WDIO31 PGTW 040300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02A (SHAKHTI) WARNING 
NR 005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.2N 64.7E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 347 NM EAST-NORTHEAST OF MASIRAH ISLAND
   MOVEMENT PAST 6 HOURS: WESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
CONSOLIDATING LOW-LEVEL CIRCULATION, WITH CURVED BANDING OVER THE
WESTERN QUADRANT OF THE LLC. A 032152Z AMSR2 36GHZ MICROWAVE IMAGE
REVEALS CONVECTIVE BANDING WRAPPING TIGHTLY INTO A MICROWAVE EYE
FEATURE, WHICH SUPPORTS THE INITIAL POSITION WITH MEDIUM
CONFIDENCE. THE INITIAL INTENSITY OF 55 KTS IS ASSESSED WITH MEDIUM 
CONFIDENCE BASED ON THE PGTW DVORAK ESTIMATE. CIMSS OBJECTIVE 
ESTIMATES RANGE FROM 41-58 KNOTS FURTHER BOLSTERING THE JTWC INITIAL 
INTENSITY ESTIMATE.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: COMPETING STEERING PATTERN WITH A STRONG 
SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTH AND NORTHWEST, AND A 
WEAKER STR TO THE SOUTH AND SOUTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   CIMSS SATCON: 58 KTS AT 032118Z
   CIMSS ADT: 43 KTS AT 040000Z
   CIMSS AIDT: 41 KTS AT 032000Z
   CIMSS D-MINT: 51 KTS AT 032154Z
   CIMSS D-PRINT: 44 KTS AT 040000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: MID-LEVEL DRY AIR ENTRAINMENT

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: TROPICAL CYCLONE (TC) 02A IS FORECAST TO TRACK
SLOWLY WEST-SOUTHWESTWARD THROUGH TAU 24 ALONG THE SOUTHEASTERN
PERIPHERY OF THE PRIMARY STEERING RIDGE POSITIONED OVER THE SAUDI
PENINSULA. THE STR TO THE SOUTHEAST WILL REMAIN WEAK THROUGH THIS
PERIOD. AFTER TAU 24, THE SYSTEM WILL BE EFFECTIVELY BOXED IN WITH
RIDGING TO THE NORTHWEST (SAUDI PENINSULA), TO THE SOUTHEAST
(EXTENDING WESTWARD FROM CENTRAL INDIA) AND TO THE SOUTH (BUILDING
RIDGE). CONSEQUENTLY, TRACK MOTION WILL BE ERRATIC, WITH A SLOW
TURN SOUTHWARD TO SOUTHEASTWARD. DETERMINISTIC MODELS VARY
SIGNIFICANTLY ON THE LOCATION OF THIS STALL AND TURN, WITH A LARGE
SPREAD BETWEEN THE MODELS. TC 02A IS EXPECTED TO WEAKEN RAPIDLY
AFTER TAU 36 DUE TO THE ENTRAINMENT OF SIGNIFICANT DRY AIR THROUGH
ALL LEVELS. AFTER TAU 48, THE SYSTEM WILL BE EMBEDDED WITHIN A VERY
DRY ENVIRONMENT, WHICH WILL LEAD TO DISSIPATION NO LATER THAN TAU
96. AS THE SYSTEM WEAKENS, IT WILL TRACK EASTWARD TO
EAST-NORTHEASTWARD ALONG THE NORTHERN PERIPHERY OF THE LOW-LEVEL
RIDGE TO THE SOUTH.  

MODEL DISCUSSION: DETERMINISTIC GUIDANCE IS IN GOOD AGREEMENT
THROUGH TAU 24. AFTER TAU 24, GUIDANCE DIVERGES QUICKLY WITH
INCREASING UNCERTAINTY IN THE JTWC TRACK FORECAST AND MAJOR
DIFFERENCES IN THE TIMING OF THE SHARP EASTWARD RECURVE. DESPITE
THE RAPIDLY EVOLVING STEERING PATTERN, PROBABILISTIC GUIDANCE IS IN
FAIR AGREEMENT SUPPORTING THE JTWC TRACK FORECAST. OVERALL, THERE
IS LOW CONFIDENCE IN THE JTWC INTENSITY FORECAST DUE TO THE
PRESENCE OF DRY AIR THROUGH THE FORECAST PERIOD, WHICH IS HAMPERING
CONVECTIVE DEVELOPMENT.  

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