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.

Tropical Storm Unala has formed in the far west of the Central Pacific, from Invest 90C. I actually suspect this was a tropical storm yesterday, if not a day or so before, and it seems like CPHC are admitting they were late upgrading it based on some of the words of their first advisory. Unala has a small area of deep convection near the LLCC, and an intensity of 35kts. Unala is not in a very favourable environment, as shear is moderate to strong. This is in part due to Tropical Storm Pewa to it's west. Therefore, it is likely Unala is at it's peak and will begin to weaken very soon. In fact, CPHC have just issued a special advisory indicating Unala dissipating in the next 24hrs, as even stronger shear awaits it as it approaches the international dateline. It should however, make it into the West Pacific before dissipation.

12W has been upgraded to Tropical Storm Trami, with winds now at 35kts. Convection has expanded over the LLCC and some banding features have also formed in the southern quadrant of the storm. An upper level low to the northwest is supressing convective development in the northern quadrant of Trami, which accounts for it's slightly squashed state on this side. However, the upper level low is forecast ot weaken, providing an environment more favourable for significant intensification. The track forecast remains the same- the ridge to the south steering Trami east will slowly weaken, to be replaced by a ridge to the north. For a while, the two ridges will battle for steering influence for Trami, which will result in a period of slow northward motion before Trami swings back west in response to the northern ridge winning out. Taiwan need to be wary of Trami as the storm is expected to become a typhoon prior to landfall on the north side of the country. Eastern China also need to watch as Trami will go on to impact there afterwards.

Erin has been downgraded to a 30kt tropical depression again this morning as it turns to the west. The LLCC is entirely exposed and there is no deep convection associated with the system. Unless convection returns, Erin will degenerate into a remnant low as soon as this afternoon.

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.

12W has changed little since this morning and remains a 30kt tropical depression. Tropical Depression 13W to the north has weakened and is no longer a tropical cyclone- so it appears we have been robbed of seeing a Fujiwara Interaction. 12W is still expected to push north then west over the coming days as ridging to the north builds and assumes steering influence from the ridge to the south currently steering it.

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.

13W has opened up into a wave and no longer has a closed circulation and therefore no longer qualifies as a tropical cyclone. 13W fast forward speed to the west may be partly to blame for this. 13W's remnants are now forecast to continue to move briskly westwards towards China over the next day or so, and interact minimally, if at all, with the larger TD 12W to the south.

The Atlantic really is a bore fest at the moment, much more interesting in the Pacific lol. I'm sure things will change soon but there is shear shear and more shear at the moment, not to mention the dry air.

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.

Tropical Depression 13W has formed, nearly 100 miles east-northeastwards of Okinawa. The small depression has winds of 25kts, and some deep convection covering the LLCC. 13W is forecast to move westwards initially, followed by a southwards turn east of Taiwan as the system begins a Fujiwara Intercast with Tropical Depression 12W, currently to the southwest. As 13W is the smaller of the two systems, it is expected to be absorbed by TD 12W. The resultant system is then expected to reach typhoon strength whilst closing in on northern Taiwan. Some stregthening is expected of 13W over the coming days, but as it gets dragged towards 12W, shear could cause it to weaken. An alternative scenario is that 13W could remain far enough away from 12W for absorption not to take place, but this is not considered a likely scenario at this time. Even though the JTWC forecast shows 13W reaching typhoon strength by day 5, this strength is expected to be achieved after the two systems have merged into one. 13W's track: 12W's track:

Tropical Depression 12W has formed, a few hundred miles east-southeast of Taiwan, and nearly 400 miles south-southwest of Okinawa. Convection is steadily increasing near the LLCC, but there is no evidence of banding features yet. Winds are at 30kts. The depression is moving southeastwards currently but is expected to swing northeast then back northwest and west towards northern Taiwan over the coming days. This is due to a rather interesting scenario of Fujiwara Interaction with Tropical Depression 13W to the northeast. The east and then northeast motion is expected due to a small ridge to the south, then the swing north and back west is forecast due to direct binary interaction with TD 13W. 12W is expected to be the dominant system, and possibly absorb 13W. Though this is the more favoured solution, it is possible that instead 13W will absorb 12W. The resultant system is forecast to become a typhoon over warm waters and low shear as it moves westwards towards northern Taiwan along a newly built ridge to the north. As ever with Fujiwara Interaction, there is much uncertainty. Other scenarios include the systems not merging at all if they manage to keep a fair seperation distance.

