WDPS31 PGTW 101500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 30P (MAILA) WARNING NR 
018//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 8.4S 154.3E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 712 NM NORTHEAST OF CAIRNS, AUSTRALIA
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 02 KTS
   SIGNIFICANT WAVE HEIGHT: 19 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
RAPIDLY WEAKENING SYSTEM, WITH A MOSTLY OBSCURED AND ILL-DEFINED
LOW LEVEL CIRCULATION CENTER (LLCC). A 101118Z ASCAT-B PARTIAL PASS
REVEALED A WEAK LLCC WITH 40-45 KNOT WINDS ALONG THE NORTHERN AND
WESTERN FLANKS OF THE CENTER. THE INITIAL POSITION IS ASSESSED WITH
HIGH CONFIDENCE BASED ON THE ASCAT DATA. THE INITIAL INTENSITY IS
ALSO ASSESSED WITH HIGH CONFIDENCE, WITH THE ASCAT PASS CONFIRMING
FROM THE MAJORITY OF THE SUBJECTIVE AND OBJECTIVE INTENSITY
ESTIMATES OUTLINED BELOW. ENVIRONMENTAL CONDITIONS ARE HIGHLY
UNFAVORABLE, WITH THE SYSTEM NOW MOVING DIRECTLY OVER A POOL OF
VERY COOL (ESTIMATED AT 18-20C) WATERS, MODERATE EASTERLY SHEAR AND
MODERATE WESTWARD OUTFLOW ALOFT.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: COMPETING STEERING PATTERN, BETWEEN A
BELT OF DEEP WESTERLIES ALONG THE EQUATOR AND AN EXTENSION OF THE
SUBTROPICAL RIDGE (STR) OVER THE CORAL SEA. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   KNES: T3.5 - 55 KTS
   ABRF: T3.0 - 45 KTS
   CIMSS ADT: 49 KTS AT 101130Z
   CIMSS AIDT: 44 KTS AT 101130Z
   CIMSS D-MINT: 43 KTS AT 100755Z
   CIMSS D-PRINT: 36 KTS AT 101130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
   VWS: 15-20 KTS
   SST: 18-20 CELSIUS
   OUTFLOW: MODERATE WESTWARD
   OTHER FACTORS: HIGH MID-LEVEL EASTERLY SHEAR RESULTING IN A
HIGHLY TILTED VORTEX.

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THE FORECAST HAS BEEN TRUNCATED TO 48
HOURS DUE TO THE EXTREMELY RAPID WEAKENING OF TC 30P. 

FORECAST DISCUSSION: TC 30P HAS UNDERGONE AN EXTREMELY RAPID
DETERIORATION AND WEAKENING, DUE TO THREE COINCIDENT FACTORS.
FIRST, THE SYSTEM MOVED OVER A POOL OF VERY COOL (HAFS-A MODELED AT
18C-20C) WATERS UPWELLED TO THE SURFACE. SECOND, BY AN INFLUX OF
STRONG LOW-LEVEL WEST-SOUTHWESTERLY FLOW PENETRATING INTO THE INNER
CORE AND DISRUPTING THE VORTEX. FINALLY, PERSISTENT MODERATE
EASTERLY SHEAR COMPLETED THE JOB STARTED BY THE COOL POOL. THE
SYSTEM HAS REMAINED QUASI-STATIONARY OVER THE PAST DAY OR TWO,
CAUGHT AGAIN BETWEEN COMPETING AND BALANCED STEERING FLOWS, WITH A
BELT OF STRONG WESTERLIES ALONG THE EQUATOR AND AN EXTENSION OF THE
STR TO THE SOUTH IN THE CORAL SEA. OVER THE NEXT 12 TO 24 HOURS,
THE RIDGE TO THE SOUTH IS FORECAST TO RECEDE WESTWARD, AND A NEW
ANTICYCLONE IS EXPECTED TO DEVELOP TO THE SOUTHEAST OF TC 30P. THIS
WILL OPEN UP A WINDOW OF OPPORTUNITY FOR THE SYSTEM TO GRADUALLY
BEGIN TRACKING SOUTHWESTWARD OVER THE COURSE OF THE FORECAST
PERIOD. REGARDING INTENSITY, AS THE SYSTEM BEGINS TO MOVE AWAY FROM
THE COLD POOL, IT WILL MOVE INTO A MORE FAVORABLE OCEANIC
ENVIRONMENT, HOWEVER, THE COMBINATION OF PERSISTENT EASTERLY SHEAR
AND STRENGTHENING SOUTHWESTERLY FLOW INTO THE REMNANT VORTEX, WILL
INHIBIT THE CHANCES OF REINTENSIFICATION. THE SYSTEM IS FORECAST TO
DISSIPATE BELOW THE WARNING THRESHOLD WITHIN 48 HOURS, TO THE
NORTHEAST OF MILNE BAY. WHILE THE FORECAST EXPLICITLY CALLS FOR
DISSIPATION WITHIN 48 HOURS, THE REMNANTS OF TC 30P COULD PASS
ROUND THE EASTERN TIP OF PAPUA NEW GUINEA AND EMERGE INTO THE CORAL
SEA AFTER TAU 72. WHILE IT IS CURRENTLY ASSESSED AS A LOW
PROBABILITY, SOME OF THE MESOSCALE GUIDANCE SUGGESTS A
REINTENSIFICATION ONCE THE SYSTEM MOVES INTO THE CORAL SEA, AND
THIS SCENARIO CANNOT BE COMPLETELY RULED OUT.

MODEL DISCUSSION: THE GUIDANCE SUITE IS RELATIVELY ALIGNED THROUGH
THE SHORT DURATION OF THE FORECAST PERIOD. THE MOST SIGNIFICANT
OUTLIERS ARE THE EC-AIFS WHICH SHOWS A NORTHWARD TRACK THROUGH TAU
48, AND THE GFS WHICH IS SIGNIFICANTLY FASTER THAN ALL THE OTHER
GUIDANCE, DEPICTING THE CENTER OF THE SYSTEM IN THE NORTHERN CORAL
SEA AT TAU 48. THE REMAINDER OF THE GUIDANCE SHOWS A SLOW
PROGRESSION SOUTHWESTWARD GENERALLY EAST OF WOODLARK ISLAND. THE
JTWC FORECAST IS PLACED NEAR THE CONSENSUS MEAN, WHICH ITSELF LIES
ON THE WESTERN EDGE OF THE GUIDANCE ENVELOPE. CONFIDENCE IN THE
TRACK REMAINS LOW HOWEVER, DUE TO THE UNCERTAINTIES ASSOCIATED WITH
THE WEAK STEERING PATTERN AND THE TIMING OF THE FORECASTED CHANGES
IN THE RIDGING STRUCTURE. INTENSITY GUIDANCE IS IN OVERALL GOOD
AGREEMENT. THE SHIPS, COAMPS-TC, HWRF AND HAFS-A ALL DEPICT A
CONTINUANCE OF THE RAPID WEAKENING PHASE, DIPPING BELOW 35 KNOTS
BETWEEN 24 AND 48 HOURS. OF NOTE, THE COAMPS-TC DEPICTS A
REINTENSIFICATION AFTER TAU 24. THE JTWC FORECAST IS POSITIONED
NEAR THE HAFS-A TRACKER WITH MEDIUM CONFIDENCE. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: LOW
   INTENSITY 00-72 HR: MEDIUM//
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