WDPN31 PGTW 072100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 07W (SEVEN) WARNING 
NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 24.1N 149.6E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 241 NM WEST OF MINAMI TORI SHIMA, JAPAN
   MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 10 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A WEAK,
DISORGANIZED, AND FRAGMENTED SYSTEM WITH THE MAIN CONVECTION
SHEARED SOUTHEASTWARD OF AN ILL-DEFINED, ELONGATED, AND PARTIALLY
EXPOSED LOW LEVEL CIRCULATION (LLC), THE INITIAL POSITION IS PLACED
WITH MEDIUM CONFIDENCE BASED ON A RAGGED MICROWAVE LLC IN THE
071542Z AMSR2 IMAGE. THE INITIAL INTENSITY IS ALSO PLACED WITH
MEDIUM CONFIDENCE BASED ON OVERALL ASSESSMENT OF THE WIND FIELD
THAT INDICATES STRONGER WINDS UP TO 35KTS ALONG THE SOUTHEASTERN
PERIPHERY UNDER THE DEEP CONVECTIVE CELLS, AS EVIDENCED IN THE
071540Z GCOM WINDSPEED IMAGE. HOWEVER, THE IMMEDIATE CIRCULATION
AND THE NORTHWEST SEMICIRCLE ARE RELATIVELY WEAK WITH 20KT MAX
WINDS. ANALYSIS INDICATES AN INCREASINGLY FAVORABLE ENVIRONMENT
WITH WARM SST, AND INCREASING VENTILATION ALOFT, ONLY TEMPERED BY
MODERATE VWS AND THE LACK OF LOW LEVEL CONSOLIDATION.

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

CURRENT STEERING MECHANISM: WEAK LOW-LAYER SUBTROPICAL RIDGE TO THE
NORTHEAST. 

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

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TD 07W WILL TURN NORTHWESTWARD THEN WESTWARD
AS THE STR BUILDS. AFTER TAU 36, THE SYSTEM WILL TRACK MORE
NORTHWESTWARD TOWARD YOKOSUKA AS THE STR RECEDES WITH THE APPROACH
OF A MID-LATITUDE TROUGH FROM THE NORTHWEST. DECREASING VWS AND
INCREASING POLEWARD OUTFLOW WILL FUEL A STEADY INTENSIFICATION TO
75KTS BY TAU 120.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT
WITH A GRADUAL SPREAD TO 283NM BY TAU 120. HOWEVER, GIVEN THE
VARIABILITY WITH A DEVELOPING SYSTEM, THERE IS ONLY MEDIUM
CONFIDENCE IN THE JTWC TRACK AND INTENSITY FORECASTS.  

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