CPAC: TROPICAL DEPRESSION HILDA (11E)

[clfenwi]

WTPA45 PHFO 270859
TCDCP5

TROPICAL DEPRESSION HILDA DISCUSSION NUMBER 20
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP112009
1100 PM HST WED AUG 26 2009

HILDA REMAINS WEAK AND HAS TURNED SHARPLY TO THE WEST-NORTHWEST.
BETWEEN 200 PM AND 800 PM HST...THE SMALL LOW LEVEL VORTEX MARKING
THE CENTER OF HILDA MOVED TOWARD THE WEST-NORTHWEST. THERE WAS SOME
UNCERTAINTY IN THE POSITIONS FROM PHFO...SAB AND JTWC...BUT ALL THE
DVORAK FIXES...AS WELL AS MICROWAVE IMAGES...SHOWED A JOG TO THE
WEST-NORTHWEST. THE TRACK GUIDANCE HAD BEEN SHOWING A TURN TO THE
WEST-NORTHWEST BUT HILDA HAD KEPT MOVING WEST-SOUTHWEST. IT LOOKS
LIKE HILDA HAS FINALLY STARTED MOVING ALONG A TRACK CLOSER TO THE
MODEL GUIDANCE. THE CURRENT FORECAST SHIFTS THE TRACK SUBSTANTIALLY
TO THE RIGHT OF THE PREVIOUS TRACK AND CLOSER TO THE CENTER OF THE
GUIDANCE ENVELOPE.

SUBJECTIVE DVORAK FIXES CAME IN WITH CI NUMBERS OF 2.0 AND 2.5. A
600 PM QUIKSCAT PASS STILL SHOWED A WELL ORGANIZED CIRCULATION WITH
A SMALL AREA OF 30 KT WINDS NORTHWEST OF THE CENTER. I HAVE KEPT
THE INITIAL INTENSITY AT 30 KT. BETWEEN 200 PM AND 1000 PM THERE
WAS A MODEST INCREASE IN CONVECTION AS A NARROW CURVED BAND OF
CONVECTION FORMED NORTH OF THE CENTER. WITH THE INTENSITY UNCHANGED
OVER THE PAST 6 HOURS AND SOME RECENT INCREASE IN CONVECTION...I
HAVE KEPT THE INTENSITY AT 30 KT FOR THE NEXT 12 HOURS AND WITH A
GRADUAL WEAKENING AFTER THAT. SHEAR OVER THE SYSTEM IS FORECAST TO
BE MODEST AND SEA SURFACE TEMPERATURES REMAIN WARM. HOWEVER...
DESPITE THE GENERALLY FAVORABLE-APPEARING ENVIRONMENT HILDA REMAINS
QUITE SICKLY AND FEW CYCLONES THAT BECOME THIS WEAK MANAGE TO
RE-INTENSIFY SIGNIFICANTLY.



FORECAST POSITIONS AND MAX WINDS

INITIAL 27/0900Z 13.7N 152.5W 30 KT
12HR VT 27/1800Z 13.7N 153.8W 30 KT
24HR VT 28/0600Z 13.9N 155.6W 25 KT
36HR VT 28/1800Z 14.4N 157.5W 25 KT...DISSIPATING
48HR VT 29/0600Z 15.0N 159.5W 25 KT...DISSIPATING
72HR VT 30/0600Z 17.0N 164.0W 25 KT...REMNANT LOW
96HR VT 31/0600Z...DISSIPATED

$$
FORECASTER DONALDSON

[Cyclenall]

Basically, I had "high hopes" for when this system first formed in the Epac but then I got busy and didn't follow it. Thankfully I didn't invest any time into this Cpac failure. It seems like it happens every time other than Ioke in 2006. It strengthened when there was shear and then when that goes away, it falls apart. There is very little skill I believe in the Cpac and it's pretty random from what I have seen.

[clfenwi]

[Chacor]

WTPA45 PHFO 271445
TCDCP5

TROPICAL DEPRESSION HILDA DISCUSSION NUMBER 21
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP112009
500 AM HST THU AUG 27 2009

HILDA REMAINS WEAK. THE DEPRESSION SEEMS TO BE TRACKING
WEST-NORTHWEST BUT FINDING THE CENTER HAS BEEN A CHALLENGE.

CURRENT INTENSITIES WERE 2.0 FROM JTWC AND SAB AND 2.5 FROM PHFO. I
HAVE KEPT THE INTENSITY UNCHANGED AT 30 KT. THE CONVECTIVE BAND
NORTH OF THE CENTER HAS MOSTLY DISSIPATED. NEW CONVECTION HAS
DEVELOPED TO THE SOUTHWEST...BUT THE MOST ACTIVE CONVECTION IS SOME
DISTANCE FROM THE CENTER. THE POORLY ORGANIZED CONVECTIVE PATTERN
INDICATES A RATHER WEAK SYSTEM. SEA SURFACE TEMPERATURES REMAIN
WARM ALONG THE FORECAST TRACK BUT DRY AIR ALOFT TO THE NORTH OF THE
DEPRESSION AND NORTHWEST SHEAR GREATER THAN 20 KT SHOULD CAUSE
CONTINUED WEAKENING. I EXPECT HILDA WILL BE A REMNANT LOW WITHIN 72
HOURS.

