WDPN31 PGTW 172100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 23W (TWENTYTHREE) 
WARNING NR 007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 18.8N 119.9E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 383 NM EAST-SOUTHEAST OF HONG KONG
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A WEAK
LOW LEVEL CIRCULATION (LLCC) JUST OFF THE COAST OF LUZON,
ASSOCIATED WITH TROPICAL DEPRESSION (TD) 23W. THE SYSTEM IS
CURRENTLY TRACKING NORTHWESTWARD, WITH THE LLCC OBSCURED BY
CONVECTIVE ACTIVITY. THE INITIAL POSITION IS PLACED WITH MEDIUM
CONFIDENCE BASED ON THE AVAILABLE INFRARED IMAGERY, AS WELL AS AN
EXTRAPOLATION FROM A PREVIOUSLY ASSESSED SCATTEROMETRY PASSES OVER
THE CENTER OF THE SYSTEM AS IT RE-EMERGED OVER THE SOUTH CHINA SEA.
AGENCY FIXES ARE IN GOOD AGREEMENT WITH THE CURRENT POSITION.
INITIAL INTENSITY OF 25 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED AGENCY AND OBJECTIVE INTENSITY ESTIMATES LISTED BELOW.

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: T1.5 - 25 KTS
   CIMSS SATCON: 40 KTS AT 171755Z
   CIMSS ADT: 33 KTS AT 171730Z
   CIMSS AIDT: 33 KTS AT 171730Z
   CIMSS D-MINT: 25 KTS AT 171755Z
   CIMSS D-PRINT: 23 KTS AT 171930Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE 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: A SHORTWAVE TROUGH PASSING TO THE NORTH WILL
GIVE TD 23W ROOM TO CONTINUE TRACKING NORTHWESTWARD OVER THE NEXT
48 HOURS. THE STRENGTHENING OF INFLUENCE FROM THE STR AFTERWARD
WILL PUT THE SYSTEM ON A WESTWARD TRACK AS IT APPROACHES LAND.
CONDITIONS CONTINUE TO LOOK MARGINALLY FAVORABLE WITH WARM (29-30
C) SEA SURFACE TEMPERATURES (SST), LOW (10-15 KTS) VERTICAL WIND
SHEAR (VWS) AND MODERATE POLEWARD OUTFLOW. WHILE TD 23W IS NOT
EXPECTED TO REDEVELOP INTO A WELL-DEFINED FEATURE, IT IS EXPECTED
TO REACH TROPICAL STORM INTENSITY, WITHIN THE NEXT 12-24 HOURS.
LANDFALL IS EXPECTED TO OCCUR JUST NORTHEAST OF HONG KONG, WITHIN
36-48 HOURS, AND TD 23W IS FORECAST TO DISSIPATE OVER LAND BY THE
END OF THE CURRENT FORECAST PERIOD.

MODEL DISCUSSION: MODEL GUIDANCE REMAINS IN GOOD AGREEMENT ON A
CONTINUED NORTHWESTWARD TRACK AND A PEAK INTENSITY OF 35-45 KTS.
CROSS-TRACK SPREAD AT TAU 12 IS MEASURED AT 90 NM AND EXPANDS TO
OVER 200 NM AT THE TIME OF LANDFALL, CONTRIBUTING TO INCREASED
UNCERTAINTY, PARTICULARLY IN REGARD TO THE LANDFALL LOCATION.
INTENSITY GUIDANCE REMAINS GOOD WITH MINIMAL VARIATION AMONG THE
MULTI-MODEL CONSENSUS MEMBERS. ALL MODELS INDICATE A POTENTIAL FOR
SLIGHT INTENSIFICATION IN THE NEAR FUTURE, FOLLOWED BY RAPID
WEAKENING BEGINNING AROUND TAU 24-36, ASSOCIATED WITH THE TIMELINE
OF THE LANDFALL.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   INTENSITY 00-72 HR: HIGH//
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