WDPN31 PGTW 302100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 33W (KOTO) WARNING NR 
025//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.9N 111.8E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 213 NM EAST-SOUTHEAST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A VERY
RAGGED, AND ASYMMETRIC 33W. BASED ON THE EIR AND A 301618Z GMI
PASS, THE VORTEX HAS BEEN COMPLETELY DECOUPLED AND IS RAPIDLY
SHALLOWING OUT AS IT IS OVERTOPPED BY A VERY DRY AIR MASS PUSHING
IN FROM THE NORTHWEST. HAFS-A MODEL CROSS-SECTIONS INDICATE THE
VORTEX LIKELY IS NOW RESTRICTED BELOW 600MB, AND THE EIR SUGGESTS
ITS PROBABLY EVEN SHALLOWER THAN THAT. ANIMATED WATER VAPOR IMAGERY
SUGGESTS THE RELATIVELY DEEP, DRY AIR MASS EXTENDS FAR TO THE
NORTHWEST, WITH ADDITIONAL SURGES OF EVEN DRIER AIR LIKELY TO MOVE
IN OVER THE NEXT DAY OR SO. THE INITIAL POSITION IS ASSESSED WITH
HIGH CONFIDENCE BASED ON THE PARTIALLY EXPOSED LOW LEVEL
CIRCULATION CENTER (LLCC) IN THE EIR AND EXTRAPOLATION OF A WEAK
LOW EMISSIVITY REGION (LER) EVIDENT IN THE MICROWAVE IMAGERY
DISCUSSED ABOVE. THE INITIAL INTENSITY IS ASSESSED WITH HIGH
CONFIDENCE, BASED ON MULTIPLE AGENCY DVORAK FINAL-T NUMBERS BETWEEN
T2.0-T2.5, AND EXTRAPOLATION OF AN EARLIER ASCAT PASS WHICH
INDICATED MAXIMUM WINDS OF 30-35 KNOTS. THE ENVIRONMENT HAS CLEARLY
DETERIORATED, FASTER THAN ANTICIPATED. SHEAR REMAINS RELATIVEY LOW,
BUT THE COMBINATION OF MODEST SSTS, WEAK OUTFLOW ALOFT AND THE DRY
MID-LEVEL AIR HAVE DEALT 33W A CRUSHING BLOW.

INITIAL WIND RADII BASIS: SAR DATA 

CURRENT STEERING MECHANISM: COMPETING STEERING PATTERN.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T3.0 - 45 KTS
   DEMS: T3.0 - 45 KTS
   CIMSS SATCON: 45 KTS AT 301811Z
   CIMSS ADT: 43 KTS AT 301730Z
   CIMSS AIDT: 35 KTS AT 301730Z
   CIMSS D-MINT: 39 KTS AT 301811Z
   CIMSS D-PRINT: 32 KTS AT 301830Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 5-10 KTS
   SST: 25-27 CELSIUS
   OUTFLOW: WEAK RADIAL
   OTHER FACTORS: DRY MID-LEVEL AIR MOVING IN FROM THE NORTHWEST.  

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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: TS 33W HAS CONTINUED TO TRACK SLOWLY TOWARDS
THE NORTHWEST DURING THE OVERNIGHT HOURS, ALONG THE WESTERN SIDE OF
A BUILDING RIDGE OVER LUZON. THE RIDGE IS RAPIDLY BUILDING
NORTHWESTWARD AND WILL MEET UP AND MERGE WITH A RIDGE CENTERED OVER
SOUTHERN MYANMAR WITHIN THE NEXT 12 HOURS AT MOST. HENCE, TS 33W
HAS LIKELY REACHED ITS NORTHERNMOST POINT, OR IF IT HAS NOT, IT
MOST CERTAINLY WILL IN THE NEAR-TERM. UPON REACHING THE INFLECTION
POINT, TS 33W WILL VERY QUICKLY TURN SOUTHWESTWARD, ALONG THE
EASTERN FLANK OF THE RIDGE OVER INDOCHINA, CONTINUING ALONG THIS
TRAJECTORY THROUGH THE REMAINDER OF THE FORECAST PERIOD. WHILE
THERE IS A GOOD AMOUNT OF UNCERTAINTY IN THE EXACT TRACK, THE
CURRENT FORECAST CALLS FOR THE CENTER TO REMAIN OFFSHORE THROUGH
THE FORECAST PERIOD. HAVING BEEN SMOTHERED BY DRY AIR ALOFT,
ACCOMPANIED BY WEAK TO NON-EXISTENT OUTFLOW ALOFT, THE SYSTEM WILL
SLOWLY SPIN DOWN OVER THE DURATION OF THE FORECAST PERIOD, WITH TS
33W DISSIPATING JUST OFFSHORE OF SOUTHEASTERN VIETNAM BY TAU 72. 

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE, WITH THE EXCEPTION
OF NAVGEM AND JGSM, IS IN RELATIVELY GOOD AGREEMENT, INDICATING A
SHARP TURN SOUTHWESTWARD WITHIN THE NEXT 12 HOURS OR SO, WHICH
CONTINUES THROUGH THE REMAINDER OF THE FORECAST PERIOD. CROSS- AND
ALONG-TRACK SPREAD IS LESS THAN YESTERDAY, WITH ALL MODELS TRENDING
TOWARDS THE GDM MEAN WHICH HAS BEEN, AND REMAINS, CONSISTENTLY
OFFSHORE THROUGH THE FORECAST PERIOD. THE JTWC FORECAST IS
POSITIONED NEAR THE EMCWF DETERMINISTIC TRACKER, JUST WEST OF THE
GDM TRACKER, WITH MEDIUM CONFIDENCE. INTENSITY GUIDANCE IS IN GOOD
AGREEMENT ON A SLOW BUT STEADY WEAKENING TREND THROUGH DISSIPATION,
LENDING HIGH CONFIDENCE TO THE JTWC FORECAST. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   INTENSITY 00-72 HR: HIGH//
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