WDPN31 PGTW 080300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (MARIA) WARNING NR 
005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.4N 143.8E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 574 NM SOUTH-SOUTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
STORM 06W (MARIA) WITH A WELL-DEFINED CONVECTIVE BANDING WRAPPING
INTO THE LOW-LEVEL CIRCULATION CENTER (LLCC) ALONG THE SOUTHERN AND
EASTERN SEMICIRCLES. ANIMATED IMAGERY ALSO SHOWS A WARM SPOT
FORMING OVER THE CENTER, HINTING AT THE EARLY STAGES OF AN EYE. THE
PRESENCE OF DRY AIR ALONG THE NORTHWESTERN PERIPHERY SEEMS TO HAVE
KEPT THE SYSTEM FROM FURTHER INTENSIFYING OVER THE PAST 6 HOURS
THOUGH. ENVIRONMENTAL ANALYSIS REMAINS CONDUCIVE FOR FURTHER
INTENSIFICATION CHARACTERIZED BY STRONG POLEWARD AND EQUATORWARD
OUTFLOW ALOFT, LOW (5-10 KTS) VERTICAL WIND SHEAR, AND WARM (30-31
C) SEA SURFACE TEMPERATURES. THE INITIAL POSITION IS PLACED WITH
MEDIUM CONFIDENCE BASED ON EXTRAPOLATION FROM A 072215Z GMI 89 GHZ
IMAGE REVEALING THE BANDING WRAPPING INTO THE LLCC. THE INITIAL
INTENSITY OF 40 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE
OBJECTIVE AND SUBJECTIVE INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A SUBTROPICAL
RIDGE (STR) TO THE EAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T3.0 - 45 KTS
   CIMSS ADT: 39 KTS AT 080000Z
   CIMSS AIDT: 41 KTS AT 080000Z
   CIMSS DPRINT: 45 KTS AT 080000Z
   CIMSS DMINT: 43 KTS AT 072213Z

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: MEDIUM

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: 06W IS FORECAST TO CONTINUE TRACKING
NORTHEASTWARD ALONG THE WESTERN PERIPHERY OF THE STR TO THE EAST
OVER THE NEXT 24 HOURS. AFTER TAU 24, THE SYSTEM IS EXPECTED TO
TRACK MORE NORTHWARD THROUGH TAU 72 AS THE RIDGE REORIENTS. AFTER
TAU 72, THE SYSTEM IS FORECAST TO TURN NORTHWESTWARD AS RIDGING
EXTENDS OVER HOKKAIDO. REGARDING INTENSITY, 06W IS FORECAST TO
QUICKLY INTENSIFY OVER THE NEXT 36-48 HOURS TO A PEAK INTENSITY OF
75 KTS IN RESPONSE TO THE FAVORABLE ENVIRONMENTAL FACTORS. AFTER
TAU 48, COOLING SEA SURFACE TEMPERATURES AND THE PRESENCE OF DRY
AIR AS THE SYSTEM MOVES NORTHWARD WILL CAUSE WEAKENING TREND FOR
THE REMAINDER OF THE FORECAST PERIOD. 

MODEL DISCUSSION: MODEL GUIDANCE CONTINUES TO BE IN A BIFURCATION
SCENARIO. GFS AND GFS ENSEMBLE MEAN CONTINUE TO MAKE UP THE
WESTERNMOST MEMBERS, MAKING A SHARP WESTWARD TURN AFTER TAU 60 DUE
TO BUILDING RIDGING ACROSS NORTHERN JAPAN. ECMWF DETERMINISTIC AND
NAVGEM REMAIN DEPICTING A NORTHEASTWARD TRACK AFTER TAU 72.
CONVERSELY, THE ECMWF ENSEMBLE MEAN TRACKS THE VORTEX STRAIGHT
WESTWARD AFTER TAU 72, LIKE GFS, BUT FURTHER NORTH, BETWEEN TOKYO
AND MISAWA. IN FACT, ALL CONSENSUS MEMBERS NOW TRACK THE SYSTEM
NORTH OF TOKYO, SHOWING A SLIGHTLY MORE NORTHWARD TREND IN THE
WESTWARD TRACKING GUIDANCE. THE DIFFERENCES IN TRACK SPEEDS SEEMS
TO BE THE CAUSE OF THE BIFURCATION BETWEEN GFS AND THE ECMWF
DETERMINISTIC. ECMWF HAS A FASTER TRACK SPEED AND THEREFORE CATCHES
THE AXIS OF THE RIDGE BEFORE IT HAS TIME TO BUILD ENOUGH TO TURN IT
WESTWARD. GFS HAS A SLOWER TRACK SPEED AND IS TRAPPED BEFORE MAKING
IT TO THE RIDGE AXIS. THE TRACK SPEEDS OF 06W WILL BE CLOSELY
MONITORED OVER THE NEXT COUPLE DAYS TO GIVE MORE INSIGHT TO WHICH
OF THE TWO SCENARIOS OCCUR. THE JTWC FORECAST TRACK HEDGES TOWARDS
THE MORE WESTWARD MEMBERS WITHOUT COMPLETELY FOLLOWING THE GFS
MODEL DEPICTION. AS A RESULT, THE JTWC TRACK FORECAST IS PLACED
WITH OVERALL LOW CONFIDENCE. RAPID INTENSIFICATION AIDS ARE STILL
TRIGGERING FOR THE SYSTEM, AND THE JTWC INTENSITY FORECAST IS
HOLDING ON TO THE RAPID INTENSIFICATION OUTCOME WITH A PEAK
INTENSITY OF 75 KTS AROUND TAU 36. NON-RI AIDS DEPICT A MORE MODEST
PEAK OF AROUND 55-60 KTS. THE VARIANCE BETWEEN TRACK SOLUTIONS WILL
CAUSE A LARGE DISCREPANCY IN THE INTENSITY FORECAST AFTER TAU 72.
IF THE SYSTEM CONTINUES POLEWARD, IT WILL ENTER THE COOLER WATERS
AND WEAKEN QUICKLY. IF THE SYSTEM TRACKS WESTWARD, THE ENVIRONMENT
WILL BE MORE FAVORABLE FOR INTENSIFICATION WITH WARMER WATERS, LESS
VERTICAL WIND SHEAR, AND BETTER OUTFLOW ALOFT. THIS WOULD CAUSE 06W
TO BE NEAR OR ABOVE TYPHOON STRENGTH AS IT MAKES LANDFALL. OVERALL,
THE JTWC INTENSITY FORECAST IS ALSO PLACED WITH LOW CONFIDENCE.

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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