Tropical Cyclone Jade

[Somerset Squall]

Invest 95S has become sufficiently organised to be classified as a tropical cyclone, with an initial intensity of 35kts. TC 26S is located northeast of Madagascar, and is tracking west-southwestwards towards the coast. JTWC is expecting 26S to continue to track west-southwestwards with a coastal crossing forecast to occur around 36hrs, as the subtropical ridge to the south remains strong. However, MeteoFrance are disagreeing, forecasting the ridge to weaken sending the storm south parallel to the east coast of Madagascar. It's tricky to forecast which solution will evolve, especially when the steering largely depends on how vertically deep 26S gets.

26S is expected to strengthen over the next couple days. JTWC expect a peak of 55kts before landfall though it's worth noting the cyclone may become stronger than this if it heads southwards and misses land. Shear is low, sea temps the hottest in the basin and outflow is good in both poleward and equatorward direction. Banding features are forming, indicative of a strengthening storm, though convection near the centre is currently lacking which may make intensification slow at first. However, in the favourable conditions there is nothing but land stopping this system strengthening over the next couple days. Northeast Madagascar need to keep a close eye on 26S.

Edited April 4, 2009 by Somerset Squall

[Cookie]

this needs to be an eye on like you say.

Storm Alert issued at 4 Apr, 2009 18:00 GMT

Tropical Storm TWENTYSIX 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 CAT 1 or above is 25% in about 36 hours

probability for TS is 55% in about 36 hours

Yellow Alert City(s) and Town(s)

Ambodifototra (16.9 S, 49.9 E)

probability for CAT 1 or above is 20% in about 48 hours

probability for TS is 50% in about 36 hours

Antalaha (14.9 S, 50.2 E)

probability for CAT 1 or above is 15% in about 36 hours

probability for TS is 45% in about 36 hours

Maroantseta (15.4 S, 49.7 E)

probability for CAT 1 or above is 15% in about 48 hours

probability for TS is 45% in about 36 hours

Toamasina (18.2 S, 49.4 E)

probability for CAT 1 or above is 10% in about 48 hours

probability for TS is 35% in about 48 hours

Note that

Yellow Alert (Elevated) is CAT 1 or above to between 10% and 30% probability, or TS to above 50% probability.

CAT 1 means Tropical Cyclone strength winds of at least 74 mph, 119 km/h or 64 knots 1-min sustained.

TS means Tropical Storm strength winds of at least 39 mph, 63 km/h or 34 knots 1-min sustained.

[Cookie]

tracking map

[Somerset Squall]

Thanks for the maps Cookie.

26S has intensified overnight, and is now Tropical Cyclone Jade, with an intensity of 50kts. Convection has steadily increased near the centre, and banding features continue to wrap into Jade's circulation. Latest satellite imagery depicts what looks like an eye but I think this may just be a gap in convection. Jade so far has always had a slight problem maintaining deep convection near the centre, but the cyclone looks better organised than yesterday, so it's safe to say Jade will intensify some more.

As for tracking, MeteoFrance's forecast track has shifted Jade more westwards, and JTWC continue to insist on direct landfall in northeastern Madagascar. MeteoFrance are less aggressive on strengthening due to land interaction, and forecast gradual weakening in around 24hrs time. JTWC have also toned down on intensification and now aren't expecting Jade to make cat 1 on SS scale, due to a faster west track towards land. Either way, Madagascar is likely to weaken Jade in the long run, and Jade is likley to provide flooding rains and gales to the eastern half of the country.

Edited April 5, 2009 by Somerset Squall

[Cookie]

Storm Alert issued at 5 Apr, 2009 6:00 GMT

Tropical Storm TWENTYSIX 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 60% in about 24 hours

Green Alert City(s) and Town(s)

Vohimarina (13.3 S, 49.9 E)

probability for TS is 50% in about 24 hours

Antalaha (14.9 S, 50.2 E)

probability for TS is 50% in about 24 hours

Maroantseta (15.4 S, 49.7 E)

probability for TS is 45% in about 24 hours

Note that

Yellow Alert (Elevated) is CAT 1 or above to between 10% and 30% probability, or TS to above 50% probability.

Green Alert (Low) is TS to between 31% and 50% probability.

CAT 1 means Tropical Cyclone strength winds of at least 74 mph, 119 km/h or 64 knots 1-min sustained.

TS means Tropical Storm strength winds of at least 39 mph, 63 km/h or 34 knots 1-min sustained.

[Somerset Squall]

Jade has slowed a little as she approaches the northeast coast of Madagascar. Jade has also strengthened a little more than anticipated, and is now a 65kt, cat 1 cyclone on the SS scale. The eye feature has been intermittent in satellite imagery, and a central dense overcast feature has persisted. Excellent banding features continue to wrap into the tight LLC. However, Jade is only a few hours from landfall so further intensification isn't likely. Jade will then continue to move inland and dissipate over the rugged terrain of northern Madagascar. There is a small chance that a more southward turn will keep a portion of the circulation over water, but excessive land interaction will probably still cause dissipation even if the more southward track materialises. Well done to the JTWC for consistantly predicting landfall where MeteoFrance was going for a southward track over water, and for also predicting Jade would reach cat 1 intensity on the initial forecasts.

As Cookie's warnings suggest, northern Madagascar is in for a bumpy ride. This area of the world is used to landfalling TC's but nonetheless widespread damage and flooding is a real possibility. Indeed, some very heavy rains are already spreading inland.

