SIO: Tropical Low 04U (INVEST 98S)

[jaguarjace]

98S INVEST 151221 0000 8.4S 106.3E SHEM 20 1006

[wxman57]

Overnight ASCAT indicates a well-defined LLC and 35kt winds, meaning it is likely already a tropical storm.

Note the purple (35kt) vectors in the image below:

[supercane]

Earlier JTWC TCFA:
WTXS21 PGTW 210730
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
140 NM EITHER SIDE OF A LINE FROM 8.6S 106.1E TO 11.7S 109.0E
WITHIN THE NEXT 06 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 210700Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 9.0S 106.6E. THE SYSTEM IS MOVING SOUTHEASTWARD AT 05 KNOTS.
2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 8.7S
106.2E IS NOW LOCATED NEAR 9.0S 106.6E, APPROXIMATELY 173 NM SOUTH
OF JAKARTA. ANIMATED MULTISPECTRAL SATELLITE IMAGERY AND A 202319Z
SSMIS 91 GHZ IMAGE REVEAL A COMPACT LOW-LEVEL CIRCULATION CENTER
(LLCC) WITH PERSISTENT DEEP CONVECTIVE BANDING BEGINNING TO WRAP
TIGHTLY INTO THE SYSTEM. RECENT SCATTEROMETRY DATA DEPICTS A FAIRLY
SYMMETRIC WIND FIELD WITH 25 TO 30 KNOT WINDS OVER THE EASTERN SEMI-
CIRCLE, ENHANCED BY TOPOGRAPHIC EFFECTS. THE UPPER LEVEL ENVIRONMENT
IS FAVORABLE FOR DEVELOPMENT WITH MODERATE (15 TO 20 KNOTS) VERTICAL
WIND SHEAR OFFSET BY EXCELLENT UPPER LEVEL DIVERGENCE OVER THE
SYSTEM. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30
KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1000 MB.
DUE TO INCREASED CONSOLIDATION OF THE LLCC, THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
220730Z.//
NNNN

And from Jakarta:
Indonesian Agency for Meteorology Climatology and Geophysics
Jakarta Tropical Cyclone Warning Centre (TCWC)

TROPICAL CYCLONE OUTLOOK

Tropical Cyclone Outlook for Southern Indonesia area
Issued Monday, 21th December 2015, Time 08.00 Western Indonesia Time

Current Tropical Cyclone in the Southern Indonesia area:
None.

Tropical cyclone development possibility:
Suspect area with minimum pressure 1006 mb is observed in Hindian Ocean South of West Java near 8.4 S 106.3 E, about 221 km south-southwest of Jakarta, and moving East-southeast.
Possibility to develop into tropical cyclone:
Tuesday (tomorrow) : medium possibility
Wednesday (tomorrow +1): small possibility
Thursday (tomorrow +2) : small possibility

Note:
Small possibility means possibility for the suspect area to develop into tropical cyclone is less than 10%.
Medium possibility means possibility for the suspect area to develop into tropical cyclone is about 20%-40%.
Large possibility means possibility for the suspect area to develop into tropical cyclone is more than 50%.

Southern Indonesia area is area within equator to 11 S and 90 to 141 E.

Latest Dvorak from SSD:
TXXS21 KNES 211815
TCSSIO

A. TROPICAL DISTURBANCE (98S)
B. 21/1730Z
C. 9.8S
D. 107.3E
E. FIVE/HIMAWARI-8
F. T1.5/2.5/S0.0/24HRS
G. IR/EIR/SWIR/SSMIS
H. REMARKS...SYSTEM BEING SHEARED. LLCC LOCATED LESS THAN 1.25 DEGREES
FROM DG FOR A DT OF 2.0. MET AND PT=1.5. FT IS BASED ON MET DUE TO LOW
CONFIDENCE IN CENTER FIX POSITION.
I. ADDL POSITIONS
21/1148Z 9.3S 107.2E SSMIS

...VELASCO

[Alyono]

How do these rsmcs miss these. Kind of embarassed that jakarta misses this. Hate to call out the home rsmc but it needs to be done in this case

[supercane]

WTXS21 PGTW 220100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT CANCELLATION//
REF/A/JOINT TYPHOON WRNCEN PEARL HARBOR HI/210721Z DEC 15//
AMPN/REF IS TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. REMARKS: THIS CANCELS REF A (WTXS21 PGTW 210730). THE AREA OF
CONVECTION PREVIOUSLY LOCATED NEAR 9.4S 107.1E, IS NOW LOCATED NEAR
9.7S 107.7E, APPROXIMATELY 215 NM SOUTH-SOUTHEAST OF JAKARTA,
INDONESIA. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY AND A
212257Z SSMIS MICROWAVE IMAGE REVEAL CONVECTIVE BANDING HAVE
UNRAVELED AND WEAKENED AS THE LOW LEVEL CIRCULATION CENTER HAS
BECOME ILL-DEFINED. GLOBAL MODELS DO NOT INDICATE ANY SIGNIFICANT
DEVELOPMENT OF THIS SYSTEM. MAXIMUM SUSTAINED SURFACE WINDS ARE
ESTIMATED AT 15 TO 20 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.//
NNNN

[jaguarjace]

98S INVEST 151223 0000 9.4S 108.4E SHEM 25 1004

[jaguarjace]

Tropical Cyclone Outlook for the Western Region
Issued at 2:38 pm WST on Wednesday 23 December 2015
for the period until midnight WST Saturday 26 December 2015.

Potential Cyclones:
A tropical low (04U) was near 10.0S 108.3E at midday WST Wednesday 23 December and has been
moving slowly southeast. The system has shown signs of development overnight and if the trend continues
there is a chance the system develops into a tropical cyclone tomorrow. The system is forecast to weaken
during Friday and Saturday.

Likelihood this system being a tropical cyclone in the Western Region on:
Thursday: Moderate
Friday: Moderate
Saturday: Low

[euro6208]

Has a TC or even a category 1 cyclone ever hit Indonesia before?