Tropical Disturbance Summary For area Equator to 25S, 160E to 120W
ISSUED FROM RSMC NADI Mar 030924 UTC.
TROPICAL DISTURBANCE TD09F CENTRE [1007HPA] WAS ANALYSED NEAR 15.5S
AND 174.2E AT 030600UTC. TD09F SLOW MOVING. POSITION POOR BASED ON
HIMAWARI 8 IR IMAGERY AND PERIPHERAL OBSERVATIONS. SST AROUND 30
DEGREES CELSIUS.
CONVECTION REMAINS PERSISTENT OVER SUPPOSED LLCC IN THE PAST 12 TO 24
HOURS. ORGANISATION REMAINS POOR. CYCLONIC CIRCULATION EXTENDS UP TO
700HPA. SYSTEM LIES ALONG AN UPPER RIDGE IN A LOW SHEARED
ENVIRONMENT.
GLOBAL MODELS HAVE PICKED UP THE SYSTEM AND INITIALLY MOVE IT
SOUTHEAST THEN SOUTH WITH SLIGHT INTENSIFICATION.
POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE IN THE
NEXT 24 TO 48 HOURS IS LOW.
(1) AN AREA OF CONVECTION (INVEST 97P) HAS PERSISTED NEAR
14.3S 174.3E, APPROXIMATELY 275 NM NORTHWEST OF NADI, FIJI. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY AND A 030725Z 91GHZ SSMIS MICROWAVE
IMAGE DEPICT FLARING, UNORGANIZED CONVECTION ABOVE A BROAD LOW LEVEL
CIRCULATION (LLC). THE UPPER LEVEL ENVIRONMENT IS VERY FAVORABLE,
WITH LOW (5-10 KNOT) VERTICAL WIND SHEAR AND STRONG DIVERGENCE ALOFT
DUE TO AN UPPER LEVEL ANTICYCLONE LOCATED JUST WEST OF THE LLC. SEA
SURFACE TEMPERATURES ARE WARM (28-30 CELSIUS) AND WILL SUPPORT
FURTHER DEVELOPMENT. GLOBAL DYNAMIC MODELS GENERALLY AGREE ON 97P
REACHING TROPICAL STORM STRENGTH BETWEEN TAU 36 AND TAU 60. IN
ADDITION MODELS PREDICT A SLOW SOUTHEASTWARD TRACK BEFORE TURNING
SOUTHWEST IN THE MID TERM. MAXIMUM SUSTAINED SURFACE WINDS ARE
ESTIMATED AT 10 TO 15 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED
TO BE NEAR 1010 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS LOW.
(1) THE AREA OF CONVECTION (INVEST 97P) PREVIOUSLY LOCATED
NEAR 14.3S 174.3E, IS NOW LOCATED NEAR 15.8S 173.1E, APPROXIMATELY
276 NM WEST-NORTHWEST OF NADI, FIJI. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY INDICATES A WEAK, ASYMMETRIC LOW LEVEL CIRCULATION
(LLC) WITH FLARING CONVECTION SHEARED TO THE NORTHEAST BECAUSE OF
MODERATE WESTERLY VERTICAL WIND SHEAR ASSOCIATED WITH A SHORTWAVE
TROUGH. A 041020Z ASCAT IMAGE SHOWS 20-30 KNOT WINDS IN THE
SOUTHEASTERN QUADRANT OF A BROAD CIRCULATION. SST REMAINS WARM (28-
30 CELSIUS) AND SUPPORTS FURTHER DEVELOPMENT. GLOBAL MODELS TRACK
THE SYSTEM SOUTHWEST AND DEVELOP 97P IN THE TAU 36-60 RANGE AS THE
TROUGH WEAKENS AND ENVIRONMENTAL CONDITIONS IMPROVE. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1004 MB. THE POTENTIAL FOR
THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS UPGRADED TO MEDIUM.
** WTPS11 NFFN 051200 ***
TROPICAL DISTURBANCE ADVISORY NUMBER A1 ISSUED FROM RSMC NADI
Mar 051326 UTC.
TROPICAL DEPRESSION 09F CENTRE 998HPA WAS LOCATED NEAR 15.4S 171.8E
AT 051200 UTC. POSITION POOR BASED ON HIMAWARI 8 EIR IMAGERY AND
PERIPHERAL SURFACE REPORTS. TD09F MOVING WEST-SOUTHWEST AT ABOUT 05
KNOTS. MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT
ABOUT 25 KNOTS.
DEEP CONVECTION REMAINS PERSISTENT. OVERALL ORGANISATION IMPROVED
SLIGHTLY IN THE PAST 24 HOURS. CYCLONIC CIRCULATION EXTENDS UP TO
500HPA. SYSTEM LIES SOUTH OF AN UPPER RIDGE IN A LOW TO MODERATE
SHEARED ENVIRONMENT. SST AROUND 30 DEGREES CELCIUS. DVORAK ANALYSIS
BASED ON 0.3 WRAP YIELDS DT=2.0. PT AND MET AGREE. THUS YIELDING
T2.0/2.0/D1.0/24HRS.
GLOBAL MODELS HAVE PICKED UP THE SYSTEM AND MOVE IT WEST-SOUTHWEST
WITH FURTHER INTENSIFICATION.
POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE IN THE
NEXT 24 TO 48 HOURS IS MODERATE TO HIGH.
FORECASTS :
AT 12 HRS VALID AT 060000 UTC 15.8S 170.8E MOV WSW AT 06 KT WITH 30
KT CLOSE TO CENTRE
AT 24 HRS VALID AT 061200 UTC 16.3S 169.5E MOV WSW AT 06 KT WITH 35
KT CLOSE TO CENTRE
OUTLOOK :
AT 36 HRS VALID AT 070000 UTC 16.7S 168.2E MOV WSW AT 06 KT WITH 45
KT CLOSE TO CENTRE
AT 48 HRS VALID AT 071200 UTC 17.0S 167.4E MOV WSW AT 06 KT WITH 50
KT CLOSE TO CENTRE
THE NEXT TROPICAL DISTURBANCE ADVISORY ON TROPICAL DEPRESSION 09F
WILL BE ISSUED AROUND 052000 UTC.
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