WDPN31 PGTW 210900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 22W (TWENTYTWO) 
WARNING NR 004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.WDPN31 PGTW 210900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 22W (TWENTYTWO) 
WARNING NR 004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.4N 130.1E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 535 NM EAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 17 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY
EXPOSED ELONGATED CIRCULATION WITH CONVECTIVE BANDS WRAPPING IN TO
THE CENTER OF THE CIRCULATION. CONVECTIVE BANDING WRAPS PRIMARILY
AROUND THE WESTERN PERIPHERY OF THE CIRCULATION. AN EARLIER 210041Z
METOP-C ASCAT PASS DEPICTS THE WESTERN PERIPHERY OF THE CIRCULATION
ALONGSIDE THE ELONGATED CENTER. THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE BASED ON THE AFOREMENTIONED SCATTEROMETERY AND
ANIMATED MSI. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON A 210502Z GCOM W1 AMSR2 WIND SPEED IMAGE DEPICTING 25-30KT
WINDS TO THE NORTH AND SOUTH OF THE CIRCULATION.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.0 - 25 KTS
   RJTD: T1.5 - 25 KTS
   CIMSS SATCON: 38 KTS AT 210441Z
   CIMSS ADT: 33 KTS AT 210530Z

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL DEPRESSION (TD) 22W WILL TRACK
WESTWARD FOR THE NEXT TWELVE HOURS AS IT APPROACHES THE
SOUTHWESTERN PERIPHERY OF A STR TO THE NORTH, AND ROUND THE RIDGE
NORTHWESTWARD FROM TAU 12-36. A DEEP-LAYER TROUGH WILL ERODE THE
STR TO THE NORTH, AND THE STEERING WILL BE PICKED UP ON THE
LOW-LEVELS BY A RIDGE EXTENDING OVER THE YELLOW SEA. THE SYSTEM
WILL INTENSIFY TO A PEAK OF 55KTS WHILE IN AN ENVIRONMENT WITH
SUBSTANTIAL UPPER-LEVEL DIVERGENCE, HIGH SEA SURFACE TEMPERATURES,
AND LOW TO MODERATE VERTICAL WIND SHEAR FOR THE FIRST 48 HOURS.
BETWEEN TAU 48-72, THE SYSTEM WILL PASS OVER NORTHERN LUZON AND
WEAKEN DUE TO TOPOGRAPHIC INTERACTION WITH MOUNTAINOUS TERRAIN. THE
SYSTEM WILL PASS OUT OVER WATER AT TAU 72, AT WHICH TIME THE SYSTEM
WILL SLIGHTLY INTENSIFY TO 50KTS THROUGH THE END OF THE FORECAST
WHILE STRUGGLING AGAINST MODERATE TO HIGH SHEAR IN THE SOUTH CHINA
SEA. 

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THAT THE SYSTEM WILL TRACK OVERALL NORTHWESTWARD OVER THE NEXT 36
HOURS BEFORE TURNING WESTWARD AND TRACKING OVER NORTHERN LUZON. THE
CONFIDENCE IN THE JTWC FORECAST IS SUPPORTED BY A CROSS-TRACK
SPREAD OF 189NM BY TAU 120. THE INTENSITY GUIDANCE HAS MINIMAL
SPREAD OF INTERPRETATIONS BETWEEN GFS, WHICH HAS A PEAK OF 65KTS BY
TAU 36, AND HAFS-A, WHICH PEAKS AT 55KTS AT TAU 36. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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