TCFA - 萨摩亚东北热带扰动04F(99P) - 12.1S 168.2W

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WTPS21 PGTW 310200
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 99P) REISSUED//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/300153ZDEC2025//
AMPN/REF A IS A TROPICAL CYCLONE FORMATION ALERT.//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
125 NM EITHER SIDE OF A LINE FROM 13.3S 165.2W TO 18.6S 165.9W
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 28 TO 33 KNOTS. METSAT
IMAGERY AT 310000Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 13.4S 165.2W. THE SYSTEM IS MOVING EASTWARD AT 11 KNOTS.
2. REMARKS:THE AREA OF CONVECTION (INVEST 99P) PREVIOUSLY LOCATED NEAR
13.8S 167.5W IS NOW LOCATED NEAR 13.4S 165.2W, APPROXIMATELY 254 NM EAST
OF MANU ISLANDS. ANIMATED ENHANCED MULTISPECTRAL SATELLITE IMAGERY (MSI)
DEPICTS CONVECTIVE BANDING ON THE EASTERN SIDE OF A PARTIALLY EXPOSED
LOW LEVEL CIRCULATION CENTER. A 302026Z ASCAT REVELED A HIGHLY
ASYMMETRIC WIND FIELD WITH 25-30 KNOT WINDS CONFINED TO THE EASTERN
SEMICIRCLE. ENVIRONMENTAL ANALYSIS FOR THE AREA INDICATES MARGINALLY
FAVORABLE ENVIRONMENT FOR 99P WITH WARM SEA SURFACE TEMPERATURES (29-30
C), MODERATE TO HIGH VERTICAL WIND SHEAR (20-25 KTS), AND GOOD POLEWARD
OUTFLOW ALOFT. GLOBAL DETERMINISTIC MODELS SHOW 99P TRACKING SOUTHWARD
AND MAINTAINING AN ASYMMETRIC WIND FIELD OVER THE NEXT 24-48 HOURS.
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 28 TO 33 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 998 MB. THE
POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS HIGH. THIS SUPERSEDES REF A
(WTPS21 PGTW 300200).
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
010200Z.
//
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Tropical Disturbance Summary For area Equator to 25S, 160E to 120W
ISSUED FROM RSMC NADI Dec 310756 UTC.

TROPICAL DISTURBANCE TD04F CENTRE [1003HPA] WAS ANALYSED NEAR 14.1S
164.3W AT 310600UTC. POSITION FAIR BASED ON HIMAWARI-9 IR IMAGERY.
TD04F SLOW MOVING.

DEEP CONVECTION CONTINUES TO PERSIST TO THE EAST OF SUPPOSED LLCC.
TD04F LIES IN A MODERATE TO HIGH SHEARED ENVIRONMENT WITH GOOD UPPER
DIVERGENCE AND WARM SST AROUND 29 DEGREES CELSIUS. GOOD EQUATORWARD
OUTFLOW AS WELL AS STRONGER UPPER DIVERGENCE JUST TO THE EAST OF
SUPPOSED LLCC.

HOWEVER, DRY AIR INTRUSION FROM THE SOUTHWEST OF THE SYSTEM AS WELL
AS HIGH SHEAR TO THE SOUTH WHICH COULD IMPACT THE SYSTEM AND HINDER
DEVELOPMENT.

GLOBAL MODELS HAVE WEAKEN THE SYSTEM AS IT TRACKS SOUTHWARDS.

THE POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE IS
LOW IN THE NEXT 24-48HRS.
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NO OTHER SIGNIFICANT TROPICAL DISTURBANCE ANALYSED OR FORECAST IN THE
AREA.

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Tropical Disturbance Summary For area Equator to 25S, 160E to 120W
ISSUED FROM RSMC NADI Dec 312225 UTC.

TROPICAL DISTURBANCE TD04F CENTRE [1003HPA] WAS ANALYSED NEAR 18.1S
164.5W AT 312100UTC. POSITION FAIR BASED ON HIMAWARI-9 VIS/IR
IMAGERY. TD04F SLOW MOVING.

DEEP CONVECTION CONTINUES TO PERSIST TO THE EAST OF SUPPOSED LLCC.
TD04F LIES IN A MODERATE TO HIGH SHEARED ENVIRONMENT WITH GOOD UPPER
DIVERGENCE TO THE EAST AND WARM SST AROUND 28 DEGREES CELSIUS. GOOD
EQUATORWARD OUTFLOW AS WELL AS STRONGER UPPER DIVERGENCE JUST TO THE
EAST OF SUPPOSED LLCC.

HOWEVER, DRY AIR INTRUSION FROM THE SOUTHWEST OF THE SYSTEM AS WELL
AS HIGH SHEAR TO THE SOUTH OF THE SYSTEM AND HINDER DEVELOPMENT.

