WDPS31 PGTW 070300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 30P (MAILA) WARNING NR 
009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 9.9S 156.4E
   INITIAL INTENSITY: 90 KTS
   GEOGRAPHIC REFERENCE: 667 NM SOUTH OF KAPINGAMARANGI
   MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 02 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS AN INNER
CONVECTIVE CORE THAT REMAINS ASYMMETRIC, WITH INFRARED AND VISIBLE
IMAGERY BOTH SUGGESTING AN INCOMPLETE EYEWALL IS PRESENT. THE EYE
ITSELF HAS RECENTLY BECOME A LITTLE BETTER DEFINED IN JUST THE PAST
2 HOURS, BUT OVERALL HAS REMAINED MOSTLY CLOUD-COVERED OVER THE
PAST 6 HOURS. COUPLED MODELS CONTINUE TO ANALYZE A POOL OF UPWELLED
WATER COOLER THAN 26 DEGREES CELSIUS BENEATH AT LEAST A PORTION OF
THE VORTEX. ASIDE FROM THIS UPWELLING, THE ENVIRONMENT IS GENERALLY
FAVORABLE, WITH LIGHT EASTERLY SHEAR BEING THE ONLY OTHER
HINDRANCE. THE INITIAL INTENSITY IS SET AT 90 KT BASED ON A BLEND
OF AGENCY DVORAK ESTIMATES, OBJECTIVE SATELLITE-BASED ESTIMATES,
AND A 061906Z RCM-3 SAR PASS. THERE IS ONLY MEDIUM CONFIDENCE IN
THIS ESTIMATE, AS THE SHORT-TERM DIRECTIONAL INTENSITY TREND HAS
NOT YET BECOME CLEAR.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: EQUATORIAL WESTERLY WIND BURST TO THE
NORTH AND SUBTROPICAL RIDGE OVER AUSTRALIA TO THE SOUTHWEST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   KNES: T6.0 - 115 KTS
   ABRF: T5.0 - 90 KTS
   CIMSS ADT: 61 KTS AT 062030Z
   CIMSS AIDT: 63 KTS AT 062030Z
   CIMSS D-PRINT: 99 KTS AT 070040Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 10-15 KTS
   SST: 24-28 CELSIUS
   OUTFLOW: MODERATE WESTWARD
   OTHER FACTORS: PROBABLE OCEANIC UPWELLING BENEATH THE VORTEX

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: TROPICAL CYCLONE 30P (MAILA) REMAINS A TRICKY
STORM TO PREDICT ACROSS MULTIPLE DIMENSIONS OF THE FORECAST. MAILA
CONTINUES TO MEANDER SLOWLY IN THE SOLOMON SEA, MIRED BETWEEN A
NEAR-EQUATORIAL WESTERLY WIND BURST TO THE NORTH AND A SUBTROPICAL
RIDGE OVER EASTERN AUSTRALIA TO THE SOUTHWEST. COUPLED MODELS LIKE
HAFS-A AND HWRF ASSESS THAT THIS SLOW MOTION HAS GENERATED OCEANIC
UPWELLING OF WATERS COOLER THAN 26 DEGREES CELSIUS BENEATH THE
STORM, LIKELY CAUSING THE OBSERVED STRUCTURAL DEFECTS OF THE INNER
CORE. THE SHORT-TERM INTENSITY FORECAST IS A CHALLENGE. COUPLED
MODELS EXPECT THE INNER CORE TO BACKTRACK WESTWARD OVER THE COLD
WAKE, CAUSING TEMPORARY WEAKENING. HOWEVER, SLIGHT DEVIATIONS IN
THIS TRACK COULD CHANGE HOW MUCH OF THE INNER CORE OVERLAPS THE COLD
WAKE, ALTERING THE AMOUNT OF WEAKENING, OR EVEN RESULTING IN
STRENGTHENING INSTEAD. THE SHORT-TERM TRACK IS ALSO DIFFICULT, AS
MODELS DISAGREE ON HOW SOON MAILA WILL BEGIN ACCELERATING WESTWARD
TOWARDS PAPUA NEW GUINEA. THE GFS, ECMWF, AND HAFS-A CONTINUE TO BE
MUCH FASTER THAN THE UKMET, GALWEM, AIFS, AND EXPERIMENTAL GOOGLE
DEEPMIND ENSEMBLE MEAN. THE JTWC FORECAST CONTINUES TO SPLIT THE
DIFFERENCE BETWEEN THESE TWO GROUPS, SHOWING 30P APPROACHING THE
PAPUAN PENINSULA JUST AFTER 72 HOURS. BY THIS TIME, THE CYCLONE'S
WESTWARD MOTION IS EXPECTED TO HAVE CARRIED IT BEYOND ITS ORIGINAL
COLD WAKE, ALLOWING SOME REINTENSIFICATION TO AROUND 100 KT.
HOWEVER, RISING MID-LEVEL EASTERLY SHEAR AND INTERACTION WITH THE
TALL OWEN STANLEY MOUNTAINS ARE EXPECTED TO ABRUPTLY DISRUPT AND
WEAKEN MAILA AS IT PASSES NEAR OR OVER THE PAPUAN PENINSULA. THE
DEGREE OF WEAKENING WILL BE QUITE SENSITIVE TO HOW CLOSE THE
CYCLONE PASSES TO THE PENINSULA. AS A RESULT, MODEL INTENSITY
SPREAD IS QUITE LARGE AT AND BEYOND 72 HOURS. DURING THE 96 TO 120 
HOUR PERIOD, THE SUBTROPICAL RIDGE DRAPED ACROSS EASTERN AUSTRALIA 
AND THE CORAL SEA IS EXPECTED TO DIRECT 30P WEST-SOUTHWESTWARD 
TOWARDS NORTHEASTERN AUSTRALIA.

MODEL DISCUSSION: THE JTWC TRACK FORECAST IS PLACED NEAR THE
MULTI-MODEL CONSENSUS BETWEEN THE TWO GROUPINGS OF FAST AND SLOW
MODEL PROJECTIONS. CROSS-TRACK MODEL SPREAD IS AVERAGE, BUT
ALONG-TRACK SPREAD IS LARGER THAN NORMAL. THE JTWC INTENSITY
FORECAST LEANS STRONGLY TOWARD THE COUPLED MODELS HAFS-A AND HWRF
SHORT-TERM DUE TO THEIR AWARENESS OF OCEANIC UPWELLING OCCURRING
BENEATH THE VORTEX, THEN CLOSE TO THE BROADER MULTI-MODEL CONSENSUS
AFTER 36 HOURS.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 00-72 HR: LOW
   INTENSITY 72-120 HR: LOW//
NNNN