WDXS31 PGTW 221500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 27P (NARELLE) WARNING 
NR 019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.1S 131.5E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 102 NM SOUTH-SOUTHEAST OF DARWIN,
AUSTRALIA
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: OVER LAND

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
SHALLOW VORTEX WITH ENHANCED CONVECTION DEVELOPING TO THE WEST OVER
THE BONAPARTE GULF. A 220911Z WSFM 89 GHZ MICROWAVE IMAGE SHOWS
WEAK CONVECTION OUTLINING THE ASSESSED CENTER WITH THE BULK OF THE
CONVECTION LOCATED TO THE WEST. THE INITIAL POSITION IS PLACED WITH
MEDIUM CONFIDENCE BASED ON ANIMATED RADAR IMAGERY FROM KATHERINE
(TINDAL) AND A NEARBY OBSERVATION FROM DOUGLAS RIVER. THE INITIAL
INTENSITY OF 35 KTS IS ASSESSED WITH LOW CONFIDENCE BASED ON
FURTHER WEAKENING OVER LAND AND OVERALL STRUCTURE OF THE SYSTEM. 
CURRENT ENVIRONMENTAL CONDITIONS ARE UNFAVORABLE DUE TO THE SYSTEM 
BEING OVER LAND.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: NORTHERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) ANCHORED OVER CENTRAL AUSTRALIA.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 10-15 KTS
   SST: OVER LAND
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD
   OTHER FACTORS: TERRAIN INTERACTION

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL CYCLONE NARELLE HAS CONTINUED ON A
WEST-SOUTHWESTWARD TRACK ACROSS THE TOP END OVER THE PAST 6 HOURS.
IT IS FORECAST TO CONTINUE ON THIS TRAJECTORY THROUGH TAU 72. TC
NARELLE WILL EMERGE OVER THE BONAPARTE GULF JUST BEFORE TAU 12 THEN
MAKE ITS THIRD LANDFALL NORTH OF WYNDHAM NEAR TAU 18. THE SYSTEM
WILL TRACK ALONG THE KIMBERLY COAST THEN EMERGE BACK OVER WATER IN
THE INDIAN OCEAN SOUTHEAST OF ADELE ISLAND AROUND TAU 36. THE
SYSTEM IS EXPECTED TO CONTINUE ON A WEST-SOUTHWESTWARD TRACK
PARALLELING THE COAST THROUGH TAU 72, WHERE IT WILL APPROACH THE
NORTHWESTERN EXTENT OF THE STR AND TURN MORE SOUTHWESTWARD. THE
CURRENT FORECAST CALLS FOR A TRACK OVER THE NORTHWEST COAST OF THE
EXMOUTH PENINSULA, THOUGH THIS PORTION OF THE FORECAST REMAINS
UNCERTAIN. THE SYSTEM IS FORECAST TO MAINTAIN ITS INTENSITY AS IT
TRANSITS OVER LAND, THOUGH A BRIEF PERIOD OF INTENSIFICATION IS
POSSIBLE WHILE IT MOVES THROUGH THE BONAPARTE GULF. ANY INCREASE IN
INTENSITY WILL THEN BE DEGRADED AGAIN AS NARELLE MOVES OVER THE
KIMBERLY REGION DUE TO FURTHER LAND INTERACTION. ONCE THE SYSTEM
REEMERGES OVER THE INDIAN OCEAN IN A HIGHLY FAVORABLE ENVIRONMENT
WITH LOW VERTICAL WIND SHEAR (VWS) AND VERY WARM (30 C) SEA SURFACE
TEMPERATURES IT WILL RAPIDLY INTENSIFY. A PEAK INTENSITY OF AROUND
100 KNOTS IS FORECAST TO OCCUR NEAR TAU 96. AFTER TAU 96
INTERACTION WITH THE WESTERN AUSTRALIAN COAST NEAR THE EXMOUTH
PENINSULA AND COOLING SEA SURFACE TEMPERATURES WILL INITIATE A
WEAKENING TREND.

MODEL DISCUSSION: MODEL TRACK GUIDANCE CONTINUES TO HAVE GOOD
AGREEMENT THROUGH TAU 72 WITH A CROSS-TRACK SPREAD OF 160 NM. AFTER
TAU 72, MODELS BEGIN TO DIVERGE RESULTING IN A SIGNIFICANT
CROSS-TRACK (550 NM) SPREAD AT TAU 120. NOTABLY, THE ECMWF AND
ECMWF ENSEMBLE MEAN HAVE SEPARATED FROM THE MAIN GROUP OF GUIDANCE,
MAINTAINING THE TRACK FARTHER TO THE NORTHWEST OFF THE COAST. IN
THE OTHER EXTREME THE EC-AIFS MAINTAINS A LANDFALL NEAR DAMPIER,
COMPRISING THE EASTERNMOST MODEL SOLUTION. THE REMAINDER OF
GUIDANCE IS SITUATED WITHIN A 70 NM RADIUS TO THE EAST OR WEST OF
LEARMONTH. THE JTWC TRACK FORECAST IS PLACED CLOSE TO THE
MULTI-MODEL CONSENSUS THROUGH TAU 72, THEN SLIGHTLY CLOSER TO THE
GOOGLE DEEPMIND ENSEMBLE MEAN THROUGH TAU 120. CONFIDENCE IN THE
TRACK FORECAST IS HIGH THROUGH TAU 72 AND LOW THEREAFTER. MODEL
INTENSITY GUIDANCE AGREES MAINTAINING A STEADY INTENSITY THROUGH
TAU 24, BECOMING GRADUAL INTENSIFICATION THROUGH TAU 48. MODELS
AGREE ON QUICK REDEVELOPMENT AFTER TAU 48 WITH THE EXCEPTION OF
HAFS-A, WHICH PREDICTS A VERY BROAD VORTEX RATHER THAN THE
CONSOLIDATED CIRCULATION DEPICTED IN THE OTHER MODELS. PEAK
INTENSITIES HAVE DROPPED SLIGHTLY COMPARED TO THE PREVIOUS MODEL
RUN, RANGING FROM 80-100 KTS. THE JTWC INTENSITY FORECAST IS PLACED
NEAR THE CONSENSUS THROUGH TAU 48 THEN ON THE HIGHER END OF THE
GUIDANCE ENVELOPE THROUGH THE END OF THE FORECAST PERIOD AS
CONDITIONS ARE STILL EXPECTED TO BE HIGHLY FAVORABLE FOR
DEVELOPMENT.

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