GLOBAL MODELS HAVE WEAKEN THE SYSTEM AS IT TRACKS SOUTHWARDS.

THE POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE IS
LOW IN THE NEXT 24-48HRS.
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NO OTHER SIGNIFICANT TROPICAL DISTURBANCE ANALYSED OR FORECAST IN THE
AREA.

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SUBJ/TROPICAL CYCLONE FORMATION ALERT REISSUED //
WTPS21 PGTW 010200
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
130 NM EITHER SIDE OF A LINE FROM 12.7S 165.0W TO 19.5S 166.1W
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 25 TO 30 KNOTS. METSAT
IMAGERY AT 010200Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 17.8S 165.5W. THE SYSTEM IS MOVING SOUTH-SOUTHWESTWARD AT 13
KNOTS.
2. REMARKS:
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1000 MB. THE
POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS HIGH. THIS SUPERSEDES REF A.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY 020200Z.
//

ABPW10 PGTW 010200
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS REISSUED/010200Z-010600ZJAN2026//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
   A. TROPICAL CYCLONE SUMMARY: NONE.
   B. TROPICAL DISTURBANCE SUMMARY: NONE.
   C. SUBTROPICAL SYSTEM SUMMARY: NONE.
2. SOUTH PACIFIC AREA (WEST COAST OF SOUTH AMERICA TO 135 EAST):
   A. TROPICAL CYCLONE SUMMARY: NONE.
   B. TROPICAL DISTURBANCE SUMMARY: NONE.
   C. SUBTROPICAL SYSTEM SUMMARY:
      (1) THE AREA OF CONVECTION (INVEST 99P) PREVIOUSLY LOCATED NEAR
13.8S 164.3W IS NOW LOCATED NEAR 17.8S 165.5W, APPROXIMATELY 366 NM
SOUTHEAST OF PAGO PAGO, AMERICAN SAMOA. THE SYSTEM IS CURRENTLY
CLASSIFIED AS A SUBTROPICAL CYCLONE, GENERALLY CHARACTERIZED AS HAVING
BOTH TROPICAL AND MIDLATITUDE CYCLONE FEATURES. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY (MSI) DEPICTS A BROAD, PARTIALLY-EXPOSED LOW LEVEL
CIRCULATION CENTER (LLCC) WITH LINEAR CONVECTION CONFINED TO THE
EASTERN PERIPHERY. 99P IS LOCATED UNDERNEATH A STRONG UPPER-LEVEL
CYCLONE, CAUSING THE CIRCULATION TO BE HIGHLY ASYMMETRIC. A 312047Z
METOP-C ASCAT IMAGE REVEALED THE ASYMMETRIC NATURE OF THE WIND FIELD.
20-25 KNOT WINDS ARE CONFINED TO THE EASTERN SEMICIRCLE WITH MUCH
WEAKER (5-10 KTS) WINDS WITHIN THE WESTERN SEMICIRCLE. ENVIRONMENTAL
ANALYSIS REVEALS A MARGINAL ENVIRONMENT FOR TROPICAL DEVELOPMENT WITH
STRONG POLEWARD OUTFLOW AND WARM SEA SURFACE TEMPERATURES (28-29 C)
OFFSET BY MODERATE TO HIGH VERTICAL WIND SHEAR (20-25 KTS) AND
SIGNIFICANT DRY AIR ENTRAINMENT FROM THE WEST. GLOBAL MODELS ARE IN
GOOD AGREEMENT PORTRAYING A SOUTHWARD TRACK OVER THE NEXT 24 HOURS.
GLOBAL MODELS ALSO GENERALLY AGREE ON 99P STRUGGLING TO CONSOLIDATE
OVER THE NEXT 24 HOURS DUE TO THE MARGINAL ENVIRONMENT. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30 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 DOWNGRADED TO MEDIUM.
      (2) NO OTHER SUBTROPICAL SYSTEMS.
3. JUSTIFICATION FOR REISSUE: DOWNGRADED AREA IN PARA. 2.C.(1) TO
MEDIUM.//
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Tropical Disturbance Summary For area Equator to 25S, 160E to 120W
ISSUED FROM RSMC NADI Jan 010658 UTC.

TROPICAL DISTURBANCE TD04F CENTRE [1003HPA] WAS ANALYSED NEAR 19.0S
165.0W AT 010600UTC. POSITION FAIR BASED ON HIMAWARI-9 VIS/IR
IMAGERY. TD04F SLOW MOVING.

DEEP CONVECTION CONTINUES TO PERSIST TO THE EAST SOUTHEAST OF
SUPPOSED LLCC. TD04F LIES IN A MODERATE TO HIGH SHEARED ENVIRONMENT
WITH GOOD UPPER DIVERGENCE AND WARM SST AROUND 28 DEGREES CELSIUS.
GOOD EQUATORWARD OUTFLOW AS WELL AS STRONGER UPPER DIVERGENCE JUST TO
THE EAST OF SUPPOSED LLCC.

