WDPN31 PGTW 052100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 07W (SEVEN) 
WARNING NR 005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.6N 120.3E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 220 NM SOUTH-SOUTHWEST OF TAIPEI, TAIWAN
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 17 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY REVEALS
LOW-LEVEL CLOUDS WRAPPING UNDER FLARING CONVECTION LOCATED OVER THE
WEAKLY-DEFINED LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL
POSITION IS BASED ON LOW CLOUD TRACING IN THE AFOREMENTIONED EIR
IMAGERY AND IS LOCATED NEAR THE PGTW, RJTD, AND KNES FIXES. A
051739Z AMSR2 89 GHZ MICROWAVE IMAGE DEPICTS A LINEAR AREA OF DEEP
CONVECTION OVER THE WESTERN SEMICIRCLE OF THE LLCC, FURTHER
SUPPORTING THE INITIAL POSITION. THE INITIAL INTENSITY IS SET WITH
HIGH CONFIDENCE BASED ON A 051343Z ASCAT-C BULLESYE IMAGE SHOWING
30KT WINDS IN ALL QUADRANTS EXCEPT THE SOUTHERN QUADRANT.
ADDITIONALLY, THE 30KT INITIAL INTENSITY IS IN GOOD AGREEMENT WITH
THE ADT INTENSITY ESTIMATE.

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

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR)
POSITIONED TO THE NORTH AND NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   KNES: T2.0 - 30 KTS
   CIMSS ADT: 33 KTS AT 051740Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE WESTWARD

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 07W IS EXPECTED TO CONTINUE TRACKING
NORTHWESTWARD THROUGH TAU 12 UNDER THE STEERING INFLUENCE OF A
SUBTROPICAL RIDGE (STR) TO THE NORTHEAST. SHORTLY AFTER TAU 12, TD
07W IS FORECAST TO MAKE LANDFALL ALONG SOUTHEAST CHINA WHERE IT
WILL THEN TURN TO A NORTH-NORTHWESTWARD TRACK THROUGH TAU 36. DUE
TO THE CURRENT MARGINALLY FAVORABLE CONDITIONS, TD 07W SHOULD
MAINTAIN ITS CURRENT INTENSITY THROUGH TAU 12. HOWEVER, AFTER TAU
12, INCREASING VERTICAL WIND SHEAR (GREATER THAN 25 KTS) AND
FRICTIONAL LAND EFFECTS (AFTER LANDFALL) WILL QUICKLY WEAKEN THE
SYSTEM AS IT MOVES INLAND. DISSIPATION IS EXPECTED BY TAU 36, IF
NOT SOONER. 


MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT AS
THE SYSTEM APPROACHES THE COAST, REACHING 85 NM SPREAD BY TAU 12.
AFTERWARDS, THE MODELS BEGIN TO DIVERGE AS THE SYSTEM WEAKENS OVER
LAND. OVERALL, THERE IS MEDIUM CONFIDENCE IN THE TRACK FORECAST.
THERE IS ALSO MEDIUM CONFIDENCE IN THE INTENSITY FORECAST AS THERE
IS SOME UNCERTAINTY IN THE FORECAST INTENSITY NEAR TAU 12. AS VWS
INCREASES, THE SYSTEM COULD WEAKEN MORE RAPIDLY AS IT PROGRESSES
NORTHWESTWARD, REACHING 25KTS BY TAU 12. HOWEVER, BASED ON THE
CURRENT OVERHEAD CONVECTION, THE FORECAST HOLDS INTENSITY STEADY
OVER THE NEXT 12 HOURS WHICH IS IN LINE WITH THE JTWC INTENSITY
CONSENSUS GUIDANCE. 

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