WDPN32 PGTW 190900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (RAGASA) WARNING NR 
004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.1N 130.7E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 568 NM EAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: WESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
STORM 24W (RAGASA) WITH PERSISTENT INTENSE CONVECTION ALONG THE
SOUTHERN PERIPHERY OF THE SYSTEM. THE WIND FIELD HAS CONTINUED TO
CONSOLIDATE OVER THE PAST 6 HOURS, WITH A NOTABLY IMPROVED
SYMMETRY. RECENT SCATTEROMETER DATA SHOWS THAT GALE FORCE WINDS ARE
NOW PRESENT IN ALL BUT THE NORTHWESTERN QUADRANT. A 190431Z AMSR2
89 GHZ MICROWAVE IMAGE REVEALED THE DEFINED LOW-LEVEL CLOUD LINES
WITH THE DEEP CONVECTION BEGINNING TO WRAP AROUND THE EASTERN
EXTENT OF THE CIRCULATION. ENVIRONMENTAL ANALYSIS INDICATES THAT
24W IS IN A FAVORABLE ENVIRONMENT CHARACTERIZED BY STRONG
EQUATORWARD OUTFLOW ALOFT, LOW (5-10 KTS) VERTICAL WIND SHEAR, AND
WARM (29-30 C) SEA SURFACE TEMPERATURES. THE INITIAL POSITION IS
PLACED WITH MEDIUM CONFIDENCE BASED ON THE ANIMATED MSI AND
EXTRAPOLATION FROM THE MENTIONED AMSR2 MICROWAVE IMAGE. THE INITIAL
INTENSITY OF 40 KTS IS ALSO ASSESSED WITH MEDIUM CONFIDENCE BASED
ON THE AGENCY DVORAK AND OBJECTIVE INTENSITY ESTIMATES LISTED
BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE FROM THE 190003Z METOP-B
ASCAT SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A SUBTROPICAL
RIDGE TO THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T2.5 - 35 KTS
   CIMSS SATCON: 39 KTS AT 190610Z
   CIMSS ADT: 37 KTS AT 190610Z
   CIMSS AIDT: 35 KTS AT 190610Z
   CIMSS D-MINT: 40 KTS AT 190446Z
   CIMSS D-PRINT: 42 KTS AT 190610Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: 24W IS FORECAST TO TRACK RATHER SLOWLY
NORTHWESTWARD OVER THE NEXT 48 HOURS AS THE SUBTROPICAL RIDGE TO
THE NORTH CONTINUES TO BUILD. NEAR TAU 72, THE RIDGE WILL HAVE
BUILT IN AND WILL HAVE MORE INFLUENCE ON STEERING THE VORTEX. 24W
WILL THEN INCREASE TRACK SPEEDS AS IT PASSES THROUGH THE LUZON
STRAIT WITH A MORE WEST-NORTHWESTWARD TRAJECTORY. THIS MOTION WILL
THEN PERSIST THROUGH THE REMAINDER OF THE FORECAST PERIOD AS THE
SYSTEM APPROACHES THE SOUTHERN COAST OF CHINA. REGARDING INTENSITY,
24W IS FORECAST TO RAPIDLY INTENSIFY OVER THE NEXT 48 HOURS TO
AROUND 100 KTS. ENVIRONMENTAL CONDITIONS WILL BE NEARLY PERFECT FOR
RAPID DEVELOPMENT AS THE SYSTEM TAPS INTO AN IMPROVED POLEWARD
OUTFLOW CHANNEL OVER THE NEXT 24 HOURS. A PEAK INTENSITY OF AROUND
120 KTS IS FORECAST TO OCCUR NEAR TAU 72, NORTH OF LUZON. EASTERLY
VERTICAL WIND SHEAR IS EXPECTED TO INCREASE TO 15-20 KTS AT TAU 96
AND ONWARD, CAUSING 24 TO SLIGHTLY WEAKEN AS IT HEADS FOR THE
SOUTHERN COAST OF CHINA. 

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE CONTINUES TO BE IN
GOOD AGREEMENT WITH A 90 NM CROSS-TRACK SPREAD AT TAU 72 WHICH
OPENS UP TO 180 NM AT TAU 120. THE JTWC TRACK FORECAST IS PLACED
CLOSE TO THE MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE THROUGH TAU
72 AND MEDIUM CONFIDENCE THEREAFTER. THE INTENSITY HAS MORE
UNCERTAINTY. NEARLY ALL RAPID INTENSIFICATION AIDS ARE TRIGGERING
THIS MODEL RUN. PEAK INTENSITIES RANGE FROM 95 KTS (GFS) TO 135 KTS
(HAFS-A), ALL OCCURRING AT TAU 72. MESOSCALE MODELS ARE PRETTY CLOSE
IN TERMS OF THE PEAK INTENSITY WITH COAMPS-TC, HWRF, AND HAFS-A
RANGING FROM 115-135 KTS. THE JTWC INTENSITY FORECAST CALLS FOR A
PEAK OF 120 KTS, IN LINE WITH THE MESOSCALE MODEL GUIDANCE. NEARLY
ALL MODELS HAVE A WEAKENING TREND AFTER TAU 72, TO VARYING DEGREES.
THE JTWC INTENSITY FORECAST IS PLACED WITH OVERALL LOW CONFIDENCE
DUE TO THE INHERENT UNCERTAINTY REGARDING RAPID INTENSIFICATION. 

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