WDPN31 PGTW 270900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 20W (MINDULLE) WARNING NR 020//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.9N 136.6E
   INITIAL INTENSITY: 95 KTS
   GEOGRAPHIC REFERENCE: 393 NM SOUTHWEST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 42 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS TY 20W
CONTINUING TO STRUGGLE TO OVERCOME THE EFFECTS OF STRONG UPWELLING
AND TO COMPLETE AN EYEWALL REPLACEMENT CYCLE (ERC). ANIMATED
VISIBLE AND INFRARED IMAGERY SUGGESTS THAT THE INNER EYEWALL HAS
DISINTEGRATED, WITH A RAGGED AND DISCONTINUOUS SECONDARY EYEWALL
DOING ITS BEST TO FORM. A PARTIAL 270145Z GMI 89GHZ MICROWAVE PASS
SHOWED A FAIRLY SOLID SECONDARY EYEWALL TO THE SOUTHEAST OF THE
CENTER, BUT UNFORTUNATELY THE LACK OF ANY BULLSEYE MICROWAVE DATA
SINCE 21Z MEANS THAT THE STATUS OF THE ERC CANNOT BE CONFIRMED AT
THIS TIME. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE
BASED ON THE TIGHT CLUSTER OF AGENCY FIXES WITHIN THE RAGGED EYE.
DVORAK CURRENT INTENSITY ESTIMATES REMAIN ABOUT HALF TO ONE FULL
T-NUMBER TOO HIGH, HELD THERE BY CONSTRAINTS, WHILE THE OBJECTIVE
ADT AND SATCON SEEM TO BE BETTER ALIGNED WITH THE OVERALL STRUCTURE
IN THE VIS AND IR IMAGERY. THE INITIAL INTENSITY IS ASSESSED WITH
MEDIUM CONFIDENCE AT 90 KNOTS, ROUGHLY IN THE AVERAGE BETWEEN
AGENCY DATA-T AND CURRENT INTENSITY ESTIMATES AND CLOSE TO THE ADT
ESTIMATE. FORWARD MOTION HAS TICKED UP A BIT, NOW MOVING NORTHWEST
AT 03 KNOTS, BUT THE SYSTEM STILL HAS A BIT TO GO BEFORE IT MOVES
OUT OF THE COLD WAKE IT HAS CREATED FOR ITSELF. HWRF SST ESTIMATES
IN THE INDUCED COLD POOL ARE AS LOW AS 24C, WHICH MAY IN FACT BE
RATHER TRUTHFUL BASED ON THE VERY RAPID DETERIORATION SEEN IN THE
SYSTEMS STRUCTURE. OTHERWISE, THE ENVIRONMENT REMAINS FAVORABLE
WITH LOW VWS AND ROBUST OUTFLOW ALOFT AND AS THE SYSTEM CONTINUES
MOVING NORTH IT WILL ENCOUNTER STEADILY INCREASING SSTS AND OHC.

INITIAL WIND RADII BASIS: PERSISTENCE FROM A 260101Z ASCAT-B
SCATTEROMETER PASS. 

CURRENT STEERING MECHANISM: COMPETING STEERING BETWEEN A DEEP
SUBTROPICAL RIDGE (STR) CENTERED NEAR GUAM AND AN EASTWARD
EXTENSION OF A STR CENTERED NEAR SHANGHAI.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   RJTD: T6.0 - 115 KTS
   RCTP: T5.5 - 102 KTS
   KNES: T5.5 - 102 KTS
   CIMSS SATCON: 100 KTS AT 270416Z
   CIMSS ADT: 90 KTS AT 270540Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL
   OTHER FACTORS: UPWELLING INDUCED COLD POOL. 

