SPAC: 05F - Post-Tropical

[cycloneye]

SH, 91, 2025020100, , BEST, 0, 166S, 1655E, 15, 0, DB

https://www.ssd.noaa.gov/PS/TROP/DATA/A ... 912025.dat

[cycloneye]

THE AREA OF CONVECTION (INVEST 91P) PREVIOUSLY LOCATED NEAR
18.5S 164.3E IS NOW LOCATED NEAR 18.9S 164.1E, APPROXIMATELY 236 NM WEST-
SOUTHWEST OF PORT VILLA, VANUATU. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
(MSI) DEPICTS A FULLY-EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) EMBEDDED
IN THE MONSOON TROUGH EXTENDING THROUGH THE SOUTH PACIFIC WITH FLARING
CONVECTION TO THE SOUTHEAST OF THE SYSTEM ASSOCIATED WITH THE SOUTH
PACIFIC CONVERGENCE ZONE (SPCZ). ENVIRONMENTAL ANALYSIS REVEALS MARGINAL
CONDITIONS MOVING FORWARD WITH A GOOD EQUATORWARD OUTFLOW CHANNEL ALOFT
AND VERY WARM SEA SURFACE TEMPERATURES OF 30-32 C, OFFSET BY MODERATE TO
HIGH VERTICAL WIND SHEAR OF 30-35 KNOTS. GLOBAL DETERMINISTIC MODELS
INDICATE WEAK DEVELOPMENT OVER THE NEXT 24 HOURS, WITH A SOUTHWARD TRACK
AND A SMALL WINDOW OF POTENTIAL TC INTENSITY. MAXIMUM SUSTAINED SURFACE
WINDS ARE ESTIMATED AT 23 TO 28 KNOTS. MINIMUM SEA LEVEL PRESSURE IS
ESTIMATED TO BE NEAR 1001 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS UPGRADED TO
MEDIUM.

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FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
120 NM EITHER SIDE OF A LINE FROM 18.8S 164.0E TO 22.7S 170.5E
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 23 TO 28 KNOTS. METSAT
IMAGERY AT 020600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 19.0S 164.2E. THE SYSTEM IS MOVING SOUTHWARD AT 05 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 91P) PREVIOUSLY LOCATED NEAR
18.5S 164.3E IS NOW LOCATED NEAR 19.0S 164.2E, APPROXIMATELY 238 NM
NORTH-NORTHWEST OF NOUMEA, NEW CALEDONIA. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY (MSI) DEPICTS AN EXPOSED LOW LEVEL CIRCULATION CENTER
(LLCC), JUST NORTH OF NEW CALEDONIA, WITH WIDESPREAD CONVECTION TO THE
NORTH AND SOUTHEAST. ENVIRONMENTAL ANALYSIS REVEALS A MARGINAL
ENVIRONMENT FOR DEVELOPMENT WITH HIGH VERTICAL WIND SHEAR OF 30-40
KNOTS, STRONG POLEWARD AND EQUATORWARD OUTFLOW, AND WARM SEA SURFACE
TEMPERATURES (SST) OF 28-29 C. GLOBAL DETERMINISTIC MODELS INDICATE
WEAK DEVELOPMENT OVER THE NEXT 24 HOURS, WITH AN EAST-SOUTHEASTWARD
TRACK AND A SMALL WINDOW OF POTENTIAL TC INTENSITY. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 23 TO 28 KNOTS. MINIMUM SEA LEVEL PRESSURE
IS ESTIMATED TO BE NEAR 1001 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS HIGH.

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Tropical Disturbance Summary For area Equator to 25S, 160E to 120W
ISSUED FROM RSMC NADI Feb 020904 UTC.

TROPICAL DISTURBANCE 05F CENTRE [1000HPA] WAS ANALYSED NEAR 19.2S
164.7E AT 020600UTC. POSITION FAIR BASED ON HIMAWARI-9 IR/VIS IMAGERY
WITH ANIMATION.
TD05F MOVING SOUTH-SOUTHEAST AT ABOUT 8 KNOTS.

LLCC EMBEDDED UNDER SMALL AREA OF CONVECTION. ORGANISATION REMAINS
POOR. TD05F LIES IN AN AREA OF HIGH SHEAR AND MODERATE UPPER
DIVERGENCE ESPECIALLY TO THE EAST OF THE SUPPOSED LLCC. CYCLONIC
CIRCULATIONS EXTEND UP TO 700HPA. SST IS AROUND 29 DEGREES CELSIUS.
GLOBAL MODELS HAVE PICKED UP THIS SYSTEM AND CONTINUE TO IT
SOUTH-SOUTHEASTWARDS WITH LITTLE INTENSIFICATION.

POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE IN THE
NEXT 24 TO 48 HOURS IS LOW TO MODERATE.

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TROPICAL DEPRESSION 05F CENTRE [998HPA] WAS ANALYSED NEAR 20.6S
167.7E AT 022100UTC. POSITION POOR BASED ON HIMAWARI-9 VIS IMAGERY
WITH ANIMATION.
TD05F MOVING EAST-SOUTHEAST AT ABOUT 13 KNOTS.

