WDPN32 PGTW 190300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (RAGASA) WARNING NR 
003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.0N 131.3E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 602 NM EAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: WESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A
CONSOLIDATING, BROAD AND SLIGHTLY ELONGATED LOW-LEVEL CIRCULATION
CENTER (LLCC) ASSOCIATED WITH TROPICAL STORM (TS) 24W (RAGASA). THE
LLCC IS PARTIALLY EXPOSED TO THE NORTH, PRIMARILY DUE TO THE
PRESENCE OF DRY AIR, WHICH CONTINUES TO IMPEDE CONVECTIVE 
DEVELOPMENT. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE 
BASED ON A 190003Z METOP-B ASCAT PASS SHOWING A CONSOLIDATING, BUT 
STILL ASYMMETRICAL WIND FIELD, WITH STRONGEST WINDS PRIMARILY LOCATED 
TO THE SOUTH AND NORTHEAST. ANIMATED VISIBLE SATELLITE IMAGERY 
REVEALS STRONG EQUATORWARD OUTFLOW CHANNEL SUPPORTING THE 
DEVELOPMENT. ADDITIONAL ENVIRONMENTAL ANALYSIS INDICATES FAVORABLE 
CONDITIONS INCLUDING WARM (29-30 C) SEA SURFACE TEMPERATURES AND LOW 
(10-15 KTS) VERTICAL WIND SHEAR.

INITIAL WIND RADII BASIS: DRY AIR ENTRAINMENT FROM THE NORTH

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T2.0 - 30 KTS
   CIMSS ADT: 35 KTS AT 182030Z
   CIMSS AIDT: 34 KTS AT 182030Z
   CIMSS D-MINT: 32 KTS AT 182133Z
   CIMSS D-PRINT: 30 KTS AT 190040Z

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

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 24W IS EXPECTED TO TRACK SLOWLY
WEST-NORTHWESTWARD OVER THE NEXT 24 HOURS, AS IT REMAINS IN A WEAK
STEERING ENVIRONMENT. AT AROUND TAU 24, A STR TO THE NORTHEAST WILL
STRENGTHEN, CAUSING A SLIGHT ACCELERATION OF THE SYSTEM AND A SHIFT
TO A MORE NORTHWESTWARD TRACK OVER THE FOLLOWING 12 HOURS. AFTERWARD, 
THE RIDGE WILL CONTINUE TO BUILD AND EXTEND EASTWARD, CAUSING THE 
SYSTEM TO RETURN TO A WEST-NORTHWESTWARD TRACK THROUGHOUT THE 
FORECAST PERIOD. TS RAGASA IS EXPECTED TO CONTINUE INTENSIFYING 
WITHIN A FAVORABLE ENVIRONMENT UNTIL APPROXIMATELY TAU 96, WITH 
PERIODS OF RAPID INTENSIFICATION (RI) POSSIBLE, REACHING PEAK 
INTENSITY OF 115-125 KTS BETWEEN TAUS 72 AND 96. THE PRIMARY LIMITING 
FACTOR TO DEVELOPMENT IS THE DRY AIR TO THE NORTH. HOWEVER, NUMERICAL 
MODEL GUIDANCE CONTINUES TO SUGGEST THAT THE SYSTEM WILL OVERCOME 
THESE IMPACTS WITHIN 36-48 HOURS. TOWARDS THE END OF THE FORECAST 
PERIOD, TS 24W IS EXPECTED TO BEGIN WEAKENING DUE TO INTERACTIONS 
WITH THE TOPOGRAPHY OF NORTHERN LUZON, SOUTHERN TAIWAN, AND 
EVENTUALLY THE SOUTHEASTERN COAST OF CHINA.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE SHOWS FAIR
CONSISTENCY THROUGHOUT THE FORECAST, WITH ALL MODELS PREDICTING A
GENERAL NORTHWESTWARD TRACK. ALL AVAILABLE GUIDANCE INDICATES A
PASSAGE THROUGH THE LUZON STRAIT, WITH MOST MODELS FAVORING A 
CENTERED POSITION. SHORT-TERM JTWC TRACK FORECAST IS ASSESSED WITH 
HIGH CONFIDENCE, AS WITNESSED BY A CROSS-TRACK OF APPROXIMATELY 90 NM 
AT TAU 24, EXPANDING TO JUST 105 NM AT TAU 72. AS CROSS-TRACK SPREAD
INCREASES TO 250 NM JUST BEFORE LANDFALL, SO DOES THE TRACK FORECAST 
UNCERTAINTY, AND THEREFORE THE JTWC LONG-TERM TRACK IS LAID WITH 
MEDIUM CONFIDENCE, WHILE REMAINING CLOSE TO THE MULTI-MODEL 
CONSENSUS. THE JTWC INTENSITY FORECAST IS PLACED ON THE HIGHER END OF 
THE CONSENSUS GUIDANCE WITH MEDIUM CONFIDENCE THROUGH TAU 72, WITH 
MAJORITY OF THE DETERMINISTIC GUIDANCE SIGNALING STRONG 
INTENSIFICATION, SUPPORTED BY MULTIPLE RAPID INTENSIFICATION
(RI) AIDS (RIDE AND COAMPS-TC RI AID). AFTER TAU 72, THE GUIDANCE
BECOMES MORE DIVERGENT, WITH THE MOST CONSERVATIVE DETERMINISTIC
GFS FORECASTING A PEAK OF 95-100 KTS AND THE MOST AGGRESSIVE HAFS-A
MODEL INDICATING A MAXIMUM WIND SPEED OF 130-135 KTS AROUND TAU 96.
THE OVERALL INTENSITY SPREAD AT PEAK IS CURRENTLY 40 KTS, REFLECTING 
IMPROVING, BUT STILL LOW CONFIDENCE IN THE INTENSITY FORECAST BEYOND 
TAU 72.

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