CAT 2 US TC 05S(DARIAN):short-term intensification again//Invest 98B// 2519utc

JTWC IS ISSUING 12HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON TC 05S(DARIAN). 3HOURLY SATELLITE BULLETINS ARE ISSUED ON INVEST 98B.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TROPICAL CYCLONE 05S (DARIAN) FLARED UP AGAIN DURING THE PAST 8 HOURS. 12 HOURS AGO THE EYE HAD COLLAPSED AND THE EYEWALL OVER THE NORTHEAST QUADRANT WAS ALL BUT GONE DUE TO MID-LEVEL DRY AIR ENTRAINMENT AND 15KTS OF NORTHWESTERLY VERTICAL WIND SHEAR. NOW THE EYE HAS RE-DEVELOPED AND IS SURROUNDED BY A RING OF DEEP AND VIGOROUS CONVECTION. THREE SSMIS MICROWAVE SERIES--251038Z 251103Z AND 251248Z--VERIFY IMPROVED ORGANIZATION AND THE MOST RECENT JTWC DVORAK ASSESSMENT HAS RISEN TO T5.0 USING THE EYE TECHNIQUE ON A RAGGED 15NM EYE. KNES AND FMEE ARE ALSO WEIGHING IN AT T5.0. SEA SURFACE TEMPERATURES INCREASED A DEGREE TO 27C AND STORM MOTION HAS ACCELERATED ENOUGH TO REDUCE THE EFFECTS OF UPWELLING ON THE STORM. DARIAN IS MOVING THROUGH A PATCH OF 26-27 DEGREE WATERS. VERTICAL WIND SHEAR REMAINS STEADY NEAR 15KTS BUT DEEP MOISTURE SURROUNDING THE CORE IS EXPANDING. ANIMATED WATER VAPOR IMAGERY ALSO INDICATES THE MID AND HIGH LEVEL MOISTURE FIELDS ARE EXPANDING AND THAT THE SYSTEM HAS EXCELLENT AND IMPROVING RADIAL OUTFLOW.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TROPICAL CYCLONE 05S WILL LEAVE THE STEERING INFLUENCE OF THE NEAR EQUATORIAL RIDGE DURING THE NEXT 12 HOURS AND BEGIN A LAZY ROLL OVER TO THE SOUTHWEST LEG OF ITS JOURNEY. 26-27 DEGREE CELSIUS SEA WATERS ALONG TRACK COUPLED WITH VERTICAL WIND SHEAR THAT ONLY INCREASES BY A KNOT OR TWO OVER THE NEXT 24 HOURS WILL MAKE FOR A SLOW DECLINE IN INTENSITY. DRY AIR ENTRAINMENT WILL ALSO STEADILY WRAP AROUND THE SYSTEM AND EVENTUALLY STRANGLE THE CORE, BUT THIS TOO WILL BE A SLOW PROCESS. THE SUBTROPICAL TRANSITION PROCESS WILL ALSO BE A SLOW ONE, WITH THE SYSTEM NOT EXPECTED TO COMPLETE SUBTROPICAL TRANSITION UNTIL IT IS SOUTH OF THE 25TH LATITUDE. NO PRONOUNCED CHANGES IN THE ENVIRONMENT ARE EXPECTED, JUST A GRADUAL INCREASE IN UNFAVORABLE FACTORS. SEA SURFACE TEMPERATURES WILL FALL TO 25C DURING THE NEXT 24 HOURS BUT AFTER THAT THEY WILL REMAIN IN THE 24-25 DEGREE RANGE THROUGH THE DURATION OF THE FORECAST. VERTICAL WIND SHEAR WILL INCREASE BUT REMAIN BELOW 20 KNOTS THROUGH TAU 36. HENCE, THE BASIS FOR A SLOW AND STEADY DECLINE ALONG A SOUTHWESTWARD TRACK SCENARIO.

MODEL DISCUSSION: TRACK GUIDANCE HAS BEEN RELIABLE AND REMAINS TIGHT THROUGH THE DURATION OF THE FORECAST. THE JTWC TRACK FORECAST STAYS VERY CLOSE TO THE MULTI-MODEL CONSENSUS. INADEQUACIES IN THE INTENSITY GUIDANCE ARE NOW IN THE REARVIEW MIRROR AND THE STABLE ENVIRONMENT IS GIVING MUCH HIGHER CONFIDENCE TO THE SCENARIO OF A GRADUAL DECLINE THROUGH SUBTROPICAL TRANSITION.

THE AREA OF CONVECTION (INVEST 94B) PREVIOUSLY LOCATED NEAR 9.3N 82.9E HAS DISSIPATED AND IS NO LONGER SUSPECT FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE IN THE NEXT 24 HOURS.