CPAC: JULIO - Post-Tropical

[Yellow Evan]

WTPA44 PHFO 141440
TCDCP4

TROPICAL STORM JULIO DISCUSSION NUMBER 43
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP102014
500 AM HST THU AUG 14 2014

DEEP CONVECTION ASSOCIATED WITH JULIO HAS BEEN PUSHED AWAY MORE THAN
60 NM TO THE SOUTH OF THE LLCC...WHICH APPEARS TO BE EMERGING FROM
BENEATH REMNANT LAYERED CLOUDS. THIS SYSTEM IS CLEARLY WINDING DOWN
AS IT CRAWLS NORTHEASTWARD BENEATH DEBILITATING SHEAR. SATELLITE FIX
AGENCIES PROVIDED CURRENT INTENSITY ESTIMATES RANGING FROM
4.0...FROM CPHC AND SAB...TO 3.5 FROM JTWC. THE UW-CIMSS ADT WAS
3.7. AN 0812Z ASCAT PASS CAPTURED THE ENTIRE CIRCULATION AND SHOWED
45 KT WIND BARBS WITHIN A NARROW SWATH ABOUT 30 NM SE OF THE LLCC.
MOST OF THIS DATA CORROBORATES THE WEAKENING TREND NOTED IN
SATELLITE PRESENTATION...SO THE INITIAL INTENSITY WILL BE SET TO 55
KT FOR THIS FORECAST PACKAGE.

FORWARD MOTION FOR THIS SYSTEM HAS INCREASED SLIGHTLY FROM THE
PREVIOUS FORECAST PACKAGE...WITH ANIMATION SHOWING MOVEMENT TOWARD
THE NORTHEAST...040 DEGREES...AT 4 KT OVER THE PAST SIX HOURS.
EXCEPT FOR THE BAM SUITE...WHICH WANTS TO SWING JULIO BACK SHARPLY
TO THE LEFT...TRACK GUIDANCE IS RATHER TIGHTLY PACKED TAKING JULIO
GENERALLY TO THE NORTH NORTHEAST. INTERESTINGLY...TRACK LENGTH FOR
THE VARIOUS MODELS KEEPS GETTING SHORTER WITH EACH RUN AS IT BECOMES
OBVIOUS THAT THIS SYSTEM IS NOT LIKELY TO SPRINT OFF IN ANY
DIRECTION BEFORE DISSIPATION. THE FORECAST TRACK LENGTH HAS
GENERALLY BEEN SHORTER THAN GUIDANCE FOR THE PAST FEW DAYS...AND
REMAINS SO NOW. WE WILL CONTINUE TO FOLLOW THE CONSENSUS
TRACK...TVCN IN PARTICULAR...WHICH KEEPS THE TRACK JUST RIGHT OF
GFDL AND HWRF BUT JUST LEFT OF ECMWF.

SHEAR ACROSS JULIO WILL REMAIN AT OR ABOVE 18 KT THROUGH 24
HOURS...AND NEAR 30 KT FOR THE NEXT 6 HOURS...CAUSING SHIPS TO
COMPLETELY DISSIPATE THIS SYSTEM BY SATURDAY MORNING. THE OTHER
INTENSITY MODELS DRAG OUT SYSTEM WEAKENING THROUGH AT LEAST 96
HOURS...WITH JULIO GENERALLY DEPICTED AS DECREASING BELOW TROPICAL
STORM STRENGTH AT 36 TO 48 HOURS. GIVEN THE DEGREE OF WEAKENING SEEN
IN SATELLITE PRESENTATION OVER THE PAST SIX HOURS AND DECREASING
SSTS ALONG THE FORECAST TRACK...WE WILL WEAKEN JULIO A BIT FASTER
THAN IN PREVIOUS PACKAGES...TO A TROPICAL DEPRESSION AT 48 HOURS. WE
THEN FORECAST EXTRATROPICAL TRANSITION...AND POSSIBLE
DISSIPATION...AT 72 HOURS.

FORECAST POSITIONS AND MAX WINDS

INIT 14/1500Z 31.6N 158.5W 55 KT 65 MPH
12H 15/0000Z 32.0N 158.1W 45 KT 50 MPH
24H 15/1200Z 32.8N 157.8W 40 KT 45 MPH
36H 16/0000Z 33.6N 157.7W 35 KT 40 MPH
48H 16/1200Z 34.6N 157.7W 30 KT 35 MPH
72H 17/1200Z 37.1N 157.6W 25 KT 30 MPH...POST-TROP/EXTRATROP

$$
FORECASTER POWELL

[hurricanes1234]

Where's Julio?

