WDPN31 PGTW 052100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 02W (PENHA) WARNING NR 
008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 9.3N 125.8E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 425 NM SOUTHEAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
STORM (TS) 02W (PENHA) AS A DETERIORATING CIRCULATION WITH A NOW
BROAD STRUCTURE AND CLOUD TOP TEMPERATURES WARMING RAPIDLY WITHIN
ASSOCIATED DEEP CONVECTION. THE INITIAL POSITION IS PLACED WITH
MEDIUM CONFIDENCE BASED ON ANIMATED EIR IMAGERY OF THE LOW LEVEL
CIRCULATION CENTER (LLCC) COMPLETELY OBSCURED BY THE CENTRAL DENSE
OVERCAST FEATURE, BUT CONSISTENT WITH LOCAL OBSERVATIONS OVER
NORTHERN MINDANAO. THE INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH
MEDIUM CONFIDENCE BASED ON EXTRAPOLATION FROM AN EARLIER 051223Z
METOP-C PARTIAL PASS AND THE OBJECTIVE AND SUBJECTIVE ESTIMATES
LISTED BELOW.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE CENTERED EAST OF THE
PHILIPPINES 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   RJTD: T2.5 - 35 KTS
   CIMSS SATCON: 47 KTS AT 051530Z
   CIMSS AIDT: 43 KTS AT 051530Z
   CIMSS D-MINT: 39 KTS AT 051717Z
   CIMSS D-PRINT: 44 KTS AT 051900Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 25-30 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: TOPOGRAPHICAL INTERACTION WITH PHILIPPINE ISLANDS

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: TS 02W HAS STARTED A NORTHWESTWARD TRACK AS
THE SUBTROPICAL RIDGE OVER THE PACIFIC RETREATS TO THE EAST.
TOPOGRAPHICAL INTERACTION WILL CONTINUE TO DEGRADE THE STRUCTURE OF
THE STORM ALONG WITH COOLER SEA SURFACE TEMPERATURES (26 C TO 27 C)
WITHIN THE SULU SEA, HIGH VERTICAL WIND SHEAR (25-30 KTS), POOR
OUTFLOW, AND SIGNIFICANT DRY AIR ENTRAINMENT FROM THE WEST AND
NORTH. THIS FORECASTED ENVIRONMENT WILL RESULT IN TS 02W BEING
UNABLE TO REGAIN STRONG VERTICAL STRUCTURE WHILE TRANSITING OVER
THE NORTHERN PORTION OF THE SULU SEA. COLD SURGE PUSHING IN FROM
THE NORTH WILL BREAK OPEN WHAT REMAINS OF THE CIRCULATION CAUSING
TS 02W TO DISSIPATE OVER WATER BY TAU 48.

MODEL DISCUSSION: CROSS TRACK SPREAD AMONGST MODEL GUIDANCE IS 60
NM AT TAU 36. NAVGEM FAVORS A NORTHERN TRACK WHILE GFS REFLECTS A
SOUTHERN TRACK PUSHING THE CENTER JUST NORTH OF PALAWAN. THE JTWC
FORECASTED TRACK LIES CLOSE TO THE MULTI MODEL CONSENSUS WITH
MEDIUM CONFIDENCE. INTENSITY SPREAD IS BETWEEN 10-15 KTS THOUGH
MAJORITY OF THE MODELING KEEPS THE SYSTEM AT A WEAK 30-35 KT
INTENSITY AS IT TRACKS ACROSS THE PHILIPPINE ISLANDS. THE JTWC
FORECASTED INTENSITY REFLECTS VALUES CLOSE TO THE MULTI MODEL
CONSENSUS WITH MEDIUM CONFIDENCE. 

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