SIO: ABELA - Post-Tropical

[1900hurricane]

A rare Southern Hemisphere winter invest has been designated, the first of the 2016-2017 Southern Hemisphere Tropical Cyclone Season. 12Z location was analyzed at 4.9*S, 83.5*E. There doesn't appear to be much model support for development, but that's not too surprising considering the time of year. Those that do develop 90S keep it weak and move it generally west.

[1900hurricane]

JTWC is giving 90S a medium chance at development in the next 24 hours.

ABIO10 PGTW 131800
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE INDIAN
/OCEAN/131800Z-141800ZJUL2016//
RMKS/
1. NORTH INDIAN OCEAN AREA (MALAY PENINSULA WEST TO COAST OF AFRICA):
A. TROPICAL CYCLONE SUMMARY: NONE.
B. TROPICAL DISTURBANCE SUMMARY: NONE.
2. SOUTH INDIAN OCEAN AREA (135E WEST TO COAST OF AFRICA):
A. TROPICAL CYCLONE SUMMARY: NONE.
B. TROPICAL DISTURBANCE SUMMARY:
(1) THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 6.4S 76.4E,
IS NOW LOCATED NEAR 8.7S 72.3E, APPROXIMATELY 75 NM SOUTH-SOUTHWEST
OF DIEGO GARCIA. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A
DEFINED LOW LEVEL CIRCULATION CENTER (LLCC) WITH DEVELOPING CENTRAL
CONVECTION NOW EVIDENT. A 131348Z SSMIS 91GHZ MICROWAVE IMAGE SHOWS
AN IMPROVED LLCC WITH CONVECTION ALONG THE SOUTHERN AND WESTERN
PORTION OF THE LLCC. OBSERVATIONS FROM DIEGO GARCIA SHOW DECREASING
PRESSURE OVER THE PAST 24 HOURS AS THE DISTURBANCE PASSED TO THE
SOUTH. UPPER LEVEL ANALYSIS SHOWS AN IMPROVED ENVIRONMENT WITH
DECREASING VERTICAL WIND SHEAR (10-15 KNOTS) AND GOOD DIVERGENCE
WITH AN ENHANCED POLEWARD OUTFLOW CHANNEL, EVIDENT ON WATER VAPOR
IMAGERY. SEA SURFACE TEMPERATURES ARE FAVORABLE NEAR 28 CELSIUS.
GLOBAL MODELS REMAIN MIXED WITH GFS THE MOST AGGRESSIVE SHOWING
STRONGER GRADIENT WINDS WRAPPING AROUND THE LLCC AS IT TRACKS
SOUTHWESTWARD TOWARDS MADAGASCAR. MAXIMUM SUSTAINED SURFACE WINDS
ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS
ESTIMATED TO BE NEAR 1005 MB. DUE TO THE LLCC CONSOLIDATION AND
IMPROVED UPPER LEVEL ENVIRONMENT, THE POTENTIAL FOR THE DEVELOPMENT
OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS
UPGRADED TO MEDIUM.
(2) NO OTHER SUSPECT AREAS.//
NNNN

[1900hurricane]

Tropical Cyclone Formation Alert now up.

WTXS21 PGTW 151600
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
A 210 NM RADIUS OF 8.5S 69.0E 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 151200Z INDICATES THAT A
CIRCULATION CENTER IS LOCATED NEAR 8.5S 69.0E. THE SYSTEM IS
MOVING NORTHEASTWARD AT 08 KNOTS.
2. REMARKS: ANIMATED INFRARED SATELLITE IMAGERY AND A 151322Z SSMIS
91GHZ IMAGE REVEAL PERSISTENT DEEP CONVECTION AND SHALLOW BANDING
WRAPPING INTO THE LLCC. PREVIOUS ASCAT IMAGERY SHOWS 25 TO 30 KNOTS
OF WIND ON THE SOUTHWEST QUADRANT WRAPPING INTO THE SYSTEM. A RECENT
OBSERVATION ALSO SHOWS 30 KNOT WINDS APPROXIMATELY 250 NM SOUTHEAST
OF THE SYSTEM. ENVIRONMENTAL CONDITIONS HAVE IMPROVED
SLIGHTLY OVER THE PAST 24 HOURS WITH VERTICAL WIND SHEAR RELAXING
OVER THE CIRCULATION CENTER BUT STILL RELATIVELY HIGH TO THE NORTH
AND GOOD DIVERGENT OUTFLOW. SEA SURFACE TEMPERATURES ARE ALSO
FAVORABLE FOR DEVELOPMENT NEAR 28 CELSIUS. CURRENTLY THERE IS NO
DOMINANT STEERING MECHANISM AS A LONG WAVE TROUGH TO THE SOUTH HAS
SUFFICIENTLY WEAKENED THE SUBTROPICAL RIDGE (STR) PREVIOUSLY TAKING
THE DISTURBANCE ON A SOUTHWEST TRACK. GLOBAL MODELS ARE IN GOOD
AGREEMENT THAT THE DEEP-LAYERED STR WILL REESTABLISH ITSELF BY TAU
24 TO 36 STEERING THE SYSTEM ON A SOUTHWESTERN TRACK.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
161600Z.
//
NNNN

[wxman57]

ASCAT pass at 1624Z today indicated 35k winds south of the center. It appears to be a tropical storm. Official RSMC for the basin says there are no significant disturbances in the South Indian Ocean. Significance is relative, I guess.

[wxman57]

Overnight ASCAT indicates it's a TS. JTWC began issuing advisories on Tropical Cyclone 1S. However, the official RSMC of the region in La Reunion Island doesn't recognize it. If a tropical storm forms in the ocean, and the official agency of the basin doesn't acknowledge it, does it exist?

[Darvince]

It may pass through Fantala's upwelling around when it starts weakening. Also AFAIK Meteo France has a requirement that all four quadrants must have 35kt winds in order for it to become a tropical storm, but idk why they aren't calling it a depression at least.

[stormwise]

Does it exist Hell Yeah.




Its not frontal, and has got spiral banding with a good outflow.

[cycloneye]

Is named ABELA.

01S ABELA 160717 1200 11.9S 64.4E SHEM 45 989

[1900hurricane]

Impressively, it looks like Abela may be trying to build some sort of eyewall structure. It doesn't have much in the way of favorable conditions left though. In addition to sea surface temperatures dropping off soon, environmental conditions get quite hostile around 15*S or so.