WDPN31 PGTW 041500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 31W (KALMAEGI) WARNING NR 014//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 10.6N 120.8E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 240 NM SOUTH OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: WESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TYPHOON
(TY) 31W (KALMAEGI) NOW CIRCULATING OVER THE SULU SEA, JUST EAST OF
PALAWAN. CONVECTIVE ACTIVITY HAS FLARED AND EXPANDED OVER THE PAST
6 HOURS AS THE SYSTEM APPEARS TO BE REGAINING SOME STRENGTH. THE
ENVIRONMENT HAS BECOME SLIGHTLY MORE FAVORABLE PRIMARILY DUE TO
VERTICAL WIND SHEAR (VWS) MAGNITUDE DECREASING TO 15-20 KTS.
OUTFLOW REMAINS STRONG AND SEA SURFACE TEMPERATURES RANGE FROM 29 C
TO 30 C. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED
ON THE EIR IMAGERY AND AGENCY FIXES. THE INITIAL INTENSITY OF 70
KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE OBJECTIVE BEST
TRACK AND AGENCY ESTIMATES.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T3.5 - 55 KTS
   DEMS: T4.5 - 77 KTS
   CIMSS ADT: 63 KTS AT 041130Z
   CIMSS AIDT: 63 KTS AT 041130Z
   CIMSS D-MINT: 55 KTS AT 041148Z
   CIMSS D-PRINT: 56 KTS AT 041200Z

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

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TY KALMAEGI WILL NOW TRACK WEST-NORTHWESTWARD
AS STEERING FROM THE SUBTROPICAL RIDGE TO THE NORTH TRANSFERS TO
THE BUILDING RIDGE OVER THE GULF OF TONKIN. THERE IS STILL SOME
TIME REMAINING FOR TY KALMAEGI TO UNDERGO MINOR RE-STRENGTHENING AS
IT APPROACHES THE NORTHERN PORTION OF PALAWAN, PHILIPPINES. AFTER
TRACKING OVER PALAWAN, TY KALMAEGI IS FORECAST TO INTENSIFY AGAIN
CONTINUING TO TRACK THROUGH MARGINALLY FAVORABLE CONDITIONS OVER
THE SOUTH CHINA SEA, CHARACTERIZED BY WARM (29 C TO 30 C) SEA
SURFACE TEMPERATURES AND RELATIVELY LOW (15-20 KTS) VERTICAL WIND
SHEAR. PEAK INTENSITY WILL BE 95 KTS AROUND TAU 36. TY KALMAEGI
WILL MAKE LANDFALL SOUTH OF QUY NHON, VIETNAM, BETWEEN TAU 48 AND
72. A RAPID WEAKENING TREND WILL FOLLOW. THE SYSTEM WILL FULLY
DISSIPATE OVER LAND BY TAU 96.

MODEL DISCUSSION: MODEL GUIDANCE HAS COME INTO A BETTER AGREEMENT
WITH A CROSS-TRACK SPREAD UNDER 70 NM UNTIL TAU 36. AFTERWARDS MOST
OF THE MODEL MEMBERS REMAIN WITHIN 70 NM OF EACH OTHER WITH THE
EXCEPTION OF NAVGEM, WHICH REMAINS FASCINATED WITH THE MORE
NORTHWESTWARD TRACK. THE JTWC OFFICIAL TRACK LIES CLOSE TO THE
MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE. GUIDANCE ON INTENSITY
HAS ALSO IMPROVED. GFS HAS REJOINED THE OTHER MEMBERS IN REFLECTING
MAX INTENSITIES OF 85-90 KNOTS. HAFS-A REMAINS AN OUTLIER DEPICTING
A MAX INTENSITY OF 100 KTS. THE JTWC FORECAST REFLECTS INTENSITIES
JUST UNDER HAFS-A GUIDANCE UNTIL TAU 36 AND REMAINS CLOSE TO THE
MULTI-MODEL CONSENSUS FOR THE REMAINDER OF THE FORECAST PERIOD.  

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   TRACK 72-120 HR: HIGH
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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