WDPN33 PGTW 290300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 22W (NALGAE) WARNING NR 08//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
    A. TYPHOON (TY) 22W (NALGAE), LOCATED APPROXIMATELY 800 NM EAST-
NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 06 KNOTS 
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY 
SHOWS A SYMMETRICAL, COMPACT, AND DEEPENING SYSTEM WITH DEEP 
CONVECTION IN ALL QUADRANTS. A 281519Z TRMM IMAGE REVEALED A SMALL 
MICROWAVE EYE AS WELL AS THICK CURVED BANDING IN ALL QUADRANTS. A 
281500Z OCEANSAT IMAGE INDICATES THAT THE AREAS OF GALE AND STORM 
FORCE WINDS SURROUNDING THE STORM ARE RELATIVELY SMALL. ANIMATED 
WATER VAPOR IMAGERY REVEALS THE POLEWARD OUTFLOW INTO AN UPPER LEVEL 
TROUGH IS NEARLY ENDED AS THE TROUGH PASSES RAPIDLY DOWNSTREAM. 
IMPINGEMENT ON POLEWARD OUTFLOW HAS EASED DURING THE PAST SIX HOURS, 
HOWEVER, AND OUTFLOW IN GENERAL HAS IMPROVED SIGNIFICANTLY. ANIMATED 
INFRARED IMAGERY DEPICTS A SURGE IN COLD CLOUD TOPS ASSOCIATED WITH 
THE INCREASING CONVECTION. TY 22W IS A WEST RUNNER, STEERING 
STEADILY ALONG THE SOUTHERN PERIPHERY OF THE SUBTROPICAL RIDGE. THE 
CURRENT INTENSITY IS BASED ON DVORAK ANALYSES OF 65 KNOTS FROM BOTH 
PGTW AND KNES. TY 22W IS CURRENTLY UNDER VERY LITTLE VERTICAL WIND 
SHEAR AND SEA SURFACE TEMPERATURES ALONG TRACK ARE 28 TO 29 DEGREES. 
3. FORECAST REASONING. 
    A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY.
    B. TY 22W WILL RUN DEAD WEST ALONG THE SOUTHERN PERIPHERY OF THE 
SUBTROPICAL RIDGE. 500 MB PROGS INDICATE THAT A MID- TO UPPER LEVEL 
ANTICYCLONE BETWEEN TAIWAN AND OKINAWA WILL BUILD EASTWARD AND 
BECOME THE DOMINANT STEERING MECHANISM IN THE NEXT 48 HOURS, DRIVING 
THE STORM WESTWARD AT A VERY STEADY SPEED. THERE ARE SOME 
DISCREPANCIES IN TRACK GUIDANCE THAT ARE SLOWING CONSENSUS. THREE 
VORTEX TRACKERS (NOGAPS, GFDN, AND WBAR) ATTEMPT TO DRIVE THE STORM 
INTO THE RIDGE, WHILE THE STRAIGHT-RUNNING GROUP (ECMWF, GFS, AND 
JGSM) GUIDE THE SYSTEM STEADILY ACROSS THE NORTHERN TIP OF LUZON AND 
INTO THE SOUTH CHINA SEA. GIVEN THE STRENGTH OF THE RIDGE, THE 
POLEWARD TRACKERS ARE EASILY DISMISSED AND THE JTWC TRACK FORECAST 
STAYS SOUTH OF CONSENSUS AND FASTER, CLOSE TO ECMWF, EGRR, AND GFS. 
TY 22W WILL LOSE ITS POLEWARD OUTFLOW CHANNEL AND DEVELOP RADIAL 
OUTFLOW DURING THE NEXT 24 HOURS. LOW VERTICAL WIND SHEAR AND 
FAVORABLE SEA SURFACE TEMPERATURES ARE EXPECTED TO REMAIN ALMOST 
UNCHANGED THROUGH TAU 72. THE PRIMARY WEAKENING MECHANISM FOR TY 22W 
WILL BE LAND INTERACTION WITH NORTHERN LUZON. THE FORECASTED 
INTENSITY TREND IS LIMITED TO A CLIMATOLOGICAL RATE BASED ON THE 
BEHAVIORS OF TY 20W AS IT TRACKED THROUGH THE PHILIPPINE SEA AND TO 
THE CURRENT OUTFLOW PATTERN.   
   C. THE UPPER LEVEL ANTICYCLONE SHIFTING FROM NORTHEASTERN TAIWAN 
TO JUST EAST OF THE RYUKYUS BY TAU 72 WILL BUILD A FIRM RIDGE 
EXTENDING WESTWARD INTO SOUTHERN CHINA. THIS WILL PREVENT ANY 
SIGNIFICANT POLEWARD MOVEMENT AND DRIVE THE STORM ALONG A STRAIGHT 
WESTERLY ACROSS THE SOUTH CHINA SEA. THE STORM SHOULD RAPIDLY 
RECOVER LOST INTENSITY FROM THE TRACK OVER LUZON, BUT RISING 
VERTICAL WIND SHEAR WILL PREVENT THE STORM FROM INTENSIFYING BEYOND 
THE LEVEL AT WHICH IT CROSSED THE LUZON STRAIT. THE JTWC FORECAST IN 
THE EXTENDED PERIOD IS SIGNIFICANTLY FASTER THAN CONSENSUS AND CLOSE 
TO EGRR, ECMWF, AND GFS.//
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