REMARKS:
131500Z POSITION NEAR 17.3S 173.7W.
13DEC20. TROPICAL CYCLONE (TC) 06P (SIX), LOCATED APPROXIMATELY 225 NM SOUTHWEST OF PAGO PAGO, AMERICAN SAMOA HAS TRACKED WEST-SOUTHWESTWARD AT 12 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS CONVECTIVE SPIRAL BANDS WRAPPING INTO AN OBSCURED LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON THE POSITION OF THE LLCC IN THE EIR LOOP.
THE INITIAL INTENSITY IS ASSESSED AT 35 KTS AND IS HEDGED SLIGHTLY HIGHER THAN MULTI-AGENCY DVORAK CURRENT INTENSITY ESTIMATES OF T2.0 (30 KTS, PGTW AND KNES) DUE TO THE PRESENCE
OF 35 KTS WINDS IN DATA FROM A 130936Z ASCAT-B PASS. TC 06P IS TRACKING ALONG THE NORTHWESTERN PERIPHERY OF A DEEP LAYER SUBTROPICAL RIDGE POSITIONED TO THE SOUTHEAST AND THROUGH A FAVORABLE ENVIRONMENT WITH LOW (10-15 KTS) VERTICAL WIND SHEAR (VWS), WARM (28-29 CELSIUS) SEA SURFACE TEMPERATURES (SST) AND WEAK OUTFLOW ALOFT. THE SYSTEM WILL TRACK GENERALLY SOUTHWESTWARD THROUGH TAU 24. THE ENVIRONMENT WILL REMAIN FAVORABLE FOR INTENSIFICATION AND SUPPORT GRADUAL
INTENSIFICATION TO 45 KTS BY THIS TIME. THEREAFTER, THE STEERING RIDGE WILL BEGIN A GRADUAL EASTWARD RETREAT DUE TO INTERACTION WITH A MIDLATITUDE SHORTWAVE TROUGH PROPAGATING FROM THE WEST. AS THE RIDGE RE-POSITIONS AND BUILDS TO THE EAST THE STORM MOTION WILL TURN FROM SOUTHWESTWARD TO SOUTHEASTWARD AFTER TAU 24. GRADUAL INTENSIFICATION WILL CONTINUE THROUGH
TAU 48 AND LEAD TO A PEAK INTENSITY OF 55 KTS BY THAT TIME. THEREAFTER, THE SYSTEM WILL BEGIN EXTRATROPICAL TRANSITION(ETT) AS IT APPROACHES THE BAROCLINIC ZONE AND BEGIN TO WEAKEN DUE TO HIGH (30+ KTS) VWS. BY TAU 96, THE SYSTEM WILL WEAKEN TO 35 KTS AND COMPLETE ETT. NUMERICAL MODEL TRACK GUIDANCE IS IN
TIGHT AGREEMENT THROUGH TAU 24 WITH SIGNIFICANT DIVERGENCE THEREAFTER. THIS DIVERGENCE IN MODEL SOLUTIONS IN THE LATER
TAUS LENDS OVERALL FAIR CONFIDENCE IN THE JTWC FORECAST TRACK WHICH IS PLACED ALONG THE MULTI-MODEL CONSENSUS. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 131200Z IS 13 FEET. NEXT WARNINGS AT 132100Z, 140300Z, 140900Z AND 141500Z. REFER TO TROPICAL CYCLONE 05P (FIVE) WARNINGS (WTPS31 PGTW) FOR SIX-HOURLY UPDATES.
TROPICAL DISTURBANCE ADVISORY NUMBER C3 ISSUED FROM RSMC NADI
Dec 131408 UTC.
TROPICAL DEPRESSION TD03F CENTRE [1002HPA] WAS LOCATED NEAR 17.2S
173.6W AT 131200 UTC. POSITION POOR BASED ON HIMAWARI-8 IR IMAGERY
AND PERIPHERY SURFACE REPORTS.
TD03F MOVING SOUTH AT ABOUT 10 KNOTS. MAXIMUM 10-MINUTE AVERAGE WINDS
NEAR THE CENTRE ESTIMATED AT ABOUT 30 KNOTS. DEPRESSION INTENSIFYING.
DEEP CONVECTION REMAINED PERSISTENT OVER LLCC. ORGANISATION HAS
SLIGHTLY IMPROVED WITH PRIMARY BANDS TRYING TO WRAP ONTO LLCC. SYSTEM
LIES UNDER AN UPPER RIDGE IN A MODERATE UNDER AN UPPER RIDGE WITH
GOOD UPPER DIVERGENCE AND OUTFLOW. CYCLONIC CIRCULATION EXTENDS UPTO
500HPA. SST IS AROUND 30 DEGREES CELSIUS. DVORAK ANALYSIS BASED ON
CURVED PATTERN, WITH 0.30 WRAP ON LOG 10 SPIRAL, YIELDING DT=1.5. MET
AND PT AGREE. FT BASED ON DT THUS, YIELDING T1.5/1.5/D0.5/24HRS.
GLOBAL MODELS DEVELOP THE DEPRESSION AND MAINTAINS ITS SOUTHWESTWARD
TRACK AND EVENTUALLY ACCELERATING IT IN A SOUTHEASTWARDS DIRECTION.
THE POTENTIAL FOR TD02F TO DEVELOP INTO A TROPICAL CYCLONE IN THE
NEXT 24 TO 48 HOURS IS MODERATE TO HIGH.
FORECASTS :
AT 12 HRS VALID AT 131200 UTC 17.8S 173.4W MOV SW AT 08 KT WITH 30 KT
CLOSE TO CENTRE
AT 24 HRS VALID AT 140000 UTC 18.7S 173.8W MOV SW AT 06 KT WITH 35 KT
CLOSE TO CENTRE
OUTLOOK :
AT 36 HRS VALID AT 141200 UTC 19.3S 173.6W MOV SSW AT 05 KT WITH 40
KT CLOSE TO CENTRE
AT 48 HRS VALID AT 150000 UTC 19.2S 172.6W MOV S AT 04 KT WITH 40 KT
CLOSE TO CENTRE
