Summary
This unnamed tropical cyclone was reanalysed well after the event to have reached cyclone intensity. A low formed in the central Indian Ocean southwest of Cocos Island on 7-10 January, reached cyclone intensity on 11 January, peaking at category 2 intensity (50 kn) later that day before weakening during 12 January after crossing west of 90oE outside the Australian region.
There were no known impacts from this system.
Meteorological Description
A low formed in the central Indian Ocean southwest of Cocos Island on 7-9 January, then intensified to reach cyclone intensity on 11 January, peaking at category 2 intensity (50 kn) later that day (refer Figure 1). Microwave imagery indicated a small system and a partial eye signature (as shown in Figure 2), and gales were estimated to extend only 60 nm (110 km) from the centre.
The cyclone weakened during 12 January after crossing west of 90oE outside the Australian region. The gale radius expanded on the southern side during its weakening phase as it interacted with the sub-tropical ridge to the south and accelerated to the west southwest.
Impact
Nil.
Observations
Nil.
Note: This cyclone was formally upgraded to TC intensity following a reanalysis in 2020, making use of microwave imagery that was not available in real-time.
Table 1. Best track summary for Unnamed Tropical Cyclone, 10 -13 January 1997.
Note: Add 8 hours to convert to WST. Refer to best track database for complete track details.|
Year |
Month |
Day |
Hour (UTC) |
Position Latitude S |
Position Longitude E |
Max wind 10min knots |
Central Pressure hPa |
Rad. of Gales nm |
|
1997 |
01 |
10 |
0000 |
-17.6 |
92.5 |
25 |
1002 |
|
|
1997 |
01 |
10 |
0600 |
-18.0 |
92.5 |
30 |
1002 |
|
|
1997 |
01 |
10 |
1200 |
-18.5 |
92.4 |
30 |
1002 |
|
|
1997 |
01 |
10 |
1800 |
-18.7 |
92.0 |
30 |
1000 |
|
|
1997 |
01 |
11 |
0000 |
-19.0 |
91.4 |
35 |
998 |
60 |
|
1997 |
01 |
11 |
0600 |
-19.7 |
90.8 |
40 |
996 |
60 |
|
1997 |
01 |
11 |
1200 |
-20.5 |
90.3 |
50 |
991 |
60 |
|
1997 |
01 |
11 |
1800 |
-21.3 |
89.6 |
50 |
992 |
60 |
|
1997 |
01 |
12 |
0000 |
-22.0 |
88.2 |
50 |
992 |
60 |
|
1997 |
05 |
12 |
0600 |
-22.7 |
86.8 |
50 |
992 |
70 |
|
1997 |
05 |
12 |
1200 |
-23.6 |
85.6 |
40 |
996 |
70 |
|
1997 |
05 |
12 |
1800 |
-24.6 |
84.2 |
35 |
998 |
70 |
|
1997 |
05 |
13 |
0000 |
-25.5 |
82.8 |
30 |
1000 |
|
|
1997 |
05 |
13 |
0600 |
-26.0 |
81.6 |
30 |
1000 |
|
|
1997 |
05 |
13 |
1200 |
-17.6 |
92.5 |
30 |
1002 |
|
|
1997 |
05 |
13 |
1800 |
-18.0 |
92.5 |
30 |
1002 |
|
Figure 1. Track of Unnamed Tropical Cyclone, 7 -13 January 1997
All times in UTC.
Figure 2. SSMI 85 GHz microwave imagery at 1213 UTC 11 Jan. (left) and AVHRR enhanced IR image at 1236UTC 11 Jan. (right). Images courtesy of HURSAT.
