central pacific Typhoon Pewa

[Somerset Squall]

The first named storm since Tropical Storm Omeka in 2010 has developed in the Central Pacific, about 1,250 miles southwest of Kauai. Intensity is 35kts. Pewa has deep convection covering the LLCC, which has remained persistant through the day. Pewa is in an area of low shear and warm sea temperatures, and excellent outflow. This suggests that Pewa should intensify over the next few days as it heads west-northwestwards. I would not be surprised to see Pewa become a hurricane at some point in the next few days. In a few days time, as Pewa moves into the West Pacific basin, it should begin to weaken as shear is expected to rise. Even though Pewa is forecast to cross over into the West Pacific basin, it will retain it's name.

 

Track map showing Pewa not far from the international dateline and the West Pacific basin:

 

Edited August 16, 2013 by Somerset Squall

[Coast]

 

 

Tropical Storm Pewa forms, no threat to Hawaii

 

A tropical disturbance far southwest of the main Hawaiian Islands has formed into Tropical Storm Pewa, according to the Central Pacific Hurricane Center. Forecasters said as of 5 p.m. Friday, Pewa was located 1,340 miles southwest of Lihue, or 605 miles southwest of Johnston island. It was moving west-northwest at 13 miles per hour.

 

Pewa had maximum sustained winds of 50 miles per hour with higher gusts. Forecasters expect Pewa to reach peak intensity in warm waters far south of the Hawaiian islands over the next 36 to 48 hours, and then weaken.  Forecasters said Pewa is steadily moving west and poses no threat to Hawaii. However, they also said forecasts should be monitored by mariners and aviators.

 

 

http://www.hawaiinewsnow.com/story/23160467/tropical-storm-pewa-forms-no-threat-to-hawaii

 

 

[Somerset Squall]

Pewa has strengthened overnight, and now has winds of 45kts. The storm retains deep convection over the LLCC, and there are banding features in the western quadrant. In about 24hrs, Pewa is expected to cross the dateline and move into the far eastern reaches of the West Pacific basin, as a near northwesterly motion is forecast to persist. After Pewa crosses into the West Pacific, it is expected to continue to strengthen in low shear and warm water, and become a typhoon (note that if it reached 65kts prior to crossing the dateline it would become a hurricane, but this is unlikely and as it moves into the West Pacific and reaches 65kts it will be named a typhoon as are all other tropical cyclones that reach that intensity in the West Pacific basin). CPHC note that the intensity forecast beyond 3 days is difficult as it all depends on how close to and how much Pewa interacts with an upper level low currently near Wake Island. The closer Pewa gets to the upper level low, the more likely it is to begin to weaken. However, if the upper level low diminishes or remains far enough away from Pewa, Pewa could continue to intensify. A lot of uncertainties, but one thing is certain, Wake Island will probably feel the affects of Pewa in 4 to 5 days time as the current track brings Pewa very close to that island.

[summer blizzard]

Tiny but a beauty, expected to become a typhoon as it crosses into the west pacific tomorrow.

 

[Somerset Squall]

Pewa has strengthened further and is now a 55kt tropical storm. The compact storm has a central dense overcast flanked by banding, all signs of a maturing system. Pewa will be crossing the international dateline tomorrow and moving into the West Pacific basin. Shortly after, Pewa is forecast to reach typhoon strength, and continue strengthening for the next couple days. As I mentioned before, Pewa's intensity forecast is then uncertain because of the possible interaction with an upper level low currently well to the northwest of Pewa. The upper level low could cause some weakening, but after that Pewa may well strengthen again as it moves into the wide expanse of very warm waters of the West Pacific and the upper level low moves away.

Edited August 18, 2013 by Somerset Squall

[Coast]

 

7:30 a.m. Sunday, Aug. 18, Japan time: News is somewhat better for Okinawa, though the island isn’t entirely out of the woods yet. Tropical Depression 13W appears to be dying out as it meanders west toward China, but 12W is still out there, forecast to circle north and west toward China over the next few days as a mid-level tropical storm. Kadena Air Base’s extended forecast still calls for Tuesday and Wednesday to be wet and windy, 35- to 40-mph winds Tuesday evening into Wednesday morning.

