TC 25P(HAROLD) now near Cat 4, approaching Vanuatu.TC 24S(IRONDRO) peaking near Cat 3US

2020 APR 04 0315UTC SOUTH PACIFIC & SOUTH INDIAN

TC #25P #HAROLD SOUTH PACIFIC
As of 06:00 UTC Apr 04, 2020:
Location: 14.3°S 163.8°E
Maximum Winds: 110 kt
Gusts : 135 kt
Minimum Central Pressure: 946 mb
CATEGORY US: 3
INTENSIFYING
REMARKS:
040900Z POSITION NEAR 14.4S 164.9E.
04APR20. TROPICAL CYCLONE 25P (HAROLD), LOCATED APPROXIMATELY 287
NM NORTHWEST OF PORT VILA, VANUATU, HAS TRACKED SOUTHEASTWARD AT
07 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY SHOWS AN INTENSE SYSTEM WITH DEEPENING CONVECTION AND VERY
COLD CLOUD TOPS SURROUNDING A PINHOLE EYE THAT IS FILLING WITH
CLOUDS. THE INITIAL POSITION IS BASED WITH HIGH CONFIDENCE ON THE
EYE IN MSI IMAGERY AND SUPPORTED BY A 040620Z SSMIS 37GHZ IMAGE. THE
INITIAL INTENSITY IS ASSESSED AT 110 KNOTS, HEDGED SLIGHTLY UNDER
PHFO AND PGTW DVORAK CURRENT INTENSITY (CI) ESTIMATES OF T6.0 (115
KTS) BUT IN LINE WITH THE ADVANCED DVORAK TECHNIQUE CI OF T5.8 (110
KTS). ENVIRONMENTAL ANALYSIS INDICATES THAT TC 25P LIES IN A HIGHLY
FAVORABLE ENVIRONMENT, WITH VERY ROBUST DIVERGENT OUTFLOW, WARM (29-
30 DEG CELSIUS) SSTS AND LOW TO MODERATE (15-20 KNOTS) VERTICAL WIND
SHEAR (VWS), WITH A RELATIVE SHEAR VALUE MUCH LOWER DUE TO STORM
MOTION AND SHEAR VECTORS BEING IN PHASE. TC 25P IS TRACKING SLOWLY
SOUTHEASTWARD ALONG THE WESTERN PERIPHERY OF A NEAR-EQUATORIAL RIDGE
TO THE EAST. AN EXTENSION OF THE SUBTROPICAL RIDGE WILL BUILD INTO
THE SOUTHEAST OF TC 25P OVER THE NEXT 24-36 HOURS, WHICH WILL IN
TURN LEAD TO VERY SLOW, NEARLY QUASI-STATIONARY SOUTH-SOUTHEASTWARD
MOVEMENT. BEYOND TAU 48, THE AFOREMENTIONED EXTENSION OF THE STR
WEAKENS, ALLOWING TC 25P TO ACCELERATE SOUTHEASTWARD THROUGH THE END
OF THE FORECAST PERIOD. TC 25P IS FORECAST TO SLIGHTLY INTENSIFY
FURTHER TO 120 KTS IN THE NEXT 12 HOURS AS IT TAPS INTO HIGHLY
DIVERGENT UPPER LEVEL FLOW WHILE REMAINING IN A RELATIVELY LOW VWS
ENVIRONMENT. HOWEVER, QUASI-STATIONARY MOVEMENT IN A REGION OF
MIDDLING OCEAN HEAT CONTENT (OHC) WATER WILL COMPETE WITH THE ROBUST
OUTFLOW TO LIMIT MUCH FURTHER INTENSIFICATION AND BEGIN A WEAKENING
TREND AFTER TAU 24. AFTER TAU 48, THE ENVIRONMENT WILL FURTHER
DETERIORATE AS THE SYSTEM EXPERIENCES INCREASING VWS AND CONVERGENCE
ALOFT, AND DECREASING SSTS. BY TAU 96, THE SYSTEM WILL BEGIN TO
INTERACT WITH MID-LATITUDE WESTERLIES AND BEGIN SUBTROPICAL
TRANSITION. NUMERICAL GUIDANCE ALL AGREE ON THE GENERAL
SOUTHEASTWARD TRACK AND SLOW FORWARD MOTION THROUGH TAU 48, BUT
DIFFER ON THE DEGREE, WITH SOME MODELS INDICATING A MOVEMENT DUE
SOUTH OR EVEN SOUTHWEST AT ONE OR TWO KNOTS BEFORE TURNING
SOUTHEAST, WHILE OTHERS MOVE STRAIGHT SOUTHEAST AT THREE TO FOUR
KNOTS THROUGH THE ENTIRE FORECAST. BEYOND TAU 48, MODELS COME INTO
MUCH BETTER AGREEMENT ON BOTH THE TRACK AND FORWARD MOTION. THE JTWC
FORECAST TRACK DRIFTS SLOWLY SOUTHEASTWARD BEFORE ACCELERATING
SOUTHEASTWARD AFTER TAU 72. DUE TO THE OVERALL HIGH UNCERTAINTY IN
THE GUIDANCE IN THE FIRST 48 HOURS AND THE GENERAL UNCERTAINTY IN
THE STEERING ENVIRONMENT, THERE IS LOW CONFIDENCE IN THE JTWC
FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 040600Z IS 30
FEET.

TC #24S #IRONDRO