TY 02W(MALAKAS):powerful CAT 4,forecast to race towards higher latitudes//Invest 92S: subtropical//Invest 91S and Remnants of 03W,13/09utc

JTWC IS ISSUING 6HOURLY WARNINGS ON TY 02W(MALAKAS).3HOURLY SATELLITE BULLETINS ARE ISSUED ON 02W, THE REMNANTS OF 03W AND ON INVEST 92S.

13/07UTC.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TY MALAKAS HAS STEADILY INTENSIFIED OVER THE PREVIOUS SIX HOURS, AND LIKELY REACHED ITS PEAK INTENSITY, BASED ON THE ANIMATED VISIBLE AND INFRARED IMAGERY, AT AROUND THE 130400Z HOUR. SUBSEQUENT IMAGERY SHOWS THE EYE FEATURE HAS BECOME MORE RAGGED AND LESS SYMMETRICAL, AND ALSO BECOMING MORE CLOUD-FILLED SINCE 130400Z. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A NICELY SYMMETRICAL CORE OF CONVECTION WITH AN EXPANSIVE AREA OF FLARING CONVECTION AND SPIRAL BANDS TO THE EAST, BUT LITTLE TO NO CONVECTION ON THE WESTERN PERIPHERY, WHERE DRY, STABLE AIR IS PRECLUDING ANY CONVECTIVE DEVELOPMENT. A 130647Z SSMIS 91GHZ IMAGE SHOWED A COMPLETE EYEWALL, THOUGH THE NORTHWESTERN SIDE IS WEAK AND FRAGMENTED, INDICATIVE OF SOME MID-LEVEL DRY AIR TO THE NORTH. THE IMAGERY ALSO HINTS AT A POSSIBLE SECONDARY EYEWALL BEGINNING TO DEVELOP, PARTICULARLY ACROSS THE SOUTHERN HALF OF THE CIRCULATION. THE INITIAL POSITION WAS ASSESSED WITH HIGH CONFIDENCE BASED ON A 35KM MICROWAVE EYE IN A 130532Z GMI 37GHZ IMAGE. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE, ABOVE ALL OF THE AGENCY FIXES, IN A NOD TOWARDS THE SATCON AND AIDT, BUT A BIT BELOW THE CIMSS ADT VALUES, IN LIGHT OF THE OUTSTANDING MICROWAVE EYE DEPICTION. THE OVERALL ENVIRONMENT REMAINS FAVORABLE FOR THE TIME BEING, BUT IS BECOMING INCREASINGLY LESS SO WITH EACH PASSING HOUR. TY 02W IS TRACKING NORTHEASTWARD ALONG THE WESTERN SIDE A SOUTHWEST TO NORTHEAST SUBTROPICAL RIDGE (STR) TO THE EAST.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: THERE ARE NO SIGNIFICANT CHANGES FORECAST IN THE TRACK OF TY MALAKAS AND THE SYSTEM WILL CONTINUE TO ACCELERATE TOWARDS THE NORTHEAST THROUGHOUT THE DURATION OF THE FORECAST PERIOD. AS MENTIONED, THE ENVIRONMENT IS STILL FAVORABLE FOR THE TIME BEING, BUT GIVEN THE DECREASING SSTS, REDUCED OHC AND POTENTIAL FOR A NEAR-TERM EYEWALL REPLACEMENT CYCLE (ERC), THE SYSTEM HAS LIKELY REACHED ITS PEAK. IN THE NEAR-TERM, THE INTENSITY IS FORECAST TO REMAIN STEADY THROUGH 12H, BUT THEN DROPS OFF SHARPLY BY 24H AS THE DRY AIR ENTRENCHED TO THE WEST BEGINS TO NOSE ITS WAY INTO THE CORE OF THE SYSTEM AND THE DECREASED SSTS AND INCREASED SHEAR BEGIN TO HAVE A SIGNIFICANT IMPACT. BY 36H, SHEAR IS FORECAST TO INCREASE TO ABOVE 35 KNOTS, AND THE SYSTEM WILL BEGIN TO DECOUPLE, ACCELERATING THE WEAKENING TREND. SIMULTANEOUSLY THE SYSTEM BEGINS TO INTERACT WITH THE BAROCLINIC ZONE TO THE NORTH, MARKING THE BEGINNING OF EXTRATROPICAL TRANSITION (ETT). TY MALAKAS WILL TRANSITION TO A STRONG GALE-FORCE EXTRATROPICAL LOW NO LATER THAN 72H, AND LIKELY AS EARLY AS 60H, WELL EAST OF HONSHU.

