WDPN31 PGTW 031500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 05W (AERE)
WARNING NR 013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 28.6N 126.5E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 144 NM NORTH-NORTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A FULLY
EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) DEVOID OF ANY DEEP
CONVECTIVE ELEMENTS. ANIMATED WATER VAPOR IMAGERY AND UPPER-LEVEL
ATMOSPHERIC MOTION VECTORS INDICATE A TROPICAL UPPER TROPOSPHERIC
TROUGH (TUTT) IS STILL LOCATED DIRECTLY OVER THE SYSTEM INDUCING
UNFAVORABLE VERTICAL WIND SHEAR (VWS) AND UPPER-LEVEL SUBSIDENCE. A
030859Z SMAP PASS INDICATES WIND SPEEDS WHEN CORRECTED FOR A 1-MIN
WIND AVERAGE SHOW 29-34 KNOT WINDS IN THE EASTERN AND NORTHERN
QUADRANTS OF THE LLCC. DUE TO THE FULLY EXPOSED LLCC, THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE. THE INITIAL INTENSITY OF
30 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE SMAP PASS
AND RJTD DVORAK INTENSITY ESTIMATE REFLECTING SLIGHTLY HIGHER AT 35
KNOTS AND PGTW DVORAK INTENSITY ESTIMATE AS WELL AS CIMSS ADT
SHOWING SLIGHTLY LOWER AT 25 KNOTS.

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

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE TO THE
EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T2.0 - 30 KTS
   CIMSS ADT: 25 KTS AT 030840Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 25-30 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: WEAK POLEWARD
   OTHER FACTORS: TROPICAL UPPER TROPOSPHERIC TROUGH OVER THE
LOW-LEVEL CIRCULATION

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 05W (AERE) IS FORECAST TO TRACK
NORTH-NORTHEASTWARD THROUGH TAU 36 UNDER THE STEERING INFLUENCE OF
THE STR TO ITS EAST. CURRENTLY IN AN MARGINALLY UNFAVORABLE
ENVIRONMENT CHARACTERIZED BY STRONG VERTICAL WIND SHEAR (25-30
KNOTS), SUBSIDENCE ALOFT PROVIDED BY THE TUTT AND DRY
AIR ENTRAINMENT SOMEWHAT OFFSET NEAR TAU 36 WHEN THE TUTT IS
FORECAST TO FILL AND OUTFLOW IMPROVE. AFTER TAU 36 THE SYSTEM IS
FORECAST TO MAKE LANDFALL AND TRAVERSE THE ISLAND OF JAPAN TRACKING
EAST-NORTHEASTWARD AND EVENTUALLY EASTWARD RETURNING BACK OVER
WATER SOUTH OF TOKYO AFTER TAU 72. MODEL OUTPUT INCREASINGLY
INDICATES THAT BAROCLINIC INFLUENCES FROM THE MID-LATITUDE FLOW
PATTERN WILL ALLOW FOR SOME DEGREE OF INTENSIFICATION AND INDICATE
A POTENTIAL FOR TRANSITION TO A SUBTROPICAL OR EXTRATROPICAL
STRUCTURE NEAR THE END OF THE FORECAST PERIOD.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN GOOD AGREEMENT WITH THE
JTWC FORECAST SCENARIO HOWEVER THE TIMING AND SPEED OF THE EASTWARD
TURN IS UNCERTAIN. THERE ARE HOWEVER, STILL A FEW MEMBERS OF GFS,
ECMWF AND COAMPS ENSEMBLES THAT INDICATE A POTENTIAL NORTHERN TRACK
INTO THE YELLOW SEA. THEREFOR THE JTWC FORECAST TRACK HAS BEEN
PLACED WITH MEDIUM CONFIDENCE. RELIABLE INTENSITY GUIDANCE IS IN
GOOD AGREEMENT THROUGH TAU 48 WITH ALL MEMBERS SHOWING A STAGNATION
IN INTENSITY AFTER WHICH COTI (COAMPS-TC NAVGEM VERSION) AND HWRF
SHOW COMPLETE DISSIPATION WHILE THE REMAINING GUIDANCE INDICATES AN
INTENSIFICATION TREND IN THE EXTENDED FORECAST. FOR THIS REASON THE
JTWC INTENSITY FORECAST IS PLACED
INITIALLY WITH HIGH CONFIDENCE THEN AFTER TAU 72 WITH MEDIUM
CONFIDENCE.

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