WDPN31 PGTW 060900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 05W (AERE) WARNING 
NR 024//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 34.0N 141.7E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 120 NM SOUTH-SOUTHEAST OF NARITA AIRPORT
   MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 25 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS THE MAIN
SURFACE CIRCULATION IS BEGINNING TO JOIN WITH THE UPPER LEVEL LOW
FEATURE JUST EAST OF HONSHU, TO THE NORTHEAST OF HACHIJO-JIMA
ISLAND. THE MAIN CONVECTIVE STRUCTURE HAS MOVED WELL TO THE EAST OF
THE SURFACE LLC WITH VERY LITTLE CONVECTION NEAR THE LLC ITSELF.
TD05W APPEARS TO BE TRANSITIONING INTO A SUBTROPICAL SYSTEM
CURRENTLY AND HAS AN OVERALL ASYMMETRIC AND BAROCLINIC LEAF STRUCTURE
ON THE MSI LOOP. THE INITIAL POSITION IS PLACED WITH LOW CONFIDENCE
BASED ON BOTH 060544Z SSMIS 37GHZ AND 89GHZ IMAGES. THE INITIAL
INTENSITY OF 25 KNOTS IS ASSESSED WITH LOW CONFIDENCE BASED ON LACK
OF OBSERVATIONS AND IS WEAKLY BASED UPON OBJECTIVE DVORAK ESTIMATES
FROM ADT AND SATCON (LISTED BELOW). THE PGTW FIX POSITION AND
INTENSITY ARE ASSESSED USING THE SUBTROPICAL METHOD, YIELDING AN
OVERALL HIGHER INTENSITY. THE CURRENT ENVIRONMENT REMAINS
UNFAVORABLE FOR TROPICAL CYCLONE DEVELOPMENT WITH SEA SURFACE
TEMPERATURES SLIGHTLY ABOVE 25C, HIGH VWS, BEING SLIGHTLY OFFSET BY
THE UPPER LEVEL DIFFLUENT OUTFLOW ALOFT, AND A STRONG POSITIVE
VORTICITY LOBE ASSOCIATED WITH A 500MB TROUGH RESIDING SLIGHTLY
EAST OF THE MAIN LLC.

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

CURRENT STEERING MECHANISM: NORTHERN PERIPHERY OF A DEEP LAYER
SUBTROPICAL RIDGE (STR) TO THE SOUTH 


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   CIMSS SATCON: 43 KTS AT 060343Z
   CIMSS ADT: 33 KTS AT 060230Z

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   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 05W IS ANTICIPATED TO MOVE SLOWLY EAST, DURING
ITS SUBTROPICAL TRANSITION. DURING THE TRANSITION, THE UPPER LEVEL
FEATURE WILL MERGE WITH TD 05W AND INTENSIFY TD 05W AGAIN TO TROPICAL
STORM STRENGTH, REACHING PEAK INTENSITY OF 35 KNOTS BY TAU 24. THE
OVERALL EASTWARD PROGRESSION WILL BEGIN SLOWING AS TD 05W MOVES INTO
A WEAK STEERING ENVIRONMENT, AND ITS OVERALL MOTION BECOMES
QUASI-STATIONARY THROUGH TAUS 36-48. THE SYSTEM IS THEN EXPECTED TO
BECOME FULLY SUBTROPICAL BY TAU 36. FROM TAU 36 AND BEYOND,
TROPICAL DEVELOPMENT WILL BE FURTHER HINDERED BY AN INCREASE OF DRY
AIR ENTRAINMENT, AND OCEAN TEMPERATURES DECREASING TO THE NORTH.
THEREAFTER, TD 05W WILL MOVE NORTH UNDER THE REX BLOCK PATTERN UNTIL
THE BLOCKING MECHANISM BREAKS DOWN BETWEEN TAU 60 AND 72. ONCE THE
REX BLOCK BREAKS DOWN AND THE STR REORIENTS TO A NORTH SOUTH AXIS,
EAST OF THE SYSTEM, TD 05W WILL EJECT QUICKLY TO THE NORTH. AS THE
SYSTEM QUICKLY MOVES NORTH, IT WILL WEAKEN RAPIDLY DUE TO HIGHER
VWS, AND COOLER SSTS, AND DROP BELOW TD STRENGTH BY TAU 96 BEFORE
EVER REACHING MAINLAND HONSHU, OR HOKKAIDO. 

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE REMAINS IN FAIR
AGREEMENT IN THE FIRST 12-24 HRS AS THE SYSTEM TRACKS EAST BEFORE
MOVING IN A SLIGHTLY EAST-SOUTHEASTERLY DIRECTION BETWEEN TAUS
24-48. BY TAU 48, ALL GUIDANCE SUGGESTS A QUASI-STATIONARY LOOPING
MOTION DUE TO THE WEAK STEERING PATTERN AND REX BLOCK SITUATION.
THE FORECAST TRACK APPEARS TO LOOP BACK IN A COUNTERCLOCKWISE
MANNER BY TAU 48. THE HIGH UNCERTAINTY IN THE EXACT TRACK BETWEEN
TAUS 48-72 INDUCES LOW CONFIDENCE IN THE OVERALL JTWC FORECAST
TRACK DUE TO THE ERRATIC MOTION. ALL GUIDANCE SUGGESTS A NORTHWARD
TRACK BY TAU 72-96. CONFIDENCE IN THE OVERALL INTENSITY IS ALSO
LOW, DUE TO THE UNCERTAINTIES IN THE INITIAL INTENSITY ALONG WITH
ALL MODELS CONSTRAINED WITHIN A 5 KNOT ENVELOPE THROUGH THE
DURATION OF THE FORECAST.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: LOW
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: LOW
   INTENSITY 72-120 HR: LOW//
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