WDPN31 PGTW 050300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 31W (KALMAEGI) WARNING NR 016//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 11.4N 119.1E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 687 NM EAST-SOUTHEAST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 19 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TYPHOON (TY)
31W RE-INTENSIFYING AS THE SYSTEM CONTINUES TO TRACK NORTHWESTWARD
IN THE SOUTH CHINA SEA. WATER VAPOR IMAGERY REVEALS FAVORABLY
STRONG DIFFLUENT NORTHEASTERLY FLOW WITH DRY AIR TO THE NORTHWEST.
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A
042325Z GPM GMI 37GHZ IMAGE REVEALING A LOW-LEVEL MICROWAVE EYE
FEATURE ALONGSIDE THE AFOREMENTIONED ANIMATED MSI. THE INITIAL
INTENSITY OF 75 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE
AGENCY AND OBJECTIVE FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: A SUBTROPICAL RIDGE TO THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T4.5 - 77 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   CIMSS SATCON: 72 KTS AT 042241Z
   CIMSS D-MINT: 71 KTS AT 042323Z
   CIMSS D-PRINT: 68 KTS AT 050040Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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: TY 31W WILL CONTINUE TO TRACK NORTHWESTWARD
UNDER THE STEERING INFLUENCE OF THE SUBTROPICAL RIDGE TO THE NORTH.
THE SYSTEM IS ANTICIPATED TO MAKE LANDFALL BETWEEN TAU 36-48. THE
ENVIRONMENT WILL REMAIN FAVORABLE FOR INTENSIFICATION TO A PEAK OF
100KTS AT TAU 24 WITH FAVORABLE VERTICAL WIND SHEAR, WARM SEA
SURFACE TEMPERATURES, AND STRONG EQUATORWARD OUTFLOW. HIGH VERTICAL
WIND SHEAR AT TAU 36 WILL RESULT IN WEAKENING SLIGHTLY PRIOR TO
LANDFALL. TOPOGRAPHIC INTERACTION WITH COASTAL VIETNAM CAUSE
FURTHER WEAKENING, ULTIMATELY LEADING TO DISSIPATION BY THE END OF
THE FORECAST PERIOD.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THAT TY 31W WILL REMAIN ON A NORTHWESTWARD TRACK THROUGH THE END OF
THE FORECAST PERIOD. THE CROSS-TRACK SPREAD AT LANDFALL IS 50NM,
CONTRIBUTING HIGH CONFIDENCE TO THE TRACK FORECAST. THE INTENSITY
GUIDANCE IS ALSO IN GOOD AGREEMENT WITH A SPREAD OF PEAK
INTENSITIES BETWEEN 85-115KTS. SEVERAL RAPID INTENSIFICATION AIDS
HAVE TRIGGERED, INDICATING A HIGH PROBABILITY OF RI WITHIN THE NEXT
24 HOURS, AND IS REFLECTED IN THE JTWC PEAK INTENSITY OF 100KTS AT
TAU 24.

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