WDPN32 PGTW 041500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (MAYSAK) WARNING NR 
012//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.3N 107.8E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 108 NM EAST OF HANOI, VIETNAM
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
CONSOLIDATING CIRCULATION DEFINED BY DEEP CONVECTION WRAPPING OVER
THE SOUTHERN AND EASTERN SIDE OF THE LOW-LEVEL CIRCULATION CENTER
(LLCC). A 041139Z SSMIS PASS SHOWCASES THE CURVATURE OF THE
CONVECTION. THE SYSTEM HAS EXCELLENT EQUATORWARD EXHAUST, ALTHOUGH
THE OUTFLOW IS RESTRICTED ON THE POLEWARD SIDE DUE TO THE PRESENCE
OF MODERATE VERTICAL WIND SHEAR (VWS). THE ENVIRONMENT HAS BECOME
UNFAVORABLE BECAUSE THE EFFECTS OF HIGH SEA SURFACE TEMPERATURE AND
RICH DEEP-LAYER MOISTURE ARE MORE THAN OFFSET BY LAND INTERACTION
AND MODERATE VWS. THE INITIAL POSITION IS ASSESSED WITH MEDIUM
CONFIDENCE BASED ON RADAR IMAGERY AND THE CURL OF THE CONVECTION ON
SATELLITE IMAGERY. GIVEN THE SLIGHT IMPROVEMENT IN THE CONVECTIVE
SIGNATURE, THE INITIAL INTENSITY IS RAISED TO 50 KTS WITH MEDIUM
CONFIDENCE BASED ON A BLEND OF THE T3.0-3.5 FROM PGTW, KNES, RJTD,
AND DEMS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A MID-LEVEL
SUBTROPICAL RIDGE (STR) CENTERED NEAR THE RYUKYU ISLANDS

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T3.5 - 55 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T3.5 - 55 KTS
   DEMS: T3.0 - 45 KTS
   CIMSS SATCON: 50 KTS AT 040840Z
   CIMSS ADT: 53 KTS AT 041200Z
   CIMSS AIDT: 49 KTS AT 041200Z
   CIMSS D-MINT: 47 KTS AT 041138Z
   CIMSS D-PRINT: 44 KTS AT 041200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 20-25 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD
   OTHER FACTORS: LAND INTERACTION

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: THE MID-LEVEL STR TO THE EAST IS STEERING
TROPICAL STORM 10W POLEWARD, WHICH IS ON THE VERGE OF MAKING
LANDFALL ALONG THE BORDER OF CHINA AND VIETNAM. THE SYSTEM WILL
TURN TOWARDS THE NORTHEAST AT TAU 12 AND MAINTAIN THAT MOTION UNTIL
DISSIPATION OCCURS AT TAU 36. TS MAYSAK HAS RUN OUT OF TIME TO
INTENSIFY, GIVEN THAT THE CIRCULATION WILL IMMINENTLY LOSE ITS
SOURCE OF ENERGY FROM THE WARM WATERS OF THE GULF OF TONKIN. STEADY
TO RAPID DECAY WILL COMMENCE DUE TO THE FRICTIONAL AND DRYING
EFFECTS OF LAND AND RESULT IN DISSIPATION BY TAU 36.

MODEL DISCUSSION: THE MODEL TRACKERS ARE TIGHTLY PACKED WITHIN AN
UNCERTAINTY ENVELOPE SPANNING 40 NM AT TAU 24. NAVGEM IS THE ONLY
OUTLIER, WHICH TAKES THE SYSTEM STRAIGHT NORTH RATHER THAN THE
NORTHEAST DIRECTION DEPICTED BY ALL OTHER MODELS. THE JTWC FORECAST
TRACK IS LAID WITHIN THE TIGHT GROUPING THROUGH TAU 36 WITH HIGH
CONFIDENCE. HAFS-A, COAMPS-TC, AND GFS PREDICT THAT STEADY TO RAPID
WEAKENING WILL OCCUR IMMINENTLY. THE JTWC INTENSITY FORECAST
CONCURS WITH THE INTENSITY GUIDANCE AND DISSIPATES TS MAYSAK BY TAU
36 WITH HIGH CONFIDENCE.

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