WDPN32 PGTW 291500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 34W (THIRTYFOUR) 
WARNING NR 011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 5.2N 107.5E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 339 NM SOUTH OF HO CHI MINH CITY, VIETNA
   MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
DEPRESSION 34W WITH A HIGHLY COMPACT, PARTIALLY EXPOSED LOW-LEVEL
CIRCULATION CENTER (LLCC) AND FLARING CONVECTION SHEARED OFF TO THE
WEST. A 291328Z METOP-B ASCAT PASS REVEALED THE VERY SMALL, YET
DEFINED, CIRCULATION WITH 25-30 KNOT WINDS THROUGHOUT THE EASTERN
SEMICIRCLE. ENVIRONMENTAL ANALYSIS INDICATES THAT 34W IS IN A
MARGINAL ENVIRONMENT CHARACTERIZED BY WEAK OUTFLOW ALOFT, MODERATE
TO HIGH (20-25 KTS) EASTERLY VERTICAL WIND SHEAR, AND WARM (27-28
C) SEA SURFACE TEMPERATURES. THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE BASED ON THE PARTIALLY EXPOSED LLCC IN ANIMATED EIR
IMAGERY. THE INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH HIGH
CONFIDENCE BASED ON THE AFOREMENTIONED METOP-B ASCAT PASS.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: NORTHWESTERN PERIPHERY OF A NEAR
EQUATORIAL RIDGE (NER) CENTERED OVER BORNEO. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   KNES: T2.0 - 30 KTS
   DEMS: T2.5 - 35 KTS
   CIMSS ADT: 37 KTS AT 291200Z
   CIMSS AIDT: 31 KTS AT 291200Z
   CIMSS D-MINT: 30 KTS AT 290837Z
   CIMSS D-PRINT: 26 KTS AT 291200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 20-25 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: WEAK WESTWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

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

FORECAST DISCUSSION: 34W IS FORECAST TO TRACK NORTHEASTWARD, ALONG
THE NORTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE POSITIONED OVER
BORNEO THROUGHOUT THE FORECAST PERIOD. 34W IS FORECAST TO WEAKEN
OVER THE NEXT 24 HOURS AS EASTERLY SHEAR AND DRY AIR IMPACT THE
VORTEX. THESE TWO FACTORS ARE EXPECTED TO CAUSE 34W TO DISSIPATE
AROUND TAU 24. THE COMPACT NATURE OF 34W MAKES IT MORE SUSCEPTIBLE
TO CHANGES IN THE ENVIRONMENT, POTENTIALLY ALLOWING FOR AN EVEN
EARLIER DISSIPATION. THE PRIMARY FACTOR WILL BE HOW LONG 34W IS
ABLE TO MAINTAIN CONVECTIVE ACTIVITY AS THE SYSTEM IS LIKELY TO
DISSIPATE SOON AFTERWARD.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN MODERATE
AGREEMENT WITH ALL MODELS DEPICTING A NORTHEASTWARD TRACK. HOWEVER,
THERE IS A 130 NM CROSS-TRACK SPREAD AT TAU 24, PRIMARILY CAUSED BY
GALWEM, WHICH TURNS THE VORTEX NORTHWARD AFTER TAU 12. INTENSITY
GUIDANCE GENERALLY AGREES ON WEAKENING FROM TAU 0 TO TAU 24. AFTER
TAU 24, SOME MODELS APPEAR TO REINTENSIFY THE SYSTEM, BUT IN
ACTUALITY, THEY BEGIN TO MERGE THE VORTEX WITH THAT OF TS 33W TO
THE NORTH. 

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