WDPS32 PGTW 012100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 16P (SIXTEEN) 
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.8S 161.9E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 437 NM WEST-NORTHWEST OF PORT VILA,
VANUATU
   MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TRAILING APPROXIMATELY 800NM BEHIND TC 15P (JUDY), ANIMATED
MULTISPECTRAL SATELLITE IMAGERY (MSI) REVEALS THAT TC 16P HAS TWO
PRIMARY CELLS OF PERSISTENT DEEP CONVECTION THAT ARE CONSOLIDATING
OVER THE LOW LEVEL CIRCULATION CENTER (LLCC). A FORTUITOUS SUITE OF
SSMIS IMAGERY, SPECIFICALLY A 011754Z 89GHZ COLOR COMPOSITE
MICROWAVE IMAGE SHOWS CURLING BANDS OF DEEP CONVECTION WRAPPING
INTO AN OPEN AND SLIGHTLY ELONGATED LLCC. THE INITIAL POSITION IS
PLACED WITH HIGH CONFIDENCE BASED ON MSI AND SSMIS IMAGERY. THE
INITIAL INTENSITY OF 40 KTS IS ASSESSED WITH LOW CONFIDENCE BASED
ON AN UNFORTUNATE LACK OF SATELLITE WIND SPEED PRODUCTS COUPLED
WITH AGENCY DVORAK INTENSITY ESTIMATES HISTORICALLY TRAILING BEHIND
THE FORECAST INTENSITY. THESE ESTIMATES OR LACK THEREOF ARE
COUNTERED BY PERSISTENT RAPID INTENSIFICATION (RI) AIDS AND A
SIGNIFICANTLY IMPROVED AND TIGHTER CONVECTIVE STRUCTURES AND
BANDING FEATURES.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: TRANSITIONING STEERING INFLUENCE FROM A
NEAR EQUITORIAL RIDGE (NER) TO A SUB-TROPICAL RIDGE (STR) TO THE
EAST-SOUTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   KNES: T1.0 - 25 KTS
   PHFO: T2.0 - 30 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG RADIAL
   OTHER FACTORS: UPPER-LEVEL POINT SOURCE PROVIDING VIGEROUS
OUTFLOW. 

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: LOW
   INITIAL WIND RADII: LOW

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: TC 16P IS FORECAST TO LARGELY MIMIC THE TRACK
OF TC 15P (JUDY). AS THE SYSTEM CONTINUES TO TRANSITION ITS
STEERING INFLUENCE TO THE STR TO THE EAST-SOUTHEAST IT WILL
CONTINUE TRACKING GENERALLY SOUTHEASTWARD OVER THE NEXT 48 HOURS.
DURING THIS TIME, THE SYSTEM WILL BE IN A FAVORABLE ENVIRONMENT
CHARACTERIZED BY WARM SEA SURFACE TEMPERATURES AND VIGOROUS OUTFLOW
ALOFT SLIGHTLY OFFSET BY MODERATE VERTICAL WINDS SHEAR. THESE
FACTORS ARE FORECAST TO STRENGTHEN 16P TO 90 KTS AND POSSIBLY
HIGHER BY TAU 48. AS 16P CONTINUES POLEWARD OF THE STR NEAR TAU 72,
VERTICAL WIND SHEAR BEGINS TO CLIMB, DRY AIR ENTRAINMENT INCREASES
AND THE SYSTEM PASSES SOUTH OF THE 26 C ISOTHERM, THESE FACTORS
HERALD THE START OF SUB-TROPICAL TRANSITION (STT). OVER THE NEXT 24
HOURS, THESE FACTORS CONTINUE TO INCREASE AND THE SYSTEM FINALLY
BEGINS TO WEAKEN THROUGH TAU 96 AFTER WHICH TC 16P IS FORECAST TO
BE FULLY SUB-TROPICAL.

MODEL DISCUSSION: WITH THE EXCEPTION OF NVGM TO THE NORTH,
NUMERICAL MODELS ARE IN GOOD AGREEMENT THAT TC 16P WILL CONTINUE
POLEWARD OF THE STR AND COMPLETE STT NEAR TAU 96. FOR THIS REASON
THE JTWC FORECAST TRACK IS PLACED WITH HIGH CONFIDENCE. RELIABLE
MODEL INTENSITY GUIDANCE IS IN GOOD AGREEMENT THAT TC 16P WILL
STEADILY INTENSIFY WITH SEVERAL AIDS INDICATING RAPID
INTENSIFICATION THROUGH TAU 48 WITH ALL MEMBERS SHOWING A PEAK
INTENSITY NEAR TAU 60 AFTER WHICH STEADY WEAKENING THROUGH THE
FORECAST PERIOD. FOR THIS REASON THE JTWC INTENSITY FORECAST IS
PLACED WITH MEDIUM CONFIDENCE.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   TRACK 72-120 HR: HIGH
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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