Typhoon Chan-hom

[Somerset Squall]

Invest 97W has continued to get better organised today and has been classified as a 35kt tropical storm by JMA. Chan-hom is still in it's formative stages, with a lop-sided appearance due to moderate shear. This shear will slow intensification for Chan-hom, but shouldn't be enough to weaken it. Waters are warm, and the system has a good equatorward outflow channel which sould allow for some modest intensification in the moderately sheared conditions. A ridge to the south and southeast should keep Chan-hom on a general east to northeast track for the next day or so, taking the storm across the south China Sea towards the Philippines. It appears likely that Chan-hom will eventually affect the Philippines but it is uncertain how strong the system will be. Rains should slowly ease across southeast Vietnam as the system pulls away from the coast.

Edited May 6, 2009 by Ross B

[Cookie]

thanks for the update mate

[Somerset Squall]

Thanks for the track maps Cookie, clearly shows the expected path towards the Philippines. This track is still currently forecast. Chan-hom has moved a little more northwards than expected due to blocking to the east but an eastwards track is expected to occur as the ridge currently steering the system re-orientates itself to lie south of the storm. Intensity has increased to 45kts this morning, as good outflow and warm sea temps offset moderate shear. If the shear can ease a touch then a more rapid intensification is possible. I certainly wouldn't rule out Chan-hom becoming a typhoon as it still has 3 days over the warm waters of the south China Sea. Chan-hom is likely to make landfall on the west coast of Luzon which will cause aggressive weakening around 96hrs time due to land interaction with rugged terrain.

Edited May 4, 2009 by Somerset Squall

[Somerset Squall]

Chan-hom has maintained an intensity of 45kts over the last 12hrs. Moderate shear is slowing any real intensity gains, though looking at the latest CIMSS shear charts this shear should slowly ease. This will allow Chan-hom to strengthen more steadily, and I still think the system will become a typhoon prior to landfall western Luzon. Chan-hom has been moving erratically northwards today but an eastward track should materialise tomorrow as the ridge to the east swings to the south of the storm. The eastwards track will eventually bring Chan-hom onshore in Luzon where rapid weakening will occur over the rugged mountains.

Edited May 4, 2009 by Somerset Squall

[Cookie]

thanks for the updates mate. It would be good in one way to get a typhoon but another very bad as I don't want it becoming a typhoon before it hits land.

[Cookie]

looks like it will become a typhoon before landfall

[Somerset Squall]

Chan-hom has begun the northeastwards turn towards Luzon. Intensity has increased to 55kts, but over the last few hours, banding as deteriorated and the overall convective coverage has shrunk. However, this is not unusual for strengthening tropical storms, which often intensify in fits and starts. Chan-hom's structure has been undergoing some changes over the last 12hrs, the LLC has become much larger and the windfield has expanded. The larger system is therefore having a few problems strengthening with any speed. However, conditions are really very favourable for further development, and JTWC expect a peak of 80kts prior to landfall. This is obviously not great news at all, especially as the east side of the country was badly affected by Kujira. This intensification is expected as shear will remain low, waters warm and outflow very good, particularly in a poleward direction.

[Somerset Squall]

Chan-hom is on the verge of becoming a typhoon. Intensity is now at 60kts, and the storm is much better organised than this time yesterday. Chan-hom has a good central dense overcast feature with a contracting LLC tucked in beneath. Banding has improved and an eye should appear soon as waters are warm, shear is low and outflow is good. Chan-hom is then forecast to make landfall in Luzon and rapidly weaken over rugged terrain. A ridge is then expected to build to the east of the system, blocking any further eastwards motion but instead causing the storm to slowly move northwards along the length of Luzon. This means Chan-hom is likely to dissipate over Luzon but also flooding rains are likely to be prolonged. The situation for the Philippines doesn't look great, the only thing on their side is experience of landfalling typhoons.

Edited May 6, 2009 by Somerset Squall

[Somerset Squall]

Chan-hom is now a category 1 typhoon, with an intensity of 70kts. An eye is emerging, embedded in the tight CDO feature. Some more strengthening is possible in the next 12hrs before Chan-hom starts to interact with land.

