WDPN31 PGTW 072100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 04W (MUN) WARNING 
NR 
025//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 38.0N 148.3E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 360 NM EAST-SOUTHEAST OF MISAWA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS NOTHING BUT
FIELDS OF STRATOCUMULUS LEFT WITH THIS SYSTEM AS IT ROLLS INTO THE
HIGHER LATITUDES. THE LOW LEVEL VORTEX IS EXPOSED AND CLEARLY VISIBLE 
IN ALL TYPES OF IMAGERY YET STILL MAINTAINS A TIGHT WRAP.  DURING THE 
PAST 12 HOURS THE SYSTEM ROUNDED THE WESTERN FLANK OF THE SUBTROPICAL 
RIDGE AND IS NOW RUNNING TOWARDS A MERGE INTO THE BAROCLINIC ZONE.  
HOWEVER, THE DISPLACEMENT BETWEEN THE SYSTEM AND THE POLAR FRONT JET 
(PFJ) REMAINS FAR ENOUGH AND THE ANGLE OF APPROACH LOW ENOUGH THAT 
THE SYSTEM IS IN AN ENVIRONMENT WHERE IT WILL SURVIVE AND DECAY ONLY 
VERY SLOWLY OVER THE NEAR TERM AS IT COOLS FROM BELOW.

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

CURRENT STEERING MECHANISM: THE NORTHWESTERN FLANK OF THE
SUBTROPICAL RIDGE. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.0 - 30 KTS
   CIMSS ADT: 25 KTS AT 071420Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 30+ KTS
   SST: 19-20 CELSIUS
   OUTFLOW: WEAK POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THE SYSTEM WILL NOT COMPLETE
SUBTROPICAL TRANSITION BUT WILL RATHER UNDERGO EXTRA-TROPICAL
TRANSITION. 

FORECAST DISCUSSION: THE PFJ IS WELL NORTH OF HOKKAIDO SO IT WILL
BE A LONG SLOW MERGE INTO THE BAROCLINIC ZONE FOR TROPICAL
DEPRESSION HUN. AS IT GRADUALLY FADES POLEWARD, VERTICAL WINDSHEAR
WILL INCREASE FROM ABOVE AND COOLING WATERS WILL WEAKEN IT FROM
BELOW AND THE SYSTEM WILL BE UNFINDABLE SOMEWHERE NEAR THE 45TH
LATITUDE. THE LATEST SATELLITE FIX FROM JTWC AT THE TIME OF THIS
BULLETIN WAS POSITION ONLY WITH THE DVORAK CLASSIFIED AS TOO
WEAK. DISSIPATION IS JUST A MATTER OF TIME.

MODEL DISCUSSION: MODELS ARE IN EXCELLENT AGREEMENT ON BOTH TRACK
AND INTENSITY TRENDS. NO VORTEX TRACKERS CARRY THE SYSTEM BEYOND
TAU 36 WITH EXCEPTION OF THE HAFS-A MODEL. 

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