WDXS31 PGTW 102100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 19S (GOMBE) WARNING 
NR 009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.9S 41.4E
   INITIAL INTENSITY: 80 KTS
   GEOGRAPHIC REFERENCE: 384 NM NORTH OF EUROPA ISLAND
   MOVEMENT PAST 6 HOURS: WESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 27 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS
PERSISTENT, TIGHTLY WRAPPED DEEP CONVECTION ASSOCIATED WITH 19S BUT
STILL NO CLEAR EYE FEATURE. HOWEVER, RECENT MICROWAVE SATELLITE
IMAGERY, INCLUDING A 101537Z SSMIS PASS, CONTINUES TO DEPICT A
WELL-DEFINED EYE BENEATH THE UPPER-LEVEL CIRRUS SHIELD. THE INITIAL
POSITION IS SITUATED DOWNSTREAM FROM A MICROWAVE EYE FEATURE
EVIDENT IN THE AFOREMENTIONED SSMIS PASS AND IS CONSISTENT WITH A
RECENT PGTW INFRARED-BASED SATELLITE FIX WITH HIGH CONFIDENCE. THE
INTENSITY OF 80 KNOTS IS BASED, WITH MEDIUM CONFIDENCE, ON A
CONSENSUS OF MULTIAGENCY DVORAK FIXES RANGING FROM 77 TO 90 KNOTS,
A 101537Z SATCON ESTIMATE OF 74 KNOTS AND RECENT AIDT VALUES OF 83
KNOTS.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE TO THE
SOUTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   FMEE: T5.0 - 90 KTS
   CIMSS SATCON: 74 KTS AT 101648Z
   CIMSS ADT: 74 KTS AT 101815Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 0-5 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG WESTWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 19S WILL CONTINUE TO TRACK WESTWARD ALONG
THE NORTHERN PERIPHERY OF THE CURRENT SUBTROPICAL STEERING RIDGE
FOR THE NEXT 36 HOURS, MAKING LANDFALL NEAR OR JUST TO THE NORTH OF
ANGOCHE, MOZAMBIQUE BEFORE TAU 12. ADDITIONAL INTENSIFICATION TO A
PEAK OF UP TO 100 KNOTS IS EXPECTED PRIOR TO LANDFALL, SUPPORTED BY
HIGH SEA SURFACE TEMPERATURES, LOW VERTICAL WIND SHEAR AND
FAVORABLE UPPER-LEVEL OUTFLOW. AFTER LANDFALL, STEADY TO RAPID
WEAKENING WILL OCCUR, WITH DISSIPATION BELOW 35 KNOTS BY TAU 48.
AFTER TAU 36, A WEAKNESS IS EXPECTED TO DEVELOP IN THE STEERING
RIDGE TO THE SOUTH WITH SIMULTANEOUS BUILDING OF A
MERIDIONALLY-ORIENTED RIDGE TO THE EAST OF THE SYSTEM. RIDGING TO
THE EAST WILL EVENTUALLY BECOME THE PREDOMINANT STEERING MECHANISM
AND TURN 19S TOWARD A POLEWARD TO SOUTHEASTWARD TRAJECTORY. THE
REMNANT CIRCULATION OF 19S IS EXPECTED TO REEMERGE OVER THE
MOZAMBIQUE CHANNEL AFTER TAU 72, CONSOLIDATE AND REINTENSIFY UNDER
THE INFLUENCE OF A WARM SEA SURFACE AND FAVORABLE UPPER-LEVEL
SUPPORT. THERE IS A SMALL PROBABILITY THAT 19S WILL EITHER
DISSIPATE FULLY AND REMAIN OVER LAND OR REEMERGE OVER THE
MOZAMBIQUE CHANNEL TOO WEAK OF A CIRCULATION TO RECONSOLIDATE.
HOWEVER, THIS ALTERNATIVE OUTCOME APPEARS VERY UNLIKELY AT THIS
TIME, WITH THE MAJORITY OF AVAILABLE MODEL GUIDANCE SUPPORTING THE
PRIMARY FORECAST SCENARIO OR REINTENSIFICATION.

MODEL DISCUSSION: THE MAJORITY OF CONSENSUS MODEL TRACK FORECASTS
ARE IN AGREEMENT WITH A WESTWARD TRACK INTO MOZAMBIQUE FOLLOWED BY
A POLEWARD TO SOUTHEASTERN TURN AND REEMERGENCE INTO THE MOZAMBIQUE
CHANNEL AROUND OR JUST AFTER TAU 72. HOWEVER, THE NAVGEM AND GALWEM
SOLUTIONS ARE NOTEWORTHY OUTLIERS, DEPICTING LONGER TRACKS OVER
LAND WITH LIKELY DISSIPATION. THE UKMET MODEL SOLUTION ALSO
INDICATES A LONGER OVER-LAND TRACK, BUT DOES SHOW EVENTUAL
REEMERGENCE OVER THE MOZAMBIQUE CHANNEL IN THE EXTENDED PERIOD. THE
UKMET MOGREPS ENSEMBLE, ON THE OTHER HAND, IS CONSISTENT WITH THE
REST OF THE GUIDANCE PACKAGE FAVORING THE PRIMARY FORECAST
SCENARIO. THE CURRENT JTWC FORECAST TRACK IS CONSISTENT WITH THE
MAJORITY GROUPING OF CONSENSUS MODELS, MULTI-AGENCY ENSEMBLES AND
PREVIOUS FORECAST TRACKS, WITH MEDIUM CONFIDENCE THROUGH TAU 72 AND
LOW CONFIDENCE DUE THE POSSIBILITY OF AN ALTERNATE SCENARIO IN THE
EXTENDED PERIOD. INTENSITY FORECAST MODELS ARE IN GOOD AGREEMENT
THROUGHOUT THE FORECAST, BUT THERE IS SOME UNCERTAINTY IN THE
PRE-LANDFALL INTENSIFICATION TREND IN THE NEAR-TERM AND THE RATE OF
OVER-LAND WEAKENING IN THE MEDIUM TERM, LENDING MEDIUM CONFIDENCE
TO THE INITIAL PORTION OF THE FORECAST. WITH THE SMALL POSSIBILITY
OF DISSIPATION OF THE CIRCULATION OVER LAND STILL IN PLAY,
CONFIDENCE IN THE EXTENDED INTENSITY FORECAST IS LOW.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
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