THE DVORAK FIXES HAD LATITUDES RANGING FROM 13.6N TO 14.0N WITH
LONGITUDES AROUND 152.7. HOWEVER...ANIMATION OF FOG-CHANNEL DATA
SUGGESTS THE CENTER MAY BE FARTHER NORTHWEST. THERE HAVE BEEN NO
RECENT MICROWAVE PASSES TO HELP OUT AND THE CENTER LOCATION IS
RATHER UNCERTAIN. THE OBJECTIVE AIDS ALL SHOW A GENERALLY
WEST-NORTHWEST TRACK. THE CURRENT FORECAST TRACK HAS BEEN SHIFTED
FARTHER TO THE RIGHT AND IS NOW A BIT TO THE RIGHT OF CENTER OF THE
FORECAST TRACK ENVELOPE.


FORECAST POSITIONS AND MAX WINDS

INITIAL 27/1500Z 14.7N 153.5W 30 KT
12HR VT 28/0000Z 15.0N 155.0W 30 KT
24HR VT 28/1200Z 15.5N 157.0W 25 KT
36HR VT 29/0000Z 16.0N 159.0W 25 KT...DISSIPATING
48HR VT 29/1200Z 16.7N 161.0W 25 KT...DISSIPATING
72HR VT 30/1200Z 18.0N 165.0W 25 KT...REMNANT LOW
96HR VT 31/1200Z...DISSIPATED

$$
FORECASTER DONALDSON

[clfenwi]

WTPA45 PHFO 272054
TCDCP5

TROPICAL DEPRESSION HILDA DISCUSSION NUMBER 22
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP112009
1100 AM HST THU AUG 27 2009

VISIBLE IMAGES REVEAL THAT THE CENTER OF HILDA IS PARTIALLY EXPOSED
TO THE NORTHEAST OF AN AREA OF DEEP CONVECTION THIS MORNING.
SUBJECTIVE SATELLITE ESTIMATED INTENSITIES ARE 2.0 / 30 KT FOR 1800
UTC FROM THE THREE FIX AGENCIES...AND GIVEN A 1645 UTC QUIKSCAT
PASS THAT SUGGESTED THE CONTINUED EXISTENCE OF 30 KT WINDS NORTH OF
THE CENTER...THE CURRENT INTENSITY WILL BE HELD AT 30 KT.

HILDA IS MOVING TOWARD THE WEST...280/11...WITH THIS MOTION A LITTLE
SOUTH OF THAT CONTAINED IN THE PREVIOUS ADVISORY...NECESSITATED BY
A MICROWAVE-ASSISTED SHIFT SOUTHWARD IN THE OVERNIGHT BEST TRACK
POSITIONS. THIS MOTION MATCHES WELL WITH ANIMATION OF VISIBLE
IMAGERY EXTENDING BACK TO YESTERDAY AFTERNOON. HILDA IS MOVING
WESTWARD TO THE SOUTHEAST OF A MID- AND HIGH-LEVEL ANTICYCLONE
CENTERED NORTHWEST OF THE HAWAIIAN ISLANDS...WITH THIS FEATURE
FORECAST TO TRACK WEST IN TANDEM WITH HILDA...MAINTAINING SOME
SEMBLANCE OF NORTHERLY SHEAR OVER THE SYSTEM THROUGHOUT. THE
CURRENT TRACK FORECAST IS SIMILAR TO THAT CONTAINED IN THE PREVIOUS
ADVISORY...SAVE FOR THE SOUTHWARD SHIFT IN THE INITIAL POSITION...
AND IS CLOSE TO THE TVCN...WHICH HAS BEEN VERIFYING WELL WITH
HILDA.

HILDA APPEARS TO BE SLOWLY WINDING DOWN...AS CONVECTION STRUGGLES TO
PERSIST OVER THE CENTER. ALTHOUGH SSTS REMAIN SUFFICIENTLY HIGH
ALONG THE FORECAST TRACK...NONE OF THE INTENSITY FORECAST GUIDANCE
INDICATES SIGNIFICANT RE-INTENSIFICATION OF HILDA...WITH
NORTHWESTERLY SHEAR REMAINING A SIGNIFICANT INHIBITOR. HAVE
CONTINUED WITH THE TREND OF HILDA WEAKENING TO A REMNANT LOW WITHIN
THE NEXT COUPLE OF DAYS.


FORECAST POSITIONS AND MAX WINDS

INITIAL 27/2100Z 14.1N 155.0W 30 KT
12HR VT 28/0600Z 14.4N 156.7W 25 KT
24HR VT 28/1800Z 14.8N 158.9W 25 KT...DISSIPATING
36HR VT 29/0600Z 15.2N 161.1W 25 KT...DISSIPATING
48HR VT 29/1800Z 15.9N 163.2W 25 KT...REMNANT LOW
72HR VT 30/1800Z...DISSIPATED

$$

FORECASTER BIRCHARD

[Aslkahuna]

Shear is not the only problem storms have in CENPAC, the area is dominated by deep Trade flow which tends to have moisture confined to levels below H7 with very dry air above. this can be seen by the fact that the air above the observatory on the Big Island is some of the driest on the Planet which is good for IR Astronomy but not so good for Tropical Cyclones.

