WDPN31 PGTW 240300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W (TRAMI) WARNING NR 
015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.0N 121.2E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 144 NM NORTH OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: OVER LAND

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS SHALLOWING
CONVECTION OVER A LOW-LEVEL CIRCULATION CENTER PASSING OVER CENTRAL
LUZON. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON
A 232236Z SSMIS PASS, SATELLITE POSITION FIXES FROM PGTW AND RJTD,
AND NEARBY SYNOPTIC OBSERVATIONS. THE INITIAL INTENSITY OF 45 KTS
IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A SUBJECTIVE DVORAK
ESTIMATE FROM RJTD AND SUPPORTING SURFACE PRESSURE OBSERVATIONS. TS
22W HAS TAKEN AN EQUATORWARD JOG WHILE MOVING WESTWARD ACROSS THE
MOUNTAINOUS TERRAIN OF CENTRAL LUZON OVER THE PAST SIX HOURS.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   RJTD: T3.0 - 45 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 10-15 KTS
   SST: OVER LAND
   OUTFLOW: STRONG WESTWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 22W IS EXPECTED TO CONTINUE TRACKING
GENERALLY WESTWARD ALONG THE PERIPHERY OF SUBTROPICAL RIDGING TO
THE NORTH THROUGH TAU 96. SLOW INTENSIFICATION WILL OCCUR AFTER THE
SYSTEM REEMERGES OVER WATER IN ABOUT SIX HOURS, SUPPORTED BY
CONTINUED FAVORABLE WESTWARD OUTFLOW ALOFT AND LIMITED BY THE
EXPANSE SIZE OF THE CIRCULATION AND INCREASING EASTERLY VERTICAL
WIND SHEAR. BY TAU 48, THE INCREASING SHEAR SHOULD INDUCE A
WEAKENING TREND THAT IS EXPECTED TO CONTINUE THROUGH THE REMAINDER
OF THE FORECAST PERIOD. BY TAU 96, THE SUBTROPICAL STEERING RIDGE
SHOULD ERODE AHEAD OF A DEVELOPING MID-LATITUDE TROUGH WHILE A NEAR 
EQUATORIAL RIDGE BUILDS TO THE SOUTH OF THE SYSTEM, CAUSING TS 22W TO 
ENTER A COMPETING STEERING ENVIRONMENT AND EVENTUALLY TAKE A SLOW 
TURN 
EASTWARD BY TAU 120.

MODEL DISCUSSION: NUMERICAL MODEL FORECAST GUIDANCE IS IN GOOD
AGREEMENT REGARDING EVOLUTION OF THE OVERALL STEERING PATTERN AND
THE INTENSITY TREND, WITH NAVGEM THE NOTABLE EXCEPTION AS A
OUTLIER WELL TO THE NORTH OF THE PRIMARY MODEL GROUPING. GFS ALSO
DEPICTS A TRACK SLIGHTLY FARTHER TO THE WEST NEAR THE COAST OF
VIETNAM IN THE EXTENDED PERIOD. MODEL INTENSITY FORECAST GUIDANCE
SUGGESTS MODEST NEAR-TERM INTENSIFICATION AND WEAKENING AFTER TAU 48, 
ALTHOUGH THE JTWC FORECAST IS HELD A BIT ABOVE THE GUIDANCE PACKAGE 
IN 
THE EXTENDED RANGE AS PASSAGE OVER VERY WARM WATER AND FAVORABLE 
OUTFLOW ARE EXPECTED TO HOLD THE SYSTEM ABOVE THE TROPICAL STORM 
THRESHOLD. 

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