(1) THE AREA OF CONVECTION (INVEST 91W) PREVIOUSLY LOCATED
NEAR 9.8N 109.9E, IS NOW LOCATED NEAR 11.1N 109.1E, APPROXIMATELY
135 NM EAST OF HO CHI MINH CITY, VIETNAM. ANIMATED MULTI-SPECTRAL
SATELLITE IMAGERY SHOWS AN EXPOSED WELL DEFINED LOW LEVEL
CIRCULATION CENTER (LLCC) WITH DEEP CONVECTION PRIMARILY TO THE
NORTH AND WEST. A 122331Z AMSU-B 89GHZ MICROWAVE IMAGE SHOWS WEAK
CONVECTION DUE TO LAND INTERACTION. UPPER-LEVEL ANALYSIS INDICATES
MARGINALLY FAVORABLE CONDITIONS WITH GOOD DIFFLUENCE ALOFT, MODERATE
TO HIGH (20-30KTS) VERTICAL WIND SHEAR, AND CONDUCIVE SST (28C).
GLOBAL MODELS KEEP THIS SYSTEM QUASI-STATIONARY AND DO NOT DEPICT
FURTHER DEVELOPMENT AT THIS TIME. MAXIMUM SUSTAINED SURFACE WINDS
ARE ESTIMATED AT 12 TO 18 KNOTS. MINIMUM SEA LEVEL PRESSURE IS
ESTIMATED TO BE NEAR 1006 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS DOWNGRADED
TO LOW.
B. TROPICAL DISTURBANCE SUMMARY:
(1) THE AREA OF CONVECTION (INVEST 99P) PREVIOUSLY LOCATED
NEAR 12.4S 173.8E, IS NOW LOCATED NEAR 14.2S 175.8E, APPROXIMATELY
230 NM NORTH-NORTHWEST OF FIJI. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY AND A 140305Z AMSU-B 89GHZ MICROWAVE IMAGE SHOW A BROAD LOW
LEVEL CIRCULATION CENTER (LLCC) WITH FRAGMENTED BANDING ALONG THE
NORTHERN PERIPHERY, ASSOCIATED WITH STRONG CONVERGENT FLOW. A
132158Z ASCAT PASS SHOWS AN ELONGATED CIRCULATION WITH STRONGER
WINDS (20-25 KT) WRAPPING INTO THE LLCC FROM THE NORTHERN AND
SOUTHERN SEMI-CIRCLES. THE DISTURBANCE IS CURRENTLY LOCATED IN A
FAVORABLE ENVIRONMENT DUE PRIMARILY TO MODERATE VERTICAL WIND SHEAR
(20-25 KTS), WARM SEA SURFACE TEMPERATURES AND GOOD DIFFLUENCE
ALOFT. GLOBAL MODELS INDICATE SLOW DEVELOPMENT OVER THE NEXT 2 DAYS
AS THIS DISTURBANCE TRACKS SOUTHWARD. MAXIMUM SUSTAINED SURFACE
WINDS ARE ESTIMATED AT 18 TO 23 KNOTS. MINIMUM SEA LEVEL PRESSURE IS
ESTIMATED TO BE NEAR 1005 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS UPGRADED TO
MEDIUM.
WWPS21 NFFN 140600
Tropical Disturbance Summary For area Equator to 25S, 160E to 120W
ISSUED FROM RSMC NADI Dec 140848 UTC.
TROPICAL DISTURBANCE 04F [ 1004HPA] ANALYSED NEAR 14.5S 175.5E AT
140600UTC SLOW MOVING. POSITION POOR BASED ON HIMAWARI IR IMAGERY AND
PERIPHERAL SURFACE OBSERVATION. SST AROUND 30 DEGRESS CELCIUS.
CONVECTION PERSISTENT IN THE PAST 24 HOURS. SYSTEM LIES UNDER A UPPER
DIFFLUENT REGION IN A LOW SHEARED ENVIRONMENT. CYCLONIC CIRCULATION
EXTENDS OVER TO 700HPA.
GLOBAL MODELS HAVE PICKED UP THE SYSTEM WITH SOUTHEAST MOVEMENT AND
GRADUAL INTENSIFICATION.
THE POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE IN
THE NEXT 24 TO 48 HOURS IS MODERATE.
NO OTHER SIGNIFICANT TROPICAL DISTURBANCE ANALYSED OR FORECAST IN THE
AREA.
WTPS11 NFFN 150000
TROPICAL DISTURBANCE ADVISORY NUMBER A3 ISSUED FROM RSMC NADI
Dec 151422 UTC.
TROPICAL DEPRESSION TD04F CENTRE 1000HPA WAS ANALYSED NEAR 15.8S
174.5E AT 150000UTC. POSITION POOR BASED ON HIMAWARI-8 IR/VIS IMAGERY
AND PERIPHERAL SURFACE REPORTS. DEPRESSION MOVING SOUTH-SOUTHWEST AT
ABOUT 05 KNOTS. MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THE CENTRE
ESTIMATED AT ABOUT 25 KNOTS.
DEEP CONVECTION REMAINS PERSISTENT. ORGANISATION HAS IMPROVED PAST 24
HOURS. OUTFLOW GOOD. SST AROUND 29 DEGREE. SYSTEM LIES IN A MODERATE
UPPER DIVERGENCE REGION AND IN A LOW TO MODERATE SHEARED ENVIRONMENT.
DVORAK ANALYSIS BASED 0.3 WRAP YIELDS DT=2.0, MET AND PT AGREE. FT
BASED ON DT. THUS YIELDING, T2.0/2.0/D1.0/24HRS.
GLOBAL MODELS HAVE PICKED UP THE SYSTEM AND SLOWLY MOVE IT SOUTHWARDS
WITH GRADUAL INTENSIFICATION.
FORECASTS :
AT 12 HRS VALID AT 151200 UTC 16.2S 174.5E MOV S AT 03KT WITH 30KT
CLOSE TO CENTRE
AT 24 HRS VALID AT 160000 UTC 16.5S 174.9E MOV SE AT 03KT WITH 35KT
CLOSE TO CENTRE.
OUTLOOK:
AT 36 HRS VALID AT 161200 UTC 16.9S 175.2E MOV SE AT 03KT WITH 40KT
CLOSE TO CENTRE
AT 48 HRS VALID AT 170000 UTC 17.4S 175.3E MOV SE AT 03KT WITH 45KT
CLOSE TO CENTRE.
THE NEXT TROPICAL DISTURBANCE ADVISORY ON TD04F WILL BE ISSUED AROUND
150800UTC.
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