EPAC: HILDA- Post-Tropical

[Kingarabian]

You can see it here.


Here's the post:

Most areas of deep low pressure create their own area of minimal shear as latent heat from condensation is released into the environment directly above the storm. This is what aids in development of these deep lows. As the center weakens, cloud tops cool, and this heat transfer slows down. All the 40 and 50 knot shear surrounding the storm then has a chance to start attacking the periphery of the storm, eventually creating a sheared environment and killing the low.

[Yellow Evan]

You can see it here.


Here's the post:

Most areas of deep low pressure create their own area of minimal shear as latent heat from condensation is released into the environment directly above the storm. This is what aids in development of these deep lows. As the center weakens, cloud tops cool, and this heat transfer slows down. All the 40 and 50 knot shear surrounding the storm then has a chance to start attacking the periphery of the storm, eventually creating a sheared environment and killing the low.

Makes sense then. I've just never seen it with small storms.

I've seen it happen visually (where a wall of shear forms) in WPAC typhoons and that is what I was referring to originally:



(Linfa, Chan-hom, and Nangka six weeks ago)

[Yellow Evan]

WTPA25 PHFO 090235
TCMCP5

HURRICANE HILDA FORECAST/ADVISORY NUMBER 13
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP102015
0300 UTC SUN AUG 09 2015

THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.

HURRICANE CENTER LOCATED NEAR 14.1N 144.5W AT 09/0300Z
POSITION ACCURATE WITHIN 15 NM

PRESENT MOVEMENT TOWARD THE WEST-NORTHWEST OR 290 DEGREES AT 10 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 950 MB
MAX SUSTAINED WINDS 115 KT WITH GUSTS TO 140 KT.
64 KT....... 20NE 20SE 10SW 10NW.
50 KT....... 50NE 40SE 20SW 50NW.
34 KT.......110NE 80SE 70SW 100NW.
12 FT SEAS..200NE 100SE 150SW 200NW.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 14.1N 144.5W AT 09/0300Z
AT 09/0000Z CENTER WAS LOCATED NEAR 13.9N 144.0W

FORECAST VALID 09/1200Z 14.6N 146.0W
MAX WIND 115 KT...GUSTS 140 KT.
64 KT... 30NE 25SE 20SW 20NW.
50 KT... 60NE 50SE 30SW 50NW.
34 KT...115NE 90SE 80SW 105NW.

FORECAST VALID 10/0000Z 15.5N 147.6W
MAX WIND 110 KT...GUSTS 135 KT.
64 KT... 30NE 25SE 20SW 20NW.
50 KT... 60NE 50SE 30SW 50NW.
34 KT...125NE 90SE 80SW 110NW.

FORECAST VALID 10/1200Z 16.5N 148.9W
MAX WIND 100 KT...GUSTS 120 KT.
64 KT... 30NE 25SE 20SW 20NW.
50 KT... 60NE 50SE 30SW 50NW.
34 KT...125NE 100SE 80SW 110NW.

FORECAST VALID 11/0000Z 17.5N 149.8W
MAX WIND 85 KT...GUSTS 105 KT.
50 KT... 50NE 40SE 30SW 40NW.
34 KT...120NE 100SE 80SW 105NW.

FORECAST VALID 12/0000Z 19.2N 150.8W
MAX WIND 65 KT...GUSTS 80 KT.
50 KT... 40NE 30SE 20SW 30NW.
34 KT...105NE 90SE 70SW 90NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 125 NM
ON DAY 4 AND 150 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY

OUTLOOK VALID 13/0000Z 20.2N 151.7W
MAX WIND 45 KT...GUSTS 55 KT.

OUTLOOK VALID 14/0000Z 21.0N 153.0W
MAX WIND 40 KT...GUSTS 50 KT.

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 14.1N 144.5W

NEXT ADVISORY AT 09/0900Z

$$
FORECASTER R BALLARD

[Kingarabian]

000
WTPA45 PHFO 090247
TCDCP5

HURRICANE HILDA DISCUSSION NUMBER 13
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP102015
500 PM HST SAT AUG 08 2015

OVER THE PAST FEW HOURS...HILDA APPEARS AS THOUGH IT MAY HAVE
PEAKED IN INTENSITY. ALTHOUGH DEEP COLD CONVECTIVE TOPS CONTINUE TO
SURROUND THE CENTER...THE EYE HAS BECOME ILL-DEFINED AND CLOUD-
FILLED IN THE CONVENTIONAL SATELLITE IMAGERY. THE SUBJECTIVE DVORAK
INTENSITY ESTIMATES WERE UNANIMOUS WITH CI OF 6.0 FROM ALL THE
AGENCIES...THUS 115 KT WILL BE USED FOR THE ADVISORY.