 

As for Tropical Storm Pewa, the Wake Island group is still in for a gusty Wednesday afternoon. Pewa is forecast to pass some 70 miles north of Wake at 4 p.m., packing 80-mph sustained winds and 98-mph gusts at its center. Still keeping a sharp lookout

 

.

http://www.stripes.com/blogs/pacific-storm-tracker/pacific-storm-tracker-1.106563/tropical-depressions-12w-13w-3-tropical-storm-pewa-2-1.235970

[summer blizzard]

Having looked further it will probably last another week but its moving north too quickly not to be picked up well before Japan, a harmless fish.

[Somerset Squall]

Pewa is crossing the internation dateline, the first named storm to do so since Hurricane Ioke in 2006 at tropical storm/hurricane intensity (though 2009's Tropical Storm Maka did in 2009, but this storm became a tropical storm in the Central Pacific, degenerated into a remnant low, crossed the dateline as a low, then briefly re-attained tropical storm status in the West Pacific). JTWC has issued their first warning on the storm as a West Pacific system.

 

Pewa has maintained a 55kt intensity this morning. The storm's convective canopy has shrunk and become a little ragged this morning. This is in no doubt due to the proximity of the large Invest 90C to Pewa's east, which is now restricting Pewa's outflow. Pewa may also feel some shear from the upper level low to the northwest soon. With all this in mind, Pewa's intensification, if any, will probably be slow over the next day or so. In fact, given Pewa's small size, I wouldn't be surprised if it weakened a little during this time. In a few days time, Pewa should sufficiently distance itself from both Invest 90C and the upper level low, and find an environment of low shear and very warm sea temps, with the oceanic heat content extending to a great depth. Because of this, JTWC are forecasting Pewa to strengthen to become a category 2 typhoon on the SS scale by Thursday. This is uncertain though, especially if the upper level low deosn't move away/fill as quickly as expected, or invest 90C grows larger or develops more.  

[Somerset Squall]

Pewa is near typhoon strength. Winds are up to 60kts this morning. The upper level low has distanced itself from Pewa, relaxing any shear and improving outflow. Pewa remains a compact system with a solid central dense overcast having redeveloped with the beginnings of an eye emerging. Conditions appear favourable for Pewa to become quite an intense typhoon over the next 5 days as shear is expected to remain low, waters warm and outflow good.

[Coast]

[Somerset Squall]

Pewa is now a typhoon with winds of 65kts. Further strengthening is expected but this may be slow initially due to Fujiwara Interaction with TS Unala to the east. As Unala is smaller and weaker, Pewa will be the dominant system and absorb Unala. Pewa should then resume strenghening in low shear amd very warm water.

[summer blizzard]

Pewa now forecast to reach 105KT (just shy of a category 3 super typhoon). As i suspected the system will also be caught before it heads close to Japan.

[Somerset Squall]

Super Typhoon status isn't reached until 130kts (cat 4), unless you are on about a scale I'm unaware of SB?

 

Pewa has lost typhoon status this evening, and has weakened to 60kts. Southerly shear has increased over Pewa, and I also suspect the absorption of former TS Unala has disrupted the organisation of Pewa a little. The southerly shear is now expected to persist for a day or two, and although not destructively strong, it'll probably keep Pewa from intensifying for a day or so. Thereafter, shear is set to ease on the northwesterly track, so strengthening should resume, and as SB says, Pewa is expected to attain cat 3 status. Interestingly, JTWC forecast Pewa to slow and drift west by day 5 as the ridging to the east steering Pewa weakens and leaves the storm in a weak steering environment.

 

Edited August 19, 2013 by Somerset Squall

[Coast]

Busy times out there!

 

 

 

NASA's Aqua satellite passed over the tropical cyclone known as Pewa after it strengthened into a typhoon in the northwestern Pacific Ocean. The Aqua satellite image revealed that Pewa had developed a small eye. On Sunday, Aug. 18, Pewa was a tropical storm when it crossed the International Date Line and moved from the Central Pacific to the Northwestern Pacific Ocean. Pewa now falls under the forecast authority of the Joint Typhoon Warning Center.

