TROPICAL CYCLONE CHABA STEADILY INTENSIFYING, TC 01S

TROPICAL CYCLONE CHABA


REMARKS:
262100Z POSITION NEAR 20.6N 127.4E.
TYPHOON 16W (CHABA), LOCATED APPROXIMATELY 365 NM SOUTH
OF KADENA AIR BASE, OKINAWA HAS TRACKED WEST-NORTHWESTWARD 
AT 06 KNOTS DURING THE PAST SIX HOURS. ANIMATED INFRARED
IMAGERY SHOWS SIGNIFICANT INTENSIFICATION OF THE POLEWARD 
OUTFLOW CHANNEL DURING THE PAST 12 HOURS, WHICH HAS AIDED 
INTENSIFICATION OF THE STORM. THE CURRENT INTENSITY IS 
BASED ON DVORAK ESTIMATES OF 77 KNOTS FROM PGTW AND RJTD
AND AN OFF-HOUR 26/1930Z PGTW ESTIMATE OF 102 KNOTS. 
A BUILDING EXTENSION OF THE SUBTROPICAL RIDGE HAS FORCED 
THE SYSTEM ONTO A MORE WESTWARD TRACK DURING THE PAST 12 HOURS, 
RESULTING IN A TIGHTER CPA TO OKINAWA. HOWEVER, THE RIDGE IS NOW 
SHOWING SIGNS OF WEAKENING, WHICH WILL ALLOW THE STORM TO MAKE A 
GRADUAL TURN TO THE NORTH. CHABA IS EXPECTED TO REACH PEAK INTENSITY 
AS IT CRESTS THE RIDGE NEAR TAU 36 AND BEGINS ITS NORTHEASTWARD 
TRACK. INTERACTION WITH THE BAROCLINIC ZONE HAS BEEN MINIMAL THUS 
FAR BUT WILL INCREASE RAPIDLY ONCE THE STORM CROSSES 
25 NORTH, WHERE IT WILL BEGIN EXTRA-TROPICAL TRANSITION.
NUMERICAL MODELS ARE IN FAIR AGREEMENT ON TRACK THROUGH
TAU 48 BUT THE MAJORITY STEER THE SYSTEM EAST OF OKINAWA. 
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 261800Z IS 26 FEET.
NEXT WARNINGS AT 270300Z, 270900Z, 271500Z AND 272100Z.//
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TROPICAL CYCLONE 01S


REMARKS:
261500Z POSITION NEAR 11.3S 86.3E.
TROPICAL CYCLONE (TC) 01S (ONE), LOCATED APPROXIMATELY 850 NM EAST-
SOUTHEAST OF DIEGO GARCIA, HAS TRACKED SOUTHWARD AT 07 KNOTS OVER 
THE PAST SIX HOURS. THIS IS THE FIRST SYSTEM OF THE 2011 SOUTHERN 
HEMISPHERE TROPICAL CYCLONE SEASON. VERTICAL WIND SHEAR (VWS) HAS 
RELAXED OVER THE SYSTEM AND HAS ALLOWED FOR DEEP CONVECTION TO BUILD 
BACK OVER THE CENTER, ELEVATING DVORAK ESTIMATES FROM PGTW AND FMEE 
TO A T2.5 OR 35 KNOTS. A 260407Z ASCAT PASS ALSO SUGGESTS THE LLCC 
HAS STRENGTHENED TO 35 KNOTS. IN ADDITION, A 261112Z SSMI 37H 
MICROWAVE IMAGE SHOWS PRONOUNCED LOW LEVEL BANDING WRAPPING INTO A 
DISTINCT LLCC. CURRENTLY THE CYCLONE IS VENTING TO THE WEST AND 
SOUTHEAST AHEAD OF A LONGWAVE UPPER LEVEL TROUGH. THIS TROUGH ALSO 
APPEARS RESPONSIBLE FOR BOUTS OF ELEVATED VWS. LESS THAN SIX HOURS 
AGO THE LLCC HAD BEEN FULLY EXPOSED TO THE EAST OF THE DEEP 
CONVECTION. SLOW INTENSIFICATION IS ANTICIPATED OVER THE NEXT FEW 
DAYS AS VWS GRADUALLY EASES WITH THE PASSAGE OF THE TROUGH 
DOWNSTREAM. THE SYSTEM WILL CONTINUE TO TRACK ALONG THE NORTHERN 
PERIPHERY OF A LOW TO MID-LEVEL STEERING RIDGE TO THE SOUTH, THEN 
TRANSFER TO ANOTHER STEERING RIDGE FURTHER TO THE WEST AS THE MID-
LEVEL REFLECTION OF THE TROUGH PASSES AROUND TAU 48. VWS IS AGAIN 
EXPECTED TO ELEVATE NEAR DAY 4 AND WILL SLOWLY WEAKEN THE SYSTEM. 
SEA SURFACE TEMPERATURES REMAIN FAVORABLE THROUGHOUT THE FORECAST 
AND BEGIN TO TAPER NEAR 20S. THIS WARNING SUPERSEDES AND CANCELS REF 
A, NAVMARFCSTCEN 252251Z OCT 10 TROPICAL CYCLONE FORMATION ALERT 
(WTXS21 PGTW 252300)MAXIMUM SIGNIFICANT WAVE HEIGHT AT 261200Z IS 9 
FEET. NEXT WARNINGS AT 270300Z AND 271500Z.//
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