WDPN31 PGTW 242100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 33W (THIRTYTHREE) 
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 9.8N 123.7E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 329 NM SOUTH-SOUTHEAST OF MANILA,
PHILIPPINES
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
OVER THE PAST SIX HOURS, NOW TD 33W HAS MOVED OVER THE BOHOL SEA,
CROSSED OVER THE SOUTHERN PORTION OF BOHOL ISLAND AND IS NOW MOVING
ACROSS THE SOUTHERN SECTIONS OF CEBU. ANIMATED ENHANCED INFRARED
(EIR) SATELLITE IMAGERY DEPICTS A RELATIVELY SYMMETRICAL AREA OF
DEEP, PERSISTENT CONVECTION, REMINISCENT OF A CENTRAL DENSE
OVERCAST (CDO) FEATURE. ANIMATED RADAR DATA FROM PAGASA SHOWS A
POSSIBLE LOW LEVEL CIRCULATION CENTER (LLCC) OVER THE SOUTHERN
PORTION OF BOHOL AROUND 1800Z, MOVING TO THE WEST-NORTHWEST, AND
SURFACE OBSERVATIONS FROM TAGBILARAN INDICATE BACKING WINDS,
CURRENTLY FROM THE SOUTHWEST, INDICATIVE OF A PASSAGE OF THE CENTER
TO THE NORTH AND NORTHWEST OF THE STATION OVER THE PAST FEW HOURS.
FINALLY, A 241724Z GMI 37GHZ MICROWAVE IMAGE SHOWS A WEAK LOW
EMISSIVITY REGION (LER) ALONG THE SOUTHWESTERN COAST OF BOHOL,
GENERALLY CONSISTENT WITH THE RADAR AND OBSERVATIONAL DATA,
PROVIDING MODERATE TO HIGH CONFIDENCE IN THE INITIAL POSITION. THE
INITIAL INTENSITY IS ASSESSED WITH LOW CONFIDENCE, HEDGED A BIT
LOWER THAN THE AGGRESSIVE PGTW AND RJTD DVORAK CURRENT INTENSITY
ESTIMATES IN LIGHT OF THE WEAK WINDS REPORTED IN OBSERVATIONS FROM
AROUND THE REGION AND NEAR THE CENTER. ENVIRONMENTAL CONDITIONS ARE
FAVORABLE FOR INTENSIFICATION, WITH LOW EASTERLY WIND SHEAR, WARM
SSTS AND GOOD POLEWARD AND EQUATORWARD OUTFLOW ALOFT, OFFSET IN THE
SHORT-TERM BY DISRUPTIONS INDUCED BY THE PROXIMITY OF TERRAIN.

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

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED FAR TO THE NORTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   CIMSS D-PRINT: 30 KTS AT 241800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD
   OTHER FACTORS: LAND INTERACTION WITH THE ISLANDS OF THE CENTRAL
PHILIPPINES. 