[HurricaneBelle]

Where's Julio?

Down by the schoolyard with Paul Simon.

[Yellow Evan]

EP, 10, 2014081418, , BEST, 0, 315N, 1580W, 50, 990, TS, 34, NEQ, 70, 80, 60, 50, 1014, 160, 25, 0, 0, E, 0, , 0, 0, JULIO, M,
EP, 10, 2014081418, , BEST, 0, 315N, 1580W, 50, 990, TS, 50, NEQ, 25, 25, 10, 10, 1014, 160, 25, 0, 0, E, 0, , 0, 0, JULIO, M,

[supercane4867]

Classic post-tropical storm

[Yellow Evan]

Tropical Storm JULIO Advisory Number 44
Issued at 1100 AM HST THU AUG 14 2014
SUMMARY OF 1100 AM HST...2100 UTC...INFORMATION
-----------------------------------------------
Location: 31.6N 157.8W
ABOUT 710 MI...1145 KM N OF HONOLULU HAWAII
Maximum sustained winds: 60 MPH...95 KM/H
Present movement: ENE or 60 degrees AT 5 MPH...7 KM/H
Minimum central pressure: 990 MB...29.24 INCHES

wtf

[Kingarabian]

Tropical Storm JULIO Advisory Number 44
Issued at 1100 AM HST THU AUG 14 2014
SUMMARY OF 1100 AM HST...2100 UTC...INFORMATION
-----------------------------------------------
Location: 31.6N 157.8W
ABOUT 710 MI...1145 KM N OF HONOLULU HAWAII
Maximum sustained winds: 60 MPH...95 KM/H
Present movement: ENE or 60 degrees AT 5 MPH...7 KM/H
Minimum central pressure: 990 MB...29.24 INCHES

wtf

Constraint rules limit how fast a storm can weaken.

[Yellow Evan]

Tropical Storm JULIO Advisory Number 44
Issued at 1100 AM HST THU AUG 14 2014
SUMMARY OF 1100 AM HST...2100 UTC...INFORMATION
-----------------------------------------------
Location: 31.6N 157.8W
ABOUT 710 MI...1145 KM N OF HONOLULU HAWAII
Maximum sustained winds: 60 MPH...95 KM/H
Present movement: ENE or 60 degrees AT 5 MPH...7 KM/H
Minimum central pressure: 990 MB...29.24 INCHES

wtf

Constraint rules limit how fast a storm can weaken.

Yea, but when there's a swirl of clouds, I doubt the winds are higher than 35-40 knts.

[Yellow Evan]

WTPA44 PHFO 142031
TCDCP4

TROPICAL STORM JULIO DISCUSSION NUMBER 44
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP102014
1100 AM HST THU AUG 14 2014

STRONG NORTHERLY SHEAR FROM A PROGRESSIVE SHORTWAVE TROUGH PASSING
BY TO THE NORTH OF JULIO LAST NIGHT PUNCHED THE DEEP CONVECTION OFF
THE TOP OF THE STORM...WHICH NOW CONSISTS OF A SWIRL OF LOW-MID
LEVEL LAYERED CLOUDS. THE DVORAK CI NUMBERS WERE 3.5 FROM PHFO AND
SAB...AND 45 KT FROM JTWC. AN 0812Z ASCAT PASS OVER THE SYSTEM
SHOWED SEVERAL 45 KT WIND BARBS TO THE EAST OF THE CENTER...WHICH IS
LIKELY BIASED LOW. GIVEN ALL OF THIS DATA...THE CURRENT INTENSITY
WILL BE LOWERED TO 50 KT FOR THIS ADVISORY.

A SMALL ADJUSTMENT TO THE 12Z POSITION WAS MADE BASED ON THE
EMERGENCE OF THE LLCC FROM UNDER THE HIGHER CLOUDS. THIS RESULTS IN
AN INITIAL MOTION OF 055/4 FOR THIS ADVISORY...AS JULIO CONTINUES
MOVING THROUGH A BREAK IN THE SUBTROPICAL RIDGE. THE TRACK GUIDANCE
REMAINS IN FAIRLY GOOD AGREEMENT IN THE NEAR TERM. THE CYCLONE WILL
CONTINUE TO MOVE SLOWLY TOWARD THE ENE FOR THE NEXT DAY OR SO...AND
THEN TURN BACK TOWARD THE NORTH IN A COUPLE OF DAYS AS A HIGH OVER
THE NORTHEAST PACIFIC STRENGTHENS. THERE IS A FAIR AMOUNT OF
UNCERTAINTY IN THE TRACK BEYOND 48 HOURS DUE TO AN INCREASING SPREAD
IN THE GUIDANCE AT THAT TIME. THE OFFICIAL FORECAST IS JUST A BIT TO
THE RIGHT OF THE PREVIOUS FORECAST THROUGH THE NEXT COUPLE OF DAYS...
THEN SIMILAR TO...BUT SLOWER THAN THE PREVIOUS FORECAST PRIOR
TO DISSIPATION.

