WDXS31 PGTW 070300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 03S (THREE) 
WARNING NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 9.8S 85.4E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 782 NM EAST-SOUTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A LARGE
PERSISTENT CONVECTIVE MASS ON THE WESTERN SEMICIRCLE, OBSCURING A
LOW LEVEL CIRCULATION CENTER (LLCC) TO THE EAST. AN EARLIER 062212Z
SSMIS 91GHZ IMAGE REVEALS SHALLOW RAN BANDS WRAPPING INTO THE LLCC
POSITIONED TO THE NORTHEASTERN EDGE OF THE DEEP CURVED CONVECTIVE
BAND. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED
ON A COMBINATION OF BOTH THE 91GHZ AND 37GHZ SSMIS MICROWAVE
IMAGES. A 062106Z AMSR2 WIND SPEED PASS SHOWS A SWATH OF 35-39 KNOTS
OVER THE SOUTHWESTERN SEMICIRCLE WITH WEAKER WINDS OVER THE CENTRAL
AND EASTERN SEMICIRCLE. THE INITIAL INTENSITY OF 35 KNOTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED THE RECENT AMSR2 WIND SPEED
ESTIMATE ALONG WITH A COMBINATION OF AGENCY DVORAK AND OBJECTIVE
FIXES. ENVIRONMENTAL CONDITIONS ARE CURRENTLY MARGINALLY FAVORABLE
WITH MODERATE POLEWARD OUTFLOW, WARM (27-28C) SEA SURFACE
TEMPERATURES (SSTS), OFFSET BY HIGH (20-25 KTS) VERTICAL WIND
SHEAR.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) POSITIONED TO
THE EAST AND WEAK EQUATORIAL WESTERLIES TO THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   KNES: T3.0 - 45 KTS
   CIMSS SATCON: 40 KTS AT 062005Z
   CIMSS ADT: 35 KTS AT 0050Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 20-25 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE POLEWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 03S WILL TRACK SOUTHWESTWARD AND THEN
SOUTH-SOUTHWESTWARD IN A MARGINALLY FAVORABLE ENVIRONMENT OVER THE
NEXT 12-24 HOURS, ALONG THE WESTERN PERIPHERY OF THE SUBTROPICAL
RIDGE (STR) POSITIONED TO THE EAST. ENVIRONMENTAL CONDITIONS ARE
FORECAST TO REMAIN MARGINALLY FAVORABLE, CHARACTERIZED BY MODERATE
POLEWARD OUTFLOW, WARM (27-28C) SEA SURFACE TEMPERATURES (SSTS),
OFFSET BY HIGH (20-25KTS) VERTICAL WIND SHEAR (VWS). HOWEVER, BY
TAU 36 THE STR IS EXPECTED TO REALIGN TO A MORE NORTH-SOUTH
ORIENTATION, WHILE AN APPROACHING DEEP MID-LATITUDE SHORTWAVE
TROUGH IS FORECAST TO DIG INTO CLOSE PROXIMITY OF THE SYSTEM. AS A
RESULT TC 03S WILL MOVE INTO A SLIGHTLY MORE FAVORABLE ENVIRONMENT
WITH INCREASED POLEWARD OUTFLOW, AND INCREASED DIVERGENCE ALOFT AS
WELL AS LOWER VWS VALUES. THESE IMPROVED ENVIRONMENTAL FACTORS
COULD ALLOW FOR A BRIEF WINDOW OF INTENSIFICATION BETWEEN TAU 36
AND TAU 48. BY TAU 72, TC 03S IS FORECAST TO INTERACT WITH THE
AFOREMENTIONED APPROACHING SHORTWAVE TROUGH WHICH WILL INDUCE
INCREASED VWS AND WEAKEN THE SYSTEM. AS A RESULT TC 03S WILL BEGIN
TO RAPIDLY SLOW DOWN IN FORWARD TRACK MOTION AND THEN TURN SHARPLY
WESTWARD AS A TRANSITORY HIGH PRESSURE BUILDS POLEWARD OF THE
SYSTEM AND BECOMES THE MAIN STEERING FEATURE. BY TAU 96, TC 03S
WILL TRANSIT NORTHWEST ALONG THE NORTHERN EDGE OF THE HIGH
PRESSURE, AS THIS OCCURS THE SYSTEM WILL CONTINUE TO RAPIDLY
DISSIPATE FURTHER BY THE INFLUENCE OF DRY AIR ENTRAINMENT.


MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT
WITH A GRADUALLY EXPANDING ENVELOPE OF 170NM CROSS-TRACK SPREAD
THROUGH TAU 72. ADDITIONALLY, THE BULK OF THE ECMWF ENSEMBLE (EPS)
AND GFS ENSEMBLE (GEFS) SOLUTIONS ARE IN GOOD AGREEMENT AND SUPPORT
THE JTWC FORECAST TRACK WITH MEDIUM CONFIDENCE. THE RELIABLE
INTENSITY GUIDANCE IS IN FAIR AGREEMENT AS THE MESOSCALE INTENSITY
GUIDANCE, SPECIFICALLY HWRF AND COAMPS-TC INDICATES A HIGHER PEAK
INTENSITY OF 50 KNOTS, WHILE GFS AND DECAY SHIPS REMAINS ON THE
LOWER END OF THE INTENSITY GUIDANCE, WITH A PEAK OF 40 KNOTS.
THEREFORE, THE JTWC INTENSITY FORECAST IS CLOSE TO THE MULTI-MODEL
CONSENSUS WITH MEDIUM CONFIDENCE.
   

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