CPAC: TROPICAL DEPRESSION HILDA (11E)

[clfenwi]

The image that Hurakan posted at 10:08 PM last night is a real nice capture of the turning point for this storm. We'll have to see how it fares in the (local) late morning-early afternoon hours, but one can certainly envision Neki at 5 PM Hawaii time (11PM EDT).

EDIT: For some reason, I was mentally placing the storm much closer to 140° than it actually is. As it isn't going to move ~3.5° in 12 hours, it would, of course, be Hilda if it were to develop on the time-line I'm expecting.

[cycloneye]

If is Hilda before 140W,it retains that name or changes to Neki?

[Derek Ortt]

it keeps the same, just as Felicia did

[HURAKAN]

Convection remains strong

[Macrocane]

it keeps the same, just as Felicia did

And more recently Guillermo.

[clfenwi]

Quikscat pass 50 minutes after advisory time seems to nicely confirm what we thought we knew.

[clfenwi]

SAB went (to me) surprisingly far south on their position estimate:
22/1800 UTC 13.3N 137.0W T2.5/2.5 11E -- East Pacific

TAFB must have placed it further north as 18Z best track indicates:

EP, 11, 2009082218, , BEST, 0, 136N, 1373W, 30, 1006, TD, 34, NEQ, 0, 0, 0, 0, 1009, 150, 35, 0, 0, E, 0, , 0, 0, ELEVEN, D,

[HurricaneRobert]

This might barely squeak by as Hilda.

[HURAKAN]

952
WHXX01 KMIA 221837
CHGE77
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1837 UTC SAT AUG 22 2009

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

EAST PACIFIC OBJECTIVE AIDS FOR

TROPICAL CYCLONE ELEVEN (EP112009) 20090822 1800 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
090822 1800 090823 0600 090823 1800 090824 0600

LAT LON LAT LON LAT LON LAT LON
BAMS 13.6N 137.3W 13.9N 138.8W 14.4N 140.2W 14.8N 141.4W
BAMD 13.6N 137.3W 13.9N 139.6W 14.3N 141.9W 14.6N 144.1W
BAMM 13.6N 137.3W 14.1N 139.1W 14.7N 140.9W 15.3N 142.7W
LBAR 13.6N 137.3W 14.1N 139.3W 14.8N 141.5W 15.6N 143.7W
SHIP 30KTS 32KTS 36KTS 40KTS
DSHP 30KTS 32KTS 36KTS 40KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
090824 1800 090825 1800 090826 1800 090827 1800

LAT LON LAT LON LAT LON LAT LON
BAMS 15.2N 142.9W 16.0N 145.5W 16.2N 147.4W 16.1N 148.9W
BAMD 14.7N 146.4W 15.0N 150.6W 15.4N 154.7W 15.6N 159.0W
BAMM 15.6N 144.4W 15.6N 147.9W 15.5N 151.7W 15.2N 155.4W
LBAR 16.2N 145.8W 17.3N 149.9W 17.7N 153.3W 17.5N 156.8W
SHIP 44KTS 53KTS 57KTS 61KTS
DSHP 44KTS 53KTS 57KTS 61KTS

...INITIAL CONDITIONS...
LATCUR = 13.6N LONCUR = 137.3W DIRCUR = 270DEG SPDCUR = 9KT
LATM12 = 13.6N LONM12 = 135.4W DIRM12 = 273DEG SPDM12 = 9KT
LATM24 = 13.5N LONM24 = 133.8W
WNDCUR = 30KT RMAXWD = 35NM WNDM12 = 30KT
CENPRS = 1006MB OUTPRS = 1009MB OUTRAD = 150NM SDEPTH = D
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

$$
NNNN

[Iune]

Still a tropical depression

EP, 11, 2009082218, , BEST, 0, 136N, 1373W, 30, 1006, TD, 34, NEQ, 0, 0, 0, 0, 1009, 150, 35, 0, 0, E, 0, , 0, 0, ELEVEN, D,

[HURAKAN]

Center very close to the edge of the convection

[cycloneye]

Say hello to Hilda.