GLOBAL MODELS ARE IN GOOD AGREEMENT THAT AN UPPER LEVEL RIDGE WILL
BUILD WEST OF THE CYCLONE IN THE WAKE OF THE TROUGH...WHICH WILL
MAINTAIN A MODERATE AMOUNT OF NORTHERLY SHEAR OVER THE SYSTEM
THROUGH THE FORECAST PERIOD. IN ADDITION...THE TRACK FORECAST TAKES
JULIO SLOWLY TO THE NORTH OVER PROGRESSIVELY COOLER WATER...WHICH
WILL ALSO FURTHER WEAKEN THE SYSTEM. THE OFFICIAL FORECAST SHOWS
JULIO REACHING REMNANT LOW STATUS IN 48 HOURS.


FORECAST POSITIONS AND MAX WINDS

INIT 14/2100Z 31.6N 157.8W 50 KT 60 MPH
12H 15/0600Z 32.0N 157.3W 40 KT 45 MPH
24H 15/1800Z 32.8N 157.0W 35 KT 40 MPH
36H 16/0600Z 33.5N 157.0W 30 KT 35 MPH
48H 16/1800Z 34.4N 157.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 17/1800Z 36.0N 157.6W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 18/1800Z...DISSIPATED

$$
FORECASTER R BALLARD

[Iceman56]

Tropical Storm JULIO Advisory Number 44
Issued at 1100 AM HST THU AUG 14 2014
SUMMARY OF 1100 AM HST...2100 UTC...INFORMATION
-----------------------------------------------
Location: 31.6N 157.8W
ABOUT 710 MI...1145 KM N OF HONOLULU HAWAII
Maximum sustained winds: 60 MPH...95 KM/H
Present movement: ENE or 60 degrees AT 5 MPH...7 KM/H
Minimum central pressure: 990 MB...29.24 INCHES

wtf

Even without deep convection, winds from a tropical cyclone do not immediately dissipate. It takes awhile for the winds to spin down, and the winds and seas are still a significant hazard to mariners. Last night's ASCAT passes over Julio are proof of that. There was still a swath of 45 kt winds to the east of the center at 0812Z, and the ASCAT has a low bias at those wind speeds. Thus the previous advisory was 55 kt, and my advisory intensity is 50 kt. I addressed this in my TCD.

[RL3AO]

Tropical Storm JULIO Advisory Number 44
Issued at 1100 AM HST THU AUG 14 2014
SUMMARY OF 1100 AM HST...2100 UTC...INFORMATION
-----------------------------------------------
Location: 31.6N 157.8W
ABOUT 710 MI...1145 KM N OF HONOLULU HAWAII
Maximum sustained winds: 60 MPH...95 KM/H
Present movement: ENE or 60 degrees AT 5 MPH...7 KM/H
Minimum central pressure: 990 MB...29.24 INCHES

wtf

Constraint rules limit how fast a storm can weaken.

Yea, but when there's a swirl of clouds, I doubt the winds are higher than 35-40 knts.

If its a 990mb swirl of clouds then it has higher than 40kt winds. PGF FTW.

[supercane4867]

Tropical Storm JULIO Advisory Number 44
Issued at 1100 AM HST THU AUG 14 2014
SUMMARY OF 1100 AM HST...2100 UTC...INFORMATION
-----------------------------------------------
Location: 31.6N 157.8W
ABOUT 710 MI...1145 KM N OF HONOLULU HAWAII
Maximum sustained winds: 60 MPH...95 KM/H
Present movement: ENE or 60 degrees AT 5 MPH...7 KM/H
Minimum central pressure: 990 MB...29.24 INCHES

wtf

Even without deep convection, winds from a tropical cyclone do not immediately dissipate. It takes awhile for the winds to spin down, and the winds and seas are still a significant hazard to mariners. Last night's ASCAT passes over Julio are proof of that. There was still a swath of 45 kt winds to the east of the center at 0812Z, and the ASCAT has a low bias at those wind speeds. Thus the previous advisory was 55 kt, and my advisory intensity is 50 kt. I addressed this in my TCD.

