WTXS31 PGTW 021500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 01S (DAHLIA) WARNING NR 011//
RMKS/
1. TROPICAL CYCLONE 01S (DAHLIA) WARNING NR 011
01 ACTIVE TROPICAL CYCLONE IN SOUTH IO
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
021200Z --- NEAR 11.2S 112.0E
MOVEMENT PAST SIX HOURS - 105 DEGREES AT 07 KTS
POSITION ACCURATE TO WITHIN 040 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 045 NM NORTHEAST QUADRANT
020 NM SOUTHEAST QUADRANT
000 NM SOUTHWEST QUADRANT
020 NM NORTHWEST QUADRANT
REPEAT POSIT: 11.2S 112.0E
---
FORECASTS:
12 HRS, VALID AT:
030000Z --- 12.6S 112.1E
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 075 NM NORTHEAST QUADRANT
070 NM SOUTHEAST QUADRANT
045 NM SOUTHWEST QUADRANT
040 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 190 DEG/ 10 KTS
---
24 HRS, VALID AT:
031200Z --- 14.6S 111.8E
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT
060 NM SOUTHEAST QUADRANT
060 NM SOUTHWEST QUADRANT
030 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 195 DEG/ 12 KTS
---
36 HRS, VALID AT:
040000Z --- 16.9S 111.2E
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT
050 NM SOUTHEAST QUADRANT
050 NM SOUTHWEST QUADRANT
030 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 180 DEG/ 05 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
041200Z --- 17.9S 111.2E
MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT
040 NM SOUTHEAST QUADRANT
030 NM SOUTHWEST QUADRANT
030 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 130 DEG/ 04 KTS
---
72 HRS, VALID AT:
051200Z --- 18.8S 112.4E
MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
---
REMARKS:
021500Z POSITION NEAR 11.6S 112.0E.
TROPICAL CYCLONE 01S (DAHLIA), LOCATED APPROXIMATELY 677 NM NORTH
OF LEARMONTH, AUSTRALIA, HAS TRACKED EAST-SOUTHEASTWARD AT 07
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS A RAPIDLY WEAKENING SYSTEM WITH CONVECTION NEARLY
DIED OUT. THERE IS FAIR CONFIDENCE IN THE INITIAL POSITION BASED ON
A LOW REFLECTIVITY FEATURE OBSERVED IN A 021224Z 89GHZ AMSU IMAGE
ALSO SHOWING A SIGNIFICANT PATCH OF DRY AIR BEGINNING TO WRAP AROUND
THE SYSTEM FROM THE NORTHWEST. ANOTHER WEAK CIRCULATION CAN BE
OBSERVED IN THE SATELLITE IMAGERY TO THE SOUTHWEST OF THE SYSTEM
CENTER, IMPEDING THE LOW LEVEL WIND FLOW INTO TC 01S. THE INITIAL
INTENSITY IS ASSESSED AT 35 KNOTS WHICH IS BASED ON RECENT CURRENT
INTENSITY DVORAK ESTIMATES RANGING FROM T2.0 TO 2.5 (30 TO 35
KNOTS), AND A 43 KNOT SATCON ESTIMATE FROM 021223Z. UPPER-LEVEL
ANALYSIS SHOWS A RIDGE AXIS TO THE SOUTH OF THE SYSTEM WITH
RELATIVELY LOW VERTICAL WIND SHEAR, MODERATE DIFFLUENCE, AND A
DEGRADING EQUATORWARD OUTFLOW CHANNEL. SSTS IN THE REGION ARE
CONDUCIVE FOR FURTHER DEVELOPMENT AROUND 28 TO 29 CELSIUS, HOWEVER,
TEMPERATURES DECLINE SHARPLY POLEWARD OF 15 DEGREES SOUTH.
COINCIDING WITH THE AFOREMENTIONED MICROWAVE IMAGE, THE CIMSS TOTAL
PRECIPITABLE WATER ANIMATION SHOWS VERY DRY AIR WELL SOUTH OF THE
SYSTEM WITH A BAND OF RELATIVELY DRY AIR BEGINNING TO FEED IN FROM
THE NORTHWEST. TC 01S HAS TRACKED EAST-SOUTHEAST OVER THE LAST
SIX HOURS AS A MID-TO-LOW LEVEL RIDGE IS BUILDING OVER THE
AUSTRALIAN CONTINENT. THE RIDGE WILL BEGIN EXTENDING NORTHWARD AND
STEER TC 01S TO THE SOUTH IN THE NEXT 6 TO 12 HOURS AND THIS TRACK
WILL PERSIST THROUGH TAU 36. UPPER-LEVEL CONDITIONS ARE FORECAST TO
IMPROVE SLIGHTLY WITH AN ANTICYCLONE DEVELOPING OVER THE SYSTEM,
WHICH WILL ALLOW THE SYSTEM TO MAINTAIN TROPICAL CYCLONE STRENGTH
BETWEEN 35 AND 40 KNOTS. SHORTLY AFTER TAU 48, THE SOUTHWARD TRACK
WILL BRING TC 01S INTO AN INCREASINGLY UNFAVORABLE ENVIRONMENT.
COOLER SSTS AND DRY AIR ENTRAINMENT WILL SIGNIFICANTLY WEAKEN THE
SYSTEM, ONLY TO BE EXACERBATED BY A PASSING TROUGH INDUCING HIGH
VERTICAL WIND SHEAR. THE STEERING RIDGE WILL RETROGRADE TO THE
NORTHEAST AS THE PASSING TROUGH ERODES THE SOUTHERN PORTION OF THE
RIDGE, CAUSING THE SYSTEM TO TURN ABRUPTLY TO THE EAST. TC 01S
SHOULD FULLY DISSIPATE OVER WATER BY TAU 72. DYNAMIC MODEL GUIDANCE
SHOWS FAIRLY GOOD AGREEMENT ON THE TRACK MOTION THROUGH TAU 48,
BUT BEGINS TO DIVERGE THEREAFTER DUE TO THE RAPIDLY WEAKENING
INTENSITY. THE FORECAST TRACK IS PLACED NEAR THE MULTI-MODEL
CONSENSUS WITH GOOD CONFIDENCE. MAXIMUM SIGNIFICANT WAVE HEIGHT AT
021200Z IS 12 FEET. NEXT WARNINGS AT 022100Z, 030300Z, 030900Z AND
031500Z.
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