05S(CALVINIA) intensifying close to Mauritius/ 04P(SARAI): slowly weakening west of Tonga

TC 04P( SARAI) SOUTH PACIFIC
As of 00:00 UTC Dec 30, 2019:
Location: 20.7°S 178.6°W
Maximum Winds: 55 kt ( 100km/h)
Gusts: 70 kt ( 130km/h)
REMARKS:
300300Z POSITION NEAR 20.7S 178.3W.
30DEC19. TROPICAL CYCLONE 04P (SARAI), LOCATED APPROXIMATELY 500
NM WEST-SOUTHWEST OF NIUE, HAS TRACKED SOUTHEASTWARD AT 03 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
SHOWS A PARTIALLY EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH
A SMALL AMOUNT OF FLARING CONVECTION OBSCURING THE EXACT POSITION
OF THE LLCC. TC 04P HAS STALLED OVER THE PAST 6 HOURS AND THE
CONVECTION HAS SIGNIFICANTLY DECREASED. THE INITIAL POSITION IS
SET WITH FAIR CONFIDENCE BASED ON A 292049Z ASCAT-C DIRECT PASS
THAT SHOWS A 30 NM WIDE LLCC. THE INITIAL INTENSITY IS PLACED AT
55 KTS BASED ON A CLUSTER OF 50 KT WIND BARBS TO THE SOUTHWEST OF
THE LLCC IN THE 292049Z ASCAT-C PASS AND A DVORAK INTENSITY
ESTIMATE OF 3.5 (55 KTS) FROM PGTW. UPPER-LEVEL ANALYSIS REVEALS
AN UNFAVORABLE ENVIRONMENT FOR DEVELOPMENT DUE TO MODERATE TO HIGH
(25-30 KT) VERTICAL WIND SHEAR (VWS) AND ONLY FAIR UPPER LEVEL
OUTFLOW TO THE EAST. AS THE SYSTEM PROGRESSES, VWS WILL CONTINUE
TO INCREASE AND CAUSE TC 04P TO STEADILY WEAKEN AS THE ENVIRONMENT
BECOMES MORE UNFAVORABLE, FULLY DISSIPATING AT TAU 120. TC 04P IS
TRACKING SOUTHEASTWARD ALONG THE SOUTHWESTERN PERIPHERY OF A NEAR
EQUATORIAL RIDGE (NER). A DEEP-LAYER TROUGH TO THE SOUTHEAST OF TC
04P IS FORECAST TO BUILD, DIGGING DEEPER INTO THE TROPICS OVER THE
FORECAST PERIOD CAUSING THE NER TO WEAKEN AND REORIENT. THIS WILL
IMPACT THE TRACK STEERING MECHANISM AND CAUSES NOTABLE VARIATIONS
IN THE MODEL SOLUTIONS. BETWEEN TAUS 12 TO 24, THE MOST DOMINANT
TRACK SOLUTION SHOWS TC 04P RECURVING TO THE NORTHEAST THROUGH TAU
72 THEN TURNING TO TRACK SOUTHEAST THROUGH THE END OF THE FORECAST
PERIOD. THE UKMET AND UKMET ENSEMBLE REMAIN OUTLIERS TO THE SOUTH,
WHICH NOW DEPICT A SLIGHT RECURVE BUT PRIMARILY TRACK TC 04P
EASTWARD WITH FASTER ALONG TRACK SPEEDS. WHEREAS, THE GFS AND GFS
ENSEMBLE SOLUTIONS TRACK THE SYSTEM FURTHER TO THE NORTH DURING
THE RECURVE AND HAVE SIGNIFICANTLY SLOWER ALONG TRACK SPEEDS. THE
JTWC TRACK FORECAST IS PLACED NEAR THE MULTI-MODEL CONSENSUS,
WHICH LINES UP WELL WITH THE AVERAGE TRACK OF THE MEMBERS THAT
MAKE UP THE DOMINANT TRACK SOLUTION. DUE TO CONTINUED SPREAD IN
THE MODEL GUIDANCE, THERE IS FAIR CONFIDENCE IN THE JTWC TRACK
FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 300000Z IS 24 FEET.
