WDPN31 PGTW 111500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 01W (WUTIP) WARNING 
NR 005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.5N 111.5E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 187 NM EAST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS DEEP
CONVECTION BUILDING SOUTHWEST OF A PARTIALLY OBSCURED LOW-LEVEL
CIRCULATION CENTER. DIVERGENT UPPER-LEVEL OUTFLOW SOUTHWESTWARD IS
IDENTIFIABLE ON WATER VAPOR IMAGERY. DISTINCT CLOUD BANDS ARE
APPARENT IN CLEAR AIR TO THE NORTHWEST, BUT THE TILTED AND BROAD 
NATURE OF THE CIRCULATION PROVIDES A CHALLENGE IN IDENTIFYING THE
LOW-LEVEL CIRCULATION CENTER ON EIR. THE INITIAL POSITION IS PLACED
WITH LOW CONFIDENCE BASED ON THE AFOREMENTIONED ANIMATED EIR AND A
111129Z F-16 SSMIS 91GHZ MICROWAVE IMAGE REVEALING THE BROAD
CONVECTIVE BANDS IN THE WESTERN PERIPHERY OF THE SYSTEM. THE
INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH LOW CONFIDENCE BASED
ON THE AGENCY AND OBJECTIVE FIXES LISTED BELOW.

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

CURRENT STEERING MECHANISM: A SUBTROPICAL RIDGE TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.0 - 30 KTS
   KNES: T1.5 - 25 KTS
   CIMSS ADT: 32 KTS AT 111130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE WESTWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   INITIAL INTENSITY: LOW
   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: TROPICAL DEPRESSION (TD) 01W IS FORECAST TO
TRACK NORTHWESTWARD ON THE SOUTHERN PERIPHERY OF A SUBTROPICAL
RIDGE TO THE NORTHEAST. THE TRACK SPEED WILL SLOW AS THE SYSTEM
APPROACHES THE RIDGE AXIS AT TAU 48. A DEEP-LAYER TROUGH WILL BEGIN
TO INTERACT WITH TD 01W AFTER TAU 72, RESULTING IN SHALLOWING OF
THE VORTEX AND AN INCREASE IN TRACK SPEED. THE SYSTEM WILL CONTINUE
TO COMBAT HIGH VERTICAL WIND SHEAR INTRODUCED FROM A TROPICAL UPPER
TROPOSPHERIC TROUGH (TUTT) CELL TO THE NORTHWEST, BUT IS EXPECTED
TO FILL WITHIN THE NEXT 12 HOURS. BY TAU 24, AN UPPER-LEVEL
SHORTWAVE TROUGH WILL ALLOW FOR A POLEWARD OUTFLOW CHANNEL AND A
MORE FAVORABLE UPPER-LEVEL ENVIRONMENT FOR DEVELOPMENT. TD 01W WILL
CONTINUE TO INTENSIFY TO A PEAK OF 50KTS BY TAU 36, AT WHICH TIME
TOPOGRAPHIC INTERACTION WITH HAINAN ISLAND WILL INITIATE A
WEAKENING TREND. THE SYSTEM WILL CONTINUE TO WEAKEN AS IT PASSES
OVER THE GULF ON TONKIN, AND CONTINUE TO MAKE LANDFALL IN MAINLAND
CHINA BETWEEN TAU 48-72. THE SYSTEM WILL DISSIPATE BY TAU 96.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN BETTER
AGREEMENT THAN PREVIOUSLY REPRESENTED IN EARLIER MODEL
INITIALIZATIONS, WITH A CLOSER TRACK SPREAD BUT STILL CONTINUES TO
HAVE A LARGE ALONG TRACK SPREAD. THIS IS DUE TO DIFFERENT
INTERPRETATIONS OF HOW STRONGLY AN UPPER-LEVEL TROUGH WILL INTERACT
WITH TD 01W, AND WHETHER THE INTERACTION WILL BEGIN BY TAU 48 OR
AFTER TAU 72. THE INTENSITY GUIDANCE IS IN MODERATE AGREEMENT WITH
A SPREAD OF PEAK INTENSITIES BETWEEN 40-60KTS. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
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