WDPN32 PGTW 041500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 32W (THIRTYTWO) 
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 8.9N 141.7E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 216 NM EAST OF YAP
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS
DEVELOPING DEEP CONVECTIVE BANDING NEARLY FULLY OBSCURING THE
LOW-LEVEL CIRCULATION CENTER (LLCC) ASSOCIATED WITH TROPICAL
DEPRESSION (TD) 32W. THE INITIAL POSITION IS PLACED WITH MEDIUM
CONFIDENCE BASED ON A 041202Z METOP-B ASCAT PASS SHOWING THE
WESTERN SEMICIRCLE OF THE LLCC. ANALYSIS CONFIDENCE IS DECREASED
DUE TO UNCERTAINTY ASSOCIATED WITH THE LACK OF RECENT DATA
COVERING THE EASTERN EXTENT OF THE CIRCULATION. THE INITIAL
INTENSITY OF 30 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE
AFOREMENTIONED PARTIAL ASCAT PASS, PERSISTENT CONVECTION AND AGENCY
DVORAK AND OBJECTIVE ESTIMATES LISTED BELOW. ENVIRONMENTAL
CONDITIONS REMAIN CONDUCIVE TO DEVELOPMENT, INCLUDING WARM (30-31
C) SEA SURFACE TEMPERATURES (SST), LOW VERTICAL WIND SHEAR (VWS) OF
5-10 KTS, GOOD EQUATORWARD OUTFLOW CHANNEL, COUNTERACTED ONLY BY
MODERATELY DRY AIR TO THE NORTH AND NORTHWEST.

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

CURRENT STEERING MECHANISM: WESTERN EXTENSION OF A SUBTROPICAL
RIDGE (STR) CENTERED TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T1.0 - 25 KTS
   KNES: T1.0 - 25 KTS
   CIMSS ADT: 28 KTS AT 041130Z
   CIMSS AIDT: 30 KTS AT 041130Z
   CIMSS D-MINT: 22 KTS AT 041018Z
   CIMSS D-PRINT: 22 KTS AT 041310Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: HIGH
   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: TD 32W IS EXPECTED TO CONTINUE CONSOLIDATING
AND INTENSIFYING OVER THE FORECAST PERIOD AS IT TRACKS TOWARD THE
NORTHERN PHILIPPINES. THE SYSTEM IS INITIALLY FORECAST TO REMAIN IN
A WEAK STEERING ENVIRONMENT DOMINATED BY A NORTHEASTERLY LOW-LEVEL
FLOW NORTH OF THE LLCC AND A WESTWARD EXTENSION OF A STR CENTERED TO 
THE NORTHEAST. THEREFORE, OVER THE NEXT 12 HOURS, TD 32W IS FORECAST 
TO TRACK VERY SLOWLY, OR EVEN REMAIN QUASI-STATIONARY, WHILE FURTHER 
CONSOLIDATING INTO A MORE COMPACT TROPICAL STORM. SIMULTANEOUSLY, THE 
EXTENSION OF THE STR IS EXPECTED TO RETROGRADE EASTWARD, ALLOWING THE 
WELL-STRUCTURED SYSTEM TO TURN NORTHWESTWARD AROUND TAU 24-36. 
AFTERWARD, THE SYSTEM WILL TRACK ALONG THE SOUTHWESTERN PERIPHERY OF 
THE RIDGE. IN TERMS OF INTENSITY, TD 32W IS EXPECTED TO REACH 
TYPHOON-LEVEL WIND MAXIMA WITHIN THE NEXT 36 HOURS AND CONTINUE 
STRENGTHENING AS IT REMAINS IN A FAVORABLE ENVIRONMENT, PROVIDED
THE VORTEX BECOMES FULLY SHIELDED FROM ENTRAINING DRY AIR.

MODEL DISCUSSION: TRACK FORECAST IS ESPECIALLY CHALLENGING AT THE 
MOMENT WITH THE SYSTEM DEVELOPING AND REMAINING IN A WEAK STEERING 
ENVIRONMENT. ADDITIONALLY, NUMERICAL MODELS DO NOT AGREE ON THE
INITIAL POSITION, WITH DETERMINISTIC GFS PERSISTENTLY INDICATING A
MORE EAST-SOUTHEASTWARD LOCATION, AS WITNESSED BY A STRONG 850 MB
VORTICITY SIGNATURE, EXTENDING ALL THE WAY TO THE 500 MB LEVEL. AS A
RESULT, THE CURRENT CROSS-TRACK SPREAD AT TAU 24 IS OVER 250 NM,
PRIMARILY DUE TO THE GFS TRACK POSITIONED 150 NM TO THE
EAST-NORTHEAST OF THE MULTI-MODEL CONSENSUS. THEREFORE, JTWC
OFFICIAL TRACK FORECAST IS LAID WITH JUST LOW CONFIDENCE IN THE
SHORT TERM. MEDIUM- TO LONG-TERM TRACK GUIDANCE HAS IMPROVED
SLIGHTLY AS MAJORITY OF THE CONSENSUS MEMBERS EXHIBIT GOOD AGREEMENT 
ON A WEST-NORTHWESTWARD TRACK, FOLLOWING THE TURN AROUND TAU 48. 
ECMWF STILL INITIATES THE SYSTEM MORE ACCURATELY, SUPPORTED BY 
SCATTEROMETRY AND SATELLITE IMAGERY. THEREFORE, THE JTWC TRACK 
FORECAST CLOSELY FOLLOWS THE MULTI-MODEL CONSENSUS, LEANING TOWARD 
SOLUTIONS FROM ECMWF AND ECENS. INTENSITY GUIDANCE SHOWS FAIR 
AGREEMENT, WITH ALL AVAILABLE DATA INDICATING STEADY INTENSIFICATION, 
WITH SEVERAL RAPID INTENSIFICATION (RI) SIGNALS PRESENT (RIDE, RICN, 
FRIA). THE JTWC INTENSITY FORECAST FOLLOWS THE MULTI-MODEL CONSENSUS 
AND IS ASSESSED WITH MEDIUM CONFIDENCE THROUGHOUT THE FORECAST 
PERIOD, AS THE ASSESSMENT SPREAD INCREASES AFTER TAU 48.

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