WDXS31 PGTW 181500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 11S (FREDDY) WARNING 
NR 032//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.2S 69.4E
   INITIAL INTENSITY: 110 KTS
   GEOGRAPHIC REFERENCE: 576 NM SOUTH-SOUTHWEST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: WESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 47 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A RECOVERING
SYSTEM THAT PREVIOUSLY UNDERWENT A SMALL PERIOD OF DETERIORATION.
TC FREDDY IS BEGINNING TO RESHAPE BACK INTO A SYMMETRICAL SYSTEM
AND NOW HAS A CLOUD FILLED EYE. A MICROWAVE EYE IS PRESENT IN THE
180921Z AMSR2 89GHZ IMAGE INDICATING A BETTER STRUCTURE THAN THE
PREVIOUS FORECAST. ANALYSIS OF THE HIGH RESOLUTION GFS AND HWRF
MODELS INDICATES THE DRY AIR THAT WAS PREVIOUSLY AFFECTING THE
MID-LEVELS IS BEGINNING TO GIVE WAY TO INCREASING MOISTURE.
ENVIRONMENTAL ANALYSIS INDICATES TC 11S TO BE IN FAVORABLE
CONDITIONS FOR CONTINUAL TROPICAL DEVELOPMENT. THESE CONDITIONS ARE
CHARACTERIZED BY CONSISTENT WESTERLY OUTFLOW ALOFT, LOW (10-15 KTS)
VERTICAL WIND SHEAR (VWS), A VERY STRONG 850 MB VORTICITY
SIGNATURE, AND WARM (27-28 C) SEA SURFACE TEMPERATURES (SST). THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE ABOVE
MENTIONED MSI AND MICROWAVE IMAGERY. THE INITIAL INTENSITY OF 110
KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A BLEND OF
MULTI-AGENCY AND AUTOMATED DVORAK ESTIMATES.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE SOUTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   KNES: T6.0 - 115 KTS
   DEMS: T6.0 - 115 KTS
   FMEE: T6.0 - 115 KTS
   CIMSS SATCON: 122 KTS AT 180918Z
   CIMSS ADT: 122 KTS AT 181300Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE WESTWARD

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 FREDDY CONTINUES ITS WEST-SOUTHWESTWARD
TRACK AS IT TRANSITS THE NORTHERN PERIPHERY OF THE STR TO THE
SOUTH. THE SYSTEM WILL CONTINUE THIS TRAJECTORY AND GRADUALLY
INCREASE IN INTENSITY TO 120 KNOTS BY TAU 48 DUE TO ENTERING AN
IMPROVING ENVIRONMENT. COPIOUS AMOUNTS OF DRY AIR WILL CONTINUE TO
SURROUND THE SYSTEM, HOWEVER, TC FREDDY WILL STAY COCOONED IN ITS
OWN MOISTURE POCKET DURING ITS FORECAST TRACK. TC 11S IS FORECAST TO
MAKE LANDFALL ON THE EAST COAST OF MADAGASCAR AFTER TAU 72 AND
DECREASE IN INTENSITY TO 50 KNOTS BY TAU 96 DUE TO LAND
INTERACTION. BY TAU 120, THE SYSTEM IS FORECAST TO RE-INTENSIFY AS
IT TRANSITS OVER THE MOZAMBIQUE CHANNEL.

MODEL DISCUSSION: THE JTWC MODEL TRACK CONSENSUS REMAINS IN TIGHT
AGREEMENT WITH A GRADUAL SPREAD TO 80 NM BY TAU 48. AFTERWARDS, THE
SPREAD INCREASES TO 325 NM BY TAU 120 AS THE MEMBERS DISAGREE WITH
THE TRAJECTORY AFTER LANDFALL. GFS DETERMINISTIC AND ENSEMBLE
GUIDANCE TAKES TC 11S ON A MORE WEST-NORTHWESTWARD TRACK AFTER
CROSSING OVER THE MOZAMBIQUE CHANNEL, WHEREAS THE OTHER MEMBERS
KEEP THE SYSTEM ON A WEST-SOUTHWESTWARD TRACK. THE FORECAST TRACK
IS SET SLIGHTLY TO THE RIGHT OF CONSENSUS AFTER TAU 72 TO ACCOUNT
FOR THE OFFSET OF THE GFS GUIDANCE. BECAUSE OF THIS, THE JTWC
FORECAST TRACK IS PLACED WITH HIGH CONFIDENCE UP TO TAU 72, THEN
MEDIUM CONFIDENCE THEREAFTER. THE INTENSITY GUIDANCE IS ALSO IN
GOOD AGREEMENT WITH THE EXCEPTION OF GFS WHICH DECREASES THE
INTENSITY WELL BEYOND THE OTHER CONSENSUS MEMBERS. THE JTWC
INTENSITY FORECAST IS SET WITH MEDIUM CONFIDENCE THROUGHOUT THE
FORECAST PERIOD.

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