THE INITIAL MOTION IS 290/10. HILDA IS EXPECTED TO CONTINUE MOVING
TOWARD THE WNW...AND GRADUALLY TURN MORE NW WITH TIME TOWARD A
DEVELOPING WEAKNESS IN THE MID-LEVEL RIDGE LOCATED ABOUT 300
MILES EAST OF THE BIG ISLAND. AS HILDA APPROACHES THIS WEAKNESS...
THE CYCLONE WILL SLOW ITS FORWARD SPEED CONSIDERABLY. THE TRACK
FORECAST THROUGH 48 HOURS IS VERY SIMILAR TO THE PREVIOUS
FORECAST...AND ADJUSTED SLIGHTLY TO THE RIGHT AFTER 48 HOURS TO BE
IN BETTER AGREEMENT WITH THE CONSENSUS MODELS. LATE IN THE FORECAST
PERIOD...A TURN BACK TOWARD THE WNW IS ANTICIPATED AS HILDA BEGINS
TO BE INCREASINGLY UNDER THE INFLUENCE OF THE LOW LEVEL TRADE WIND
FLOW.

THE CAUSE OF THE RECENT SLIGHT DEGRADATION IN SATELLITE IMAGERY IS
UNCERTAIN...BUT MAY BE DUE TO AN EYEWALL REPLACEMENT CYCLE. ALTHOUGH
THE CURRENT FORECAST KEEPS HILDA STEADY-STATE OVERNIGHT...THERE IS
STILL A CHANCE HILDA COULD RESTRENGTHEN AS THE HURRICANE REMAINS
OVER WARM SEA SURFACE TEMPERATURES NEAR 28C...AND WEAK SHEAR AS IT
APPROACHES AN UPPER LEVEL RIDGE AXIS ROUGHLY ALONG LATITUDE 16N.
ONCE HILDA MOVES NORTH OF THIS AXIS...THE HURRICANE WILL ENCOUNTER
AN INCREASINGLY HOSTILE ENVIRONMENT WITH STRONG SHEAR THANKS TO THE
VERY PERSISTENT SUBTROPICAL JET STREAM WHICH HAS BEEN IN PLACE NEAR
THE MAIN HAWAIIAN ISLANDS. THIS SHOULD LEAD TO A RATHER RAPID
WEAKENING AFTER 24-36 HOURS. THE FORECAST INTENSITY REFLECTS
THIS...BUT IS NOT AS AGGRESSIVE WITH WEAKENING AS THE SHIPS
GUIDANCE WHICH CONTINUES TO SHOW DISSIPATION IN 5 DAYS.


FORECAST POSITIONS AND MAX WINDS

INIT 09/0300Z 14.1N 144.5W 115 KT 135 MPH
12H 09/1200Z 14.6N 146.0W 115 KT 135 MPH
24H 10/0000Z 15.5N 147.6W 110 KT 125 MPH
36H 10/1200Z 16.5N 148.9W 100 KT 115 MPH
48H 11/0000Z 17.5N 149.8W 85 KT 100 MPH
72H 12/0000Z 19.2N 150.8W 65 KT 75 MPH
96H 13/0000Z 20.2N 151.7W 45 KT 50 MPH
120H 14/0000Z 21.0N 153.0W 40 KT 45 MPH

$$
FORECASTER R BALLARD

[Yellow Evan]

CDG (sub-81C) cloud tops now almost surround the eye.

[Kingarabian]

CDG (sub-81C) cloud tops now almost surround the eye.

The eye just needs to warm.

[Yellow Evan]

CDG (sub-81C) cloud tops now almost surround the eye.

The eye just needs to warm.

I know, but you usually don't see CDG cloud tops in these kinds of hurricanes.

[Yellow Evan]

EP, 10, 2015080906, , BEST, 0, 143N, 1451W, 115, 951, HU, 64, NEQ, 25, 25, 10, 20, 1010, 180, 10, 0, 0, E, 0, , 0, 0, HILDA, D, 0, , 0, 0, 0, 0, genesis-num, 014,

[Kingarabian]

00z Euro has a TS big island land fall.

Models have shifted west for this package. Wish we had G-IV plane.

[Yellow Evan]

00z Euro has a TS big island land fall.

