WDPS31 PGTW 010900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 15P (JUDY) WARNING NR 
010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.4S 169.3E
   INITIAL INTENSITY: 105 KTS
   GEOGRAPHIC REFERENCE: 117 NM SOUTH-SOUTHEAST OF PORT VILA,
VANUATU
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHEASTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 37 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A SOMEWHAT
SYMMETRICAL SYSTEM WITH THICK CONVECTIVE BANDS WRAPPING INTO AN
ASSESSED LOW LEVEL CIRCULATION CENTER (LLCC). A 010226Z AMSR2 89GHZ
IMAGE REVEALS A BROAD SPIRAL BAND OF CONVECTION IN THE EASTERN
PERIPHERY WRAPPING INTO A MICROWAVE EYE FEATURE. ENVIRONMENTAL
ANALYSIS INDICATES TC JUDY TO BE IN FAVORABLE CONDITIONS FOR
CONTINUAL TROPICAL DEVELOPMENT. THESE CONDITIONS ARE CHARACTERIZED
BY ROBUST POLEWARD OUTFLOW ALOFT, LOW (10-15 KTS) VERTICAL WIND
SHEAR (VWS), A STRONG 850 MB VORTICITY SIGNATURE, AND WARM (28-29
C) SEA SURFACE TEMPERATURES (SST). THE INITIAL POSITION IS PLACED
WITH HIGH CONFIDENCE BASED ON THE AFOREMENTIONED MSI, THE NEW
CALEDONIA RADAR LOOP, AND MULTI-AGENCY FIX LOCATIONS. THE INITIAL
INTENSITY OF 105 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A
BLEND OF MULTI-AGENCY AND AUTOMATED DVORAK ESTIMATES.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   KNES: T6.0 - 115 KTS
   PHFO: T5.5 - 102 KTS
   NFFN: T5.5 - 102 KTS
   CIMSS SATCON: 83 KTS AT 010226Z
   CIMSS ADT: 90 KTS AT 010630Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TC JUDY CONTINUES ITS SOUTH-SOUTHEASTWARD
TRACK AS IT HUGS THE OUTER PERIPHERY OF THE STR TO THE EAST. BY TAU 
12,
THE SYSTEM WILL REACH ITS MAX INTENSITY OF 110 KNOTS, FOLLOWED BY A
SHIFT SOUTHEASTWARD AND DECREASE IN INTENSITY TO 95 KNOTS BY TAU
24. BY TAU 36, TC JUDY WILL THEN DECREASE IN INTENSITY AGAIN TO 80
KNOTS AS IT CROSSES OVER COOLER (25-26 C) SSTS. BY TAU 48, TC 15P
WILL PICK-UP TRACK SPEED AND DECREASE IN INTENSITY TO 70 KNOTS AS
IT WILL BEGIN ITS SUBTROPICAL TRANSITION. IN ADDITION AT THIS TIME,
TC 15P WILL BEGIN TO ENTER A MORE HOSTILE ENVIRONMENT CHARACTERIZED
BY STRONGER VWS AND CONTINUOUS DRY AIR FROM THE WEST BEING WRAPPED
INTO THE SYSTEM. BY TAU 72, TC JUDY WILL BECOME FULLY SUBTROPICAL.

MODEL DISCUSSION: THE JTWC TRACK CONSENSUS MEMBERS ARE IN
RELATIVELY GOOD AGREEMENT WITH A CONTINUAL SOUTH-SOUTHEASTWARD
TRACK, FOLLOWED BY A SOUTHEASTWARD TRACK IN THE LATER TAUS. THE
NAVGEM TRACKER IS THE OUTLIER WITH A MORE SOUTHWARD TRACK AFTER TAU
24 THAN THE OTHER MEMBERS. BECAUSE OF THIS, THE JTWC FORECAST TRACK
IS PLACED SLIGHTLY TO THE LEFT OF CONSENSUS AFTER TAU 24. THE
FORECAST MODEL ENVELOPE HAS A 41 NM SPREAD BY TAU 24 WHICH
PROGRESSIVELY INCREASES TO 167 NM BY TAU 72. AS A RESULT, THE JTWC
FORECAST TRACK IS SET WITH MEDIUM CONFIDENCE. THE JTWC INTENSITY
CONSENSUS MEMBERS ARE ALSO IN GOOD AGREEMENT SHOWING AN INCREASE IN
INTENSITY AT TAUS 12, THEN A GRADUAL DECREASE THROUGHOUT THE
FORECAST PERIOD. 

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