09UTC: TC LORNA(25S) near peak intensity, forecast to be extratropical in 72hours


Warning 20/JTWC



REMARKS:
280900Z POSITION NEAR 17.2S 89.7E.
TROPICAL CYCLONE (TC) 25S (LORNA), LOCATED APPROXIMATELY 500 NM
SOUTHWEST OF COCOS ISLAND, HAS TRACKED SOUTH-SOUTHEASTWARD AT 11
KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY SHOWS THAT DESPITE BEING ASYMMETRIC DUE TO
SOUTHERLY VERTICAL WIND SHEAR (VWS), THE SYSTEM HAS A 10 NM WIDE
EYE. THERE IS HIGH CONFIDENCE IN THE INITIAL POSITION OWING TO THE
EYE. ADDITIONALLY, THE POSITION IS SUPPORTED BY A 280246Z MHS 89 GHZ
MICROWAVE IMAGE. THE INITIAL INTENSITY OF 75 KTS IS CONSISTENT WITH
THE PGTW DVORAK CURRENT INTENSITY ESTIMATE OF T4.5 (77 KTS).
MODERATE (10-15 KT) VWS, EXCELLENT POLEWARD OUTFLOW, AND MARGINAL
(26-27 CELSIUS) SEA SURFACE TEMPERATURE SUGGEST THE ENVIRONMENT IS
SOMEWHAT FAVORABLE, BUT THAT IS LIKELY SHORT-LIVED. TC 25S IS
TRACKING ALONG THE WESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR).
BY TAU 48, TC 25S WILL BE ON THE POLEWARD SIDE OF THE STR AXIS AND
BEGIN ACCELERATING INTO THE MID-LATITUDE WESTERLIES. BASED ON THE
RECENT SPIKE IN INTENSITY DUE TO THE EYE FORMING, THE FORECAST
PHILOSOPHY HAS SHIFTED FROM A DISSIPATION SCENARIO TO AN
EXTRATROPICAL TRANSITION (ETT) SCENARIO. BY TAU 36, INTERACTION WITH
THE BAROCLINIC ZONE WILL MARK THE BEGINNING OF ETT, WITH COMPLETION
EXPECTED BETWEEN TAU 48 AND TAU 72. THROUGHOUT THE FORECAST, THE
ENVIRONMENT WILL BE INCREASINGLY HOSTILE DUE TO HIGH VWS AND COOL
SST AND STEADY WEAKENING IS EXPECTED FOR THE DURATION OF THE
FORECAST. THE DYNAMIC MODEL GUIDANCE DEPICTS A SIMILAR TRACK TO THE
JTWC TRACK FORECAST, LENDING HIGH CONFIDENCE IN THE JTWC FORECAST
TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 280600Z IS 27 FEET. NEXT
WARNINGS AT 281500Z, 282100Z, 290300Z AND 290900Z.//
NNNN


0830UTC
0830UTC

06UTC FY2G
06UTC FY2G

03UTC FY2G
03UTC FY2G

Rédigé par PATRICK HOAREAU le Dimanche 28 Avril 2019 à 15:14