Models have shifted west for this package. Wish we had G-IV plane.

Shift was bound to happen given the more southerly and westerly movement expected.

[Kingarabian]

[srainhoutx]

G-IV is not at Hickam. Been chatting the past hour with my buddy that will pilot the first mission. They are looking forward to getting some good data on the way out to penetrate Hilda later tonight...

[cycloneye]

HURRICANE HILDA DISCUSSION NUMBER 15
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP102015
500 AM HST SUN AUG 09 2015

AFTER A SEVERAL HOUR PERIOD WHERE THE CONVECTION SURROUNDING THE
CENTER OF HILDA WARMED AND SHRANK...COLD CLOUD TOPS HAVE RECENTLY
INCREASED IN AREA AND NOW NEARLY ENCIRCLE THE CENTER...WITH A
RAGGED CLOUD-FILLED EYE READILY APPARENT IN INFRARED IMAGERY. A
BLEND OF SUBJECTIVE DVORAK INTENSITY ESTIMATES FROM PHFO/SAB/PGTW
YIELDS DATA-T NUMBERS NEAR 5.0/90 KT AND CURRENT INTENSITY /CI/
VALUES NEAR 5.5/102 KT...WHILE ADT YIELDS VALUES NEAR 5.5. BASED ON
THIS DATA...THE INITIAL INTENSITY FOR THIS ADVISORY HAS BEEN SET AT
100 KT. A WELL-PLACED 0717Z ASCAT PASS CONFIRMED WHAT WAS FAIRLY
OBVIOUS FROM SATELLITE...THAT HILDA IS A SMALL SYSTEM...AND THIS
DATA LED TO A REDUCTION IN THE TROPICAL STORM FORCE WIND RADII. U.S.
AIR FORCE HURRICANE HUNTERS ARE SCHEDULED TO BEGIN FLYING MISSIONS
INTO HILDA THIS EVENING...AND WILL PROVIDE INCREASED INSIGHT INTO
HILDA/S STRUCTURE.

HILDA CONTINUES TO MOVE STEADILY TOWARD THE WEST-NORTHWEST THIS
MORNING...WITH AN INITIAL MOTION VECTOR OF 290/11 KT. THE HURRICANE
IS BEING STEERED BY A MID- AND UPPER-LEVEL HIGH CENTERED FAR TO
THE NORTHEAST...AND AN ASSOCIATED RIDGE THAT EXTENDS WESTWARD FROM
THE HIGH. LATER TODAY AND TONIGHT HILDA WILL REACH THE WESTERN
TERMINUS OF THE RIDGE...AND A TURN TOWARD THE NORTHWEST WILL ENSUE.
A SIGNIFICANT DECREASE IN FORWARD SPEED IS EXPECTED BY MONDAY AS
STEERING CURRENTS BECOME QUITE WEAK...WITH FORWARD MOTION REDUCED TO
A CRAWL ON DAYS 3 AND 4 AS HILDA APPROACHES HAWAII FROM THE
SOUTHEAST. A MUCH WEAKER HILDA IS FORECAST TO MAKE A TURN TOWARD THE
WEST-NORTHWEST WITH SOME INCREASE IN FORWARD SPEED AT THE END OF THE
FORECAST PERIOD. THE OFFICIAL TRACK FORECAST HAS BEEN NUDGED
WESTWARD THROUGH DAY 3...CLOSELY FOLLOWING THE TVCN CONSENSUS...AND
SHIFTED MORE SIGNIFICANTLY TOWARD THE SOUTHWEST ON DAYS 4 AND 5...
INFLUENCED BY 06Z GFS/00Z ECMWF GUIDANCE.

AS HILDA SLOWLY ROUNDS THE RIDGE AND GAINS LATITUDE...IT WILL
ENCOUNTER INCREASING WESTERLY SHEAR ASSOCIATED WITH THE SUBTROPICAL
JET STREAM...WHICH IS FORECAST TO BE ENHANCED AS A CLOSED LOW ALOFT
TAKES SHAPE NORTH OF HAWAII. THIS INCREASE IN VERTICAL SHEAR WILL
PLACE HILDA IN AN ENVIRONMENT WHICH IS CONDUCIVE FOR WEAKENING...
GRADUAL AT FIRST...AND MORE PRONOUNCED TOWARD THE END OF THE
FORECAST PERIOD AS SHEAR VALUES APPROACH 40 KT. IN THE MEANTIME...
LITTLE CHANGE IN INTENSITY IS FORECAST TODAY...WITH STEADY WEAKENING
ANTICIPATED THEREAFTER. THE INTENSITY FORECAST FOLLOWS THE IVCN
CONSENSUS...BUT REMAINS HIGHER THAN SHIPS GUIDANCE...WHICH IS
THOUGHT TO BE TOO AGGRESSIVE IN DISSIPATING THE CYCLONE...WHICH IT
DOES BY DAY 4.


