WDPN31 PGTW 230300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W (TRAMI) WARNING NR 
011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.7N 124.4E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 208 NM EAST-NORTHEAST OF MANILA,
PHILIPPINES
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY
EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) TO THE NORTHEAST OF THE
PRIMARY BROAD CENTRAL CONVECTION ASSOCIATED WITH TROPICAL STORM 22W
(TRAMI). THE CONVECTIVE ACTIVITY REMAINED CONSISTENT OVER THE LAST
SIX HOURS, INDICATING LACK OF FURTHER DEVELOPMENT, AS 22W IS GETTING 
CLOSER TO LUZON. UPPER LEVEL OUTFLOW IS MODERATE, HOWEVER LIMITED 
PRIMARILY TO THE WESTWARD DIRECTION DUE TO SOUTHWESTWARD VERTICAL WIND 
SHEAR. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON 
THE ANIMATED MULTISPECTRAL IMAGERY. THE INITIAL INTENSITY OF 45 KTS IS 
ASSESSED WITH MEDIUM CONFIDENCE BASED ON A COMBINATION OF AUTOMATED 
AND AGENCY ESTIMATES LISTED BELOW. JTWC INTENSITY IS ESTIMATED ABOVE 
THE AUTOMATED DVORAK ANALYSIS DUE TO THE LARGE SIZE OF THE SYSTEM NOT 
BEING COMPLETELY ACCOUNTED FOR IN THE ADT, WHICH DOES NOT ENCOMPASS 
THE CONVECTIVE BANDING ON THE NORTHERN SIDE OF TS 22W.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE
NORTH-NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T3.0 - 45 KTS
   DEMS: T3.0 - 45 KTS
   CIMSS SATCON: 42 KTS AT 220730Z
   CIMSS ADT: 32 KTS AT 230000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE WESTWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: LOW

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TROPICAL STORM 22W IS FORECAST TO CONTINUE
TRACKING NORTHWESTWARD FOR THE NEXT 12 HOURS, AFTER WHICH IT IS
EXPECTED TO TURN WESTWARD, UNDER THE INFLUENCE OF THE SUBTROPICAL
RIDGE TO THE NORTHEAST, AND MAKE LANDFALL OVER CENTRAL LUZON. TS
22W TRANSIT OVER LAND WILL COINCIDE WITH A TEMPORARY BREAK IN THE
RIDGING TO THE NORTH, HOWEVER AS THE SYSTEM RE-EMERGES OVER THE
WATERS OF SOUTH CHINA SEA, THE RIDGE WILL REBUILD AND INFLUENCE THE
PREDOMINANTLY WESTWARD TRACK OF TRAMI. AS THE SYSTEM COMPLETES THE
TRANSIT OVER LUZON, A LEESIDE JUMP SCENARIO IS INDICATED BY SEVERAL
NUMERICAL MODELS AS A SOUTHERN KINK IN THE TRACK AROUND TAU 36. AS THE 
SYSTEM CONTINUES TRANSITING WEST, IT WILL ENCOUNTER FAVORABLE 
ENVIRONMENT, LEADING TO A PEAK INTENSITY OF 60 KTS AROUND TAU 72, 
HOWEVER POSITIVE IMPACTS FROM THE HIGH SEA SURFACE TEMPERATURES, HIGH 
OCEAN HEAT CONTENT AND MODERATE TO LOW VERTICAL WIND SHEAR WILL BE 
OFFSET BY A NORTHEASTERLY SURGE OF COLDER AND DRY AIR. THEREFORE TS 
22W IS FORECAST TO START WEAKENING TOWARDS THE END OF THE FORECAST 
PERIOD. ANOTHER RIDGE BUILDING OVER SOUTHEAST ASIA WILL BECOME A 
FACTOR IN A POTENTIAL FOR TS 22W TO MAKE LANDFALL OVER VIETNAM OR 
REMAIN OVER WATER, TRACKING EITHER NORTH OR SOUTH OF THE 120 TAU 
POSITION.

MODEL DISCUSSION: JTWC FORECAST IS LAID NEAR THE MULTI-MODEL
CONSENSUS WHICH IS COMPRISED OF A FAIRLY CLOSE GUIDANCE OF NO
BIGGER THAN 70 NM CROSS-TRACK SPREAD THROUGHOUT THE FORECAST
PERIOD. THERE IS SOME UNCERTAINTY ASSOCIATED WITH THE AFOREMENTIONED 
LEESIDE JUMP AND THE LOCATION OF THE RE-EMERGENT LLCC, WITH A COUPLE 
MODELS, INCLUDING GFS SUGGESTING A MORE SOUTHERN TRACK. FOLLOWING THE 
LANDFALL OVER NORTHERN PHILIPPINES, ALL NUMERICAL MODEL GUIDANCE 
SUGGESTS A WESTWARD TRACK THROUGHOUT THE FORECAST PERIOD. ANOTHER 
UNCERTAINTY CHECKPOINT HOWEVER IS IDENTIFIABLE AT TAU 120 AND BEYOND, 
WHERE THE TRACK OF TS 22W WILL BE DETERMINED PRIMARILY BY THE 
DEVELOPMENT AND STRENGTH OF THE RIDGE FORMING OVER SOUTHEAST ASIA. GFS 
INDICATES A LANDFALL OVER VIETNAM WHILE OTHERS TAKE THE TRACK SOUTH 
OVER WATER WITH INITIAL SOUTHWARD TURN, AND A POTENTIAL RECURVING 
SCENARIO TOWARDS THE NORTHEAST (ECMWF, GEFS, NAVGEM, UKMET).

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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