Tropical Cyclone Elnus

[Somerset Squall]

We have another cyclone in the Southern Indian Ocean, Tropical Cyclone 09S (soon to be Elnus). The storm is located inbetween Mozambique and Madagascar and is trapped in a weak steering environment between two anticyclones west and east. The anticyclone to the west is expected to eventually become the dominant steering influence once it builds northwards which should force 09S on a slow southwesterly track. The JTWC warns that the area is known for erratic moving cyclones and as this one is in a weak steering environment it needs to be closely watched because and wobbles could bring it closer to Mozambique or Madagascar.

09S is expected to strengthen as shear remains low, sea temps remain high and outflow remains good. We could potentially end up with a strong cyclone here which isn't good as land is easily within it's reach. It is already bringing heavy rains to Western Madagascar so flooding is likely.

Satellite image here (09S is to the left of the image):

From: http://cimss.ssec.wisc.edu/tropic/real-tim...xxirmet5bbm.jpg

[Cookie]

well post any warnings when I get them

[Somerset Squall]

Elnus isn't strengthening as quickly as originally anticipated as westerly shear has begun to impinge on the storm. Elnus is slowly drifting southwestward and this motion (with perhaps a more southward turn) is expected to continue, which will prevent landfall unless any unexpected turns occur. Although Elnus is over water, it is still bring heavy rains to Madagascar.

[Cookie]

thanks for the update mate

[Somerset Squall]

Thanks Cookie.

Elnus has continued to weaken as shear remains strong over the cyclone. JTWC currently has Elnus at 35kt but Meteofrance only class the cyclone as a tropical depression and don't expect it to restrengthen. The JTWC only call for very modest strengthening as improving outflow after 24hr will battle high shear and lowering sea temps. As the environment is far from favourable for Elnus it seems that it won't become very strong at all unless the shear eases. Later in the forecast period, a curve eastwards is predicted and it may make a landfall in Southern Madagascar, but this is highly uncertain. If it does make a landfall, rain will be the major problem as winds aren't expected to be all that intense. Heavy rains are already affecting many parts of Madagascar in association with Elnus so the debate whether or not it will make a landfall isn't all that important unless Elnus manages to overcome the environment and become stronger.

[Cookie]

Storm Alert issued at 3 Jan, 2008 0:00 GMT

Tropical Depression ELNUS is forecast to strike land to the following likelihood(s) at the given lead time(s):

Green Alert Country(s) or Province(s)

Madagascar

probability for TS is 35% in about 36 hours

Green Alert City(s) and Town(s)

Toliara (23.4 S, 43.7 E)

probability for TS is 35% in about 48 hours

[Somerset Squall]

Thanks for the alert Cookie.

Indeed, Elnus is now very close to Southern Madagascar. However, it is a dissapating storm.

Latest remarks from JTWC:

REMARKS:

031500Z POSITION NEAR 23.7S 42.1E.

TROPICAL CYCLONE (TC) 09S (ELNUS), LOCATED APPROXIMATELY 390 NM SOUTH-

WEST OF ANTANANARIVO, MADAGASCAR, HAS TRACKED SOUTHEASTWARD AT 12 KNOTS

OVER THE PAST 06 HOURS. ANIMATED MULTISPECTRAL AND WATER VAPOR IMAGERY

INDICATES THE LOW LEVEL CIRCULATION CENTER (LLCC) HAS BECOME FULLY EXPOSED

AS A COLD CORE UPPER LEVEL LOW HAS MOVED OVER IT SUPPRESSING MOST CONVECTION.

THE UPPER LEVEL LOW HAS ALSO CAUSED THE STORM TO TRANSITION TO A SHALLOW

WARM CORE SYSTEM, OVER THE LAST 12 HOURS. THE TRACK SPEED HAS INCREASED

SIGNIFICANTLY DUE TO THE STRENGTHENING OF THE STEERING RIDGE TO THE NORTH-

EAST. THE INITIAL WARNING INTENSITY ESTIMATE IS BASED A 020646Z ASCAT PASS

INDICATING 35 KNOTS OF WIND NORTHEAST AND SOUTHEAST OF THE LLCC. THE STORM

WILL CONTINUE TO BE STEERED SOUTHEASTWARD BY AN EQUATORWARD EXTENSION OF THE

SUBTROPICAL RIDGE OVER MADAGASCAR. THE STORM WILL SLOWLY WEAKEN THROUGH TAU

24 AS IT DISSIPATES OVER WATER. THE DISSIPATION WILL BE CAUSED BY THE UPPER

LEVEL LOW HINDERING OUTFLOW AND TRACK WATERS WITH LOW OCEAN HEAT CONTENT.

MAXIMUM SIGNIFICANT WAVE HEIGHT AT 031200Z IS 16 FEET. NEXT WARNINGS AT

040300Z AND 041500Z.//

[Cookie]

most likely the final upate,

Storm Alert issued at 3 Jan, 2008 12:00 GMT

Tropical Storm ELNUS is forecast to strike land to the following likelihood(s) at the given lead time(s):

Yellow Alert Country(s) or Province(s)

Madagascar

probability for TS is 65% within 12 hours

Green Alert City(s) and Town(s)

Toliara (23.4 S, 43.7 E)

probability for TS is 40% within 12 hours

[Somerset Squall]

Elnus has now turned extratropical. It could re-intensify as an extratropical system as it continues to plunge south into the Southern Oceans but Elnus's tropical life is now over.