WDPN31 PGTW 141500
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 08W (MA-ON)//WARNING NR 13//
RMKS/
1. FOR METEOROLOGISTS.
2. TYPHOON (TY) 08W (MA-ON), LOCATED APPROXIMATELY 250 NM SOUTHEAST
OF IWO TO, JAPAN, HAS TRACKED JUST NORTH OF WESTWARD AT 11 KNOTS OVER
THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY AND RECENT
MICROWAVE IMAGERY (141034Z SSMIS AND 141121Z AMSU) SHOW A WELL-
DEFINED EYE WITH SPIRAL BANDING WRAPPING INTO THE LLCC FROM ALL 
QUADRANTS. A MAJORITY OF THE DEEPEST CONVECTION REMAINS ALONG THE 
SOUTHWESTERN QUADRANT, WHICH IS EVIDENT IN THE AFOREMENTIONED 
MICROWAVE PASSES. THERE IS HIGH CONFIDENCE IN THE CURRENT POSITION 
BASED ON A MICROWAVE EYE IN THE AMSU IMAGE AND THE 14/1132Z PGTW EYE 
FIX. THE CURRENT INTENSITY IS BASED ON DVORAK ESTIMATES RANGING FROM 
90 TO 102 KNOTS FROM PGTW, RJTD, AND KNES. RADIAL OUTFLOW CONTINUES 
TO BE ENHANCED BY A MESO-SCALE ANTICYCLONE POSITIONED OVER THE 
SYSTEM, HOWEVER ANIMATED WATER VAPOR REVEALS THAT UPPER LEVEL 
TROUGHING IS CAUSING SLIGHT SUBSIDENCE ALONG THE NORTHERN PERIPHERY 
OF THE SYSTEM AND HINDERING POLEWARD OUTFLOW. TROPICAL UPPER 
TROPOSPHERIC TROUGH (TUTT) CELLS LOCATED TO THE WEST-NORTHWEST AND 
EAST-SOUTHEAST OF THE SYSTEM CONTINUE TO PROVIDE ENHANCED OUTFLOW 
INTO THESE REGIONS. VERTICAL WIND SHEAR REMAINS LESS THAN 15 KNOTS. 
TY 08W IS CURRENTLY TRACKING ALONG THE SOUTHERN PERIPHERY OF A DEEP-
LAYERED SUBTROPICAL RIDGE (STR) POSITIONED EAST OF TOKYO, JAPAN.
3. FORECAST REASONING
   A. THERE ARE NO SIGNIFICANT CHANGES IN FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING BULLETIN.
   B. TY 08W IS EXPECTED TO CONTINUE TRACKING GENERALLY WESTWARD
THROUGH TAU 48 AND INTENSIFY AT A STEADY PACE AS IT TRACKS OVER WARM
SEA SURFACE TEMPERATURES (> 30 DEGREES CELSIUS) AND REMAINS WITHIN A
FAVORABLE UPPER LEVEL ENVIRONMENT. AFTER TAU 48, TY 08W WILL BEGIN
TO TURN POLEWARD AS IT MODIFIES THE STEERING RIDGE, WHICH WILL RECEDE
TO THE EAST. A TRANSITORY MID-LATITUDE TROUGH, CURRENTLY LOCATED OVER
EASTERN CHINA, WILL AID IN RIDGE EROSION AND RE-ORIENTATION.  
   C. AFTER TAU 72, TY MA-ON WILL TURN INCREASINGLY POLEWARD AS IT 
HEADS TOWARD THE SOUTHERN ISLANDS OF SHIKOKU AND KYUSHU. ALTHOUGH, 
WIND SHEAR IS EXPECTED TO INCREASE AS THE SYSTEM CONTINUES TO TRACK 
POLEWARD, TY 08W IS NOT EXPECTED TO WEAKEN SIGNIFICANTLY AS IT 
APPROACHES SOUTHERN JAPAN. NUMERICAL MODEL GUIDANCE IS IN GOOD 
AGREEMENT WITH THE TRACK FORECAST THROUGH TAU 48, BEFORE NOTABLE 
DIVERGENCE OCCURS IN THE LATER TAUS. EGRR AND ECMWF ARE THE WESTERN 
OUTLIERS, TRACKING THE SYSTEM FURTHER WESTWARD IN ANTICIPATION OF 
DIRECT CYCLONE INTERACTION (DCI) WITH A DISTURBANCE IN THE EAST 
PHILIPPINE SEA, BEFORE SHARPLY TURNING THE SYSTEM POLEWARD. NOGAPS 
AND GFS ARE THE EASTERN OUTLIERS, CONTINUING TO INDICATE A SHARP RE-
CURVE SCENARIO IN RESPONSE TO A MORE PRONOUNCED WEAKENING OF THE 
STR. THIS FORECAST IS CONSISTENT WITH THE PREVIOUS  JTWC FORECAST 
TRACK POSITIONED SLIGHTLY RIGHT OF CONSENSUS THROUGH TAU 96 IN FAVOR 
OF A MORE SOLID STR AND MARGINAL DCI. DUE TO THE WIDE SPREAD IN 
NUMERICAL MODEL GUIDANCE IN THE LATER TAUS, THE FORECAST AT TAU 120 
REMAINS SLIGHTLY LEFT OF CONSENSUS TO BE CONSISTENT WITH PREVIOUS 
JTWC FORECASTS UNTIL MODEL GUIDANCE COMES INTO BETTER AGREEMENT.//
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