WDIO31 PGTW 312100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02A (ASNA) WARNING NR 
008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 23.3N 63.2E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 300 NM NORTHEAST OF MASIRAH ISLAND
   MOVEMENT PAST 6 HOURS: WESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 19 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
CYCLONE 02A (ASNA) WITH A COMPACT CENTRAL DENSE OVERCAST (CDO) THAT
IS BEING BLOWN OFF WESTWARD DUE TO THE EASTERLY SHEAR ACTING ON THE
SYSTEM. THE LOW-LEVEL CIRCULATION CENTER IS PARTIALLY EXPOSED ON
THE EASTERN SEMICIRCLE IN RESPONSE TO THE COMBINATION OF THE
EASTERLY SHEAR AND DRY AIR THAT IS BEING PULLED INTO THE SYSTEM.
ENVIRONMENTAL ANALYSIS INDICATES THAT 02A IS IN A MARGINAL
ENVIRONMENT CHARACTERIZED BY THE MODERATE EQUATORWARD OUTFLOW
ALOFT, MODERATE VERTICAL WIND SHEAR (VWS), DRY AIR ENTRAINMENT, AND
WARM SEA SURFACE TEMPERATURES. THE INITIAL POSITION IS PLACED WITH
MEDIUM CONFIDENCE BASED ON A 311708Z NOAA-19 ASMUB MICROWAVE IMAGE
WHICH SHOWS THE LOW-LEVEL CLOUDS WRAPPING INTO THE CIRCULATION
CENTER. THE INITIAL INTENSITY OF 45 KTS IS ASSESSED WITH MEDIUM
CONFIDENCE BASED ON THE AGENCY DVORAK ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF AN EXTENSION
OF DEEP-LAYERED RIDGING THAT EXTENDS TO PAKISTAN.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   KNES: T3.0 - 45 KTS
   DEMS: T2.5 - 35 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD
   OTHER FACTORS: 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: 02A IS FORECAST TO BEGIN TRACKING
WEST-SOUTHWESTWARD OVER THE NEXT 12 HOURS AS THE RIDGE TO ITS
NORTHWEST BEGINS TO BUILD AND TAKES OVER AS THE PRIMARY STEERING
INFLUENCE. 02A IS THEN EXPECTED TO TRACK MORE SOUTHWESTWARD ALONG
THE SOUTHEASTERN PERIPHERY OF THAT RIDGING THROUGH THE REMAINDER OF
THE FORECAST PERIOD. THE ENVIRONMENT WILL CONTINUE TO BE MARGINAL
THROUGH TAU 12, THOUGH 02A IS EXPECTED TO MAINTAIN A MOIST CORE
CAUSING A STAGNANT INTENSITY OF 45 KTS. AFTER TAU 12 THE VWS AND
DRY AIR ENTRAINMENT WILL ONLY INCREASE, CAUSING THE SYSTEM TO BEGIN
A WEAKENING TREND. BY TAU 36, 02A IS FORECAST TO WEAKEN BELOW
TROPICAL STORM STRENGTH AS THE CORE OF THE SYSTEM IS QUICKLY TAKEN
OVER BY EXTENSIVE DRY AIR. 

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN VERY GOOD
AGREEMENT WITH A MERE 40 NM CROSS-TRACK SPREAD BETWEEN CONSENSUS
MEMBERS AT TAU 36. THEREFORE, THE JTWC TRACK FORECAST IS PLACED
WITH HIGH CONFIDENCE. INTENSITY GUIDANCE IS ALSO IN VERY GOOD
AGREEMENT ON A WEAKENING TREND AFTER TAU 12 WITH DISSIPATION NEAR
TAU 36. AS A RESULT, THE JTWC INTENSITY FORECAST IS ALSO PLACED
WITH HIGH CONFIDENCE.

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