Earth's second Cat 5 of 2012: Super Typhoon Jelawat

Earth's newest addition to the Category 5 tropical cyclone club is Super Typhoon Jelawat, which has intensified to a Category 5 typhoon with 160 mph winds. Jelawat is Earth's second Category 5 storm of 2012; the other was Super Typhoon Sanba (175 mph winds), which hit Okinawa earlier this month as a Category 3 storm. The two Category 5 storms for 2012 match the total from all of last year. Fortunately, Jelawat is located well east of the Philippine Islands, and the storm is not expected to hit land over the next two days. However, the storm's outer spiral bands have brought flooding to Zamboanga del Norte province in the eastern Philippines, where 8400 people were evacuated and one person is missing. Wind shear is a light 5 - 10 knots over Jelawat, and the typhoon is over very warm ocean waters of 29°C. These warm waters extend to great depth, which should allow Jelawat to maintain major typhoon status for at least two more days. Satellite loops show an impressive, well-organized typhoon with a large symmetric area of heavy thunderstorms with cold cloud tops.

The models have come into much better agreement on the track of Jelawat over the next three days. The typhoon is expected to move slowly to the north-northwest to northwest, roughly parallel to the Philippines, then turn to the north a few hundred miles east of Taiwan. After that, there remains major uncertainty on where Jelawat might go. A northerly path towards Okinawa or a more northeasterly path out to sea are the two main possibilities. Wind shear will begin increasing over Jelawat beginning on Wednesday, which should cause a steady weakening of the storm.



Figure 1. MODIS satellite image of Jelawat taken at 10:10 pm EDT Monday, September 24, 2012. At the time, Jelawat was a Category 5 storm with 160 mph winds. Image credit: NASA.

Hurricane Miriam off the Baja coast now a Cat 2
Hurricane Miriam completed an eyewall replacement cycle this morning, which knocked down the storm to Category 2 strength with 105 mph winds. Satellite imagery shows that Miriam now has a large 35-mile diameter eye, and the storm has a more ragged appearance than when it peaked as a Category 3 storm with 120 mph winds on Monday. High wind shear in excess of 30 knots will attack Miriam late this week, and our two top models, the GFS and ECMWF, show Miriam dissipating before reaching central Baja on Friday.


Figure 2. Hurricane Miriam as seen by the MODIS instrument on NASA's Aqua satellite at 5pm EDT September 24, 2012. At the time, Miriam was a Category 3 hurricane with 120 mph winds. Image credit: NASA.

Persistent Nadine still out there
The Atlantic's perpetual tropical storm, Nadine, continues to wander in the Middle Atlantic, far from any land areas. Nadine will still probably be around a week from now, and is not likely to threaten any land areas for at least the next seven days. None of the reliable computer models are predicting formation of a new tropical cyclone in the Atlantic for the remainder of the week.

Jeff Masters