[Cookie]

thanks for the updates

Storm Alert issued at 6 May, 2009 18:00 GMT

Typhoon CHAN-HOM is forecast to strike land to the following likelihood(s) at the given lead time(s):

Yellow Alert Country(s) or Province(s)

the Philippines

probability for CAT 1 or above is 15% in about 24 hours

probability for TS is 65% in about 24 hours

Green Alert City(s) and Town(s)

Vigan (17.5 N, 120.5 E)

probability for TS is 50% in about 24 hours

Laoag (18.2 N, 120.7 E)

probability for TS is 35% in about 36 hours

San Jose (15.8 N, 121.5 E)

probability for TS is 35% in about 36 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 Typhoon 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]

things really starting to pick up with this system

[Iceberg]

Have to admit I totally ignored this, until some people performing some work for me asked permission just now to leave early as they work in Manila but live to the north of it. It looks to maybe hit to the north of Manila(approx 100 miles) as an 80Kt(approx) storm.

[Cookie]

moving inland

[Somerset Squall]

Indeed, Chan-hom is now moving inland, but prior to making landfall the typhoon peaked slightly higher than estimated at 85kts, making Chan-hom a cat 2 at that point. Hopefully everyone is prepared as Kujira killed 27 people a few days ago. Chan-hom will weaken and dissipate just east of Luzon in a day or so.

http://www.monstersandcritics.com/news/asi...ern_Philippines_

[Somerset Squall]

Scrap a day or so, Chan-hom is dissipating now. The LLC has been torn apart by the mountains of Luzon, and intensity is reduced to 25kts. Regeneration is not expected. Heavy rains will slowly ease in the area as the remnants of Chan-hom drift east.

[Cookie]

not as impressive as Kujira but not a bad looking system.

[Somerset Squall]

Warm waters, low shear and excellent outflow have caused Chan-hom to re-generate this morning as the LLC has reformed under the convection. Intensity is increased to 55kts. A ridge is building to the east which will force Chan-hom towards Taiwan. This northward track will take Chan-hom over cooler waters and higher shear so gradual weakening should commence from about 24hrs.

A surprsise turn of events!

[Somerset Squall]

The track forecast for Chan-hom has become more complicated. Chan-hom is now expected to continue east-northeastwards and not turn northwards towards Taiwan. This is because Chan-hom has weakened to 40kts under high shear, and as the system is less vertically deep, it is now being steered by the low level ridge to the south, in the westward low level flow. Waters will continue to cool, and shear will remain high, so further weakening is expected until dissipation prior to 48hrs. And I think this time it will be final.

Edited May 8, 2009 by Somerset Squall

[Somerset Squall]

Tragically, Chan-hom has caused 27 deaths in the Philippines, and 54,000 are homeless:

http://www.google.com/hostednews/afp/artic...PnIpiTC7syJtlpA

The LLC of Chan-hom is now entirely exposed. Intensity is now 25kts and the system has been declared a remnant low. Regeneration is not expected due to high shear.

Edited May 9, 2009 by Somerset Squall

[Cookie]

thats really bad news, Im sure the death toll will raise very sad :lol:

[Somerset Squall]

Indeed Cookie.

And so begins Chan-hom's third life. Yes, Chan-hom has re-generated again this morning, and has been re-upgraded to a 25kt tropical depression. Shear is still high, but waters are warm and poleward outflow is excellent which has tightened the LLC and enhanced convection, particularly along the northern periphery. A ridge to the east is steering Chan-hom northwards. Waters begin to cool on this track, the poleward outflow channel is soon expected to deteriorate, and shear will remain high, which should dissipate the system again in 24hrs time. But to be honest, I am not willing to say whether it will be for good, as Chan-hom really doesn't want to give up. It's not often a system dissipates twice and comes back a third time.

[Cookie]

you really doesn't want to give up, I'd love to find out how many miles this system has coverd must be a fair few

[Somerset Squall]

Chan-hom remains a 25kt tropical depression. The LLC remains very well defined, but almost entirely exposed. Deep convection however, is still flaring in the northeastern quadrant of the depression. Chan-hom has jogged westwards but is still overall moving in a northerly direction along the western periphery of a steering ridge to the east. Sea temperatures are marginal at 25C, and will continue to cool on the northwards track. Shear will remain moderate to high. Therefore, The forecast is for Chan-hom to dissipate within the next 24hrs.

[Somerset Squall]

Convection continues to distance itself from the weakening circulation of Chan-hom. Intensity has been reduced to 20kts, and JTWC have once again issued a final warning on the depression. The LLC has been entirely exposed for at least the last 12hrs so no longer meets the criteria of a tropical cyclone. The depression has been drifting north-northwest over colder waters, so regeneration is not expected. As I've learnt the hard way with this system, that doesn't mean it won't happen <_< .

[Cookie]

i'd say it gone now?