FORECAST POSITIONS AND MAX WINDS

INIT 09/1500Z 14.7N 146.7W 100 KT 115 MPH
12H 10/0000Z 15.4N 148.0W 95 KT 110 MPH
24H 10/1200Z 16.4N 149.4W 90 KT 105 MPH
36H 11/0000Z 17.3N 150.2W 75 KT 85 MPH
48H 11/1200Z 18.0N 150.8W 60 KT 70 MPH
72H 12/1200Z 19.0N 151.7W 45 KT 50 MPH
96H 13/1200Z 19.5N 153.0W 35 KT 40 MPH
120H 14/1200Z 20.0N 155.0W 30 KT 35 MPH

$$

FORECASTER BIRCHARD

[TheStormExpert]

Looks like Wxman57 was spot on when he said this had peaked last night! Looks like for the Big Island of Hawaii there will be nothing more than a Tropical Depression at best.

[HurricaneRyan]

Hilda reminds me of Iselle from last year.

[Kingarabian]

[Kingarabian]

000
WTPA35 PHFO 091435
TCPCP5

BULLETIN
HURRICANE HILDA ADVISORY NUMBER 15
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP102015
500 AM HST SUN AUG 09 2015

...HILDA WEAKENS SLIGHTLY BUT IS STILL A CATEGORY THREE HURRICANE...


SUMMARY OF 500 AM HST...1500 UTC...INFORMATION
----------------------------------------------
LOCATION...14.7N 146.7W
ABOUT 655 MI...1050 KM ESE OF HILO HAWAII
ABOUT 865 MI...1390 KM ESE OF HONOLULU HAWAII
MAXIMUM SUSTAINED WINDS...115 MPH...185 KM/H
PRESENT MOVEMENT...WNW OR 290 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...963 MB...28.44 INCHES


WATCHES AND WARNINGS
--------------------
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.

INTERESTS IN THE MAIN HAWAIIAN ISLANDS SHOULD MONITOR THE PROGRESS
OF HILDA.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 500 AM HST...1500 UTC...THE CENTER OF HURRICANE HILDA WAS LOCATED
NEAR LATITUDE 14.7 NORTH...LONGITUDE 146.7 WEST. HILDA IS MOVING
TOWARD THE WEST-NORTHWEST NEAR 13 MPH...20 KM/H. HILDA IS EXPECTED
TO GRADUALLY TURN TOWARD THE NORTHWEST AND SLOW IN FORWARD SPEED
OVER THE NEXT COUPLE OF DAYS.

MAXIMUM SUSTAINED WINDS ARE NEAR 115 MPH...185 KM/H...WITH HIGHER
GUSTS. HILDA IS A CATEGORY THREE HURRICANE ON THE SAFFIR-SIMPSON
HURRICANE WIND SCALE. GRADUAL WEAKENING IS EXPECTED TODAY...WITH
MORE SIGNIFICANT WEAKENING FORECAST MONDAY AND TUESDAY.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 25 MILES...35 KM...FROM
THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 90
MILES...150 KM.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 963 MB...28.44 INCHES.


HAZARDS AFFECTING LAND
----------------------
SURF...SWELLS ASSOCIATED WITH HURRICANE HILDA WILL PRODUCE LARGE
SURF ALONG EAST AND SOUTHEAST FACING SHORES OF THE MAIN HAWAIIAN
ISLANDS OVER THE NEXT COUPLE OF DAYS.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...1100 AM HST.

$$

FORECASTER BIRCHARD

[cycloneye]

HURRICANE HILDA DISCUSSION NUMBER 16
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP102015
1100 AM HST SUN AUG 09 2015

SATELLITE FIXES FROM HFO...SAB AND JTWC WERE IN GOOD AGREEMENT ON
BOTH LOCATION AND INTENSITY FOR HURRICANE HILDA. I HAVE SET THE
INITIAL INTENSITY AT 95 KT. THE SATELLITE SIGNATURE OF THE
HURRICANE SHOWS IT HAS WEAKENED OVER THE PAST 24 HOURS. THE
EYE IS NO LONGER WELL-DEFINED. HILDA IS EXPECTED TO CONTINUE SLOWLY
WEAKENING DUE TO WEAK SOUTHWEST SHEAR AND DECREASING SEA SURFACE
TEMPERATURES.

