Advisories

WDPN32 PGTW 050300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 23W (TWENTYTHREE) 
WARNING NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.3N 136.3E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 285 NM WEST-NORTHWEST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 24 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS THE COMPACT
LOW-LEVEL CIRCULATION CENTER (LLCC) OF TROPICAL DEPRESSION (TD) 23W
WITH OCCASIONAL BURSTS OF CONVECTION THAT ARE QUICKLY SHEARED AWAY
TOWARD THE SOUTHWEST. THE LLCC HAS NOT HAD ANY SUSTAINED CONVECTION
OVER THE PAST 12 HOURS AND HAS LARGELY BEEN PERPETUATED BY THE
SURROUNDING WIND FIELD. THE SHALLOW VORTEX MAKES UP THE EASTERN EDGE
OF A MUCH BROADER CYCLONIC CIRCULATION THAT THAT CONTAINS THE MUCH
DEEPER VORTEX OF TROPICAL STORM (TS) 22W ABOUT 500 NM TO THE WEST.
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
FULLY EXPOSED LLCC IN ANIMATED MSI. THE INITIAL INTENSITY OF 25 KTS
IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A PARTIAL 042322Z
METOP-B ASCAT PASS TO THE EAST THAT SHOWED POCKETS OF 25 KT WINDS
WITHIN THE ENHANCED SOUTHERLIES TO THE EAST OF THE LLCC. THE
ENVIRONMENT IS CHARACTERIZED AS MARGINALLY UNFAVORABLE FOR FURTHER
DEVELOPMENT DUE TO MODERATE-HIGH VWS AND A TOTAL LACK OF OUTFLOW
ALOFT, DESPITE WARM SEA SURFACE TEMPERATURES.

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

CURRENT STEERING MECHANISM: WESTERN FLANK OF A SUBTROPICAL RIDGE
CENTERED TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   CIMSS SATCON: 37 KTS AT 042121Z
   CIMSS ADT: 37 KTS AT 042340Z
   CIMSS AIDT: 38 KTS AT 042340Z
   CIMSS D-MINT: 26 KTS AT 042121Z
   CIMSS D-PRINT: 26 KTS AT 050050Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 20-25 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: WEAK EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   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: TD 23W HAS TRACKED NORTH-NORTHWESTWARD OVER
THE PAST 6 HOURS UNDER THE STEERING INFLUENCE OF THE STR TO THE
EAST. THE TRACK IS FORECAST TO CONTINUE NORTH-NORTHWESTWARD TOWARD
KYUSHU AT A RELATIVELY QUICK PACE FOR THE ENTIRE FORECAST PERIOD.
THERE IS NOT EXPECTED TO BE ANY DIRECT CYCLONE INTERACTION WITH
TROPICAL STORM 22W AS TD 23W IS EXPECTED TO WEAKEN AND WASH OUT
WITHIN THE SURROUNDING WIND FIELD BY TAU 48. THE INTENSITY IS
FORECAST TO STEADILY DECREASE AS THE SYSTEM TRACKS THROUGH A REGION
OF UNFAVORABLE VWS. 

MODEL DISCUSSION: AVAILABLE MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT ABOUT THE TRACK SPEED AND DIRECTION FOR THE ENTIRE
FORECAST PERIOD. THE JTWC TRACK FORECAST IS PLACED CLOSE TO THE
MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE. MODEL INTENSITY
GUIDANCE FALLS WITHIN A 5 KT ENVELOPE AND DEPICTS A GRADUAL
WEAKENING TREND, WITH THE EXCEPTION OF GFS, WHICH DEPICTS A BRIEF
SPIKE TO 35 KTS. THE JTWC INTENSITY FORECAST FOLLOWS THE
MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE.

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