But should a low level swirl devoid of any convection be classified as a tropical cyclone? NHC always discontinues advisory if the system lacked deep convection within 120nm of its center for 12 hours despite windspeed still at gale force and Julio seems to be the case

[Yellow Evan]

Tropical Storm JULIO Advisory Number 44
Issued at 1100 AM HST THU AUG 14 2014
SUMMARY OF 1100 AM HST...2100 UTC...INFORMATION
-----------------------------------------------
Location: 31.6N 157.8W
ABOUT 710 MI...1145 KM N OF HONOLULU HAWAII
Maximum sustained winds: 60 MPH...95 KM/H
Present movement: ENE or 60 degrees AT 5 MPH...7 KM/H
Minimum central pressure: 990 MB...29.24 INCHES

wtf

Even without deep convection, winds from a tropical cyclone do not immediately dissipate. It takes awhile for the winds to spin down, and the winds and seas are still a significant hazard to mariners. Last night's ASCAT passes over Julio are proof of that. There was still a swath of 45 kt winds to the east of the center at 0812Z, and the ASCAT has a low bias at those wind speeds. Thus the previous advisory was 55 kt, and my advisory intensity is 50 kt. I addressed this in my TCD.

Why only a 5 knt decrease though? That ASCAT pass was a while ago, when it at least looked something.

When do you plan to discontinue advisories? 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.

[Iceman56]

NHC and CPHC both use 12-24 hours without deep convection in their decision to declare something post tropical, given our confidence level that persistent deep convection will not redevelop. As of my 21Z advisory, Julio had been without new deep convection for 13 hours. I do think it's pretty unlikely that persistent deep convection will redevelop. However, given that Julio was analyzed at hurricane strength 24 hours ago, and that some of the models show the shear weakening somewhat over the system in the next 24-48 hours as the anticyclone aloft tries to nose in from the west, I don't see any reason to be in a huge rush to drop it from the advisory cycle just yet. As far as only weakening it 5 knots, remember, the current intensity estimates came in at 3.5 (55 kt), 3.5 (55 kt), and 3.0 (45 kt) at 1730Z, so 50 kt is right in there with what the tropical cyclone satellite experts came up with, and agrees well with a slowly diminishing trend as suggested by the ASCAT pass and the very tightly wound LLCC on visible imagery.

p.s. If any brave soul wants to venture in there on their ship and get a measured maximum sustained surface wind back to me, be my guest. "REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 31.6N 157.8W"

[TheStormExpert]

Well this was a VERY VERY unique, interesting, rare, and somewhat record breaking storm!

[Yellow Evan]

NHC and CPHC both use 12-24 hours without deep convection in their decision to declare something post tropical, given our confidence level that persistent deep convection will not redevelop. As of my 21Z advisory, Julio had been without new deep convection for 13 hours. I do think it's pretty unlikely that persistent deep convection will redevelop. However, given that Julio was analyzed at hurricane strength 24 hours ago, and that some of the models show the shear weakening somewhat over the system in the next 24-48 hours as the anticyclone aloft tries to nose in from the west, I don't see any reason to be in a huge rush to drop it from the advisory cycle just yet. As far as only weakening it 5 knots, remember, the current intensity estimates came in at 3.5 (55 kt), 3.5 (55 kt), and 3.0 (45 kt) at 1730Z, so 50 kt is right in there with what the tropical cyclone satellite experts came up with, and agrees well with a slowly diminishing trend as suggested by the ASCAT pass and the very tightly wound LLCC on visible imagery.

p.s. If any brave soul wants to venture in there on their ship and get a measured maximum sustained surface wind back to me, be my guest. "REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 31.6N 157.8W"

Any reason why ADT values weren't factored in? I imagine the NHC would be about to pull the plug right now. Granted, the JMA would still consider this a TD

[supercane4867]

NHC and CPHC both use 12-24 hours without deep convection in their decision to declare something post tropical, given our confidence level that persistent deep convection will not redevelop. As of my 21Z advisory, Julio had been without new deep convection for 13 hours. I do think it's pretty unlikely that persistent deep convection will redevelop. However, given that Julio was analyzed at hurricane strength 24 hours ago, and that some of the models show the shear weakening somewhat over the system in the next 24-48 hours as the anticyclone aloft tries to nose in from the west, I don't see any reason to be in a huge rush to drop it from the advisory cycle just yet. As far as only weakening it 5 knots, remember, the current intensity estimates came in at 3.5 (55 kt), 3.5 (55 kt), and 3.0 (45 kt) at 1730Z, so 50 kt is right in there with what the tropical cyclone satellite experts came up with, and agrees well with a slowly diminishing trend as suggested by the ASCAT pass and the very tightly wound LLCC on visible imagery.

