Tropical Cyclone Watch Series #2
Posted by Roel Morelos on Tuesday, September 13, 2011
Tropical Depression ONYOK [18W]
Latest Data:
Location: 1,170 km East Northeast of Basco, Batanes (PAGASA)
Coordinates: 21.4°N, 134.7°E (PAGASA)
Wind strength: 55kph (PAGASA and JMA)
Accumulated rainfall near the center: 150-180mm (PAGASA and typhoon2000.com)
Movement: (present) Moving W at 7kph (PAGASA)
(forecast) WNW @ 4-7kph (PAGASA and typhoon2000.com)
Links: PAGASA: http://www.pagasa.dost.gov.ph/
typhoon2000.com: http://www.typhoon2000.ph
JTWC: http://www.usno.navy.mil/NOOC/nmfc-ph/RSS/jtwc
JMA: http://www.jma.go.jp/en/typh/
Forecast models:
credits to: PAGASA
credits to: JTWC
credits to: wunderground.com
credits to: JMA
credits to: Tropical Storm Risk
satellite imagery:
Discussion: Tropical Depression ONYOK [18W] was located (2am) at 1,170kms. NE of Basco, Batanes with winds of 55 kph. It is moving W to WNW at a speed of 7kph. Currently, a strong subtropical ridge (a.k.a. HPA) is steering TD ONYOK [18W]. Warm sea-surface temperature (SST) and low-moderate wind shear will help the system to develop, although meagerly, because TD ONYOK [18W] is lacking some good outflow especially in the western and northwestern side of the system. Over-all, the system is having a nice convection and thunderstorm presence but the main convection is to the east of the LLCC. Unless ample amount of convection starts to build near the LLCC, TD ONYOK [18W] will have a hard time strengthening. JTWC is forecasting this to become a tropical storm tomorrow (65kph) tomorrow morning or afternoon. It will exit PAR on Thursday afternoon as a borderline strong tropical storm-typhoon strength (115kph)
Various computer guidance and forecast models are showing a little agreement on their forecast for TD ONYOK [18W]. As JTWC had stated, they are having "unusually poor model guidance." JTWC had a fair forecast for the system and its track but given the strength of the STR/HPA, i am favoring a more Westward track that will bring the TD a bit south of Okinawa. A long wave trough (a LPA on higher latitude) will dig the STR and will cause weakness to the ridge. This will cause a "hole in the wall" that TD ONYOK [18W] will follow thru. This will bring the TD into WNW to NW direction towards Eastern China. After this, uncertainty arouses if whether the trough will effectively relocated the STR/HPA or another STR/HPA will develop after the trough had passed. Given the first scenario, we can expect a poleward turn and will bring ONYOK/18W closer to Korea and Japan. The second scenario will push ONYOK/18W closer to Taiwan and China. The most probable forecast as of now is that ONYOK/18W will inch closer to Taiwan and will pass to the East of China, a little farther to the west than the forecast of JTWC. Given this scenario, there will be no direct effect to the Philippines.
But given the slow forward motion of ONYOk/18W, SW monsoon will be enhanced and will bring a lot of rain to Western Luzon especially Central and Southern Luzon and Region 1. For the next 2-4 days, rainfall accumulation will amount to 60-90mm/day.CaLaBarZon, NCR, Region 1 and Batanes will take the brunt of the enhanced SW monsoon. This volume of rain will cause flashfloods and landslides especially to areas where the soil is still saturated with rainwater. Everyone living in this area, especially in the flood and landslide prone area, are advised to be alert and be on guard. Follow the warnings and instructions of the national government, LGU's, NDRRMC and PAGASA so that life may not be lost..
-RLM
September 13, 2011. 10:00am PHT
Latest Data:
Location: 1,170 km East Northeast of Basco, Batanes (PAGASA)
Coordinates: 21.4°N, 134.7°E (PAGASA)
Wind strength: 55kph (PAGASA and JMA)
Accumulated rainfall near the center: 150-180mm (PAGASA and typhoon2000.com)
Movement: (present) Moving W at 7kph (PAGASA)
(forecast) WNW @ 4-7kph (PAGASA and typhoon2000.com)
Links: PAGASA: http://www.pagasa.dost.gov.ph/
typhoon2000.com: http://www.typhoon2000.ph
JTWC: http://www.usno.navy.mil/NOOC/nmfc-ph/RSS/jtwc
JMA: http://www.jma.go.jp/en/typh/
Forecast models:
credits to: PAGASA
credits to: JTWC
credits to: wunderground.com
credits to: JMA
credits to: Tropical Storm Risk
satellite imagery:
Discussion: Tropical Depression ONYOK [18W] was located (2am) at 1,170kms. NE of Basco, Batanes with winds of 55 kph. It is moving W to WNW at a speed of 7kph. Currently, a strong subtropical ridge (a.k.a. HPA) is steering TD ONYOK [18W]. Warm sea-surface temperature (SST) and low-moderate wind shear will help the system to develop, although meagerly, because TD ONYOK [18W] is lacking some good outflow especially in the western and northwestern side of the system. Over-all, the system is having a nice convection and thunderstorm presence but the main convection is to the east of the LLCC. Unless ample amount of convection starts to build near the LLCC, TD ONYOK [18W] will have a hard time strengthening. JTWC is forecasting this to become a tropical storm tomorrow (65kph) tomorrow morning or afternoon. It will exit PAR on Thursday afternoon as a borderline strong tropical storm-typhoon strength (115kph)
Various computer guidance and forecast models are showing a little agreement on their forecast for TD ONYOK [18W]. As JTWC had stated, they are having "unusually poor model guidance." JTWC had a fair forecast for the system and its track but given the strength of the STR/HPA, i am favoring a more Westward track that will bring the TD a bit south of Okinawa. A long wave trough (a LPA on higher latitude) will dig the STR and will cause weakness to the ridge. This will cause a "hole in the wall" that TD ONYOK [18W] will follow thru. This will bring the TD into WNW to NW direction towards Eastern China. After this, uncertainty arouses if whether the trough will effectively relocated the STR/HPA or another STR/HPA will develop after the trough had passed. Given the first scenario, we can expect a poleward turn and will bring ONYOK/18W closer to Korea and Japan. The second scenario will push ONYOK/18W closer to Taiwan and China. The most probable forecast as of now is that ONYOK/18W will inch closer to Taiwan and will pass to the East of China, a little farther to the west than the forecast of JTWC. Given this scenario, there will be no direct effect to the Philippines.
But given the slow forward motion of ONYOk/18W, SW monsoon will be enhanced and will bring a lot of rain to Western Luzon especially Central and Southern Luzon and Region 1. For the next 2-4 days, rainfall accumulation will amount to 60-90mm/day.CaLaBarZon, NCR, Region 1 and Batanes will take the brunt of the enhanced SW monsoon. This volume of rain will cause flashfloods and landslides especially to areas where the soil is still saturated with rainwater. Everyone living in this area, especially in the flood and landslide prone area, are advised to be alert and be on guard. Follow the warnings and instructions of the national government, LGU's, NDRRMC and PAGASA so that life may not be lost..
-RLM
September 13, 2011. 10:00am PHT