Edited April 5, 2009 by Somerset Squall

[Cookie]

landfall not to far off now

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

Red Alert Country(s) or Province(s)

Madagascar

probability for CAT 1 or above is 55% within 12 hours

probability for TS is 75% within 12 hours

Red Alert City(s) and Town(s)

Antalaha (14.9 S, 50.2 E)

probability for CAT 1 or above is 55% within 12 hours

probability for TS is 75% within 12 hours

Yellow Alert City(s) and Town(s)

Maroantseta (15.4 S, 49.7 E)

probability for CAT 1 or above is 25% in about 24 hours

probability for TS is 75% within 12 hours

Green Alert City(s) and Town(s)

Ambodifototra (16.9 S, 49.9 E)

probability for TS is 35% within 12 hours

Note that

Red Alert (Severe) is CAT 1 or above to between 31% and 100% probability.

Yellow Alert (Elevated) is CAT 1 or above to between 10% and 30% probability, or TS to above 50% probability.

Green Alert (Low) is TS to between 31% and 50% probability.

CAT 1 means Tropical Cyclone strength winds of at least 74 mph, 119 km/h or 64 knots 1-min sustained.

TS means Tropical Storm strength winds of at least 39 mph, 63 km/h or 34 knots 1-min sustained.

[Somerset Squall]

Jade is inland and weakening. Rugged terrain is taking it's toll on the circulation and convective coverage is slowly shrinking. Intensity has been reduced to 45kts. Jade is moving southwestwards but will turn south as it rounds the periphery of a subtropical ridge aligning itself to the east. Despite the south turn, Jade is not expected to re-emerge over water. Full dissipation could occur as soon as 24hrs.

[Cookie]

slightly off topic Am I the only one who finds it a little spooky that this system formed and was named jade on the Saturday the same day jade goodys funeral took place.

[Somerset Squall]

slightly off topic Am I the only one who finds it a little spooky that this system formed and was named jade on the Saturday the same day jade goodys funeral took place.

Quite a coincidence! Didn't take much notice really.

Jade (the tropical cyclone) has unexpectedly recurved back over water. Convection is redeveloping over the centre as warm waters, low shear and good outflow is helping the storm re-intensify. Jade will skirt down the east ocast whilst gaining intensity, but rapid intensification is not likely due to land interaction. In 24hrs time, Jade will move into higher shear which sould induce a weakening trend. Jade is likely to dissipate over water in about 48hrs time.

I really wasn't expecting Jade to re-emerge over water. All forecasts were pointing to dissipation over land. It seems that Jade has found a weakness in the subtropical ridge to the east which allowed the storm to move slightly east of due south taking it back over water.

This track close to the coast is bound to bring flooding and storm surge to Eastern Madagascar. Hopefully people are as prepared as they can be.

Edited April 7, 2009 by Somerset Squall

[Cookie]

yup I agree with you their that I hope they are ready.

[Somerset Squall]

Jade continues to re-strengthen. After weakening to 30kts over land in the last couple days, intensity is back up to 45kts. Deep convection is wrapping into the well defined centre, which is located just off the coast. The favourable conditions of low shear, warm sea temps and good outflow have facilitated this re-intensification, and Jade may not be done yet. There are hints of an eye trying to form on satellite imagery, so it's difficult to say just how strong Jade will get this time round. Proximity to land is alwys going to be a limiting factor. Jade should begin to weaken in around 36hrs time as shear increases. Jade is forecast to intensify for longer now as the forward motion has slowed, meaning the cyclone will not reach the unfavourable conditions so quickly. Jade will continue to deliver heavy rains to southeastern Madagascar before slowly pulling away in a couple days time as she rounds the periphery of the subtropical ridge to the east and begins to move southeastwards out to sea.

[Somerset Squall]

3 dead and 800 homeless:

http://www.news.com.au/heraldsun/story/0,2...5-23109,00.html

(The last paragraph in the article is incorrect, there has been 12 deaths so far in Madagascar, 15 including those caused by Jade- 2 from Eric and 10 from Fanele.)

[Cookie]

very sad and not good news at all, the smaller systems can be just as bad as the big ones.

[Somerset Squall]

Jade has weakened today, and intensity has decreased to 30kts. Strong shear is removing convection from the weakening LLC. Jade is moving away from land so flooding threats should ease. Jade will begin extratropical transition in about 12 hours time, and it's possible Jade will re-strengthen during this process. Jade is likely to transform into a very deep extratropical storm in the southern oceans over the next few days.

Edited April 9, 2009 by Somerset Squall

[Cookie]

she did restrengthen earlier, was it due to the polar trough? I know their was a possibility of this happening

[Somerset Squall]

she did restrengthen earlier, was it due to the polar trough? I know their was a possibility of this happening

An approaching trough certainly played a role in sending Jade east of due south back over water, so yes, in a way.

Jade is certainly a fighter. The cyclone has intensified again this evening, and intensity has nudged back up to 35kts.

Convection has exploded over the centre as Cookie's image shows. Jade may strengthen a little more before extratropical transition begins.

[Cookie]

I like it when they don't flatly give up. makes it more interesting.

[Cookie]

forgot to add this image into my last post

[Somerset Squall]

Jade remains a 35kt tropical storm today. Strong shear continues to displace convection southeast of the LLC, but the LLC remains well defined. The storm has began extratropical transition (ET), enforced by shear and colder waters on the fast southeast track. Due to the remaining well defined LLC and an environment conducive for extratropical intensification, Jade is likely to see an increase in windspeeds as she becomes a very deep extratropical storm. Jade poses no further threat to land. ET will be complete in around 24hrs time, perhaps sooner.

[Somerset Squall]

Jade has transitioned into a cold cored system. Regeneration into a tropical system is not expected.