WDPN32 PGTW 200900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 24W (RAGASA) WARNING NR 008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.7N 129.1E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 485 NM NORTHEAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 24 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS SYMMETRIC
CONVECTIVE BANDING WRAPPING ALONG THE NORTHERN AND SOUTHERN
PERIPHERIES INTO A RAGGED EYE FEATURE OF TYPHOON (TY) 24W. A DRY
AIR SLOT IS APPARENT AS CONTINENTAL DRY AIR FROM THE NORTHWEST
WRAPS ALONG THE WESTERN AND SOUTHWESTERN PERIPHERY OF THE TYPHOON.
RAPID INTENSIFICATION HAS OCCURRED OVER THE LAST 24 HOURS, AND TY
24W HAS INTENSIFIED INTO A 70KT SYSTEM. THE CURRENT ENVIRONMENT IS
HIGHLY FAVORABLE WITH EXPANSIVE UPPER-LEVEL DIVERGENCE, AND THE
OCEAN HEAT CONTENT IS HIGH AT 129 KJ PER CM2 (SOURCED FROM NOAA
AOML DATA). THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON THE AFOREMENTIONED ANIMATED MSI. THE INITIAL INTENSITY OF
70 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY AND
OBJECTIVE FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: A COMPETING STEERING ENVIRONMENT
BETWEEN A SUBTROPICAL RIDGE TO THE NORTH AND A WEAKENING RIDGE OVER
THE SOUTH CHINA SEA

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T5.0 - 90 KTS
   KNES: T5.0 - 90 KTS
   CIMSS SATCON: 76 KTS AT 200428Z
   CIMSS ADT: 55 KTS AT 200530Z
   CIMSS AIDT: 70 KTS AT 200530Z
   CIMSS D-PRINT: 88 KTS AT 200630Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 0-5 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD AND 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 24W WILL TRACK WEST-NORTHWESTWARD ALONG THE
SOUTHERN PERIPHERY OF A SUBTROPICAL RIDGE TO THE NORTH. THE NEAR
EQUATORIAL RIDGE OVER THE SOUTH CHINA SEA WILL WEAKEN, ALLOWING THE
STORM TRACK TO GRADUALLY INCREASE AFTER TAU 48. THE ENVIRONMENT
WILL REMAIN HIGHLY FAVORABLE FOR INTENSIFICATION IN THE NEAR-TERM
AS THE SYSTEM TRACKS WESTWARD OVER SEVERAL WARM-CORE EDDIES EAST OF
LUZON. UPPER-LEVEL DIVERGENCE WILL BE ENHANCED FAVORABLY BY A JET
TO THE NORTH AND LINEAR SOUTHWESTERLY FLOW FOR THE ENTIRETY OF THE
FORECAST PERIOD. NORTH OF LUZON, TY 24W WILL REACH A PEAK INTENSITY
OF 125KTS. AFTER TAU 48, OCEAN HEAT CONTENT WILL SIGNIFICANTLY
DECREASE AND THE WATER COLUMN WILL BECOME SHALLOWER. AS TY 24W
TRACKS ALONG THE COAST OF HONG KONG, MACAO, CHINA, AND VIETNAM,
UPWELLING OF COOL WATER WILL DRIVE THE WEAKENING TREND GRADUALLY.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THAT TY 24W WILL TRACK WEST-NORTHWESTWARD OVER THE NEXT 120 HOURS.
THE CROSS-TRACK SPREAD AT TAU 120 IS 150NM. THE INTENSITY GUIDANCE
HAS SLIGHTLY LARGER UNCERTAINTY. NOTABLY, THERE IS A SIGNIFICANT
SIGNAL OF RAPID INTENSIFICATION (RI) BT THE JTWC RI AIDS. HAFS-A
AND HWRF, BOTH LEAN ON THE HIGHER END OF THE JTWC CONSENSUS, AND
PEAK AT 125KTS. GFS IS SLIGHTLY BELOW AT 115KTS, AND COAMPS-TC
PEAKS AT 100KTS. GIVEN THE REALISTIC PROBABILITY OF RI WITH THE
HIGH OCEAN HEAT CONTENT IN THE OCEAN-COUPLED MODELS, THE JTWC
INTENSITY FORECAST LIES CLOSELY TO HAFS-A AND HWRF.

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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