WDPN31 PGTW 021500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 04W (MAWAR) WARNING NR 08//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON (TY) 04W (MAWAR), LOCATED APPROXIMATELY 540 NM SOUTH-
SOUTHWEST OF KADENA AB, OKINAWA, HAS TRACKED NORTHWARD AT 07 KNOTS 
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE 
IMAGERY SHOWS DEEP CONVECTION LOCATED ALONG THE SOUTHERN AND WESTERN 
PERIPHERIES HAS CONSOLIDATED CLOSER TO THE CENTER AND OVER THE 
NORTHERN HALF OF THE SYSTEM. CONVECTION WITHIN THE NORTHWESTERN 
QUADRANT REMAINS SUPPRESSED, LIKELY IN PART TO THE APPROACHING MID-
LATITUDE TROUGH. A RECENT 020947Z WINDSAT 37H IMAGE SHOWS THE 
DEVELOPING EYE FEATURE AND THE DEEPEST CONVECTION BUILDING ALONG THE 
EASTERN HALF OF TY 04W. THE INITIAL POSITION IS BASED ON THE 
INFRARED SATELLITE LOOP AND A FIX FROM PGTW. THE CURRENT INTENSITY 
IS BASED ON DVORAK INTENSITY ESTIMATES FROM RJTD, KNES, AND PGTW 
INDICATING BETWEEN 65 AND 77 KNOTS. UPPER-LEVEL ANALYSIS AND 
ANIMATED WATER VAPOR IMAGERY SHOW THE POLEWARD OUTFLOW CHANNEL HAS 
BEEN STEADILY IMPROVING OVER THE PAST SIX HOURS AS THE LEADING EDGE 
OF AN APPROACHING MID-LATITUDE TROUGH HAS STARTED TO ENHANCE THE 
OUTFLOW. ADDITIONALLY, VERTICAL WIND SHEAR (VWS) REMAINS WEAK DUE TO 
A SUSTAINED POINT SOURCE OF DIFFLUENCE OVER THE LLCC. TY 04W IS 
CURRENTLY TRACKING ALONG THE WESTERN PERIPHERY OF THE DEEP-LAYERED 
SUBTROPICAL RIDGE (STR) WHICH IS ANCHORED FAR TO THE NORTHEAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE.
   B. A MID-LATITUDE SHORTWAVE TROUGH, CURRENTLY OVER THE EASTERN 
COAST OF CHINA, WILL CONTINUE TO ADVANCE SOUTHEASTWARD CAUSING THE 
STR TO WEAKEN ALONG THE WESTERN PERIPHERY AND BRING TY 04W MORE TO 
THE NORTH. DURING THE NEXT 12 TO 24 HOURS, TY 04W WILL SLOWLY ROUND 
THE STR AXIS, AND WILL BEGIN TO ACCELERATE TO THE NORTHEAST BY TAU 
36. INTENSIFICATION IS EXPECTED THROUGH TAU 48 AS OUTFLOW AND SEA 
SURFACE TEMPERATURE (SST) VALUES REMAIN FAVORABLE. BETWEEN TAU 48 
AND TAU 72 INCREASING VWS IS EXPECTED TO STIFLE FURTHER 
INTENSIFICATION AS TY 04W APPROACHES ZONAL WESTERLIES. ADDITIONALLY, 
AROUND TAU 72 TY 04W IS EXPECTED TO CROSS 25 DEGREES NORTH INTO LESS 
FAVORABLE SST VALUES.
   C. AFTER TAU 72, TY MAWAR IS EXPECTED TO ACCELERATE ALONG THE 
NORTHWESTERN PERIPHERY OF THE STR AND GET ABSORBED INTO THE STRONG 
WESTERLY FLOW OF THE BAROCLINIC ZONE. THE SYSTEM WILL CONTINUE TO 
SIGNIFICANTLY WEAKEN AS IT TRACKS OVER MUCH COOLER SST (LESS THAN 
25C) AND INTO HIGHER VWS. BY TAU 96, THE CYCLONE WILL BEGIN EXTRA-
TROPICAL TRANSITION (ETT) AS IT GETS EMBEDDED IN THE BAROCLINIC ZONE 
THEN COMPLETE ETT BY TAU 120. THERE IS HIGH CONFIDENCE IN THE TRACK 
FORECAST DUE TO THE TIGHT ENVELOPE IN THE NUMERICAL MODEL GUIDANCE. 
THIS FORECAST AGREES WITH THE MODEL CONSENSUS (CONW), HOWEVER IT HAS 
BEEN KEPT SLIGHTLY RIGHT AND SLOWER THAN CONW BEYOND TAU 72 AS THE 
NGPS, GFS, AND GFDN TRACKERS ARE MORE NORTHEASTERLY THAN ECMF, WHICH 
IS SLOWER AND MORE SOUTHWARD THAN CONW. THE FORECAST DURING LATER 
TAUS IS BASED ON THE ECMF TRACKER AND CONW. THE CPA TO KADENA AB HAS 
REMAINED CONSISTENT OVER THE PAST SIX HOURS.//
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