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: THE DEVELOPMENT OF AN UPPER-LEVEL LOW HEIGHT
CENTER EAST OF NORTHERN HONSHU AND THE DEEP TROUGH EXTENDING SOUTH
THEREOF, HAS BEGUN TO ERODE THE RIDGE THAT EXTENDS EAST FROM
SHANGHAI AND HAS BEEN BLOCKING 20W FROM MOVING POLEWARD OVER THE
PAST DAY OR SO. WHILE THE RIDGE IS STILL IN PLACE IT IS WEAKENING
AND ERODING FROM THE EAST AND GLOBAL MODELS INDICATE THE RIDGE WILL
BREAK WITHIN THE NEXT 12 TO 24 HOURS, ALLOWING 20W TO BREAK OUT OF
JAIL AND ESCAPE TO THE NORTH. THE SYSTEM WILL DRIFT SLOWLY
NORTHWESTWARD THROUGH TAU 24 AS THE RIDGE TO THE NORTH WEAKENS BUT
WILL RAPIDLY PICK UP STEAM THROUGH TAU 48 AS THE RIDGE TO THE EAST
REORIENTS TO A HIGH-AMPLITUDE NORTH-SOUTH AXIS. BY TAU 72, THE
APPROACH OF A DEEP MID-LATITUDE TROUGH FROM THE WEST WILL TURN TY
20W TO THE NORTHEAST, WHILE ACCELERATING IT TO OVER 20 KNOTS. THE
SYSTEM WILL REMAIN OVER THE INDUCED COLD POOL FOR ANOTHER 12 OR SO
WHICH WILL PUT THE BRAKES ON ANY INTENSIFICATION AND SHOULD RESULT
IN A SLIGHT WEAKENING THROUGH TAU 12. ONCE THE SYSTEM MOVES AWAY
FROM THIS COLD POOL HOWEVER, THE ENVIRONMENT WILL SUPPORT
INTENSIFICATION THROUGH TAU 48. MID-LEVEL DRY AIR AND SHEAR WILL
BEGIN TO IMPACT THE SYSTEM BY TAU 72, AND SHEAR IS EXPECTED TO
INCREASE DRAMATICALLY AFTER TAU 96. AS EARLY AS TAU 84 BUT
CERTAINLY NO LATER THAN TAU 96 THE SYSTEM WILL BEGIN TO INTERACT
WITH THE STRONG 200MB WESTERLIES AND BEGIN EXTRATROPICAL TRANSITION
(ETT). AS THE SYSTEM PASSES NORTH OF THE 35TH LATITUDE IT IS
EXPECTED TO COMPLETE ETT AS STORM-FORCE EXTRATROPICAL LOW PRESSURE
AREA. WHILE THE TRACK IS FORECAST TO REMAIN WELL OFFSHORE OF
HONSHU, THE EXPANDING WIND FIELD IS STILL EXPECTED BRING GALE TO
STORM-FORCE WINDS TO THE FAR EASTERN SHORE OF HONSHU. 

MODEL DISCUSSION: TRACK GUIDANCE IS DOING SURPRISINGLY WELL AND
REMAINS IN GOOD CROSS-TRACK AGREEMENT THROUGH THE FORECAST PERIOD,
A SPREAD OF 100 NM AT TAU 72 INCREASING TO 225 NM BY TAU 120.
ALONG-TRACK SPREAD MODESTLY INCREASES AFTER THE SYSTEM CURVES TO
THE NORTHEAST, BUT ONLY INCREASES TO 350 NM BY TAU 120. THE JTWC
FORECAST REMAINS CONSISTENT WITH THE PREVIOUS FORECAST, AND LIES
JUST INSIDE AND SLIGHTLY SLOWER, ESPECIALLY IN THE NEAR-TERM, THAN
THE MULTI-MODEL CONSENSUS MEAN WITH HIGH CONFIDENCE. THE MESOSCALE
MODELS SEEM TO BE PICKING UP ON THE EFFECTS OF THE UPWELLING AND
ONGOING ERC, INDICATING ANOTHER 5-10 KNOTS OF WEAKENING THROUGH TAU
12, FOLLOWED BY RE-INTENSIFICATION THEREAFTER AS THE SYSTEM MOVES
INTO MORE FAVORABLE OCEANOGRAPHIC CONDITIONS, FOLLOWED BY A STEADY
WEAKENING AS THE SYSTEM TRANSLATES POLEWARD. THE JTWC FORECAST
COAMPS-TC FOR THE DURATION OF THE FORECAST, BELOW THE CONSENSUS
MEAN THROUGH TAU 12, THEN ABOUT 5 KNOTS ABOVE IT THEREAFTER WITH
MEDIUM CONFIDENCE. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   TRACK 72-120 HR: HIGH
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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