Jelawat (Lawin) Weakens, Heads for Japan

Super-Typhoon Jelawwat (Lawin) weakened today to a typhoon, albeit a very powerful, major typhoon. Earlier this morning, Jelwat had top 1-minute sustained winds of 155mph making it a super-typhoon. Now, slightly increased wind shear allowed some weakening and top 1-minute sustained winds are now near 145mph according to the JTWC.

The eye of Typhoon Jelawat looms to the south of Ishigakijima as seen from Japanese Radar from the JMA (September 28th 2012 1:15pm JST).

The southernmost Japanese Ryuku Islands are now under the gun from this very powerful typhoon. Tropical Storm conditions with near typhoon strength gusts are already affecting these islands. This includes a gust to 68mph out of Ishigakijima as of 1pm local time.

Some of the extreme western outer bands of Jelawat are bringing rain into the coast of Taiwan. Jelawat is leaving the Philippines now but an enhancement of the monsoon trough in its wake keeps a chance for heavy rain in the forecast.

The center of Jelawat is expected to pass perilously near or over some of the Ryuku islands as it recurves. This threat area therefore includes Okinawa, an island that has been hit by two major typhoons already this year. After passing through the Ryukus, Jelawat is expected to make a landfall in mainland Japan as a rapidly weakening typhoon or tropical storm.

As is a threat with any tropical cyclone, tornadic activity is possible in the outer bands of Jelawat as it moves through the Ryukus and into mainland Japan into the weekend. Fresh-water flooding (and flash-flooding) is also a big concern especially in mainland Japan which is very mountainous. Landfalling tropical cyclones are known to dump copious amounts of rain in short periods of time over mountainous regions. Depending on the location and strength of the typhoon at landfall, damaging wind and storm surge may be a factor. Typhoon advisories and warnings are in effect for the southern half of the Ryuku islands; these will likely be extended northwards as the typhoon moves in that direction.

Meteorologically, Jelawat had another very successful eyewall replacement cycle yesterday and ended up with a massive 45mile wide eye with visible meso-scale vorticies; something observed in the eyewalls of large and powerful tropical cyclones like Hurricane Isabel (2003) and Hurricane Katrina (2005). As the ridge of high pressure built in behind Tropical Storm Ewiniar, the steering flow became more stable and Jelawat picked up its forward pace. The typhoon has now reached the edge of that ridge and is recurving around it headed north at 8mph, still fairly slowly.

Tropical storm Nadine remains respectable out in the open Atlantic as a moderate-strong Tropical Storm with 65mph winds. The Azores can be seen in the top left. Image from Navy’s Naval Research Lab Tropical Cyclone Pages (18Z September 27th 2012)

Meanwhile, Tropical Storm Nadine is a survivor in the Central Atlantic, continuing to churn now with 65mph winds as of the 11pm advisory from the NHC. Nadine is not expected to affect any land for the next five days, but could threaten the Azores again as it gets picked up by a cold front…again.

Hurricane Miriam rapidly weakened into a remnant low on approach to the Baja California peninsula and got captured by the Pacific sub-tropical ridge’s low-level steering, taking it back to the southwest. However, mid-upper level moisture from Miriam made it into the United States and could have played a role in a severe weather event yesterday and today in the mid-west and northeast.


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