WDPN32 PGTW 082100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 16W (PODUL) WARNING NR 
008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.2N 143.5E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 190 NM NORTHWEST OF AGRIHAN
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL STORM PODUL IS MOVING OUT OF THE DIURNAL MAX PERIOD AND
SHOWING A LITTLE MORE STRENGTH THAN YESTERDAY. 24 HOURS AGO THE LOW
LEVEL CIRCULATION CENTER (LLCC) WAS EXPOSED BY THE NORTHEASTERLY
VERTICAL WINDSHEAR (VWS) BUT THIS CYCLE THE SYSTEM MANAGED TO FIGHT 
IT OFF TO A MUCH GREATER EXTENT AND REMAIN UNDER THE CANOPY, ALBEIT
TOWARDS THE POLEWARD EDGE. A 081605Z AMSR2 COLOR 37-89 SHOWS THE
EQUATORWARD DISPLACEMENT OF THE DEEP CONVECTION FROM THE LLCC. THE
VORTEX IS PLACED AT THE POLEWARD EDGE OF THE DEEP CONVECTION UNDER
THE COLD DARK GREY ON THE IR-BD ENHANCEMENT BUT A LACK OF DISTINCT
BANDING MAKES THE DVORAK ASSESSMENT LESS RELIABLE THAN DESIRED.
OVERSHOOTING TOPS AND LIGHTNING STRIKES HAVE INCREASED DURING THE
PAST SEVERAL HOURS. FORTUNATELY FOR THE INTENSITY ASSESSMENT,
THE 081037Z ASCAT PASS WITH UHR PROCESSING CONFIRMED 40 TO 45 KNOTS
DURING THE PRE-DAWN HOURS.  THE CURRENT INTENSITY IS HELD AT 45KTS
TAKING THE MEAN OF AGENCY DVORAKS AND THE CIMSS OBJECTIVE
ASSESSMENTS. TS 16W HAS BEEN HEADING ON A VERY STEADY BEARING OF
300 DEGREES AT 12 KNOTS OVER THE PAST 12 HOURS, EDGING SLIGHTLY
POLEWARD DUE TO A WEAKNESS IN THE SUBTROPICAL RIDGE BETWEEN 140E
AND 130E. THE ENVIRONMENT ALONG TRACK IS EXTREMELY HARSH ON THE
POLEWARD SIDE DUE TO HIGH VWS AND SUBSTANTIALLY DRIER AIR THAN
NORMAL. THE ENVIRONMENT SOUTH OF TRACK IS BETTER, WITH STRONG
EQUATORIAL OUTFLOW OVER THE SOUTHEAST QUADRANT AND AMPLE DEEP
MOISTURE. THERE IS NOTHING TO INDICATE THAT THE UPSTREAM
ENVIRONMENT WILL BECOME LESS LOPSIDED. IN FACT VWS INCREASES
SUBSTANTIALLY OVER THE SENKAKUS.

INITIAL WIND RADII BASIS: PERSISTENCE FROM A 081037Z ASCAT PASS.  

CURRENT STEERING MECHANISM: A MID-LEVEL RIDGE EXTENDING OVER THE
BONIN ISLANDS TOWARDS TAIWAN.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T3.5 - 55 KTS
   CIMSS SATCON: 45 KTS AT 081614Z
   CIMSS ADT: 53 KTS AT 081730Z
   CIMSS AIDT: 46 KTS AT 081730Z
   CIMSS D-MINT: 33 KTS AT 081614Z
   CIMSS D-PRINT: 44 KTS AT 081730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE 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: TS 16W WILL CHUG ALONG TO THE WEST NORTHWEST
FOR THE NEXT 24 HOURS THEN BEND TO A MORE WESTWARD TRACK AS THE MID
LEVEL RIDGE BUILDING ALONG 160E BUILDS AND EXTENDS TOWARDS THE
RYUKUS. THE HARSH ENVIRONMENT WILL SLOW DEVELOPMENT TO A LOWER THAN
CLIMATOLOGICAL RATE BUT THE SYSTEM WILL STILL ATTAIN TYPHOON
STRENGTH AS IT CROSSES THE 138TH MERIDIAN. RAPID INTENSIFICATION
AND TRIPLE DIGIT INTENSITY IS LOOKING HIGHLY UNLIKELY DUE TO THE
HIGH VWS AND DRY AIR NORTH OF 20N. OKINAWA AND THE NORTHERN
SENKAKUS ARE NOT QUITE OFF THE HOOK YET AS A POLEWARD BEND TO THE
TRACK STILL REMAINS A POSSIBILITY BUT NOT A PROBABILITY. SOME OF
THE LOWER PERFORMING TRACKERS STEER THE SYSTEM THROUGH THE RIDGE
BUT THE BETTER TRACKERS KEEP THE SYSTEM SOUTH OF MIYAKOJIMA. THE
GOOD NEWS IS THAT EVEN IN THE UNLIKELY EVENT OF A TRACK TOWARD
OKINAWA, THE ENVIRONMENT ALONG THAT TRACK IS SO HARSH THAT THE
STORM WOULD LIKELY BE DRIED OUT AND TORN APART ALMOST TO THE POINT 
OF BEING UNRECOGNIZABLE IF IT MADE IT THAT FAR. THE TAIWAN-SOUTHERN
SENKAKUS SCENARIO IS MUCH MORE LIKELY, AS THE DEEP SHORT WAVE
CURRENTLY TRACKING OVER JAPAN PASSES INTO THE PACIFIC AND THE
PATTERN BECOMES EXTREMELY MERIDIONAL FOR WPAC. AS THE PATTERN
AMPLIFIES THE BONIN HIGH WILL BUILD A HIGH AMPLITUDE RIDGE ALONG
THE 165TH MERIDIAN AND EXPAND TOWARDS TAIWAN, WITH H500 HEIGHTS
EXCEEDING 5900 METERS ALL THE WAY ACROSS TAIWAN AND INTO MAINLAND
CHINA. THE POINT OF DIVERGENCE IN THE TRACKERS COMES NEAR TAU 48
AND 136E. UNTIL THEN, A SMALL THREAT EXISTS TO OKINAWA. TS 16W IS
EXPECTED TO BEGIN A DOWNTREND AS IT MOVES INTO AN EVEN HIGHER SHEAR
ZONE OVER THE EAST CHINA SEA.   

MODEL DISCUSSION: THE JTWC TRACK FORECAST RUNS EQUATORWARD OF THE
MULTI MODEL CONSENSUS FAVORING THE ECMWF ENSEMBLE AND SOME OF THE
NEW BUT IMPRESSIVE-SO-FAR AI TRACKERS. ALTHOUGH CROSS-TRACK SPREAD 
INCREASES AFTER TAU 72, ALL TRACKERS FOLLOW THE GENERAL TREND OF 
A WESTWARD RUN TO ALMOST 130E, THEN VARYING DEGREES OF A POLEWARD 
BEND WITH A WEAKENING THEREAFTER. INTENSITY GUIDANCE IS ALSO IN 
DECENT AGREEMENT SHOWING A GRADUAL UPTREND THROUGH TAU 36 FOLLOWED 
BY A SLOW DECLINE. THE JTWC INTENSITY FORECAST STAYS JUST HIGHER THAN
THE MID-LINE AND FAVORS HAFS-A. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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