Tropical Cyclone Cherono

[Somerset Squall]

At last another tropical cyclone forms in what has been a very quiet Southwest Indian Ocean tropical cyclone season. Invest 98S continued to become better organised and was designated a tropical cyclone this morning. Intensity is 35kts. Located around 500 miles south of Diego Garcia, Cherono is moving westwards along the northern periphery of a subtropical ridge to the south. This motion should persist over the next few days, with perhaps the ridge weakening by about day 4 to allow a slight poleward turn. La Reunion and Mauritius need to watch Cherono as the cyclone could be in the vicinity in about 4-5 days time. Some strengthening is likely, but may be hindered by a nearby trough. Indeed, this trough is eventually expected to get closer to Cherono to increase shear over the cyclone. Until then, waters are warm and shear is low so some modest intensification is expected at least. JTWC forecast a peak of 55kts before the shear arrives.

[Somerset Squall]

Cherono has strengthened to 40kts. Banding is impressive and a central dense overcast appears to be forming. With at least 3 days of low shear and warm sea temps ahead, and the structural improvement of Cherono, JTWC are now forecasting a peak of 70kts before weakening occurs.

[Somerset Squall]

Cherono strengthened to 45kts this morning but has since weakened to 40kts. Although shear is low and outflow good, the air is pretty dry and this is eroding Cherono's convective canopy and weakening the cyclone. As expected, shear will soon increase, and coupled with the dry air, will ulitimately kill off Cherono before the cyclone gets too close to La Reunion and Mauritius.

Interesting to note that this Southwest Indian Ocean season has been the quietest since 1926 so far. Interesting off the back of the quiestest East and West Pacific seasons on record!

[Somerset Squall]

Although the circulation of Cherono remains fairly well defined, convection has all but dissipated near this centre. Intenisty has fallen to 35kts, and JTWC have issued their final warning on the cyclone. Regeneration is not likely as the air is still rather dry and as the remnant low moves to the southwest it will encounter cooler waters and higher shear.