 

On Aug. 18, infrared satellite data showed that thunderstorm development and convection had slightly weakened, but the system remained well-organized. Forecasters at the Joint Typhoon Warning Center or JTWC, expected the slight weakening to quickly reverse itself as conditions around the storm improved. The JTWC forecast that Pewa would become a typhoon on Aug. 19, and it did.

 

NASA's Aqua satellite passed over Typhoon Pewa on Aug. 19 at 01:05 UTC shortly after it strengthened into a typhoon in the northwestern Pacific Ocean. The Moderate Resolution Imaging Spectroradiometer instrument image showed that Pewa developed a small eye surrounded by strong thunderstorms. On Monday, Aug. 19 at 0900 GMT/5 a.m. EDT, Typhoon Pewa had maximum sustained winds near 65 knots/75 mph/120 kph. It was centered near 13.9 north and 177.9 east, about 726 nautical miles east-southeast of Wake Island. Pewa was moving to the northwest at 8 knots/9.2 mph/15 kph.

 

Pewa is expected to continue to intensify as it moves northwest. The JTWC expects Pewa to pass far to the northeast of Wake Island on Aug. 21 and 22

 

 

 

http://www.sciencecodex.com/nasa_satellite_sees_pewa_become_a_typhoon-117785

 

Tropical Storm PEWA: Probability of Cat 1 or above winds to 120 hours lead

 

[Somerset Squall]

Pewa looked like it was in trouble this morning, and the storm weakened to 45kts. However, just recently, Pewa has re-intensified to 50kts, with convection building again near the LLCC, an indication perhaps that the shear may be easing. Shear is expected to continue to ease, and the small storm should find itself regaining typhoon intensity in around 24 hours time.

[Somerset Squall]

Shear has stepped up again and Pewa's LLCC is almost entirely exposed. Shear is still expected to abate, so Pewa should eventually recover. Interesting to note that Tropical Depression 03C is currently being absorbed by Pewa. This is the second cyclone to be absorbed by Pewa, the first being Unala. I can't recall a time when a tropical cyclone absorbed two other tropical cyclones, it must be a pretty rare occurence.

Edited August 20, 2013 by Somerset Squall

[Coast]

 

Tropical Storm Pewa weakened temporarily while facing adverse atmospheric conditions in the Northwestern Pacific, and NASA's Aqua satellite captured the storm in infrared light.

 

The Atmospheric Infrared Sounder or AIRS instrument aboard NASA's Aqua satellite captured an infrared image of Tropical Storm Pewa on Aug. 20 at 01:47 UTC/9:47 p.m. EDT, Aug. 19 as it weakened. The coldest cloud top temperatures and strongest storms were confined to a small area around the storm's center and in a band of thunderstorms northeast of the center. Cloud top temperatures in both of those areas were as cold as -63F/-52C. Infrared imagery since this AIRS image has shown that convection has deepened and thunderstorms have become stronger.

 

At 0900 UTC on Aug. 20, Pewa's maximum sustained winds dropped to 45 knots/51.7 mph/83.3 kph as it faced wind shear. By 1500 UTC/11 a.m. EDT, winds had strengthened to 50 knots/57.5 mph/92.6 kph. Forecasters at the Joint Typhoon Warning Center expect Pewa to strengthen into a typhoon later this week. Pewa was located near 17.5 north and 173.4 east, about 436 nautical miles east-southeast of Wake Island. Pewa is moving to the northwest at 13 knots/15 mph/24 kph and is expected to pass far to the north of Wake Island from Aug. 21 to 22.

 

 

NASA's Aqua satellite captured this infrared image of Tropical Storm Pewa (purple) on Aug. 20 at 01:47 UTC/9:47 p.m. EDT, Aug. 19 as it weakened. Coldest cloud top temperatures and strongest storms appear in purple.

 

 

Forecasters at the Joint Typhoon Warning Center noted that as Pewa moves through warm ocean waters, a decrease in vertical wind shear will happen over the next couple of days and that will allow for Pewa to strengthen to typhoon force.

