WDIO31 PGTW 311500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02A (ASNA)       
WARNING NR 007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 23.3N 64.1E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 343 NM EAST-NORTHEAST OF MASIRAH ISLAND
   MOVEMENT PAST 6 HOURS: WESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) MADE AN
APPEARANCE ON ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) AS TC
02A (ASNA) TRACKED WESTWARD AND BECAME PARTIALLY OBSCURED BY AN
AREA OF DEEP CONVECTION TO THE IMMEDIATE WEST OF THE LLCC. THE OVERALL 
SYMMETRIC SHAPE, SUPPORTED BY WELL-WRAPPED BANDS WOULD RESULT IN A 
MUCH MORE IMPRESSIVE STORM IF THE SYSTEM COULD HANG ONTO ITS MOISTURE, 
HOWEVER, DRY AIR ENTRAINMENT REMAINS THE BIGGEST HINDRANCE TO TC 02A. 
THE SOURCE OF THE LOW RELATIVE HUMIDITY (50 PCT AND BELOW) AIR IS DUE 
TO PERSISTENT DRY AIR WRAPPING INTO THE SYSTEM FROM THE ARID REGIONS 
OF THE ARABIAN PENINSULA TO THE WEST, AS WELL AS SOME DEGREE OF LAND 
INTERACTION WITH PAKISTAN TO THE NORTH BECAUSE OF THE RELATIVELY 
EXPANDED NATURE OF THE SYSTEM. A TIGHT CORE NEVER QUITE CONGEALED FOR 
TC 02A, AND NOW THE BROAD, VULNERABLE CORE IS SUFFERING THE EFFECTS OF 
MID-LEVEL DRY AIR ENTRAINMENT LIMITING FURTHER DEVELOPMENT. OUTFLOW IS 
STRONGEST IN AN EQUATORWARD CHANNEL, WITH LITTLE TO SUPPORT OUTFLOW 
ALOFT IN THE POLEWARD DIRECTION.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: COMBINED INFLUENCE OF STRONG RIDGING
OVER THE ARABIAN PENINSULA AND BROAD CYCLONIC INFLUENCE OF A LOW 
PRESSURE CENTER OVER INDIA.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   KNES: T3.0 - 45 KTS
   DEMS: T2.5 - 35 KTS
   CIMSS ADT: 34 KTS AT 311200Z
   CIMSS SATCON: 43 KTS AT 310900Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: ANY FURTHER DEVELOPMENT OF TC 02A WILL BE LIMITED 
TO THE NEXT 6-12 HOURS, AND A MARGINAL ENVIRONMENT WILL CONTRIBUTE TO 
THE GRADUAL WEAKENING AS IT TURNS SOUTHWESTWARD TO SOUTH-SOUTHWESTWARD 
AFTER TAU 24. AS IT MOVES EQUATORWARD, VERTICAL WIND SHEAR OF 
INITIALLY 8-15 KTS WILL STRENGTHEN TO A MARGINALLY UNFAVORABLE 20 KTS 
BY TAU 36. MARGINALLY FAVORABLE BUT COOLING SEA SURFACE TEMPERATURES 
(27 DEG C AND DECREASING) AND LOW OCEAN HEAT CONTENT ARE INSUFFICIENT 
TO CONTINUE TO POWER THE STORM AS IT IS OVERCOME BY DRY AIR STREAMING 
INTO THE SYSTEM AS DESCRIBED ABOVE. AS THE SYSTEM NEARS THE ARABIAN 
PENINSULA, DRY AIR FROM THE WEST WILL QUICKLY CHOKE OFF THE NECESSARY 
SUPPLY OF MOISTURE THAT ALLOWED THIS SYSTEM TO INITIALLY THRIVE. THE 
MID-LEVEL DRY AIR THAT HAS ALREADY BEGUN TO INTRUDE INTO THE CORE, AS 
EVIDENCED BY ANIMATED MSI, WILL FURTHER EXPOSE THE LLCC AS IT 
DISSIPATES BY TAU 36.

MODEL DISCUSSION: DETERMINISTIC AND PROBABILISTIC (EPS, GEFS) MODEL 
GUIDANCE HAVE COME INTO TIGHTER AGREEMENT THROUGH TAU 36 REGARDING THE 
TRACK TURNING TOWARDS THE SOUTH-SOUTHWEST AFTER TAU 24 AND STEADILY 
WEAKENING THE INTENSITY TO THE POINT OF DISSIPATION NEAR TAU 36, WHICH 
SUPPORTS THE JTWC FORECAST WITH HIGH CONFIDENCE. 

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