Thursday, May 26, 2011

Supertyphoon Songda churning with Category 4 after eyewall replacement cycle! Threaten Kadena

Akshay Deoras
Severe Weather Forecaster

Concerning- Update on SuperTyphoon Songda ( Chedeng)

The First major typhoon in western pacific Songda has reached Category 5 status yesterday. The Typhoon's eye was located at 16.2N and 125.1E apx 260km North North East of Virac,Catanduanes or 300km east of Casiguran,Aurora as of 04PM Local Time on 26th May 2011.

The IR-NHC and IR-BD spectrum imagery is showing an eyewall replacement cycle has just completed and the typhoon now having a well developed eyewall.
Such strong cyclones ( Cat3+) undergo through an EyeWall Replacement Cycle where the persisting inner eyewall stars contracting and a region of outer thunderstorms- a part of the inner banding features strengthen and replace the old eyewall. Cyclones weaken a bit during this process and so
SONGDA IS NOW A CAT.4 TYPHOON and is located 50 km East of Tuguegarao City (17.2°N, 124.3°E) with maximum sustained winds of 240.76 km/hr (130kt) and gusting to 296.32km/hr ( 160kt)

Location- 18.1N,123.9E

Supertyphoon Songda right now has a well developed eyewall and strong convergence at lower level. The upper atmospheric conditions such as the Upper Air Divergence and the upper winds are favorable right now for some intensification.

However, as the typhoon moves forward, it shall be exiting a region of stronger low level convergence,upper air divergence and shall enter into a region of increased wind shears.
Songda is also expected to start rotating away from its linear path due to a mid level trough at present around China ( Which shall move SouthEastward). The steering winds shall be due to this mid level trough (Westerlies) and shall bend the typhoon towards East when it will encounter cooler SST and shall weaken considerably after 48hrs.
However weakening has likely started now and 12hrs forecast ( 12z,27 May GMT) showing max winds at eyewall only 120kt from present 130kt

Areas affected-
All models nearly agree that Songda shall move much East of Taipei by 00z GMT of 28th May 2011. I just expect some rainfall and gusty winds in Taipei on Saturday and nothing SEVERE
The Ryuku Island WILL HAVE A CLOSE CALL of a much weakened cyclone ( Estimated to be Cat 2 with peak winds just 160km/hr

The Joint Typhoon Warning Center predicts a 30NM or 55km separation from the center of the cyclone and Kadena area by 13z (1300hrs GMT) tomorrow ( 28th May 2011)

** Warning for Gale Winds,Heavy Rains,Storm Surge in the area**

In Japan,Sasebo area shall get a bit close call 177NM by 0200hrs GMT on 29th May 2011

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