Steve

[clfenwi]

28/0000 UTC 13.4N 155.1W T1.0/1.5 HILDA -- Central Pacific

[Chacor]

WTPA35 PHFO 280232
TCPCP5

BULLETIN
TROPICAL DEPRESSION HILDA ADVISORY NUMBER 23
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP112009
500 PM HST THU AUG 27 2009

...HILDA MOVING WEST AND DISSIPATING TO THE SOUTH OF HAWAII...

AT 500 PM HST...0300 UTC...THE CENTER OF DISSIPATING TROPICAL
DEPRESSION HILDA WAS LOCATED NEAR LATITUDE 13.5 NORTH...LONGITUDE
156.1 WEST...OR ABOUT 435 MILES SOUTH OF HILO HAWAII AND ABOUT 550
MILES SOUTH-SOUTHEAST OF HONOLULU HAWAII.

THE DISSIPATING DEPRESSION IS MOVING TOWARD THE WEST NEAR 14 MPH...
AND THIS GENERAL MOTION IS EXPECTED TO CONTINUE UNTIL HILDA
DISSIPATES IN 24 TO 36 HOURS.

MAXIMUM SUSTAINED WINDS ARE NEAR 30 MPH WITH HIGHER GUSTS. HILDA IS
FORECAST TO CONTINUE WEAKENING...AND DISSIPATION IS EXPECTED IN 24
TO 36 HOURS.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 1010 MB...29.83 INCHES.

...SUMMARY OF 500 PM HST INFORMATION...
LOCATION...13.5N 156.1W
MAXIMUM SUSTAINED WINDS...30 MPH
PRESENT MOVEMENT...WEST OR 260 DEGREES AT 14 MPH
MINIMUM CENTRAL PRESSURE...1010 MB

THIS IS THE LAST PUBLIC ADVISORY ISSUED BY THE CENTRAL PACIFIC
HURRICANE CENTER ON THIS SYSTEM.

$$

FORECASTER BIRCHARD

[Cyclenall]

I was surprised when the CPHC issued the final advisory on Hilda right when there is a large burst of deep convection erupting to what might be the south-west side of the LLC. The last initial point at 13.5N 156.1W would place the center under the deep convection. They must be angry at Hilda for doing the opposite of what they forecast nearly the entire time so they call "dissipating". I really wouldn't state that re-intensification appears very unlikely but possibly more like possible.

I'm hoping this Hilda just goes nuts now unexpectedly for some good entertainment. I see no dry air and shear around, go ahead Hilda!

[clfenwi]

Yeah, the last image I posted pretty much shows the minimum. Convective activity has been straight line up since then, albeit appears to be confined to the southern semi-circle.

[clfenwi]

Recovery in the T-number:

28/0600 UTC 14.0N 156.3W T1.5/1.5 HILDA -- Central Pacific

[Cyclenall]

1000 PM HST THU AUG 27 2009

FOR THE CENTRAL NORTH PACIFIC...BETWEEN 140W AND 180

1. Dissipating tropical depression Hilda, located about 350 miles south of South Point on the island of Hawaii, moved west near 14 mph. No further official forecasts or advisories will be issued for this system unless it redevelops.

2. An area of disturbed weather about 1100 miles southwest of Lihue on Kauai moved northwest near 7 mph. This cluster of thunderstorms remained poorly organized, and likely will not develop into tropical cyclone over the next 48 hours.

Elsewhere, no tropical cyclones are expected through Saturday evening.

Dissipating is certainly not the word to use here for what Hilda has been performing for the last 5 hours. They did put "unless it redevelops" in there for the first time.

The burst of convection is looking better every hour and probably is helping the LLC greatly. Hilda is ready!

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 7.2.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 28 AUG 2009 Time : 073000 UTC
Lat : 13:28:07 N Lon : 156:58:07 W


CI# /Pressure/ Vmax
2.6 /1007.3mb/ 37.0kt


Final T# Adj T# Raw T#
(3hr avg)
2.6 2.7 2.9

Latitude bias adjustment to MSLP : +3.3mb

Center Temp : -67.2C Cloud Region Temp : -59.2C

Scene Type : UNIFORM CDO CLOUD REGION

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : EAST PACIFIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : 0.7T/6hr
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

[somethingfunny]

Hilda is reminding me of Ana. My hunch says, let it go, but for the sake of Johnston Island the CPHC may want to resume warnings on this.

[Chacor]

There's no permanent population on Johnston Island so nothing that couldn't be covered in a marine warning.

[Cyclenall]

Too bad Hilda could not maintain that appearance from early yesterday morning but I do see a slight improvement again with several bursts of deep convection starting just like before to the western side (yesterday afternoon). Currently it's back to it's crap state with a lone piece of convection hanging on. I hope these are enough to keep it alive. The latest outlook put the chances of re-generation at low but that was when it was at it's very worst yesterday...when there was no convection present.