WDPN32 PGTW 121500
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 08W//WARNING NR 05//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
   A. TROPICAL STORM (TS) 08W (MA-ON), LOCATED APPROXIMATELY 800 NM 
EAST-SOUTHEAST OF IWO TO, JAPAN, HAS TRACKED WESTWARD AT 11 KNOTS 
OVER THE PAST SIX HOURS. RECENT ANIMATED INFRARED SATELLITE IMAGERY 
(MSI) SHOWS CONVECTION CONSOLIDATING AND INTENSIFYING AROUND THE LOW 
LEVEL CIRCULATION CENTER (LLCC). A 120727Z SSMIS IMAGE SHOWS DEEP 
CONVECTION BECOMING BETTER ESTABLISHED OVER BOTH THE NORTHERN AND 
EASTERN QUADRANTS. ALTHOUGH TOTAL PRECIPITABLE WATER LOOPS SHOW THE 
AREA WEST OF THE STORM BECOMING INCREASINGLY SATURATED, THE 37GHZ 
CUT OF THE SSMIS SERIES REVEALS VERY LITTLE LOW LEVEL BANDING OVER 
THE SOUTHWESTERN QUADRANT. THE ABSENCE OF BANDING IS A RESULT OF 
SUBSIDENCE ASSOCIATED WITH A TROPICAL UPPER TROPOSPHERIC TROUGH 
(TUTT), WHICH EXTENDS ALONG THE 21ST LATITUDE. THE TUTT IS IMPINGING 
ON POLEWARD OUTFLOW. ALTHOUGH ANIMATED WATER VAPOR IMAGERY DOES SHOW 
GOOD OUTFLOW TO THE SOUTHEAST, IT ALSO SHOWS SUPPRESSED OUTFLOW OVER 
THE SOUTHWESTERN QUADRANT. THUS, TS 08W HAS SUPPRESSED OUTFLOW IN 
ALL BUT ONE QUADRANT. DIFFUSE ORGANIZATION IN THE BOUNDARY LEVEL 
CONFIRMS THAT THE SYSTEM'S ENERGY IS DISPERSED OVER A BROAD REGION, 
STEALING ENERGY AWAY FROM THE CORE. THE CURRENT INENSITY ANALYSIS IS 
BASED ON DVORAK ESTIMATES OF 35 KNOTS FROM PGTW, RJTD, AND KNES. 
VERTICAL WIND SHEAR IS APPROXIMATELY 10 KNOTS. SEA SURFACE 
TEMPERATURES ALONG TRACK RANGE FROM 30 TO 32 DEGREES. TS 08W IS 
STEERING ALONG THE SOUTHERN PERIPHERY OF THE SUB-TROPICAL RIDGE, 
WHICH EXTENDS FROM AN ANTICYLONE SOUTHEAST OF TOKYO. 
3. FORECAST REASONING.
   A. THERE IS NO CHANGE IN FORECAST PHILOSOPHY. 
   B. THE ANTICYCLONE SOUTHEAST OF TOKYO IS EXPECTED TO REMAIN 
STEADY AND STATIONARY THROUGH 72 HOURS, WHICH WILL KEEP TS 08W ON A 
STEADY WEST-NORTHWESTERLY COURSE ALONG THE SOUTHERN FLANK OF THE SUB-
TROPICAL RIDGE. VERTICAL WIND SHEAR ALONG TRACK WILL REMAIN BELOW 15 
KNOTS AND SEA SURFACE TEMPERATURES WILL REMAIN HIGH (BETWEEN 30 AND 
32 DEGREES). OUTFLOW WILL FLUCTUATE AS THE SYSTEM OCCASIONALLY LINKS 
WITH AN EMBEDDED TUTT CELL AND RECEIVES A BOOST TO POLEWARD OUTFLOW, 
BUT FOR THE MOST PART, THE TUTT WILL ACT AS A SUPPRESSING MECHANISM. 
THUS, TS 08W IS EXPECTED TO INTENSIFY AT A LESS-THAN-CLIMATOLOGICAL 
RATE THROUGH TAU 72. THE INTENSITY FORECAST FOLLOWS STIPS GUIDANCE 
CLOSELY. THE TRACK FORECAST FOLLOWS VIRTUALLY ALL AIDS AS THEY ARE 
IN TIGHT AGREEMENT, BUT THE ALONG-TRACK SPEED IS SLIGHTLY FASTER 
THAN CONSENSUS DUE TO AN OBSERVED TENDENCY OF STRAIGHT RUNNERS TO BE 
FASTER THAN CONSENSUS.
   C. BEGINNING NEAR THE TAU 84-96 PERIOD, THE SUB-TROPICAL RIDGE 
WILL WEAKEN AND RE-ORIENT TO THE SOUTHEAST AND ALLOW THE STORM TO 
TURN POLEWARD. MODEL GUIDANCE IS CONSISTENT REGARDING A TRACK SOUTH 
OF IWO TO, AND THE LONGER RANGE PROGS ARE INDICATING POLEWARD 
MOVEMENT PRIOR TO THE RYUKUS. THE SYNOPTIC PATTERN IS FAVORABLE FOR 
STEADY INTENSIFICATION THROUGH THE NEXT FIVE DAYS, ALTHOUGH THE TUTT 
WILL KEEP THE INTENSIFICATION RATE LOWER THAN NORMAL. THE FORECAST 
TRACK IS SLIGHTLY FASTER THAN CONSENSUS ALONG THE SAME TRACK, WHILE 
THE INTENSITY FORECAST IS BASED CLOSELY ON STIPS GUIDANCE.//

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