HOWEVER, DRY AIR INTRUSION FROM THE SOUTHWEST OF THE SYSTEM AS WELL
AS HIGH SHEAR TO THE SOUTH OF THE SYSTEM CAN HINDER DEVELOPMENT.

GLOBAL MODELS HAVE WEAKEN THE SYSTEM AS IT TRACKS SOUTHWARDS.

THE POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE IS
LOW IN THE NEXT 24-36HRS.
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NO OTHER SIGNIFICANT TROPICAL DISTURBANCE ANALYSED OR FORECAST IN THE
AREA.

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ABPW10 PGTW 011300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS REISSUED/011300Z-020600ZJAN2026//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
   A. TROPICAL CYCLONE SUMMARY: NONE.
   B. TROPICAL DISTURBANCE SUMMARY: NONE.
   C. SUBTROPICAL SYSTEM SUMMARY: NONE.
2. SOUTH PACIFIC AREA (WEST COAST OF SOUTH AMERICA TO 135 EAST):
   A. TROPICAL CYCLONE SUMMARY: NONE.
   B. TROPICAL DISTURBANCE SUMMARY: NONE.
   C. SUBTROPICAL SYSTEM SUMMARY:
      (1) THE AREA OF CONVECTION (INVEST 99P) PREVIOUSLY LOCATED NEAR
17.8S 165.5W IS NOW LOCATED NEAR 19.8S 166.7W, APPROXIMATELY 402 NM
SOUTHEAST OF PAGO PAGO, AMERICAN SAMOA. THE SYSTEM IS CURRENTLY
CLASSIFIED AS A SUBTROPICAL CYCLONE, GENERALLY CHARACTERIZED AS HAVING
BOTH TROPICAL AND MIDLATITUDE CYCLONE FEATURES. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY REVEALS AN EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC)
WITH SMALL AMOUNTS OF FLARING CONVECTION ALONG THE SOUTHERN PERIPHERY.
ENVIRONMENTAL ANALYSIS DEPICTS A MODERATELY FAVORABLE ENVIRONMENT FOR
DEVELOPMENT WITH POLEWARD UPPER-LEVEL OUTFLOW, MODERATE TO HIGH VERTICAL
WIND SHEAR (20 TO 25 KTS), AND WARM SEA SURFACE TEMPERATURES (27 TO 28
C). THE LLCC LIES UNDER THE BASE OF A VERY SHARP UPPER-LEVEL TROF, WHICH
IS BRINGING DRY MID-LEVEL AIR IN FROM THE WEST AND INDUCING THE HIGH
NORTHERLY SHEAR. GLOBAL MODELS AGREE ON THE DECLINE OF 99P.
DETERMINISTIC MODELS, GFS AND ECMWF, ARE UNABLE TO PICK UP ON THE SYSTEM
ANY LONGER. WHILE THE ENSEMBLE MODELS STILL REFLECT 99P AND AGREE ON IT
TRACKING GENERALLY SOUTHWARD, THERE ARE FEWER MEMBERS SUPPORTING
DEVELOPMENT OF A SIGNIFICANT SYSTEM. MAXIMUM SUSTAINED SURFACE WINDS ARE
ESTIMATED AT 23 TO 28 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO
BE NEAR 1003 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT
TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS DOWNGRADED TO LOW.
      (2) NO OTHER SUBTROPICAL SYSTEMS.
3. JUSTIFICATION FOR REISSUE: DOWNGRADED AREA IN PARA. 2.C.(1) TO LOW.//
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ABPW10 PGTW 012000
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND SOUTH
PACIFIC OCEANS REISSUED/012000Z-020600ZJAN2026//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
   A. TROPICAL CYCLONE SUMMARY: NONE.
   B. TROPICAL DISTURBANCE SUMMARY: NONE.
   C. SUBTROPICAL SYSTEM SUMMARY: NONE.
2. SOUTH PACIFIC AREA (WEST COAST OF SOUTH AMERICA TO 135 EAST):
   A. TROPICAL CYCLONE SUMMARY: NONE.
   B. TROPICAL DISTURBANCE SUMMARY: NONE.
   C. SUBTROPICAL SYSTEM SUMMARY:
      (1) THE AREA OF CONVECTION (INVEST 99P) PREVIOUSLY LOCATED NEAR
19.8S 166.7W HAS DISSIPATED AND IS NO LONGER SUSPECT FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE IN THE NEXT 24 HOURS.
      (2) NO OTHER SUBTROPICAL SYSTEMS.
3. JUSTIFICATION FOR REISSUE: DISSIPATED AREA IN PARA. 2.C.(1).//
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