 

 

http://www.sciencecodex.com/nasa_sees_tropical_storm_pewa_temporarily_weaken-117886

 

[summer blizzard]

Shear has stepped up again and Pewa's LLCC is almost entirely exposed. Shear is still expected to abate, so Pewa should eventually recover. Interesting to note that Tropical Depression 03C is currently being absorbed by Pewa. This is the second cyclone to be absorbed by Pewa, the first being Unala. I can't recall a time when a tropical cyclone absorbed two other tropical cyclones, it must be a pretty rare occurence.

Is it the ULL or the absorbtion thats causing the issues?

[Somerset Squall]

Is it the ULL or the absorbtion thats causing the issues?

I'd say it's the ULL more than anything. It did look like it was moving away a couple days ago but it has gotten close enough again to cause this shear over Pewa. It is still expected to move away from Pewa, relaxing the shear eventually. As it stands, Pewa is only a minimal tropical storm now, with winds having weakened to 35kts.

[Coast]

 

6 p.m. Wednesday, Aug. 21, Japan time: U.S. bases on Okinawa reverted to seasonal Tropical Cyclone Condition of Readiness 4 at 11:10 a.m. Wednesday. Trami, which has been upgraded to a Category 1-equivalent typhoon, didn’t impact the island directly, but one observer said it was still “a hell of a storm.†Maximum wind gust was 63 mph in Itokazu, on the island’s south side, at 3:53 a.m.; Kadena Air Base experienced a 54-mph gust as well. Trami is headed some 63 miles north of Taipei at this writing, and landfall over China is forecast for 2 a.m. Thursday local time. This is the final update on Trami.

 

Tropical Storm Pewa continues on a northwest track that will take it 243 miles east-northeast of the Wake Island group around 8 a.m. Thursday Wake time, packing 52-mph sustained winds and 63-mph gusts at its center. Pewa is forecast to keep going northwest, then stall out near the 28th parallel Monday afternoon as a Category 2-equivalent typhoon. PST will keep an eye on this one.

 

 

http://www.stripes.com/blogs/pacific-storm-tracker/pacific-storm-tracker-1.106563/typhoon-12w-trami-9-final-tropical-storm-1c-pewa-7-1.236418

[Somerset Squall]

Strong shear continues to affect Pewa. Pewa's intensity remains at 35kts. Convection is not persistant over the LLCC, but is flaring up periodically, and currently is fairly deep. The upper level low to the system's northwest is only gradually expected to develop any distance from Pewa, so it seems only slow intensification at best can be expected over the next few days. Pewa is forecast to continue heading northwestwards along the west side of a ridge to the east, then gradually turn westwards and slow in 3 days time as a trough approaches and begins to erode the ridge. It seems this trough too will inflict Pewa with shear, so Pewa is no longer forecast to regain typhoon status, and instead is forecast to peak at 55kts for the system's second peak. By day 5, Pewa could well have been picked up by the trough and sent northwards over cooler water and even higher shear, inducing further weakening or even extratropical transition.

[Somerset Squall]

The upper level low that has been forecast for days to move away from Pewa just hasn't. Pewa weakened to a 30kt tropical depression earlier today and remains one this evening. Pewa is not expected to re-strengthen at all as shear remains high. The LLCC has been exposed for most the day to the southwest of a linear area of convection. The depression has practically stalled at the moment but should lift north then northeast as it gets lifted out of the current weak steering environment by a trough. At the time of this, Pewa will become extratropical- that's if it hasn't already dissipated.

[Somerset Squall]

Pewa remains a 30kt tropical depression for now. Continued shear batters the depression, with the LLCC as a result being entirely exposed from the convection at the moment. Pewa has not moved much over the last 24hrs, but is slowly drifting westwards at the moment. Pewa should move northwards soon in response to the approaching trough.

[Coast]

[Somerset Squall]

Pewa has finally fully succumbed to the shear and no longer is a tropical cyclone. The LLC is elongated and has no persistant convection. Regeneration is not expected.