Saturday, May 11, 2013

"01B" - Cyclone not named yet! Slightly intensified and moved N-W

Analysis show that the system has moved N-W into Bay during past 12hrs.
Even it had slightly intensified.
Present location is 7.3N , 90.6E
Pressure has reduced to 993 mb
Winds gusting up to 75 kmph
"01B" will be a named Cyclone in another 8 hrs.

JTWC warning and path forecast at 8:30am IST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

TROPICAL CYCLONE 01B (ONE), LOCATED APPROXIMATELY 919 NM SOUTHWARD 
OF CHITTAGONG, BANGLADESH, HAS TRACKED NORTHWESTWARD AT 13 KNOTS
OVER THE PAST SIX HOURS. ANIMATED INFRARED (IR) SATELLITE IMAGERY 
DEPICTS BUILDING CENTRAL CONVECTION WITH A NOTICEABLE WARM SPOT OVER 
THE LOW-LEVEL CIRCULATION CENTER (LLCC). FEEDER BANDS CONTINUE TO 
GROW OVER THE WESTERN SEMI-CIRCLE. THE INITIAL POSITION IS BASED ON 
THE DEVELOPING WARM SPOT NOTICED IN IR AND A TIGHTLY CURVED NOTCH 
FEATURE IN THE 110011Z SSMIS 37H IMAGE WITH FAIR CONFIDENCE. THE 
INITIAL INTENSITY IS HELD SLIGHTLY HIGHER THAN DVORAK ESTIMATES OF 
30-35 KNOTS FROM PGTW AND KNES BASED ON THE 101810Z OSCAT PASS THAT 
SHOWED MULTIPLE 40-KNOT WIND BARBS. UPPER-LEVEL ANALYSIS SEEMS TO 
INDICATE THAT THE POINT SOURCE ALOFT MAY HAVE DISSOLVED FOR THE TIME 
BEING BUT EXCELLENT RADIAL OUTFLOW REMAINS OVER THE LLCC. VERTICAL 
WIND SHEAR VALUES FROM CIMSS ARE ESTIMATED AT 20-30 KNOTS BUT THE 
ROBUST OUTFLOW IS OFFSETTING THIS NEGATIVE FACTOR. TC 01B IS 
FORECAST TO TRACK NORTHWESTWARD THROUGH TAU 36 UNDER THE STEERING 
INFLUENCE OF WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) 
POSITIONED OVER THE NORTHEASTERN BAY OF BENGAL. THEREAFTER, TC 01B 
IS EXPECTED TO TURN POLEWARD AS THE STR WEAKENS DUE TO AN 
APPROACHING MIDLATITUDE SHORTWAVE TROUGH CURRENTLY DRAPED OVER  
NORTHERN INDIA AND THE NORTHEASTERN ARABIAN SEA. AFTER TAU 48, 
THE SYSTEM WILL RE-CURVE TOWARDS THE MYANMAR/BANGLADESH BORDER AS 
MIDLATITUDE WESTERLY FLOW DOMINATES INDIA AND THE WESTERN BAY OF 
BENGAL. TC 01B IS A LARGE CIRCULATION ENCOMPASSING ALMOST THE 
ENTIRETY OF THE BAY OF BENGAL. THEREFORE, BETA ADVECTION IS EXPECTED 
TO SUSTAIN THE NOSE OF THE STEERING STR. THIS EFFECT SHOULD CAUSE 
THE TC TO TRACK SLIGHTLY FURTHER WESTWARD OVER THE BAY OF BENGAL 
BEFORE EVENTUALLY RE-CURVING. TC 01B SHOULD INTENSIFY TO A PEAK OF 
85 KNOTS BY TAU 96 DUE TO INCREASED POLEWARD OUTFLOW TAPPED INTO THE 
WESTERLIES. BY TAU 120 THE SYSTEM SHOULD HAVE MADE LANDFALL AS A 
SIGNIFICANT TC AND BEGUN TO SPIN-DOWN DUE TO LAND INTERACTION. THERE 
IS HIGH CONFIDENCE IN THE FORECAST TRACK AS MODEL TRACKERS CONTINUE 
TO CONVERGE ON THIS SOLUTION. THE ONLY CONCERNING FACTOR IS THE SLOW 
TRACK SPEEDS OF THE ECMWF TRACKER. HOWEVER, IT IS NOW INLINE WITH 
THE RE-CURVE TOWARDS BANGLADESH AND MAY COME FURTHER INLINE WITH 
TRACK SPEEDS OVER THE NEXT COUPLE OF DAYS. MAXIMUM SIGNIFICANT WAVE 
HEIGHT AT 110000Z IS 12 FEET.

Most weather models agree to this path for "01 B"

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