WTPS31 PGTW 070300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 23P (NIRAN) WARNING NR 025//
RMKS/
1. TROPICAL CYCLONE 23P (NIRAN) WARNING NR 025
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
070000Z --- NEAR 27.3S 175.7E
MOVEMENT PAST SIX HOURS - 110 DEGREES AT 20 KTS
POSITION ACCURATE TO WITHIN 050 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
WIND RADII VALID OVER OPEN WATER ONLY
BECOMING SUBTROPICAL
RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT
055 NM SOUTHEAST QUADRANT
055 NM SOUTHWEST QUADRANT
050 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 115 NM NORTHEAST QUADRANT
070 NM SOUTHEAST QUADRANT
070 NM SOUTHWEST QUADRANT
100 NM NORTHWEST QUADRANT
REPEAT POSIT: 27.3S 175.7E
---
FORECASTS:
12 HRS, VALID AT:
071200Z --- 29.5S 177.8W
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
SUBTROPICAL
RADIUS OF 034 KT WINDS - 140 NM NORTHEAST QUADRANT
070 NM SOUTHEAST QUADRANT
080 NM SOUTHWEST QUADRANT
160 NM NORTHWEST QUADRANT
---
REMARKS:
070300Z POSITION NEAR 27.9S 177.3E.
07MAR21. TROPICAL CYCLONE 23P (NIRAN), LOCATED APPROXIMATELY 572
NM SOUTH-SOUTHWEST OF SUVA, FIJI, HAS TRACKED EAST-SOUTHEASTWARD AT
20 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) SHOWS THE SYSTEM HAS BECOME ELONGATED AND THE LOW
LEVEL CIRCULATION CENTER IS NOW FULLY EXPOSED. THE INITIAL POSITION
WAS PLACED WITH FAIR CONFIDENCE USING THE AFOREMENTIONED MSI. THE
INITIAL INTENSITY OF 50KTS IS HEDGED SLIGHTLY HIGHER THAN PGTW
ESTIMATE OF ST3.0/45KTS AND SLIGHTLY LOWER THAN THE ADVANCED DVORAK
TECHNIQUE (ADT) WITH A CURRENT INTENSITY ESTIMATE OF T3.4/53KTS AND
EXTRAPOLATED USING A PARTIAL PASS FROM A 062212Z METOP-B ASCAT
IMAGE. UPPER LEVEL ANALYSIS INDICATES STRONG POLEWARD OUTFLOW BEING
OFFSET BY VERY STRONG (30-40KTS) VERTICAL WIND SHEAR AND SEA SURFACE
TEMPERATURES (SST) 24-25C. THE CYCLONE IS MOVING ALONG THE
SOUTHWEST PERIPHERY OF THE DEEP LAYERED SUBTROPICAL RIDGE TO THE
EAST. THE HARSH UPPER LEVEL DYNAMICS, ALONG WITH THE DECREASED SSTS,
HAS DECREASED THE SYSTEM INTENSITY OVER THE PAST SIX HOURS AS THE
SYSTEM IS UNDERGOING SUBTROPICAL TRANSITION AND IS EXPECTED TO
COMPLETE SUBTROPICAL TRANSITION WITHIN THE NEXT 12 HOURS. NUMERICAL
MODELS ARE IN FAIR AGREEMENT THROUGH TAU 12 WITH ONLY A 70NM SPREAD.
THERE IS HIGH CONFIDENCE IN THE FIRST 12 HOURS OF THE FORECAST TRACK
AND LOW CONFIDENCE THEREAFTER DUE TO THE INCREASING SPREAD IN MODEL
SOLUTIONS. THIS IS THE FINAL WARNING ON THIS SYSTEM BY THE JOINT
TYPHOON WRNCEN PEARL HARBOR HI. THE SYSTEM WILL BE CLOSELY MONITORED
FOR SIGNS OF REGENERATION. MAXIMUM SIGNIFICANT WAVE HEIGHT AT
070000Z IS 27 FEET.//
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