LLCC EMBEDDED UNDER DEEP CONVECTION. ORGANISATION HAS SLIGHTLY
IMPROVED WITH PRIMARY BANDS WRAPPING IN FROM THE NORTH. THE SYSTEM
REMAINS EMBEDDED IN THE SPCZ WITH AN ELONGATED CENTRE. TD05F LIES IN
AN AREA OF HIGH SHEAR AND STRONG UPPER DIVERGENCE ESPECIALLY TO THE
EAST OF THE SUPPOSED LLCC. CYCLONIC CIRCULATIONS EXTEND UP TO 700HPA.
SST IS AROUND 28 DEGREES CELSIUS. TD05F IS BEING STEERED TOWARDS THE
EAST-SOUTHEAST ALONG THE PERIPHERY OF A SUBTROPICAL RIDGE LOCATED TO
THE NORTHEAST OF THE SYSTEM. THE DEPRESSION HAS SOME CHANCE OF
INTENSIFYING FURTHER WITHIN 24 HOURS BUT IS NOT EXPECTED TO PERSIST
DUE TO UNFAVOURABLE CONDITIONS OF HIGH SHEAR.

GLOBAL MODELS HAVE PICKED UP THIS SYSTEM AND CONTINUE TO MOVE IT
EAST-SOUTHEASTWARDS WITH SOME INTENSIFICATION.

POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE IN THE
NEXT 24 TO 48 HOURS IS MODERATE.

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TROPICAL DEPRESSION 05F CENTRE [998HPA] WAS ANALYSED NEAR 21.2S
168.2E AT 030600UTC. POSITION POOR BASED ON HIMAWARI-9 IR IMAGERY
WITH ANIMATION AND PERIPHERAL SURFACE OBSERVATIONS. TD05F MOVING
EAST-SOUTHEAST AT ABOUT 10 KNOTS.

DEEP CONVECTION HAS SHEARED TO THE EAST OF LLCC. ORGANISATION REMAINS
POOR. THE SYSTEM REMAINS EMBEDDED IN THE SPCZ WITH AN ELONGATED
CENTRE. TD05F LIES IN AN AREA OF HIGH SHEAR AND MODERATE UPPER
DIVERGENCE ALOFT WHILE GOOD UPPER DIVERGENCE REMAINS TO THE EAST OF
THE SUPPOSED LLCC. CYCLONIC CIRCULATIONS EXTEND UP TO 700HPA. SST IS
AROUND 28 DEGREES CELSIUS. TD05F IS BEING STEERED TOWARDS THE
EAST-SOUTHEAST ALONG THE WESTERN PERIPHERY OF A SUBTROPICAL RIDGE
LOCATED TO THE NORTHEAST OF THE SYSTEM. THE DEPRESSION HAS SOME
CHANCE OF INTENSIFYING FURTHER WITHIN 24 HOURS BUT IS NOT EXPECTED TO
PERSIST DUE TO UNFAVOURABLE CONDITIONS OF HIGH SHEAR.

GLOBAL MODELS HAVE PICKED UP THIS SYSTEM AND INITIALLY MOVE IT
EASTWARDS AND THEN MOVE IT EAST-SOUTHEASTWARDS WITH LITTLE
INTENSIFICATION.

POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE IN THE
NEXT 24 TO 48 HOURS IS LOW TO MODERATE.

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TROPICAL DEPRESSION 05F CENTRE [998HPA] WAS ANALYSED NEAR 21.0S
170.5E AT 040600UTC. POSITION FAIR BASED ON HIMAWARI-9 VIS/IR IMAGERY
WITH ANIMATION AND PERIPHERAL SURFACE OBSERVATIONS. TD05F MOVING EAST
AT ABOUT 06 KNOTS.

CONVECTION HAS WEAKENED OVER THE LAST 6 HOURS AND SHEARED TO THE
SOUTHEAST OF LLCC. ORGANISATION REMAINS POOR. THE SYSTEM REMAINS
EMBEDDED IN THE SPCZ WITH AN ELONGATED CENTRE. TD05F LIES IN AN AREA
OF HIGH SHEAR, MODERATE UPPER DIVERGENCE WITH GOOD UPPER DIVERGENCE
TO THE EAST OF THE LLCC. CYCLONIC CIRCULATIONS EXTEND UP TO 700HPA.
SST IS AROUND 28 DEGREES CELSIUS. TD05F IS BEING STEERED IN AND EAST
TO SOUTHEAST TRAJECTORY ALONG THE WESTERN PERIPHERY OF A SUBTROPICAL
RIDGE LOCATED TO THE NORTHEAST OF THE SYSTEM.

GLOBAL MODELS MOVE IT EAST-SOUTHEASTWARDS WITH LITTLE
INTENSIFICATION.

POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE IN THE
NEXT 24 HOURS IS LOW TO MODERATE, REDUCING TO LOW IN THE NEXT 24 TO
48 HOURS.