WTPS31 PGTW 100900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 20P (TWENTY) WARNING NR 002//
RMKS/
1. TROPICAL CYCLONE 20P (TWENTY) WARNING NR 002
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
100600Z --- NEAR 26.7S 177.4W
MOVEMENT PAST SIX HOURS - 170 DEGREES AT 16 KTS
POSITION ACCURATE TO WITHIN 040 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 165 NM NORTHEAST QUADRANT
135 NM SOUTHEAST QUADRANT
080 NM SOUTHWEST QUADRANT
070 NM NORTHWEST QUADRANT
REPEAT POSIT: 26.7S 177.4W
---
FORECASTS:
12 HRS, VALID AT:
101800Z --- 29.9S 176.4W
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
BECOMING EXTRATROPICAL
RADIUS OF 034 KT WINDS - 170 NM NORTHEAST QUADRANT
160 NM SOUTHEAST QUADRANT
070 NM SOUTHWEST QUADRANT
050 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 155 DEG/ 18 KTS
---
24 HRS, VALID AT:
110600Z --- 33.1S 174.7W
MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
WIND RADII VALID OVER OPEN WATER ONLY
BECOMING EXTRATROPICAL
RADIUS OF 034 KT WINDS - 170 NM NORTHEAST QUADRANT
160 NM SOUTHEAST QUADRANT
070 NM SOUTHWEST QUADRANT
050 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 145 DEG/ 18 KTS
---
36 HRS, VALID AT:
111800Z --- 36.1S 172.3W
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
EXTRATROPICAL
---
REMARKS:
100900Z POSITION NEAR 27.5S 177.1W.
10FEB21. TROPICAL CYCLONE 20P (TWENTY), LOCATED APPROXIMATELY 566
NM SOUTH-SOUTHEAST OF SUVA, FIJI, HAS TRACKED SOUTHWARD AT 16
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) SHOWS A WELL DEFINED AND PARTIALLY EXPOSED LOW LEVEL
CIRCULATION CENTER (LLCC), WITH MODERATE CONVECTION DISPLACED TO THE
SOUTHEAST. THE OVERALL DEPICTION IN THE MSI IS INCREASINGLY
EXTRATROPICAL, WITH THE COMMA-SHAPED CONVECTIVE ENVELOPE NOW
POLEWARD AND EASTWARD OF THE LLCC. A TIMELY 100600Z GMI 36GHZ
MICROWAVE IMAGE WITH A WELL-DEFINED LOW EMISSIVITY REGION AND LOW
LEVEL CONVECTIVE BANDING FEATURES LENT HIGH CONFIDENCE TO THE
INITIAL POSITION. THE INITIAL INTENSITY IS LOWERED TO 40 KNOTS WITH
FAIR CONFIDENCE BASED ON A BLEND OF A DVORAK CURRENT INTENSITY
ESTIMATE OF T2.5 (35 KTS) FROM PGTW, AND AN ADT ESTIMATE OF T3.0 (45
KTS), AS WELL AS AN EXTRAPOLATION OF 100116Z AMSR2 WINDSPEED
ANALYSIS WHICH SHOWED 40-50KT WINDS CONFINED TO THE SOUTHEAST
QUADRANT, WITH 35-40KT WINDS ELSEWHERE.
TC 20P IS MOVING RAPIDLY SOUTHWARD ALONG TIGHT GRADIENT BETWEEN THE
STR TO THE EAST AND DEEP MID-LATITUDE TROUGH TO THE WEST. THE
OVERALL ENVIRONMENT IS NOT SUPPORTIVE OF TROPICAL CYCLONE
DEVELOPMENT, WITH COOL (24-26C) SSTS, VERY HIGH (>30KT) VWS AND
ROBUST POLEWARD OUTFLOW. THERMAL CROSS-SECTION AND THICKNESS
ANALYSIS REVEALS THE SYSTEM HAS BOTH TROPICAL AND EXTRATROPICAL
FEATURES AT WARNING TIME. AS THE SYSTEM CONTINUES MOVING SOUTH-
SOUTHEASTWARD IT WILL ENCOUTER INCREASINGLY UNFAVORABLE CONDITIONS,
AND BECOME EMBEDDED IN THE BAROCLINIC ZONE UNDER THE UPPER-LEVEL
JET, TRANSITIONING TO A FULLY EXTRATROPICAL SYSTEM AT OR BEFORE TAU
36. NUMERICAL MODEL GUIDANCE IS IN VERY GOOD AGREEMENT THROUGH THE
FORECAST PERIOD LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK,
WHICH REMAINS CONSISTENT WITH THE PREVIOUS WARNING, NEAR THE MULTI-
MODEL CONSENSUS MEAN. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 100600Z IS
18 FEET. NEXT WARNINGS AT 101500Z, 102100Z, 110300Z AND 110900Z.//
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