130647Z SSMIS 91GHZ IMAGE SHOWED A COMPLETE EYEWALL, THOUGH THE NORTHWESTERN SIDE IS WEAK AND FRAGMENTED, INDICATIVE OF SOME MID-LEVEL DRY AIR TO THE NORTH. THE IMAGERY ALSO HINTS AT A POSSIBLE SECONDARY EYEWALL BEGINNING TO DEVELOP, PARTICULARLY ACROSS THE SOUTHERN HALF OF THE CIRCULATION.

MODEL DISCUSSION: DYNAMIC AND ENSEMBLE TRACK GUIDANCE IS IN VERY GOOD AGREEMENT, WITH MINIMAL SPREAD OF LESS THAN 280KM EVEN AT 72H. ALONG-TRACK SPREAD HAS DECREASED SINCE THE PREVIOUS RUNS, AND IS ALSO IN GOOD AGREEMENT, LEADING TO OVERALL HIGH CONFIDENCE IN THE JTWC FORECAST TRACK. WITH THE EXCEPTION OF COAMPS-TC WHICH SHOWS A NEAR-TERM INTENSIFICATION TO A PEAK OF 120 KNOTS AT 12H, THE REMAINDER OF THE INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT ON A STEADY AND RAPID WEAKENING TREND THROUGH THE FORECAST PERIOD. THE JTWC FORECAST LIES ABOUT FIVE KNOTS ABOVE THE BULK OF THE GUIDANCE THROUGH 12H, THEN LIES SLIGHTLY ABOVE THE MEAN THROUGH THE REMAINDER OF THE FORECAST WITH HIGH CONFIDENCE.

THE AREA OF CONVECTION (INVEST 03W) PREVIOUSLY LOCATED NEAR 10.6N 126.5E HAS DISSIPATED AND IS NO LONGER SUSPECT FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE IN THE NEXT 24 HOURS.

THE AREA OF CONVECTION (INVEST 92S) PREVIOUSLY LOCATED NEAR 31.4S 31.2E IS NOW LOCATED NEAR 32.0S 30.5E, APPROXIMATELY 270 KM EAST-NORTHEAST OF EAST LONDON, SOUTH AFRICA. THE SYSTEM IS CURRENTLY CLASSIFIED AS A SUBTROPICAL STORM, GENERALLY CHARACTERIZED AS HAVING BOTH TROPICAL AND MIDLATITUDE CYCLONE FEATURES. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A COMPACT SYSTEM WITH A PARTIALLY-EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) AND PERSISTENT DEEP CONVECTION OVER THE NORTHERN SEMICIRCLE. A 122245Z AMSR2 89GHZ COLOR COMPOSITE MICROWAVE IMAGE SHOWS SHALLOW BANDING WRAPPING TIGHTLY INTO A WELL-DEFINED LLCC WITH LIMITED DEEP CONVECTIVE BANDING OVER THE NORTHEAST QUADRANT. A 120737Z ASCAT-C IMAGE REVEALS A SYMMETRIC CIRCULATION WITH 35-40 KT WINDS AND A RADIUS OF MAXIMUM WINDS OF 55KM. UPPER-LEVEL ANALYSIS INDICATES THE SYSTEM IS LOCATED UNDER A BROAD UPPER LOW BUT HAS MAINTAINED VIGOROUS ANTICYCLONIC, POLEWARD OUTFLOW. SST VALUES ARE MARGINAL AT 24 TO 26C. THE SYSTEM IS VERTICALLY STACKED UNDER A 500MB LOW WITH MODERATE BAROCLINICITY BUT HAS MAINTAINED A WARM CORE. THE SYSTEM HAS DEVELOPED ORGANIZED CORE CONVECTION, WHICH HAS WEAKENED SOMEWHAT OVER THE PAST SIX HOURS, BUT MAY TRANSITION TO A TROPICAL CYCLONE IF IT CAN SUSTAIN ORGANIZED CENTRAL CONVECTION. GLOBAL MODELS INDICATE A QUASI-STATIONARY TRACK OVER THE NEXT 12-24 HOURS THEN AN EASTWARD TRACK WITHIN THE UPPER-LEVEL WESTERLIES. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 35 TO 40 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 993 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS UPGRADED TO HIGH.