TC 22S(HEROLD): intensifying to CAT3 US within 24h, TC 23P(GRETEL): beginning ET transition

TC 22S(HEROLD) SOUTH INDIAN
As of 18:00 UTC Mar 15, 2020:
Location: 15.3°S 52.7°E
Maximum Winds: 80 kt ( 150km/h)
Gusts: 100 kt ( 185km/h)
Minimum Central Pressure: 976 mb
CATEGORY US: 1
REMARKS:
152100Z POSITION NEAR 15.5S 53.2E.
15MAR20. TROPICAL CYCLONE (TC) 22S (HEROLD), LOCATED APPROXIMATELY 345
NM NORTH-NORTHWEST OF ST DENIS, LA REUNION, HAS TRACKED EASTWARD AT 06
KNOTS (KTS) OVER THE PAST SIX HOURS. THERE IS HIGH CONFIDENCE IN THE
INITIAL POSITION BASED ON A 20 NM EYEWALL SURROUNDING ABOUT 80 PERCENT
OF THE CENTER IN ENHANCED INFRARED SATELLITE IMAGERY. THE INITIAL
INTENSITY IS JUST ABOVE, BUT CONSISTENT WITH, THE PGTW/KNES DVORAK
CURRENT INTENSITY ESTIMATES OF T4.5 (77 KTS). FAVORABLE ENVIRONMENTAL
CONDITIONS (DUAL OUTFLOW CHANNELS, LOW (10-15 KT) VERTICAL WIND SHEAR
(VWS), AND WARM (28-29 CELSIUS) SEA SURFACE TEMPERATURE) SUPPORT
INTENSIFICATION. THE QUASI-STATIONARY PERIOD APPEARS TO BE ENDING AS
TC 22P HAS ACCELERATED EASTWARD OVER THE PAST SIX HOURS. THIS
ACCELERATION ID DUE TO A BUILDING NEAR-EQUATORIAL RIDGE (NER) TO THE
SOUTH. AS THE NER REORIENTS, THE TRACK WILL SHIFT EAST-SOUTHEASTWARD
TO SOUTHEASTWARD AND REMAIN THERE FOR THE DURATION OF THE FORECAST.
THROUGH TAU 24, FAVORABLE ENVIRONMENTAL CONDITIONS WILL SUPPORT
INTENSIFICATION, LIKELY PEAKING OUT AROUND 100 KTS. AFTER TAU 24,
COOLING SST AND HIGH VWS WILL CAUSE STEADY-TO-RAPID WEAKENING FOR THE
REMAINDER OF THE FORECAST. AROUND TAU 48, SUBTROPICAL TRANSITION (STT)
SHOULD BEGIN AS THE SYSTEM MOVES OVERLY COOLER WATER AND BECOMES
WEAKLY BAROCLINIC. BY TAU 72, STT SHOULD COMPLETE. WITH ABOUT 180 NM
OF SPREAD AT TAU 72, NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT.
BASED ON THAT SPREAD, THERE IS FAIR CONFIDENCE IN THE JTWC TRACK
FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 151800Z IS 23 FEET. NEXT
WARNINGS AT 160900Z AND 162100Z.//
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TC 23P(GRETEL) SOUTH PACIFIC
As of 18:00 UTC Mar 15, 2020:
Location: 25.1°S 168.3°E
Maximum Winds: 50 kt ( 95km/h)
Gusts: 65 kt ( 120km/h)
Minimum Central Pressure: 980 mb
REMARKS:
152100Z POSITION NEAR 25.9S 169.4E.
15MAR20. TROPICAL CYCLONE (TC) 23P (GRETEL), LOCATED APPROXIMATELY 780
NM NORTH-NORTHWEST OF WELLINGTON, NEW ZEALAND, HAS TRACKED
SOUTHEASTWARD AT 32 KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED
ENHANCED INFRARED (EIR) SATELLITE IMAGERY REVEALS WARMING CLOUD TOP
TEMPERATURES AND CONVECTION BEING DISPLACED POLEWARD AND EAST OF THE
LOW LEVEL CIRCULATION (LLC) DUE TO STRONG VERTICAL WIND SHEAR (VWS).
THE INITIAL POSITION IS BASED ON MID AND UPPER LEVEL TURNING IN THE
EIR IMAGERY WITH FAIR CONFIDENCE. THE INITIAL INTENSITY IS CONSISTENT
WITH DVORAK INTENSITY ESTIMATES RANGING FROM T3.0-T3.5 (45-55 KTS). A
MIDLATITUDE JET TO THE SOUTH IS PROVIDING STRONG POLEWARD OUTFLOW AND
HIGH (25-30 KT) VWS, MAKING THE UPPER LEVEL ENVIRONMENT MARGINAL. AT
27-28 CELSIUS, SEA SURFACE TEMPERATURE IS SUPPORTIVE. BETWEEN THE
UPPER LEVEL ENVIRONMENT AND SATELLITE IMAGERY, IT APPEARS TC 23P IS IN
THE EARLY STAGES OF EXTRATROPICAL TRANSITION (ETT). TC 23P IS TRACKING
ALONG THE POLEWARD PERIPHERY OF A NEAR-EQUATORIAL RIDGE, AHEAD OF AN
UPPER LEVEL TROUGH TO THE WEST. THE CURRENT TRACK AND INTENSITY ARE
EXPECTED TO CONTINUE AS THE SYSTEM UNDERGOES ETT. AROUND TAU 24, TC
23P WILL HAVE TRANSITIONED INTO A GALE FORCE, COLD CORE LOW. NUMERICAL
MODEL GUIDANCE IS IN EXCELLENT AGREEMENT, LENDING HIGH CONFIDENCE TO
THE JTWC TRACK FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 151800Z IS
32 FEET. NEXT WARNINGS AT 160300Z, 160900Z AND 161500Z.//
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