EP, 11, 2009082218, , BEST, 0, 135N, 1373W, 35, 1006, TS

ftp://ftp.tpc.ncep.noaa.gov/atcf/tcweb/ ... 009.invest

[cycloneye]

000
WTPZ41 KNHC 222034
TCDEP1
TROPICAL STORM HILDA DISCUSSION NUMBER 2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP112009
200 PM PDT SAT AUG 22 2009

VISIBLE SATELLITE PICTURES INDICATE THAT THE CENTER OF THE HILDA
LIES NEAR THE NORTHEASTERN EDGE OF A MASS OF DEEP CONVECTION.
HOWEVER...THE CONVECTION HAS BEEN DECREASING IN STRENGTH AND
COVERAGE OVER THE LAST FEW HOURS AS THE DIURNAL MINIMUM APPROACHES.
EARLIER...A 1534 UTC QUIKSCAT PASS SHOWED A COUPLE OF BELIEVABLE
30-35 KT WINDS IMMEDIATELY TO THE NORTHEAST OF THE CIRCULATION
CENTER...SUGGESTING THAT THE SYSTEM WAS NEAR TROPICAL STORM
STRENGTH AT THAT TIME. DVORAK T-NUMBERS FROM TAFB AND SAB WERE 2.5
AT 1800 UTC...AND SERVE AS THE BASIS FOR THE INITIAL
INTENSITY...WHICH IS SET AT 35 KT.

THE INITIAL MOTION IS ESTIMATED TO BE 275/09. THE LARGE-SCALE MODELS
SHOW THAT THE CYCLONE LIES TO THE SOUTH OF THE EASTERN EDGE OF A
SUBTROPICAL RIDGE OVER THE CENTRAL NORTH PACIFIC...WHICH SHOULD
STEER HILDA ON A GENERAL WESTERLY COURSE FOR THE NEXT FEW DAYS.
AROUND 72 HOURS...A DEEP MID- TO UPPER-LEVEL TROUGH IS FORECAST TO
DIG SOUTHWARD ALONG 135W...WHICH SHOULD TEMPORARILY WEAKEN
SUBTROPICAL RIDGING NORTH OF HILDA. AS A RESULT...THE FORWARD SPEED
OF THE CYCLONE SHOULD BEGIN TO SLOW IN A WEAKER DEEP-LAYER EASTERLY
FLOW. THE OFFICIAL FORECAST IS SLIGHTLY SOUTH OF THE PREVIOUS
ADVISORY TO ACCOUNT FOR THE MORE WESTERLY INITIAL MOTION.

HILDA REMAINS IN AN ENVIRONMENT CHARACTERIZED BY MODERATE
NORTHEASTERLY SHEAR...AND LITTLE CHANGE IN THE SHEAR IS EXPECTED
THROUGH AT LEAST 72 HOURS. EVEN THOUGH WATERS REMAIN SUFFICIENTLY
WARM ALONG THE FORECAST TRACK...IT APPEARS THAT THE SHEAR SHOULD BE
ENOUGH TO PRECLUDE ANY SIGNIFICANT INTENSIFICATION. TOWARD THE END
OF THE PERIOD...SOME OF THE GUIDANCE SUGGESTS THAT THE SHEAR COULD
DECREASE...WHICH COULD ALLOW FOR SOME STRENGTHENING. THE OFFICIAL
FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY...AND IS CLOSE TO THE
MODEL INTENSITY CONSENSUS.

FORECAST POSITIONS AND MAX WINDS

INITIAL 22/2100Z 13.6N 137.7W 35 KT
12HR VT 23/0600Z 13.8N 139.0W 35 KT
24HR VT 23/1800Z 14.1N 140.7W 35 KT
36HR VT 24/0600Z 14.5N 142.3W 35 KT
48HR VT 24/1800Z 14.9N 144.0W 40 KT
72HR VT 25/1800Z 15.0N 147.5W 40 KT
96HR VT 26/1800Z 15.0N 150.5W 45 KT
120HR VT 27/1800Z 15.0N 153.0W 55 KT

$$
FORECASTER KIMBERLAIN/BRENNAN

[clfenwi]

Between this and the first couple of sentences of the discussion, this isn't the most auspicious debut for a tropical storm.

[brunota2003]

While it has quite a pretty LLC, it seems Hilda likes to be naked, than have convection over her...that just simply cannot do if she plans on becoming more than just an ordinary 40 mph tropical storm.

[HURAKAN]

Not looking too good

[clfenwi]

23/0000 UTC 13.5N 138.1W T2.0/2.5 11E -- East Pacific

Not surprising, given the images Hurakan and I posted. However, as was the case at this time yesterday, we are starting to see convection near the center:

[HURAKAN]

* EAST PACIFIC SHIPS INTENSITY FORECAST *
* GOES DATA AVAILABLE *
* OHC DATA AVAILABLE *
* HILDA EP112009 08/23/09 00 UTC *

SHEAR (KT) 11 13 16 16 16 13 19 16 14 17 11 9 6
SHEAR DIR 69 64 56 59 60 40 55 55 58 51 72 63 74
SST (C) 28.1 27.9 27.9 27.8 27.8 27.6 27.5 27.4 27.4 27.4 27.3 27.4 27.6


Shear expected to remain a problem

[Ad Novoxium]

(looks at discussion:
VISIBLE SATELLITE PICTURES INDICATE THAT THE CENTER OF THE HILDA LIES NEAR THE NORTHEASTERN EDGE OF A MASS OF DEEP CONVECTION.)

