WDPN31 PGTW 142100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 01W (ONE) WARNING 
NR 
002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 9.5N 130.2E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 620 NM EAST-SOUTHEAST OF MANILA,
PHILIPPINES
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) REVEALS THAT
TROPICAL DEPRESSION (TD) 01W HAS BECOME SLIGHTLY BETTER ORGANIZED
OVER THE PAST 6 HOURS, WITH PERSISTENT DEEP CONVECTION SLIGHTLY
DISPLACED FROM THE CENTER. THE UPPER-LEVEL ENVIRONMENT HAS IMPROVED, 
WITH WIND SHEAR NOW ESTIMATED TO BE AROUND 15 KNOTS OUT OF THE EAST. 
THE SYSTEM REMAINS RELATIVELY DISORGANIZED HOWEVER, WITH A WEDGE OF 
DRY AIR ALONG THE SOUTHEASTERN FLANK HINDERING DEVELOPMENT. THE 
ENVIRONMENT IS MARGINALLY FAVORABLE, CHARACTERIZED BY WARM (28-29 C) 
SEA SURFACE TEMPERATURES AND STRONG POLEWARD OUTFLOW, AND LOW TO 
MODERATE EASTERLY VERTICAL WIND SHEAR. THE INITIAL POSITION IS PLACED 
WITH MEDIUM CONFIDENCE BASED ON LOW-LEVEL CLOUD WRAPPING PRESENT IN 
ANIMATED MSI AND THE PGTW POSITION FIX. THE POSITION IS SUPPORTED BY 
A 141706Z AMSR2 37GHZ MICROWAVE IMAGE THAT INDICATES THE CENTER IS 
OBSCURED BY THE DEEP CONVECTION. THE INITIAL INTENSITY OF 25 KTS IS 
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE CIMSS INTENSITY 
ESTIMATES AND THE AGENCY OBJECTIVE DVORAK FIXES LISTED BELOW.

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

CURRENT STEERING MECHANISM: A DEEP-LAYER SUBTROPICAL RIDGE (STR)
CENTERED TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T1.5 - 25 KTS
   CIMSS SATCON: 30 KTS AT 141800Z
   CIMSS ADT: 30 KTS AT 141930Z
   CIMSS AIDT: 29 KTS AT 141930Z
   CIMSS D-MINT: 26 KTS AT 141706Z
   CIMSS D-PRINT: 26 KTS AT 141930Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 25-30 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD

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: 01W WILL CONTINUE TO TRACK NORTHWESTWARD FOR
THE NEXT 48 HOURS WHILE IT REMAINS UNDER THE STEERING INFLUENCE OF
THE STR DIRECTLY TO ITS NORTHEAST. BETWEEN TAU 48-120, 01W WILL
CURVE TO THE NORTHEAST AS IT TRACKS AROUND THE RIDGE AXIS. 01W WILL
SLOW SLIGHTLY AS IT ROUNDS THE RIDGE AXIS AROUND TAU 72, INFLUENCED
BY A BUILDING RIDGE OVER SOUTHEAST ASIA. TD 01W WILL INTENSIFY OVER 
THE NEXT 48 HOURS, AS MODERATE EASTERLY SHEAR IS OFFSET BY ROBUST 
POLEWARD OUTFLOW ALOFT. AFTER TAU 48, SHEAR IS EXPECTED TO INCREASE 
WHILE POLEWARD OUTFLOW DECREASES AND DRY AIR RAPIDLY MOVES IN FROM 
THE NORTHWEST, INDUCING A TERMINAL WEAKENING TREND FOR THE REMAINDER 
OF THE FORECAST. 

MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT FROM TAU 0-72, SUPPORTING THE NEAR-TERM JTWC TRACK
FORECAST WITH MEDIUM CONFIDENCE. THE MODEL ENVELOPE WIDENS NEAR TAU
72 AS MODELS DISAGREE ON THE SPEED OF ADVANCE AND ANGLE OF THE
RECURVE OCCURRING IN THE LATER FORECAST. AS A RESULT, THE JTWC TRACK
FORECAST FROM TAU 72-120 IS PLACED WITH LOW CONFIDENCE. RELIABLE
INTENSITY AIDS ARE IN GOOD AGREEMENT THAT 01W WILL SLOWLY INTENSIFY
TO AROUND 45 KTS BEFORE QUICKLY WEAKENING FOR THE LATTER HALF OF
THE FORECAST. THE JTWC INTENSITY FORECAST IS ASSESSED WITH OVERALL
MEDIUM CONFIDENCE.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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