FOLLOWS A SIMILAR TREND WITH A SLIGHT
SOUTHWARD SHIFT BEYOND 24 HOURS. THE INTENSITY FORECAST IS LOWER
THAN THE CONSENSUS BEYOND 72 HOURS WHEN ISELLE IS EXPECTED TO
INTERACT WITH AN UPPER LEVEL LOW DIGGING SOUTH OVER THE NORTHWEST
HAWAIIAN ISLANDS. THERE IS A GOOD CHANCE ISELLE WILL NOT SURVIVE THE
INTERACTION WITH THIS UPPER TROUGH.


FORECAST POSITIONS AND MAX WINDS

INIT 07/2100Z 18.9N 152.2W 65 KT 75 MPH
12H 08/0600Z 19.4N 154.5W 60 KT 70 MPH
24H 08/1800Z 19.9N 157.4W 55 KT 65 MPH
36H 09/0600Z 20.4N 160.0W 45 KT 50 MPH
48H 09/1800Z 20.9N 162.2W 40 KT 45 MPH
72H 10/1800Z 21.8N 166.2W 35 KT 40 MPH
96H 11/1800Z 23.7N 172.0W 30 KT 35 MPH
120H 12/1800Z 25.9N 178.5W 25 KT 30 MPH...POST-TROP/REMNT LOW

[xtyphooncyclonex]

A station in Hilo, Hawaii is currently reporting 25 mph (45 km/h; 22 kts) accompanied by heavy rains. But the hurricane is still to their east, meaning that they may have stronger winds later on. In a few hours, the NW quadrant (most convect) would impact the area already.

http://www.wunderground.com/weather-forecast/US/HI/Hilo.html

[Yellow Evan]

Any reason why they aren't doing 2 hour updates like most US landfalls?

[Yellow Evan]

Convection increasing over the center as of late.

[galaxy401]

68 kts SMFR just found. Still a hurricane.

[Yellow Evan]

68 kts SMFR just found. Still a hurricane.

Peak flight level winds were 73 knts. Up 4 knts.

[Kingarabian]

Pressure

990.1 mb
(~ 29.24 inHg)

SFMR

68 knots
(~ 78.2 mph)

Flight level 10 second avg

73 knots
(~ 83.9 mph)

[Alyono]

that is a fairly large area of hurricane force winds

[supercane4867]

These stronger convection activities definitely helped

[supercane4867]

Dropeside measures 992mb but with 13kt wind, central pressure likely still at 991mb

Level Wind Direction Wind Speed
992mb (Surface) 195° (from the SSW) 13 knots (15 mph)

[Kingarabian]

that is a fairly large area of hurricane force winds

I think we need a Hurricane watch for Maui.

[Yellow Evan]

that is a fairly large area of hurricane force winds

I think we need a Hurricane watch Maui.

Agreed; we'll see what the CPHC says in an hour.

[Alyono]

no need for a hurricane watch for Maui

this is moving closer to 280... not clearing the Big Island

[WeatherGuesser]

My coconut clock is still off. Will this go in before sunset out there?