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: OVER THE NEXT 6 TO 12 HOURS, EXPECT SOME
OCCASIONALLY ERRATIC MOTION, AS THE EXACT TRACK OF TD 33W WILL BE
HIGHLY INFLUENCED BY THE LOCALIZED TERRAIN FEATURES. THE OFFICIAL
FORECAST DEPICTS A TRACK ACROSS SOUTHERN CEBU, CENTRAL NEGROS AND
CLIPPING THE SOUTHERN TIP OF PANAY ISLANDS AS THE SYSTEM MOVES INTO
THE NORTHERN SULU SEA. HOWEVER, A TRACK MORE OVER CENTRAL PANAY IS
POSSIBLE, AND AS DEPICTED IN A COUPLE OF THE MESOSCALE MODELS.
REGARDLESS OF EXACTLY HOW IT GETS THERE, TD 33W WILL MOVE INTO THE
SULU SEA WITHIN THE NEXT 12 HOURS, MOVING NORTHWESTWARD ALONG THE
SOUTHWESTERN PERIPHERY OF THE DEEP STR POSITIONED TO THE NORTHEAST.
THE SYSTEM IS FORECAST TO PASS NORTHERN PALAWAN WITHIN THE NEXT 24
HOURS AND MOVE INTO THE SOUTH CHINA SEA, WHERE THE TRACK BOTH SLOWS
AND TURNS MORE WESTWARD AFTER TAU 36. BEYOND TAU 36, THE TRACK
BECOMES MORE ERRATIC, SLOWING SIGNIFICANTLY AS TD 33W MOVES INTO A
COMPETING STEERING ENVIRONMENT, TRAPPED BETWEEN RIDGING TO THE WEST
AND EAST AND A WEAKNESS IN THE RIDGE TO THE NORTH. AFTER DRIFTING
SLOWLY WESTWARD FOR A COUPLE DAYS, TD 33W BEGINS TO TURN POLEWARD
AFTER TAU 96 AS THE RIDGE TO THE EAST BEGINS TO BUILD IN FROM THE
EAST. IN TERMS OF INTENSITY, AFTER BEING DISRUPTED BY FRICTIONAL
EFFECTS AS IT TRANSITS OVER CEBU AND NEGROS, THE SYSTEM RAPIDLY
RECOVERS ONCE IT MOVES INTO THE SULU SEA AND BEGINS TO STEADILY
INTENSIFY, EXPECTED TO REACH 35 KNOTS ALMOST IMMEDIATELY AFTER
MOVING INTO THE NORTHERN SULU SEA. CONTINUED FAVORABLE CONDITIONS
WILL SUPPORT STEADY INTENSIFICATION THROUGH TAU 60, WHERE THE
ACTUAL PEAK INTENSITY IS EXPECTED TO REACH 65-70 KNOTS, THOUGH THIS
IS NOT EXPLICITLY CAPTURED IN THE CURRENT FORECAST POINTS. A LOW
PROBABILITY OF RAPID INTENSIFICATION (RI) EXISTS BETWEEN TAU 36 AND
TAU 60, WHEN CONDITIONS WILL BE AT THE MOST FAVORABLE. AFTER TAU 60
HOWEVER, SHEAR IS FORECAST TO RAPIDLY INCREASE TO UNFAVORABLE
LEVELS AS THE SYSTEM BEGINS TO INTERACT WITH A LOW-LEVEL
NORTHEASTERLY COLD-SURGE EVENT. INTENSITY DROPS OFF QUICKLY AS THE
SYSTEM BECOMES COCOONED IN DRY MID-LEVEL AIR, IS CUT-OFF FROM ITS
POLEWARD OUTFLOW CHANNEL AND MOVES INTO COOLER WATERS. 

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN GOOD AGREEMENT
THROUGH TAU 72, WITH THE MODEL ENVELOPE CROSS-TRACK SPREAD
INCREASING TO 115NM. THE NAVGEM AND GFS ARE SITUATED ON THE
NORTHERN EDGE OF THE ENVELOPE, AND THE ECMWF ON THE SOUTHERN EDGE.
AFTER TAU 72, THE MODEL GUIDANCE BEGINS TO DISPERSE, WITH THE ECMWF
CONTINUING THE SYSTEM WESTWARD INTO VIETNAM WHILE THE GEFS MEAN
TURNS SHARPLY NORTHEAST THROUGH TAU 120, LEADING TO A SPREAD OF
315NM BY THE END OF THE FORECAST PERIOD. ENSEMBLE MEANS ARE IN VERY
GOOD AGREEMENT, WITH ALL MAJOR ENSEMBLES AND AI ENSEMBLES DEPICTING
A TRACK NORTH OF PALAWAN AND ACROSS THE SOUTH CHINA SEA, LENDING
HIGHER CONFIDENCE IN THE TRACK FORECAST, WHICH IS POSITIONED CLOSE
TO THE ECMWF AND GDM MEAN THROUGH TAU 72, THEN CLOSE TO THE
ECMWF-AIFS AND GDM MEAN THROUGH THE END OF THE FORECAST PERIOD.
INTENSITY GUIDANCE IS IN GOOD AGREEMENT ON THE OVERALL TREND,
THOUGH WITH A RELATIVELY LARGE AMOUNT OF UNCERTAINTY IN THE PEAK
INTENSITY. HWRF IS THE MOST AGGRESSIVE MODEL, INDICATING A PEAK
NEAR 80 KNOTS, WHILE THE GFS SHIPS GUIDANCE IS THE LEAST IMPRESSED,
PEAKING THE SYSTEM AT JUST 45 KNOTS. THE REMAINDER OF THE GUIDANCE
LIES BETWEEN THE EXTREMES, GENERALLY FOCUSED IN THE 55-65 KNOT
RANGE. THE JTWC FORECAST IS PLACED NEAR THE COAMPS-TC (CTCX) TREND
LINE, WITH MEDIUM CONFIDENCE. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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