WDPN31 PGTW 060300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 18W (EIGHTEEN) 
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 10.5N 127.5E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 453 NM EAST-SOUTHEAST OF MANILA,
PHILIPPINES
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 11 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A
CONSOLIDATING SYSTEM WITH PERSISTENT FLARING CONVECTION AND
FORMATIVE BANDS WRAPPING INTO AN OBSCURED LOW LEVEL CIRCULATION
(LLC). THE INITIAL POSITION AND INTENSITY ARE PLACED WITH HIGH
CONFIDENCE BASED ON A 052126Z SCATTEROMETRY BULLSEYE PASS SHOWING
30-KT WIND BARBS ALONG THE SOUTHERN ARC OF THE LLC. THE INITIAL
INTENSITY IS HELD ON THE HIGHER END OF AGENCY DVORAK ESTIMATES.
ANALYSIS INDICATES A MARGINALLY FAVORABLE ENVIRONMENT WITH WARM
SST, LOW VWS, AND DUAL OUTFLOW OFFSET BY STRONG SUBSIDENCE FROM A
TUTT CELL 5 DEGREES TO THE NORTH. THE CYCLONE IS TRACKING ALONG THE
SOUTHWESTERN PERIPHERY OF THE STR TO THE NORTHEAST.

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

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE
NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T1.0 - 25 KTS
   KNES: T2.0 - 30 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 0-5 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: TD 18W IS EXPECTED TO CONTINUE GENERALLY ON
ITS CURRENT TRACK FOR THE ENTIRETY OF THE FORECAST, MAKING LANDFALL
NEAR BALER, PHILIPPINES AROUND TAU 84, CROSS LUZON, THEN EXIT INTO
THE SOUTH CHINA SEA (SCS) JUST BEFORE TAU 96. THE MARGINALLY
FAVORABLE ENVIRONMENT, TEMPERED FURTHER BY OUTFLOW FROM ANOTHER
CYCLONE WEST OF GUAM THAT IS EXPECTED TO BE DOMINANT, WILL FUEL
WEAK INTENSIFICATION TO A PEAK OF 45KTS BY TAU 72; AFTERWARD, LAND
INTERACTION, MOSTLY, WILL REDUCE IT TO 40 KTS AS IT EXITS INTO THE 
SCS. THE WARM WATER MAY AID TO RE-INTENSIFY IT BACK TO 45 KTS BY TAU 
120.

MODEL DISCUSSION: THE HANDFUL OF AVAILABLE NUMERICAL MODELS ARE IN
GOOD AGREEMENT BUT GIVEN THE UNCERTAINTIES ASSOCIATED WITH A
DEVELOPING CYCLONE COUPLED WITH THE VARIABILITY IN THE IMPACT OF
THE AFOREMENTIONED SECONDARY CYCLONE, THERE IS LOW CONFIDENCE IN
THE INITIAL JTWC FORECAST TRACK AND INTENSITIES.

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