WDPN32 PGTW 030900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (MAYSAK) WARNING NR 
007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.6N 109.7E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 125 NM NORTHEAST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A SLOWLY
RECONSOLIDATING SYSTEM WITH VIGOROUS CONVECTION LIMITED TO THE
SOUTHERN SEMICIRCLE. PERSISTENT NORTHEASTERLY SHEAR HAS PREVENTED
THE CONVECTION FROM WRAPPING AROUND THE CENTRAL CORE OVER THE PAST
6 HOURS. ANIMATED RADAR IMAGERY SHOWS TS 10W SLOWLY APPROACHING THE
SOUTHERN COAST OF HAINAN ISLAND WITH PRECIPITATION LIMITED TO THE 
AREA BENEATH THE DEEP CONVECTION. THE INITIAL POSITION IS PLACED WITH 
MEDIUM CONFIDENCE PRIMARILY BASED ON THE CENTER OF ROTATION IN THE 
ANIMATED RADAR IMAGERY. THE INITIAL INTENSITY OF 35 KTS IS ASSESSED 
WITH MEDIUM CONFIDENCE BASED PRIMARILY ON THE AGENCY DVORAK FIXES OF 
T2.0-T2.5, SUPPLEMENTED BY THE CIMSS OBJECTIVE INTENSITY AIDS. 
ENVIRONMENTAL CONDITIONS ARE MARGINAL, WITH WARM SSTS, LOW OHC, 
MODERATE NORTHEASTERLY SHEAR AND MODERATE EQUATORWARD OUTFLOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED SOUTH OF KYUSHU

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T2.0 - 30 KTS
   KNES: T2.5 - 35 KTS
   CIMSS ADT: 49 KTS AT 030600Z
   CIMSS AIDT: 43 KTS AT 030600Z
   CIMSS D-MINT: 35 KTS AT 030559Z
   CIMSS D-PRINT: 39 KTS AT 030600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: LOW

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TROPICAL STORM (TS) 10W (MAYSAK) HAS CONTINUED
TO SLOWLY DRIFT TOWARD THE SOUTHERN COAST OF HAINAN ISLAND OVER THE
PAST 6 HOURS AS IT WORKS TO RECONSOLIDATE. A SOUTHWESTERN EXTENSION
OF THE PRIMARY STEERING RIDGE CENTERED TO THE NORTHEAST IS EXPECTED
TO WEAKEN IMMINENTLY AND OVER THE NEXT 12 HOURS AND INITIATE A 
NORTHWESTWARD TRAJECTORY OVER HAINAN. SHORTLY AFTER TAU 12, 10W WILL 
REEMERGE OVER THE GULF OF TONKIN ON ITS WAY TO A SECOND LANDFALL NEAR 
THE SINO-VIETNAMESE BORDER REGION AROUND TAU 36. AFTER LANDFALL, THE 
TRACK TURNS NORTHEASTWARD AROUND THE RIDGE AXIS AS THE SYSTEM 
DISSIPATES OVER LAND. THE INTENSITY IS FORECAST TO REMAIN STEADY AS 
10W CLIPS THE SOUTHWESTERN EDGE OF HAINAN, THEN BRIEFLY INCREASE TO 
40 KTS AS IT TRANSITS OVER THE GULF OF TONKIN. 

MODEL DISCUSSION: MODEL TRACK GUIDANCE HAS COME INTO MUCH BETTER
AGREEMENT WITH THE LATEST MODEL RUN, WITH THE EXCEPTION OF NAVGEM AS 
AN EASTERN OUTLIER. THE REMAINDER OF GUIDANCE HAS A CROSS-TRACK 
SPREAD OF 45 NM AT TAU 36 WHEN THE SECOND LANDFALL IS EXPECTED TO 
OCCUR. THE JTWC TRACK IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS
WITH MEDIUM CONFIDENCE THROUGHOUT THE FORECAST PERIOD. INTENSITY 
GUIDANCE IS IN GOOD AGREEMENT ABOUT THE PERIOD OF INTENSIFICATION
OVER THE GULF OF TONKIN, REMAINING WITHIN A 10 KT ENVELOPE UNTIL 
RAPID DISSIPATION OCCURS OVER THE MAINLAND. THE JTWC INTENSITY 
FORECAST IS PLACED CLOSE TO THE CONSENSUS WITH MEDIUM CONFIDENCE.

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