NEXT WARNINGS AT 300900Z, 301500Z, 302100Z AND 310300Z.//
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TC 05S(CALVINIA)  SOUTH INDIAN
As of 00:00 UTC Dec 30, 2019:
Location: 20.6°S 58.8°E
Maximum Winds: 35 kt ( 65km/h)
Gusts: 45 kt ( 85km/h)
REMARKS:
300300Z POSITION NEAR 20.7S 58.7E.
30DEC19. TROPICAL CYCLONE 05S (CALVINIA), LOCATED APPROXIMATELY 90
NM EAST-SOUTHEAST OF PORT LOUIS, MAURITIUS, HAS TRACKED
SOUTHWESTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. ANIMATED
ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN AREA OF DEEP
CONVECTION ROTATING AROUND AND OBSCURING THE LOW-LEVEL CIRCULATION
CENTER (LLCC). FURTHERMORE, IT REVEALS THAT TC 05S HAS SLOWED DOWN
SIGNIFICANTLY OVER THE PAST 6 HOURS. THERE IS GOOD CONFIDENCE IN
THE INITIAL POSITION SUPPORTED BY A 300029Z 91GHZ SSMIS MICROWAVE
IMAGE THAT SHOWS LOW-LEVEL BANDING WRAPPING INTO THE LLCC. THE
INITIAL INTENSITY IS SET AT 35 KTS WITH FAIR CONFIDENCE BASED ON A
DVORAK INTENSITY ESTIMATE OF 2.5 (35 KTS) BY PGTW AND A 291730Z
METOP-A ASCAT PASS WHICH DEPICTS A BROAD REGION OF 30-35 KT WINDS
COVERING THE SOUTHERN SEMICIRCLE OF THE CIRCULATION. TC 05S IS IN
A FAVORABLE ENVIRONMENT WITH GOOD POLEWARD OUTFLOW, LOW (10-15
KTS) VERTICAL WIND SHEAR (VWS), AND WARM (27-28 CELSIUS) SEA
SURFACE TEMPERATURES (SSTS). TC 05S IS CURRENTLY TRACKING
SOUTHWESTWARD UNDER THE STEERING INFLUENCE OF A LOW-LEVEL
SUBTROPICAL RIDGE (STR) TO THE SOUTHEAST. TC 05S IS FORECAST TO
CONTINUE TRACKING SOUTHWESTWARD THROUGH TAU 24 AS IT SLOWLY
INTENSIFIES TO 45 KTS. AS THE SYSTEM INTENSIFIES IT WILL START TO
FEEL THE EFFECTS OF A DEEP-LAYER STR THAT DEVELOPS TO THE EAST AND
WILL TRACK TC 05S SOUTH-SOUTHEAST AFTER TAU 24. THE SYSTEM WILL
CONTINUE TO TRACK SOUTH-SOUTHEASTWARD THROUGH THE REMAINDER OF THE
FORECAST PERIOD. BY TAU 72, THE SYSTEM WILL BEGIN TO INTERACT WITH
A PASSING MID-LATITUDE TROUGH CAUSING TC 05S TO ACCELERATE
SOUTHEASTWARD AND BEGIN EXTRA-TROPICAL TRANSITION (ETT) AS IT
INTERACTS WITH THE BAROCLINIC ZONE, COMPLETING ETT BY TAU 96. THE
HIGHEST AMOUNT OF TRACK UNCERTAINTY IS DURING THE FIRST 24 HOURS
OF THE FORECAST AS THE GFS AND GFS ENSEMBLE TRACK TC 05S DUE WEST
THROUGH TAU 24 BEFORE MAKING A SHARP TURN TO TRACK SOUTHEASTWARD.
OUTSIDE OF THIS INSTANCE, THE NUMERICAL MODELS ARE IN FAIR
AGREEMENT; THEREFORE, THE JTWC TRACK IS PLACED NEAR THE MULTI-
MODEL CONSENSUS WITH FAIR CONFIDENCE. MAXIMUM SIGNIFICANT WAVE
HEIGHT AT 300000Z IS 11 FEET. NEXT WARNINGS AT 301500Z AND
310300Z.//
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