Western North Pacific: TY 02W(SURIGAE) is still a powerful CAT 4 and slow-moving, forecast to weaken more rapidly after 48hours, 19/21utc update

02W(SURIGAE). 19/20UTC. 12H LOOP.

02W(SURIGAE). WARNING 26 ISSUED AT 19/21UTC.THE CURRENT INTENSITY IS LOWERED SLIGHTLY TO 115 KNOTS/CAT4, BASED ON THE PGTW FIX OF T6.0/6.5 AND ADT ESTIMATES OF T6.0. COUPLED HWRF/HYCOM OCEAN ANALYSIS SUGGESTS THAT SLOW MOVEMENT OF THE LARGE TYPHOON IS INDUCING COOLING OF THE UNDERLYING WATER, POSSIBLY CONTRIBUTING TO THE CURRENT RAGGEDNESS OF INNER CORE CONVECTION AND GRADUAL DECREASE IN INTENSITY. SURIGAE REMAINS SITUATED IN AN OTHERWISE FAVORABLE ENVIRONMENT, LOCATED JUST SOUTH OF THE AXIS OF A 200MB RIDGE, WITH LIGHT VERTICAL WIND SHEAR OF 5-10 KTS. WATER VAPOR SATELLITE IMAGERY DEPICTS A COOL, DRY MID-LATITUDE AIR MASS GETTING PULLED SOUTHWARD OVER LUZON ON THE WEST SIDE OF THE TYPHOON, BUT THERE IS NO EVIDENCE THAT THIS AIR MASS IS GETTING ENTRAINED INTO THE STORM CORE AT THIS TIME.SURIGAE IS EXPECTED TO CONTINUE MOVING SLOWLY NORTH- NORTHWESTWARD DURING THE NEXT 48 HOURS AS A WEAK UPPER-LEVEL RIDGE TO ITS EAST CONTINUES TO INDUCE A WEAK SOUTHERLY STEERING FLOW. THIS STEERING FLOW MAY STRENGTHEN SLIGHTLY AS A LOW-AMPLITUDE UPPER-LEVEL RIDGE WITHIN THE SUBTROPICAL JET (STJ) TRANSLATES EASTWARD FROM THE VICINITY OF TAIWAN TO THE NORTH OF THE TYPHOON. THUS, FORWARD SPEED IS EXPECTED TO INCREASE SLIGHTLY FROM THE CURRENT SLOTHFUL PACE WITHIN THE NEXT 12-24 HOURS. AFTER 48 HOURS, SURIGAE WILL ROUND THE NORTHWESTERN PERIPHERY OF THE RIDGE TO ITS EAST, AND A SHORTWAVE TROUGH WILL APPROACH FROM THE NORTHWEST OVER EASTERN CHINA. THE RESULTING INCREASE IN MID-LEVEL WESTERLY FLOW WILL ACCELERATE AND TURN THE CYCLONE NORTHEASTWARD BY 72 HOURS. THE TRACK FORECAST THROUGH 72 HOURS IS NUDGED SLIGHTLY EASTWARD COMPARED TO THE PREVIOUS ONE TO ACCOUNT FOR THE MORE NORTHWARD TREND IN SHORT-TERM MOTION, BUT REMAINS OF HIGH CONFIDENCE. THE INTENSITY FORECAST THROUGH 48 HOURS IS EXPECTED TO LARGELY BE A FUNCTION OF DYNAMIC OCEAN COOLING OCCURRING BENEATH SURIGAE, WHICH SHOULD CONTINUE AS THE TYPHOON MOVES SLOWLY. GRADUAL WEAKENING TO 100 KNOTS/CAT3 IS FORECAST BY 48 HOURS. THEREAFTER, VERTICAL WIND SHEAR IS EXPECTED TO INCREASE AS THE TYPHOON TURNS NORTHEASTWARD, IN RESPONSE TO INCREASING WESTERLY MID-LEVEL FLOW AND A COOLING OF BACKGROUND SEA SURFACE TEMPERATURES FROM 28C TO AROUND 26C. QUICKER WEAKENING IS LIKELY AFTER 48 HOURS AS THIS OCCURS.DURING THE 96-120 HOUR PERIOD, SURIGAE IS EXPECTED TO INTERACT WITH A STRONG LOW-LEVEL BAROCLINIC ZONE SOUTH OF JAPAN, PRESSING SOUTHWARD ACROSS THE RYUKYU ISLANDS. THIS SHOULD CATALYZE THE PROCESS OF EXTRATROPICAL TRANSITION. WEAKENING BELOW TYPHOON INTENSITY IS FORECAST THROUGH 120 HOURS, AS THE INTERACTION WITH THE STJ IS NOT PARTICULARLY FAVORABLE FOR BAROCLINIC-INDUCED REINTENSIFICATION AS A POSITIVELY-TILTED SHORTWAVE TROUGH DIGS THROUGH THE EAST CHINA SEA DUE WEST OF THE CYCLONE.

02W(SURIGAE). THE TRACK FORECAST REMAINS SIMILAR TO THE PREVIOUS ONE, NUDGED JUST SLIGHTLY NORTH THROUGH 120 HOURS TOWARD THE NEW MULTI-MODEL CONSENSUS. CONFIDENCE IS MODERATE DUE TO SOME UNCERTAINTY IN FORWARD SPEED DURING EXTRATROPICAL TRANSITION.

02W(SURIGAE). 19/1951UTC.CONTINUES TO MAINTAIN A LARGE, CLEARLY-DEFINED EYE OF 55 KM DIAMETER IN ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY. SOME EROSION OF DEEP CONVECTION IN THE INNER CORE HAS BEEN NOTED OVER THE PAST SIX HOURS, PERIODICALLY CAUSING THE APPEARANCE OF A DRY MOAT BETWEEN THE 55 KM EYEWALL AND A LARGER, OUTER RING OF DEEP CONVECTION APPROXIMATELY 95 KM IN DIAMETER. THIS OUTER RING APPEARS TO BE THE DOMINANT FEATURE IN THIS MICROWAVE IMAGE.

02W(SURIGAE). 19/1917UTC. DMSP EIR.

02W(SURIGAE). 19/18UTC.

02W(SURIGAE). 19/12UTC.

02W(SURIGAE). 02W(SURIGAE).24H SHEAR TENDENCY.UW-CIMSS Experimental Vertical Shear and TC Intensity Trend Estimates: CIMSS Vertical Shear Magnitude : 3.5 m/s (6.7 kts)Direction : 134.1deg Outlook for TC Intensification Based on Current Env. Shear Values and MPI Differential: FAVOURABLE OVER 24H.

19/21UTC. THE JTWC HAS BEEN ISSUING 6HOURLY WARNINGS ON 02W(SURIGAE) AND 3HOURLY SATELLITE BULLETINS. OVER THE SOUTH IDNIAN OCEAN INVEST 95S IS STILL ASSESSED AS HAVING LOW CHANCES OF REACHING 35KNOTS WITHIN THE NEXT 24HOURS.