WDPN31 PGTW 170300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 05W (GUCHOL) WARNING NR 
25//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUPER TYPHOON (STY) 05W (GUCHOL), LOCATED APPROXIMATELY 550 NM SOUTH 
OF KADENA AB, OKINAWA, HAS TRACKED NORTH-NORTHWESTWARD AT 12 KNOTS 
OVER THE PAST SIX HOURS. MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS 
THE EYE CONTINUES TO HAVE A COMPRESSED EYEWALL ALONG THE 
NORTHWESTERN QUADRANT EVEN THOUGH DEEP CONVECTION HAS EXPANDED ALONG 
THE SOUTHERN HALF OF THE SYSTEM. A SERIES OF MICROWAVE IMAGES 
INCLUDING A 161838Z TRMM, A 161951Z SSMI, AND A 162130Z WINDSAT SHOW 
A POSSIBLE DOUBLE WALL OF CONVECTION CLOSING AROUND THE CENTRAL WALL 
OF CONVECTION. UPPER LEVEL ANALYSIS INDICATES THE SELF-INDUCED 
MESOSCALE ANTICYCLONE OVER THE LOW LEVEL CIRCULATION CENTER (LLCC) 
CONTINUES TO VENT THE SYSTEM ALONG THE EQUATORWARD OUTFLOW CHANNEL 
AND IS BEGINNING TO SEE AN INCREASE IN POLEWARD OUTFLOW TOWARDS THE 
LEADING EDGE OF A MID-LATITUDE TROUGH, HOWEVER THE POLEWARD CHANNEL 
HAS YET TO TAP INTO THE STRONG UPPER LEVEL JET ASSOCIATED WITH THE 
TROUGH. THE INDICATIONS ARE THAT THE EYEWALL REPLACEMENT CYCLE (ERC) 
HAS STARTED AND WILL LIKELY CONTINUE THROUGH THE NEXT 24 HOURS. THE 
CURRENT INTENSITY HAS BEEN MAINTAINED AT 130 KNOTS AS THE OVERALL 
STRUCTURE REMAINS WELL ORGANIZED WITH SEA SURFACE TEMPERATURES 
(SSTS) BEING VERY FAVORABLE (30 CELSIUS), UPPER LEVEL SUPPORT 
IMPROVING, AND VERTICAL WIND SHEAR (VWS) REMAINING LOW. A 6.5/6.5 
DVORAK ESTIMATE FROM PGTW SUPPORTS THE CURRENT INTENSITY. STY 05W IS 
CURRENTLY TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A DEEP-
LAYERED SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE.
   B. STY 05W IS EXPECTED TO CONTINUE TRACKING NORTH-NORTHWESTWARD 
THROUGH TAU 12. THE TRACK WILL SLOWLY SHIFT TO A NORTHWARD TRACK AS 
THE SYSTEM ITSELF WEAKENS THE STR ALLOWING STY 05W TO MOVE POLEWARD 
TOWARD THE MID-LATITUDES. A MID-LATITUDE LOW PRESSURE SYSTEM OVER 
EASTERN CHINA WILL BEGIN TO ENHANCE THE TROUGH EXTENDING OVER THE 
EASTERN COAST OF JAPAN, HELPING TO FURTHER WEAKEN THE NORTHWESTERN 
QUADRANT OF THE STEERING STR BETWEEN TAU 24 AND 72. STY 05W IS 
EXPECTED TO MAINTAIN INTENSITY AT OR NEAR SUPER TYPHOON LEVELS OVER 
THE NEXT 36 HOURS AS IT GOES THROUGH AN ERC. THE TEMPORARY WEAKENING 
OF THE CORE EYEWALL WILL BE OFFSET BY INCREASED UPPER LEVEL SUPPORT 
WITH THE MORE NORTHWARD TRACK TOWARDS THE MID-LATITUDES AND 
FAVORABLE SSTS THROUGH APPROXIMATELY 25N (29 TO 30 DEGREES CELSIUS). 
BEYOND TAU 36 INCREASING VWS AND DECREASING SSTS WILL START TO 
WEAKEN STY 05W. WEAKENING WILL ACCELERATE BETWEEN TAU 48 AND 72 AS 
THE MAGNITUDES FOR VWS AND SSTS INCREASE. EXTRA-TROPICAL TRANSITION 
(ETT) IS EXPECTED TO BEGIN AROUND TAU 60. MODEL GUIDANCE IS IN GOOD 
AGREEMENT THROUGH TAU 48 AND BEGINS TO SPREAD AT TAU 72 WITH GFS AND 
NGPS STILL SHOWING A MORE MAINLAND JAPAN TRACK. BASED ON THE 
CONTINUED SUPPORT OF THE TROUGH OVER JAPAN EXPECTED THROUGH TAU 72, 
THESE TRACKS ARE LESS LIKELY, THEREFORE, THERE IS HIGH CONFIDENCE IN 
THE INITIAL PORTION OF THE JTWC TRACK FORECAST.
   C. IN THE EXTENDED FORECAST, STY 05W SHOULD BECOME FULLY ABSORBED 
WITHIN THE BAROCLINIC ZONE BETWEEN TAU 72 AND 96, EAST OF JAPAN. STY 
05W WILL ENCOUNTER INCREASINGLY UNFAVORABLE VWS AND SSTS (18-20 
DEGREES CELSIUS) AS IT COMPLETES ETT. EVEN THOUGH THE SYSTEM WILL 
WEAKEN RAPIDLY DUE TO THE HIGH VWS AND INTERACTION WITH LAND, IT 
WILL LIKELY MAINTAIN GALE- TO STORM-FORCE WINDS AS AN EXTRA-TROPICAL 
LOW. NUMERICAL MODELS REMAIN IN GOOD AGREEMENT WITH THE TRACK 
PASSING OVER THE EASTERN COAST OF JAPAN. THE JTWC FORECAST IS RIGHT 
OF, AND FASTER THAN CONSENSUS DURING THIS TIME TO ACCOUNT FOR THE 
INCREASED RIDGE MODIFICATION NOTED EARLIER. THERE IS HIGH CONFIDENCE 
IN THE SPEED OF THE TRACK, HOWEVER THERE IS SOME CONCERN REGARDING 
WHETHER THE SYSTEM WILL WEAKEN MORE RAPIDLY DUE TO THE CLOSE 
INTERACTION WITH COASTAL JAPAN DURING THE ETT PROCESS. THE CURRENT 
FORECAST IS BASED ON THE CONSERVATIVE INTENSITY MODEL GUIDANCE 
AVAILABLE.//
NNNN