HILDA CONTINUES TO MOVE TOWARD THE WEST-NORTHWEST...WITH AN INITIAL
MOTION OF 290/11 KT. THE HURRICANE IS BEING STEERED BY A RIDGE ALOFT
EXTENDING WEST FROM AN ANTICYCLONE ALOFT FAR TO THE NORTHEAST.
HILDA WILL REACH THE WESTERN EDGE OF THE RIDGE BY THIS EVENING AND
WE EXPECT A TURN TOWARD THE NORTHWEST AT THAT TIME. HILDA IS
EXPECTED TO START MOVING MORE SLOWLY AS IT TURNS TOWARD THE
NORTHWEST AS THE STEERING FLOW WILL BE QUITE WEAK.

FOR CLARITY AND CONVENIENCE WE USUALLY WRITE SEPARATE PARAGRAPHS
FOR INTENSITY AND MOVEMENTS...BUT THE TRACK AND INTENSITY FORECASTS
FOR HILDA CANNOT BE CONSIDERED SEPARATELY. IF HILDA WERE TO REMAIN A
STRONG AND DEEP SYSTEM...HER TRACK WOULD LIKELY TO BE INFLUENCED BY
STEERING FLOW THROUGH A DEEPER LAYER OF THE ATMOSPHERE. THAT WOULD
MEAN A MORE NORTHERLY TRACK. THE WEAKER AND SHALLOWER HILDA
BECOMES...THE MORE ITS TRACK WILL BE INFLUENCED BY THE TRADE-WIND
FLOW IN THE LOWER PART OF THE ATMOSPHERE. THAT WOULD GIVE HILDA A
MORE WESTERLY TRACK.

THE MODELS ARE SHOWING GOOD AGREEMENT ON AN ACCELERATING WEAKENING
TREND AS HILDA ENCOUNTERS SOUTHWEST SHEAR NEAR 40 KT DUE TO A
SUBTROPICAL JET STREAM SOUTH OF A TROPICAL UPPER TROPOSPHERIC
TROUGH OR TUTT. THE MODELS ARE INCREASINGLY GOOD AGREEMENT ON HILDA
TAKING A MORE WESTERLY TRACK AS IT WEAKENS. I HAVE SHIFTED THE
TRACK A BIT FURTHER TO THE LEFT...CLOSER TO THE MODEL CONSENSUS...
WHILE CONTINUING A STEADY WEAKENING.

U.S AIR FORCE HURRICANE HUNTERS ARE SCHEDULED TO BEGIN FLYING
MISSIONS INTO HILDA THIS EVENING. THE DATA FROM THESE MISSIONS
SHOULD HELP REFINE OUR FUTURE FORECASTS.

FORECAST POSITIONS AND MAX WINDS

INIT 09/2100Z 15.0N 147.4W 95 KT 110 MPH
12H 10/0600Z 15.6N 148.7W 90 KT 105 MPH
24H 10/1800Z 16.5N 149.8W 85 KT 100 MPH
36H 11/0600Z 17.3N 150.5W 70 KT 80 MPH
48H 11/1800Z 18.0N 151.0W 55 KT 65 MPH
72H 12/1800Z 18.8N 152.0W 40 KT 45 MPH
96H 13/1800Z 19.2N 153.5W 35 KT 40 MPH
120H 14/1800Z 19.5N 155.5W 30 KT 35 MPH

$$
FORECASTER DONALDSON

[Yellow Evan]

TPPZ02 PGTW 092101

A. HURRICANE 10E (HILDA)

B. 09/2031Z

C. 15.02N

D. 147.51W

E. FIVE/GOES15

F. T5.0/5.0/W1.0/24HRS STT: S0.0/03HRS

G. IR/EIR/VIS/MSI

H. REMARKS: 40A/PBO SBC/ANMTN. LLCC EMBEDDED IN B YIELDS A CF
OF 5.0. MET AND PT AGREE WITH DT. DBO DT.

I. ADDITIONAL POSITIONS:
09/1545Z 14.65N 146.33W MMHS
09/1549Z 14.68N 146.82W WIND
09/1703Z 14.73N 146.93W SSMS
09/1736Z 14.72N 146.88W GPMI
09/1903Z 15.03N 147.18W MMHS


BERMEA

[Kingarabian]