WDIO31 PGTW 010900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02A (ASNA)       
WARNING NR 010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.6N 61.9E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 218 NM NORTHEAST OF MASIRAH ISLAND
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
THE PRIMARY CONVECTION AND TOP COVER OF TC 02A (ASNA) HAS SHEARED
TO THE WEST OF THE LOW LEVEL CIRCULATION CENTER (LLCC), WHICH HAS
BECOME FULLY EXPOSED AS DEPICTED BY ANIMATED MULTISPECTRAL
SATELLITE IMAGERY (MSI). IN THE UPPER LEVELS, TC 02A IS CASTING
CIRRUS FILAMENTS OVER NORTHERN OMAN WITH ELEMENTS OF TRANSVERSE
BANDING IN THE EQUATORWARD OUTFLOW CHANNEL AND BROAD, WEAK OUTFLOW
DISPERSING POLEWARD INTO A SUBTROPICAL RIDGE OVER PAKISTAN. THE
MID-LEVELS ARE PLAGUED BY THE INTRUSION OF LOW RELATIVE HUMIDITY
AIR, AND THE REVEALED LLCC IS SURROUNDED BY SYMMETRIC, WRAPPED
BANDS OF LOW CLOUDS CONFINED TO THE LOWER LEVELS OF THE
TROPOSPHERE. THE CLEARLY IDENTIFIABLE LLCC ON VISIBLE SATELLITE
IMAGERY UNDERPINS THE PLACEMENT OF THE INITIAL POSITION WITH HIGH
CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 35 KTS BASED ON A 
010239Z HY-2B SCATTEROMETRY IMAGE WHICH RECORDED A VELOCITY MAXIMUM 
OF 34 KTS.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

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
   DEMS: T2.5 - 35 KTS
   CIMSS SATCON: 40 KTS AT 010338Z
   CIMSS ADT: 39 KTS AT 010300Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 10-15 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT

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: IN THE MIDST OF INCREASING VERTICAL WIND SHEAR,
UNRELENTING DRY AIR ENTRAINMENT INTO THE SYSTEM'S CORE, AND A PATH
THAT TAKES IT OVER DEEP WATERS AND COOLING SEA SURFACE
TEMPERATURES, THE DEMISE OF TC 02A WILL TAKE PLACE OVER THE NEXT 24
HOURS WITHOUT FURTHER INTENSIFICATION. AS EVIDENCED BY THE ANIMATED
SATELLITE IMAGERY DESCRIBED PREVIOUSLY, THE PRESENT DECOUPLING OF
TC 02A STRONGLY SUPPORTS A CONTINUED WEAKENING OF THE SYSTEM AT A
STEADY PACE UNTO DISSIPATION BY TAU 24 AS IT UNWINDS ALONG ITS
INCREASINGLY SOUTHWESTWARD TRACK.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE HAS HAD A VERY GOOD
HANDLE ON THE TRACK AND INTENSITY FORECAST FOR TC 02A. THERE IS
VERY TIGHT AGREEMENT IN BOTH THE PROBABILISTIC AND DETERMINISTIC
GUIDANCE IN REGARDS TO THE SOUTHWESTWARD TURN AND FADING INTENSITY
OF THIS SYSTEM. THE GFS DETERMINISTIC MODEL, BEING 5-10 KTS MORE
AGGRESSIVE THAN THE ECMWF, HAS REMAINED CONSISTENT RUN-TO-RUN IN
DROPPING TC 02A TO BELOW WARNING THRESHOLDS BY TAU 24. THIS
GUIDANCE SUPPORTS THE JTWC FORECAST WITH HIGH CONFIDENCE.

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