Erin restrengthened to a 35kt tropical storm overnight, as convection built closer to the LLCC. However, already the convection is distancing itself from the centre again due to southwesterly shear. Erin is turning to the west as ridging restrengthenes to the north, but should turn back northwestwards in a few days time as another weakeness opens up in the ridge. Very dry air awaits Erin, and shear is set to remain on the high side, so, despite Erin moving over warmer water over the next few days, weakening is expected, and degeneration into a remnant low anytime in the next 4 days.

The HURDAT re-analysis project will get to Faith soon, it'll be interesting to see the report.

Mmm, always puzzled me too this one. At a guess I would say one contributing factor was the forward speed of Faith, which meant it managed to speed a long way north while completing the extratropical transition process. Other than that I'm not sure.

The wave about to exit Africa is worth watching, poor Erin has moistened the environment ahead for it and punched a hole in the SAL...

Erin has struggled over the last 24hrs, and instead of strengthening, has weakened back to a tropical depression, with winds now at 30kts. Erin took a slightly more northern route than originally forecast, meaning that sea temperatures have not been so warm, and this more northerly route has sent Erin into the dry air much sooner than expected too. Sea temps do increase in a day or so along track, but the air is expected to remain dry, and shear is set to rise. Therefore, Erin will probably lose tropical cyclone status soon.

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:

It's more common in El Nino years that produced the beasts Major Hurricane Ioke in 2006 (this storm got me interested in hurricanes) and Major Hurricane Neki in 2009. But yeah it seems that there is an area of favourable conditions in the Central Pacific at the moment!

Invest 90C has been sheared overnight, and this is probably due to the outflow of 91C to the west, which itself has grown better organised. 90C has a well defined LLC, but the shear has exposed it to view from the convection. 90C's chances have been decreased to 60%, but 91C's chances have been upped to 80%.

90E became Hurricane Henriette. We now have a couple invests in the Central Pacific, and one is looking like it may become the first TC to form in the Central Pacific basin this year (3 have moved into the basin, but didn't form there (Flossie, Gil and Henriette)). Invest 90C, located directly south of Hawaii, is organising very nicely with deep convection exploding over the well defined LLCC. CPHC give a 80% chance of TC formation over the next 48hrs as shear is low and waters warm. We also have invest 91C to the west of 90C. CPHC only give a 20% chance of development but this one is showing some signs of organisation too with convection slowly increasing over the broad LLCC.

The fifth tropical depression of the season has formed south of the Cape Verde Islands, in the Eastern Atlantic. Intensity is 30kts. 05L appears close to tropical storm strength, as very deep convection is expanding near the LLCC and good banding features are taking shape in the southern quadrant of the cyclone. For the next 48hrs, shear is set to remain light and waters warm, so intensification should occur as 05L moves generally west-northwestwards along the south side of a narrow ridge. After this time, sea temperatures cool along track, and 05L should also run into the Saharan Dust Layer (SAL), which should cause 05L to begin to weaken. The weaker cyclone is then expected to turn more towards the west in the low level flow. By day 4/5, waters warm up along track again, but the SAL could still be plaguing the system by this point, so further weakening appears to be the most likely outcome at this stage, but this is uncertain.

Utor is moving inland and weakening fast. However, Utor's southern band remains over Hainan Island and has exploded into life, there's some seriously high rainfall totals coming out of that. Even though the tropical storm will weaken fast over land, rainfall will remain a serious threat for a few days yet.

92L up to 30% chance of TC formation in the next 48hrs and 40% in the next 5 days. 93L (just off the coast of Africa) is up to 40% risk in next 48hrs and 50% for the next 5 days. Conditions look favourable initially for this one before it heads into cooler waters further west. If it can get itself developed now it my have a chance of flourishing.

After re-attaining cat 3 status, Utor has weakened to cat 2 status, with winds of 85kts. The eye is very close to the coastline on satellite imagery, so landfall is imminant on the Chinese coast between Hainan Island and Hong Kong. Despite the slight weakening, winds are still of great concern along with the dangerous flooding rains leading to possible mudslides.