Advisories

WDPN32 PGTW 042100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 23W (TWENTYTHREE) 
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 24.0N 137.1E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 234 NM WEST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 17 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
DEPRESSION (TD) 23W A LACK OF PERSISTENT CONVECTION AROUND THE
POORLY ORGANIZED LOW-LEVEL CIRCULATION, THE REMNANTS OF WHICH ARE
NOW FULLY EXPOSED. THERE IS AN APPARENT MESOVORTEX ROTATING WITHIN
THE BROADER CYCLONIC WIND FIELD THAT MAY REPRESENT THE PREVIOUSLY
OBSERVED COMPACT ROTATION. A 041510Z OCEANSAT-3 SCATTEROMETRY IMAGE
REVEALED THE MESOVORTEX ON THE EASTERN EDGE OF THE BROADER
CIRCULATION AND DEPICTED WIND SPEEDS OF 30-35 KTS IN THE SOUTHEAST
QUADRANT. THE INITIAL POSITION IS PLACED WITH LOW CONFIDENCE BASED
ON THE AMBIGUOUS STRUCTURE OF THE LOW-LEVEL CIRCULATION. THE
INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED
ON THE SCATTEROMETRY DATA. THE ENVIRONMENT IS CHARACTERIZED AS
MARGINAL FOR DEVELOPMENT, WITH WARM SEA SURFACE TEMPERATURES,
LOW-MODERATE VERTICAL WIND SHEAR (VWS), AND WEAK OUTFLOW ALOFT.

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
   KNES: T1.5 - 25 KTS
   CIMSS ADT: 41 KTS AT 041750Z
   CIMSS AIDT: 41 KTS AT 041750Z
   CIMSS D-PRINT: 27 KTS AT 041920Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: WEAK EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   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: 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 INFLUENTIAL INTERACTION WITH
TROPICAL STORM 22W BASED ON THE LATEST GUIDANCE AND LACK OF
DEVELOPMENT OF 23W. THE INTENSITY IS FORECAST TO STEADILY DECREASE
AS THE SYSTEM EXITS A REGION OF ENHANCED SOUTHWESTERLY FLOW INTO AN
UNFAVORABLE REGION FOR CONVECTIVE DEVELOPMENT.  

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//
NNNN