WDPN31 PGTW 070900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 06W (SIX)     
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.6N 141.4E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 589 NM SOUTH OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A SLOWLY
CONSOLIDATING LOW-LEVEL CIRCULATION, WITH FRAGMENTED CONVECTIVE
BANDING WRAPPING INTO A RAGGED CENTER. A 070346Z AMSR2 36 GHZ
MICROWAVE IMAGE REVEALS CONVECTIVE BANDING OVER THE NORTHERN AND
WESTERN QUADRANTS WRAPPING INTO A DEFINED LOW-LEVEL CIRCULATION
CENTER, WHICH SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE.
THE INITIAL INTENSITY OF 25 KTS IS ASSESSED WITH HIGH CONFIDENCE
BASED ON THE AGENCY DVORAK ESTIMATES AND RECENT ASCAT DATA.
UPPER-LEVEL ANALYSIS INDICATES A ROBUST POLEWARD OUTFLOW CHANNEL
INTO AN UPPER-LEVEL LOW OVER NORTHERN HONSHU, WITH STRONG
EQUATORWARD OUTFLOW AND LOW VERTICAL WIND SHEAR.

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

CURRENT STEERING MECHANISM: WEAK STEERING PATTERN, WITH LOW- TO
MID-LEVEL SUBTROPICAL RIDGE (STR) DISRUPTED BY A BROAD AREA OF
CYCLONIC TURNING TO THE EAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T1.5 - 25 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   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: AFTER A SHORT PERIOD OF ERRATIC TRACK MOTION
WITHIN THE WEAKENED STEERING ENVIRONMENT, TROPICAL DEPRESSION (TD)
06W IS FORECAST TO TURN NORTHEASTWARD THEN GRADUALLY ACCELERATE
NORTHWARD AS THE STR BUILDS TO THE EAST THROUGH TAU 36. AFTER TAU
36, THE SYSTEM WILL TRACK NORTHWARD ALONG A NORTH-SOUTH ORIENTED
STR AND STEADILY INTENSIFY TO A PEAK INTENSITY OF 55 KNOTS BY TAU
72. AFTER TAU 72, THE SYSTEM WILL TURN NORTH-NORTHEASTWARD WHILE
SLOWING AS IT APPROACHES A BUILDING STR TO THE NORTH. THE POLAR
FRONT AND ITS ASSOCIATED BAROCLINIC ZONE IS LOCATED WELL TO THE
NORTH OF THE TAU 120 FORECAST POSITION, WITH NO DEEP MAJOR
SHORTWAVE TROUGH INDICATED IN THE MODELS TO INDUCE A RECURVATURE
TRACK. THEREFORE, EXTRA-TROPICAL TRANSITION IS ASSESSED AS VERY
UNLIKELY. HOWEVER, INTERACTION WITH THE UPPER-LEVEL SUBTROPICAL 
WESTERLIES IS ANTICIPATED, WHICH WILL SERVE TO WEAKEN THE SYSTEM 
AFTER TAU 72. ADDITIONALLY, SST VALUES WILL DECREASE NORTH OF 40N TO 
LESS THAN 24 C, WHICH WILL AID IN THE EVENTUAL DISSIPATION OF THE 
SYSTEM.       

MODEL DISCUSSION: DETERMINISTIC GUIDANCE IS IN GOOD AGREEMENT THROUGH 
TAU 72 WITH A 150 NM CROSS-TRACK SPREAD IN SOLUTIONS AT TAU 72. GFS 
REMAINS THE PRIMARY OUTLIER WITH A TRACK INTO NORTHERN HONSHU. 
OTHERWISE, THE REMAINDER OF THE DETERMINISTIC GUIDANCE SUPPORTS A 
POLEWARD TRACK. AFTER TAU 72, THERE IS INCREASING UNCERTAINTY IN
THE FORECAST TRACK WITH BOTH THE 070000Z EPS AND GEFS ENSEMBLES
DIVERGING SIGNIFICANTLY. EPS INDICATES A SMALL NUMBER (10 PERCENT)
OF SOLUTIONS TRACKING WEST-NORTHWESTWARD INTO NORTHERN HONSHU AND
THE BULK (90 PERCENT) TRACKING POLEWARD. GEFS SHOWS ABOUT 33
PERCENT OF ITS SOLUTIONS TRACKING THE SYSTEM INTO NORTHERN HONSHU
WITH THE MAJORITY OF SOLUTIONS INDICATING A STALL EAST OF HONSHU.
 
FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: HIGH
   INTENSITY 72-120 HR: MEDIUM//
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