WDPN31 PGTW 171500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 23W (TWENTYTHREE) 
WARNING NR 006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 18.6N 120.5E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 242 NM NORTH OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
DISORGANIZED A WEAKENING CIRCULATION WITH DEEP CONVECTIVE BANDS
WRAPPING BROADLY ALONG THE NORTHERN AND SOUTHEASTERN PERIPHERIES.
IT IS CURRENTLY ASSESSED THAT TROPICAL DEPRESSION (TD) 23W IS IN
THE PROCESS OF A PHENOMENON KNOWN AS A LEESIDE JUMP, AND THE CENTER
OF VORTICITY HAS SHIFTED NORTH OFF OF THE COAST OF CAPE BOJEADOR,
PHILIPPINES. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE
BASED ON THE AFOREMENTIONED ENHANCED INFRARED IMAGERY AND A 171308Z
GPM GMI 89GHZ IMAGE REVEALING LOW-LEVEL BANDING NORTH OF LUZON AND
A POTENTIAL CIRCULATION CENTER. THE INITIAL INTENSITY OF 25 KTS IS
ASSESSED WITH LOW CONFIDENCE BASED ON DPRINT ASSESSMENTS OF 26KTS
AND DMINT OF 27KTS.

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

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   RJTD: T1.0 - 25 KTS
   CIMSS D-MINT: 27 KTS AT 171308Z
   CIMSS D-PRINT: 26 KTS AT 171230Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: LOW
   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 WILL TRACK NORTHWESTWARD FOR THE NEXT
48 HOURS WHILE UNDER THE STEERING INFLUENCE OF A SUBTROPICAL RIDGE
POSITIONED TO THE NORTH. DURING THIS TIME, THE LOW-LEVEL FLOW OF TD
23W WILL STRUGGLE TO CONSOLIDATE AND REDEVELOP INTO A WELL-DEFINED
AND SYMMETRICAL WIND FIELD. OTHERWISE, FAVORABLE FEATURES OF WARM
SEA SURFACE TEMPERATURES, LOW VERTICAL WIND SHEAR, AND STRONG
UPPER-LEVEL DIFFLUENCE WILL ALLOW FOR INTENSIFICATION TO A PEAK OF
40KTS. BY TAU 48, THE SYSTEM IS EXPECTED TO HAVE MADE LANDFALL, AND
WILL WEAKEN WHILE CURVING WESTWARD. ULTIMATELY, TD 23W WILL
DISSIPATE OVER LAND BETWEEN TAU 72-96.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THAT TD 23W WILL TRACK NORTHWESTWARD AND CURVE WESTWARD UPON
LANDFALL, BUT HAS LARGER SPREAD TOWARDS THE END OF THE FORECAST
PERIOD. THE CROSS-TRACK SPREAD AT THE END OF THE FORECAST IS 155NM
WITH GFS LYING TO THE NORTH AND GEFS LYING TO THE SOUTH OF
CONSENSUS. THE INTENSITY GUIDANCE HAS GRADUALLY DECREASED OVER THE
LAST FEW INITIALIZATIONS, AND NOW THERE IS INCREASED CONFIDENCE
THAT THE PEAK INTENSITY IS BETWEEN 35-45KTS. 

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