Advisories

WDPN32 PGTW 131500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 13W (PEILOU) 
WARNING NR 027//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 32.9N 169.1E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 827 NM NORTH OF WAKE ISLAND
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A FULLY
EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC), WHICH IS BEGINNING TO 
ELONGATE NORTHEASTWARD ALONG A DEVELOPING WARM FRONTAL BOUNDARY. A
POCKET OF DEEP CONVECTION IS FLARING IN THE NORTHEASTERN QUADRANT,
ALONG A CONVERGENT ASYMPTOTE, AND SUPPORTED BY DIVERGENT NORTHWESTERLY 
UPPER-LEVEL FLOW. ANIMATED SHORTWAVE INFRARED (SWIR) IMAGERY DEPICTS 
OTHER FEATURES OF NOTE, INCLUDING A DEVELOPING CYCLONIC WAVE FEATURE 
TO THE SOUTH, ALONG THE DEVELOPING COLD FRONTAL BOUNDARY OR SHEARLINE, 
AND A SECOND AREA OF ROTATION EMBEDDED WITHIN A TROUGH EXTENDING WEST 
FROM TD 13W, WITHIN THE REGION OF MODERATE COLD AIR ADVECTION. BOTH OF 
THESE FEATURES ARE CLASSIC INDICATORS THAT TD 13W HAS IN FACT BEGUN 
EXTRATROPICAL TRANSITION. THE INITIAL POSITION IS ASSESSED WITH HIGH 
CONFIDENCE BASED ON THE EXPOSED LLCC IN THE EIR. THE INITIAL INTENSITY 
IS ASSESSED WITH MODERATE CONFIDENCE BASED ON THE OBJECTIVE ESTIMATES 
LISTED BELOW. ENVIRONMENTAL CONDITIONS ARE HIGHLY UNFAVORABLE, 
CHARACTERIZED BY HIGH VWS, COOL SSTS, DRY AIR ENTRAINMENT, AND 
STRENGTHENING COLD AIR ADVECTION.

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

CURRENT STEERING MECHANISM: NORTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE SOUTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   CIMSS ADT: 25 KTS AT 131200Z
   CIMSS AIDT: 31 KTS AT 131200Z
   CIMSS D-MINT: 33 KTS AT 131159Z
   CIMSS D-PRINT: 31 KTS AT 131200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
   VWS: 30-35 KTS
   SST: 25-26 CELSIUS
   OUTFLOW: STRONG EASTWARD

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 13W WILL CONTINUE TO RAPIDLY TRANSLATE
NORTHEASTWARD ALONG THE NORTHWESTERN FLANK OF THE STR TO THE SOUTHEAST 
THROUGH THE ENTIRE FORECAST PERIOD. THE SYSTEM IS ALREADY UNDERGOING 
ETT AS THE SATELLITE IMAGERY INDICATES BOTH WARM AND COLD 
FRONTOGENESIS. ADDITIONALLY, THE SYSTEM IS IN PHASE WITH BOTH A 500MB 
AND 200MB TROUGH TO THE WEST, PRESENTING A CLASSIC ETT SYNOPTIC 
STRUCTURE. OVER THE NEXT 24 HOURS, THE UPPER TROUGH WILL DEEPEN WHILE 
SIMULTANEOUSLY TD 13W MOVES INTO THE RIGHT REAR ENTRANCE REGION OF A 
JET MAXIMUM TO THE NORTHEAST. THE STRONG  BAROCLINIC FORCING WILL 
RESULT IN A MODEST AMOUNT OF RE- INTENSIFICATION AS TD 13W COMPLETES 
ETT AND BECOMES A FULLY EXTRATROPICAL LOW.

MODEL DISCUSSION: TRACK GUIDANCE IS IN STRONG AGREEMENT, WITH MINIMAL 
CROSS- OR ALONG-TRACK SPREAD, LENDING HIGH CONFIDENCE TO THE JTWC 
FORECAST TRACK. INTENSITY GUIDANCE IS ALSO IN STRONG AGREEMENT, WITH 
ALL MODELS INDICATING BAROCLINIC RE-INTENSIFICATION THROUGH ETT. CTCX 
IS THE MOST AGGRESSIVE, DEPICTING A PEAK INTENSITY OF 45 KNOTS, WHILE 
HAFS-A AND GFS REACH A PEAK OF 35 KNOTS. THE JTWC FORECAST IS PLACED 
NEAR THE HAFS-A AND GFS CONSENSUS WITH HIGH CONFIDENCE.

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