WDPN31 PGTW 211500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 22W (TWENTYTWO) 
WARNING NR 005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.1N 129.0E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 475 NM EAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A BROAD
CIRCULATION WITH CURVED DEEP CONVECTIVE BANDING OBSCURING THE
WESTERN PERIPHERY OF THE LOW-LEVEL CIRCULATION CENTER (LLCC). MID-
TO LOW-LEVEL CIRCULATION CAN BE IDENTIFIED IN THE EASTERN
SEMICIRCLE OF THE SYSTEM. TROPICAL DEPRESSION (TD) 22W CONTINUES TO
STRETCH ACROSS A SOUTHWEST-NORTHEAST AXIS BUT THE VORTICITY MAXIMA
HAS BEGUN TO CONSOLIDATE IN THE SOUTHEASTERN PORTION OF THE
CIRCULATION. A PARTIAL 211235Z METOP-B ASCAT IMAGE HIGHLIGHTS THE
BAND OF 25-30KT WINDS ENCIRCLING THE NORTHERN PERIMETER OF THE
SYSTEM. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED
ON THE AFOREMENTIONED ANIMATED EIR. THE INITIAL INTENSITY OF 30KTS
IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY AND
OBJECTIVE FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T1.5 - 25 KTS
   CIMSS ADT: 32 KTS AT 211130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TD 22W WILL CONTINUE TRACKING WESTWARD FOR THE
NEXT TWELVE HOURS APPROACHING THE ROUNDED EDGE OF THE NORTHERN STR.
THE SYSTEM WILL SHIFT TO A NORTHWESTWARD TRACK UNTIL TAU 48 AS A
DEEP-LAYER TROUGH DIGS SOUTH AND SPLITS THE ELONGATED STR. THE
STEERING ENVIRONMENT WILL BE PICKED UP BY THE SECONDARY RIDGE
CENTERED OVER THE GULF OF TONKIN, DRIVING TD 22W DUE WEST FOR THE
REMAINDER OF THE FORECAST. THE SYSTEM WILL CONTINUE TO DEVELOP AND
INTENSIFY WHILE FAVORABLE FEATURES OF HIGH SEA SURFACE TEMPERATURE
(29-30C), HIGH OCEAN HEAT CONTENT, AND STRONG POLEWARD AND
EQUATORWARD OUTFLOW WILL CONTINUE THROUGH TAU 36. THE PEAK
INTENSITY OF 55KTS WILL OCCUR AT TAU 36 IN SPITE OF MARGINALLY
FAVORABLE TO MODERATE TO HIGH VERTICAL WIND SHEAR HINDERING THE
RATE OF INTENSIFICATION, BUT THE EXPONENTIAL STRONG OUTFLOW IS
EXPECTED TO ACT AS A COUNTERWEIGHT. VERTICAL WIND SHEAR WILL
INCREASE AS THE SYSTEM TRACKS CLOSE TO LUZON AT TAU 48, BECOMING
UNFAVORABLE AND INITIATING WEAKENING JUST PRIOR TO LANDFALL ON THE
COAST OF NORTHERN LUZON. SIGNIFICANT WEAKENING WILL OCCUR WHILE
PASSING OVER LAND AND PARTICULARLY OVER THE CORDILLERA MOUNTAIN
RANGE LINING WESTERN LUZON. THE SYSTEM WILL CONTINUE MEAGERLY
INTENSIFYING AFTER PASSING BACK OUT OVER WATER AT TAU 72 IN AN
ENVIRONMENT OF WARM SEA SURFACE TEMPERATURES, FAVORABLE OUTFLOW,
AND MODERATE VERTICAL WIND SHEAR.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THAT THE SYSTEM WILL TRACK NORTHWESTWARD IN THE EARLY-TERM FORECAST
AND NEARLY DUE WEST IN THE LATE-TERM. THERE IS MORE OF A SPREAD IN
THE INTENSITY AS THE LARGE SIZE OF THE CIRCULATION BECOMES
DIFFICULT FOR THE MODELS TO ASSESS HOW SEVERELY THE SYSTEM
INTENSIFIES OR WEAKENS DUE TO VERTICAL WIND SHEAR AND LAND
INTERACTION BETWEEN TAU 48-72. THE HWRF SOLUTION IS PARTICULARLY
OUTSTANDING WITH A SOLUTION OF CONTINUOUS INTENSIFICATION AND A
PEAK OF 80KTS AT TAU 96. THE JTWC FORECAST LIES CLOSER TO THE
SOLUTION OF THE OTHER MESOSCALE MODEL, HAFS-A, WHICH FORECASTS A
PEAK OF 50KTS AT TAU 36 AND SHOWS AN INTENSIFICATION TREND AFTER
TAU 72.

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