WDPS31 PGTW 240900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 01P (LOLA) WARNING NR 
011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.1S 168.7E
   INITIAL INTENSITY: 115 KTS
   GEOGRAPHIC REFERENCE: 158 NM NORTH OF PORT VILA, VANUATU
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 40 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE (TC) 01P (LOLA) PEAKED AT OR NEAR 0000Z AND IS
ALREADY STARTING ITS ANTICIPATED RAPID WEAKENING PHASE. ANIMATED
ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THAT THE EYE
PRESENT JUST SIX HOURS AGO HAS ALREADY DISAPPEARED AND FILLED IN,
LEAVING BEHIND A REMNANT WARM SPOT IN THE MOST RECENT EIR. THE MOST
RECENT MICROWAVE IMAGERY FROM A 24504Z SSMIS PASS REVEALED A
WELL-DEFINED UPPER-LEVEL MICROWAVE EYE FEATURE IN THE 91GHZ BAND,
BUT THE LOW-LEVEL MICROWAVE EYE WAS BARELY VISIBLE AND OFFSET
SLIGHTLY TO THE NORTHEAST. THE 91GHZ IMAGE SHOWED AN IRREGULAR
EYEWALL, OPEN TO BOTH THE NORTH AND SOUTH, AND STRONG CONVECTION IN
THE EASTERN EYEWALL. THE INITIAL POSITION IS ASSESSED WITH HIGH
CONFIDENCE BASED ON A SHORT EXTRAPOLATION OF THE MICROWAVE EYE
FEATURE NOTED ABOVE. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM
CONFIDENCE, SLIGHTLY LOWER THAN THE BULK OF THE AGENCY CURRENT
INTENSITY (CI) VALUES, BUT IN LINE WITH THEIR FINAL-T OR DATA-T
VALUES, AND HEDGING DOWNWARDS AFTER THE RAPID LOSS OF THE EYE
FEATURE. AT FIRST BLUSH, THE ENVIRONMENT LOOKS SUPPORTIVE, WITH LOW
DEEP-LAYER SHEAR, RELATIVELY WARM SSTS AND ROBUST POLEWARD OUTFLOW.
HOWEVER, HIGH (30-40 KNOTS) MID-LEVEL SHEAR AND VERY DRY AIR ABOVE
500MB WILL BE THE DRIVER OF THE SYSTEMS DEMISE AND ARE ALREADY
BEGINNING TO HAVE AN IMPACT. TC 01P IS MOVING SOUTHWEST ALONG THE
PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED TO THE
EAST.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED NEAR SAMOA. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.5 - 127 KTS
   KNES: T6.0 - 115 KTS
   PHFO: T6.5 - 127 KTS
   NFFN: T6.5 - 127 KTS
   CIMSS SATCON: 120 KTS AT 240520Z
   CIMSS ADT: 127 KTS AT 240520Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 0-5 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: STRONG MID-LEVEL SHEAR AND DRY AIR.

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 01P WILL TRACK SOUTHWEST THROUGH THE
NORTHERN PORTION OF THE VANUATU ISLANDS OVER THE NEXT 12 TO 18
HOURS, THEN CONTINUE SOUTHWEST INTO THE OPEN WATERS WEST OF VANUATU
ALONG THE WESTERN SIDE OF THE STEERING RIDGE. AROUND TAU 36 THE
SYSTEM WILL TURN SOUTHWARD THEN CURVE SOUTH-SOUTHEASTWARD BY THE
END OF THE FORECAST PERIOD AS IT TRACKS AHEAD OF AN APPROACHING
MID-LATITUDE SYSTEM DEVELOPING OFF THE COAST OF AUSTRALIA. BASED ON
SATELLITE IMAGERY ANALYSIS, TC 01P LIKELY PEAKED AT OR NEAR THE
240000Z HOUR, AND HAS ALREADY BEGUN TO WEAKEN, AS THE MID-LEVEL
SHEAR AND DRY AIR BEGIN TO TAKE THEIR TOLL. ALL GLOBAL AND
MESOSCALE MODELS SUGGEST THIS IS GOING TO BE ONE OF THE MOST
DRAMATIC CASES OF RAPID WEAKENING ON RECORD. THE CIRA ADVECTED
LAYER PRECIPITABLE WATER PRODUCT AND GFS MODEL SOUNDINGS SHOW AN
EXTREMELY DRY AIR MASS ABOVE 500MB ENTRENCHED ABOVE THE SYSTEM.
THIS DRY AIR IS EXPECTED TO EXPAND IN DEPTH, ACCOMPANYING AN INFLUX
OF STRONG SOUTHWESTERLY FLOW COMING AROUND THE POLEWARD SIDE OF A
LARGE ANTICYCLONE TO THE WEST. HIGH-RESOLUTION MODELS INCLUDING
HAFS-A AND HWRF, INDICATE THESE HIGH WINDS WILL LEAD TO A FULL
DECOUPLING OF THE VORTEX WITHIN THE NEXT 24 HOURS, WHICH ALONG WITH
INCREASING DRY AIR SMOTHERING ANY CHANCE OF CONVECTIVE DEVELOPMENT,
WILL ALLOW FOR AN EXTREMELY RAPID WEAKENING OF THE SYSTEM. THE
FORECAST CALLS FOR DISSIPATION BELOW WARNING CRITERIA BY TAU 72, AS
THE SYSTEM PASSES OVER NEW CALEDONIA, BUT A FASTER RATE OF
WEAKENING IS POSSIBLE WITH ONLY A VERY WEAK REMNANT VORTEX PASSING
NEAR OR OVER NEW CALEDONIA AROUND TAU 72.    

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN FAIRLY GOOD
AGREEMENT, WITH THE BULK OF THE GUIDANCE PACKAGE CONTAINED IN AN
ENVELOPE WHICH GRADUALLY EXPANDS TO JUST 100NM BY TAU 72 AND TWO
MAIN OUTLIERS. THE NAVGEM IS ANOMALOUSLY PULLING THE SYSTEM FAR TO
THE EAST OF THE REST OF THE GUIDANCE AFTER TAU 12, AND IS
DISCARDED. ON THE WEST SIDE, THE GALWEM TRACKER IS JUST AS FAR WEST
AS NAVGEM IS EAST AND IS ALSO DISCARDED. THE JTWC FORECAST LIES
JUST EAST OF THE CONSENSUS TRACKER AND CLOSE TO THE ECMWF TRACK
WITH MEDIUM CONFIDENCE. INTENSITY GUIDANCE IS IN GOOD AGREEMENT ON
A RAPID WEAKENING TREND, BUT DOES SHOW A FAIR AMOUNT OF UNCERTAINTY
IN JUST HOW FAST THE SYSTEM WILL FALL APART. THE JTWC FORECAST LIES
ON THE HIGH END OF THE GUIDANCE, WITH THE HWRF AND COAMPS-TC
SHOWING A MUCH FASTER RATE OF WEAKENING, WITH MEDIUM CONFIDENCE. 

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