Oh, THE Hilda. Not just A Hilda, THE Hilda. I don't like harping on errors in grammar, but I like the sound of "The Hilda".

[cycloneye]

000
WTPZ41 KNHC 230232
TCDEP1
TROPICAL STORM HILDA DISCUSSION NUMBER 3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP112009
800 PM PDT SAT AUG 22 2009

THE SATELLITE PRESENTATION OF HILDA HAS NOT BEEN VERY IMPRESSIVE
DURING THE PAST SEVERAL HOURS...AS THE CENTER HAS BEEN EXPOSED MOST
OF THE TIME. HOWEVER...NEW CONVECTION HAS BEEN FORMING TO THE NORTH
AND WEST OF THE CENTER AND AN EARLIER ASCAT MICROWAVE PASS AT 1912
UTC INDICATED THAT THE WINDS WERE NEAR TROPICAL STORM FORCE AT THAT
TIME. THE INITIAL INTENSITY WILL BE KEPT AT 35 KT FOR THIS
ADVISORY...IN GOOD AGREEMENT WITH THE DVORAK CI NUMBERS FROM BOTH
TAFB AND SAB AND THE ASCAT DATA.

THE INTENSITY FORECAST FOR HILDA IS A BIT PERPLEXING...WITH LOTS OF
MIXED SIGNALS. ON ONE HAND...VERTICAL WIND SHEAR IS FORECAST TO BE
MODERATE FOR THE NEXT FEW DAYS...WHICH SHOULD HINDER DEVELOPMENT.
WATER VAPOR IMAGERY ALSO SHOW SOME MID- TO UPPER-LEVEL DRY AIR NEAR
THE CENTER OF HILDA...WHICH COULD PREVENT SUSTAINED DEEP
CONVECTION...ESPECIALLY IN A SHEARED ENVIRONMENT. DESPITE THE
MARGINAL ATMOSPHERIC CONDITIONS...ALL GUIDANCE IS SHOWING SLOW
STRENGTHENING...WITH EVERY MODEL CLOSE TO OR AT HURRICANE STRENGTH
BY 120 HOURS. IF THIS SYSTEM SURVIVES THE MARGINAL ENVIRONMENT FOR
THE NEXT COUPLE OF DAYS...THE GLOBAL MODELS SHOW THE SHEAR RELAXING
AND A MORE SIGNIFICANT INTENSIFICATION COULD OCCUR AFTER THAT TIME.
GIVEN THE ABOVE FACTORS...THE NHC INTENSITY FORECAST WILL BE
SIMILAR TO THE PREVIOUS ONE AND IS LOWER THAN MUCH OF THE GUIDANCE.

THE INITIAL MOTION IS 270/08. WEAK RIDGING APPEARS LIKELY TO STEER
THE CYCLONE TO THE WEST OR WEST-NORTHWEST FOR THE DAY OR SO UNTIL
HILDA ENCOUNTERS A TROUGH ALONG ABOUT 145W. A DEEPER SYSTEM MIGHT
TURN MORE TO THE NORTHWEST IN RESPONSE TO THE TROUGH...BUT HILDA IS
NOT EXPECTED TO BE PARTICULARLY STRONG AT THAT TIME.
THEREAFTER...THE TROUGH IS FORECAST TO LIFT OUT OF THE REGION WITH
WEAK SUBTROPICAL RIDGING EXPECTED TO BUILD NORTHWEST OF
HILDA...CAUSING A MORE WESTWARD MOTION. UNDER THE ASSUMPTION THAT
HILDA REMAINS WEAK...THE OFFICIAL FORECAST WILL REMAIN ON THE
SOUTHERN SIDE OF THE GUIDANCE ENVELOPE...A HAIR SOUTH OF THE
PREVIOUS TRACK FORECAST THROUGH 3 DAYS AND BASICALLY THE SAME
THEREAFTER.

FORECAST POSITIONS AND MAX WINDS

INITIAL 23/0300Z 13.6N 138.5W 35 KT
12HR VT 23/1200Z 13.7N 139.8W 35 KT
24HR VT 24/0000Z 14.1N 141.5W 35 KT
36HR VT 24/1200Z 14.5N 143.1W 35 KT
48HR VT 25/0000Z 14.8N 144.8W 40 KT
72HR VT 26/0000Z 15.0N 148.0W 40 KT
96HR VT 27/0000Z 15.0N 151.5W 45 KT
120HR VT 28/0000Z 15.0N 154.0W 55 KT

$$
FORECASTER BLAKE