WDPS31 PGTW 251500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 01P (LOLA) WARNING NR 
016//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.2S 166.4E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 113 NM WEST-NORTHWEST OF PORT VILA,
VANUATU
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
BASED ON THE MOST RECENT SHORTWAVE INFRARED (SWIR) IMAGERY, IT
WOULD APPEAR THAT THE LONG-ANTICIPATED DECOUPLING OF TROPICAL
CYCLONE (TC) 01P (LOLA) HAS OCCURRED WITH A VENGEANCE, FASTER THAN
ORIGINALLY THOUGHT. ANIMATED SWIR AND PROXY VISIBLE SATELLITE
IMAGERY SHOWS A VERY WEAK AND RAGGED LOW LEVEL CIRCULATION CENTER
(LLC) TO THE SOUTHWEST OF MALEKULA ISLAND AND A PERSISTENT AREA OF
CONVECTION DISPLACED OVER 100NM TO THE EAST. MOST OF THE AGENCY
POSITION FIXES ARE TRACKING THE CONVECTION AND NOT THE EXPOSED LLCC
BUT ANALYSIS OF EARLIER MICROWAVE IMAGERY AROUND THE 0600Z HOUR
SUGGESTS THAT AS EARLY AS THAT TIME, THE LLCC WAS ALREADY STARTING
TO SPLIT OFF FROM THE UPPER-LEVEL VORTEX. HOWEVER, DUE THE RAGGED
AND RATHER ILL-DEFINED NATURE OF THE EXPOSED LLCC ALONG WITH THE
VERY LARGE SPREAD IN THE FIX POSITIONS, THERE IS LOW CONFIDENCE IN
THE INITIAL POSITION. SIMILARLY, THE INITIAL INTENSITY IS ASSESSED
WITH LOW CONFIDENCE DUE TO THE FACT THAT WITH THE BROAD SPREAD IN
POSITIONS, THERE IS A LARGE AMOUNT OF UNCERTAINTY IN THE ASSOCIATED
INTENSITY FIXES, WHICH ARE BASED OFF DIFFERENT DVORAK TECHNIQUES.
THE INITIAL INTENSITY OF 55 KNOTS IS BASED PRIMARILY ON THE DRASTIC
DEGRADATION IN THE STRUCTURE, THE LACK OF CONVECTION NEAR THE
CENTER AND SUPPORTED BY THE ADT, AIDT, DPRINT AND SATCON ESTIMATES
NOTED BELOW. THE ENVIRONMENT IS CLEARLY HOSTILE, WITH HIGH
SOUTHWESTERLY SHEAR, DRY MID-LEVEL DRY AIR AND LOWER SSTS HAVING
FINALLY TAKEN THEIR TOLL ON THE SYSTEM. THE STEERING LEVEL HAS
ALREADY SHIFTED TO THE 850-700 MB LEVEL, AND THE SYSTEM IS TRACKING
SLOWLY SOUTHWESTWARD ALONG THE NORTHWEST SIDE OF THE LOW- TO
MID-LEVEL ANTICYCLONE CENTERED TO THE SOUTHEAST.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: NORTHWEST PERIPHERY OF A SHALLOW
ANTICYCLONE CENTERED TO THE SOUTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   KNES: T4.0 - 65 KTS
   PHFO: T4.5 - 77 KTS
   CIMSS SATCON: 51 KTS AT 250958Z
   CIMSS ADT: 61 KTS AT 251130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
   VWS: 25-30 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: VERY STRONG MID-LEVEL SHEAR, DRY AIR ABOVE 700MB

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: DUE TO A MORE RAPID DECOUPLING THAN
ANTICIPATED, THE FORECAST HAS BEEN TRUNCATED TO 36 HOURS. 

FORECAST DISCUSSION: TC 01P HAS JUST UNDERGONE AN EXTREMELY RAPID
VORTEX DECOUPLING EVENT, WITH THE LLCC BECOMING COMPLETELY EXPOSED
AND DEVOID OF CONVECTION IN JUST LESS THAN 12 HOURS. THE NOW NAKED
VORTEX IS UNDER THE STEERING INFLUENCE OF THE MID-LATITUDE
ANTICYCLONE FAR TO THE SOUTHEAST AND WILL TRACK SOUTHWEST FOR THE
NEXT 12 TO 18 HOURS. THE TRACK SHIFTS SOUTHWARD TOWARDS NEW
CALEDONIA AFTER TAU 24 AS THE RIDGE REORIENTS AHEAD OF AN
APPROACHING MID-LATITUDE CYCLONE MOVING OFF AUSTRALIA. HAVING
ALREADY DECIMATED THE VORTEX, SHEAR IS EXPECTED TO INCREASE EVEN
MORE OVER THE DURATION OF THE FORECAST PERIOD, DRY AIR WILL
CONTINUE TO FLOOD IN FROM THE WEST AND SSTS WILL CONTINUE TO DROP
PRECIPITOUSLY AS THE SYSTEM MOVES POLEWARD. AS A RESULT, THE SYSTEM
WILL CONTINUE TO RAPIDLY WEAKEN AND IS NOW FORECAST TO WEAKEN BELOW
WARNING THRESHOLD WITHIN THE NEXT 36 HOURS AT MOST, AS IT
APPROACHES NEW CALEDONIA. 

MODEL DISCUSSION: TRACK GUIDANCE IS IN GOOD AGREEMENT, WITH ONLY
MINIMAL SPREAD THROUGH THE SHORT DURATION OF THE FORECAST PERIOD.
HOWEVER, DUE TO THE LOW CONFIDENCE IN THE INITIAL POSITION, THE
FORECAST IS PLACED WITH ONLY MEDIUM CONFIDENCE. INTENSITY GUIDANCE
IS ALSO IN GOOD AGREEMENT ON THE RAPID WEAKENING TREND, WITH THE
BULK OF THE GUIDANCE SUPPORTING THE DISSIPATION TIMELINE, THOUGH
THE DECAY SHIPS MODELS SHOW THE SYSTEM REACHING 30 KNOTS WITHIN 24
HOURS, WHICH CANNOT BE RULED OUT. THE JTWC FORECAST LIES CLOSE TO
THE CONSENSUS MEAN WITH MEDIUM CONFIDENCE. 

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