SHEM: 23P(NIRAN) 55knots gradually intensifying over the Coral Sea// 22S(MARIAN) 90knots set on a weakening trend, 02/15utc updates

22S(MARIAN). 02/1017UTC. DMSP VISIBLE.

23P(NIRAN). WARNING 7 ISSUED AT 02/15UTC.THE ENVIRONMENT IS OVERALL FAVORABLE WITH LOW (10-15KT) VERTICAL WIND SHEAR, VERY WARM (29-30C) SSTS, PARTLY OFFSET BY LIMITED OUTFLOW ALOFT. TC 23P IS QUASI-STATIONARY IN A COL BETWEEN THE NEAR EQUATORIAL RIDGE (NER) EXTENDED FROM THE NORTH TO SOUTHEAST OF THE SYSTEM, AND THE SUBTROPICAL RIDGE TO THE WEST OVER AUSTRALIA. THE NER IS EXPECTED TO BUILD AND BECOME THE DOMINANT STEERING MECHANISM AND SLOWLY NUDGE THE SYSTEM OUT OF THE COL, AND BY 24H, DRIVE IT SOUTHEASTWARD, PASSING JUST SOUTH OF NEW CALEDONIA BEFORE AROUND 78H, AND BY 120H, SHOULD BE TO THE NORTHEAST OF NEW ZEALAND. THE MARGINALLY FAVORABLE ENVIRONMENT WILL PROMOTE A SLOW INTENSIFICATION TO A PEAK OF 80KNOTS/US CATEGORY 1 BY 96H AS THE SYSTEM TAPS INTO INCREASED POLEWARD OUTFLOW AS IT APPROACHES THE MIDLATITUDE WESTERLIES. AFTERWARD, INCREASING WIND SHEAR AND COOLING SEAS WILL BEGIN TO ERODE THE CYCLONE DOWN TO 65KNOTS BY 120H. CONCURRENTLY, IT WILL ENTER THE BAROCLINIC ZONE AND BEGIN EXTRA-TROPICAL TRANSITION.

23P(NIRAN). NUMERICAL MODELS ARE IN GENERAL AGREEMENT WITH THE TRACK FORECAST WITH SIGNIFICANT VARIATIONS IN ALONG TRACK SPEED IN THE NEAR-TERM AS THE TC TRANSITIONS FROM THE COL AND ACROSS TRACK SPREAD TO OVER 1850KM BY 120H, LENDING LOW CONFIDENCE IN THE JTWC TRACK FORECAST THAT IS LAID CLOSE TO THE MODEL CONSENSUS.

23P(NIRAN). 02/1410UTC. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS THE CENTRAL DENSE OVERCAST CONTINUED TO DEEPEN AND EXPAND. ADDITIONALLY, A 020830UTC MULTISPECTRAL SATELLITE SUNSET IMAGE, SHOWED OVERSHOOTING CLOUD TOPS AND A DIMPLE FEATURE NEAR THE CENTER.

22S(MARIAN). WARNING 10 ISSUED AT 02/15UTC.THE SYSTEM IS IN A MARGINAL ENVIRONMENT WITH LOW (10-15KT) VERTICAL WIND SHEAR AND GOOD RADIAL OUTFLOW THAT ARE OFFSET BY SUBSIDENCE ALONG THE SOUTHWEST QUADRANT CAUSED BY THE MID-LATITUDE TROUGH TO THE SOUTHWEST AND TEPID (26C) SEA SURFACE TEMPERATURE (SST). TC 22S IS QUASI-STATIONARY AND SLOWLY MOVING OUT OF A COL BETWEEN THE NEAR EQUATORIAL RIDGE (NER) TO THE NORTH-NORTHEAST AND A SUBTROPICAL RIDGE (STR) TO THE SOUTH. THE STR TO THE SOUTH IS EXPECTED TO WEAKEN, ALLOWING FOR A SECONDARY STR BUILDING IN FROM THE EAST TO ASSUME STEERING AND EVENTUALLY DRIVE THE CYCLONE SOUTH- SOUTHEASTWARD. THE MARGINAL ENVIRONMENT IS EXPECTED TO GET WORSE WITH INCREASING WIND SHEAR AND COOLING SEAS, LEADING TO GRADUAL WEAKENING WITH INTENSITY FALLING BELOW 35KNOTS BY 120H.

22S(MARIAN). NUMERICAL MODELS ARE IN A TIGHT PACK, HOWEVER, THERE ARE DIFFERENCES IN THE TIMING ON THE STEERING TRANSITION AND EVENTUAL SOUTH-SOUTHEASTWARD TRACK, LENDING FAIR CONFIDENCE IN THE JTWC TRACK FORECAST.

22S(MARIAN). 02/1415UTC.ANIMATED 12-HR ENHANCED INFRARED SATELLITE IMAGERY SHOWS THE SYSTEM HAS MAINTAINED DEEP CONVECTIVE SIGNATURE AND A RAGGED 55-KM EYE, ALBEIT WITH WARMING CLOUD TOPS IN THE CENTRAL DENSE OVERCAST..

22S(MARIAN). 02/1205UTC. SMAP(NASA) READ 67KNOT WINDS(10 MINUTES). IT SUGGESTS A CURRENT INTENSITY SLIGHTLY LOWER THAN THE 12UTC JTWC ESTIMATE, 75/80KNOTS(1 MINUTE) INSTEAD OF 90KNOTS.

02/15UTC. JTWC IS ISSUING 3HOURLY WARNING ON TC 23P(NIRAN) AND 12HOURLY WARNINGS ON TC 22S(MARIAN). 3 HOURLY SATELLITE BULLETINS ARE ISSUED FOR BOTH SYSTEMS.