p.s. If any brave soul wants to venture in there on their ship and get a measured maximum sustained surface wind back to me, be my guest. "REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 31.6N 157.8W"

Any reason why ADT values weren't factored in? I imagine the NHC would be about to pull the plug right now. Granted, the JMA would still consider this a TD

Yet last year the JMA called this Tropical Storm Yutu

[Yellow Evan]

EP, 10, 2014081500, , BEST, 0, 319N, 1577W, 45, 994, TS, 34, NEQ, 70, 90, 50, 50, 1014, 160, 25, 0, 0, E, 0, , 0, 0, JULIO, M,

[cycloneye]

TROPICAL STORM JULIO DISCUSSION NUMBER 45
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP102014
500 PM HST THU AUG 14 2014

JULIO CONTINUES TO GRADUALLY SPIN DOWN. A 2034Z ASCAT PASS
PARTIALLY CAPTURED THE WIND FIELD ON THE EAST SIDE OF THE SYSTEM.
THERE WAS A SWATH OF 35 KT WINDS THAT EXTENDED AS FAR AS 85 NM ESE
OF THE CENTER...WHICH IS ABOUT 45 KT WHEN ADJUSTING FOR THE LOW BIAS
OF THE OUTPUT AT THOSE SPEEDS. THE CI NUMBERS FROM PHFO AND SAB ALSO
CAME IN WITH 3.0...WHICH SUPPORT THE 45 KT INTENSITY FOR THIS
ADVISORY.

THE CYCLONE HAS NOT HAD ANY PERSISTENT DEEP CONVECTION BLOWING UP
NEAR THE CENTER FOR ABOUT 16 HOURS NOW...AND SO JULIO/S TIME AS A
TROPICAL CYCLONE MAY BE OVER SOON. ALTHOUGH NOT QUITE AS STRONG AS
THE SHEAR LAST NIGHT...THE MODELS KEEP MODERATE NORTHERLY SHEAR OVER
THE SYSTEM FOR THE NEXT 48 HOURS...ALONG WITH PROGRESSIVELY COOLER
SSTS...SO REGENERATION APPEARS QUITE UNLIKELY. THE FORECAST SHOWS
WEAKENING TO A REMNANT LOW WITHIN 24 HOURS.

THE TRACK GUIDANCE CONTINUES TO SHOW A NORTHWARD TURN THAT SHOULD
HAPPEN OVER THE NEXT 24 HOURS AS A HIGH STRENGTHENS OVER THE
NORTHEAST PACIFIC AND BLOCKS JULIO/S EASTWARD PROGRESS. IN FACT...
THE LAST FEW SATELLITE IMAGES SUGGEST THIS MAY ALREADY BE HAPPENING.
BEYOND ABOUT 24 HOURS...THERE IS A FAIR AMOUNT OF SPREAD AS TO WHERE
JULIO OR ITS REMNANTS GO AS JULIO BEGINS TO GET CAUGHT UP IN THE
WARM CONVEYOR BELT OF A WEAK LOW TO THE WEST. THE LATEST FORECAST IS
A COMPROMISE BETWEEN THE PREVIOUS FORECAST...AND THE SHARPER TURN
BACK TOWARD THE NORTHWEST WHICH IS SHOWN IN THE DYNAMICAL CONSENSUS
TRACKS AFTER 36 HOURS.


FORECAST POSITIONS AND MAX WINDS

INIT 15/0300Z 32.1N 157.6W 45 KT 50 MPH
12H 15/1200Z 32.5N 157.2W 35 KT 40 MPH
24H 16/0000Z 33.0N 157.1W 30 KT 35 MPH
36H 16/1200Z 33.7N 157.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 17/0000Z 34.6N 157.4W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 18/0000Z...DISSIPATED

$$
FORECASTER R BALLARD

[hurricanes1234]

Regardless, Julio has been amazing. It went against several forecasts and intensified more than expected, as well as it lasted much longer than expected. It also reintensified twice above Hawaii, when none of this was expected. Julio also became a rare storm to go in that region above Hawaii. This has been a very interesting storm in my opinion.