WDPN31 PGTW 011500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 27W (TWENTYSEVEN) 
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.6N 129.7E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 505 NM EAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: WESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
DEPRESSION (TD) 27W WITH FLARING CONVECTION SCATTERED AROUND AN
OBSCURED LOW-LEVEL CIRCULATION CENTER (LLCC). DEEP CONVECTION IS
STILL NOT WELL-ORGANIZED OVER THE CENTER, WHICH IS APPARENT IN A
010926Z SSMIS 91 GHZ MICROWAVE IMAGE. THE SSMIS IMAGE SHOWS WEAK,
FRAGMENTED BANDING WRAPPING INTO THE LLCC. THE CURRENT INTENSITY IS
A BIT DIFFICULT TO ACCURATELY ASSESS DUE TO THE LARGE DIFFERENCE
BETWEEN ASCAT DATA, AGENCY DVORAK FIXES, AND CIMSS OBJECTIVE
ESTIMATES. A 011204Z ASCAT PASS REVEALED 15-20 KTS WITHIN THE
WESTERN PERIPHERY OF THE CIRCULATION (MISSING THE DIRECT CENTER).
ON THE OTHER HAND, AGENCY DVORAK FIXES AND CIMSS ESTIMATES HOVER
AROUND THE 30-35 KNOT RANGE. AS A RESULT, THE INITIAL INTENSITY OF
25 KTS IS ASSESSED WITH LOW CONFIDENCE. THE INITIAL POSITION IS
PLACED WITH MEDIUM CONFIDENCE BASED ON THE ANIMATED EIR IMAGERY AND
EXTRAPOLATION FROM THE AFOREMENTIONED SSMIS MICROWAVE IMAGE.
ENVIRONMENTAL ANALYSIS INDICATES THAT 27W IS IN A FAVORABLE
ENVIRONMENT CHARACTERIZED BY MODERATE POLEWARD AND EQUATORWARD
OUTFLOW ALOFT, LOW (5-10 KTS) VERTICAL WIND SHEAR, AND WARM (29-30
C) SEA SURFACE TEMPERATURES.

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

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE POSITIONED TO THE
NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T2.0 - 30 KTS
   CIMSS ADT: 30 KTS AT 011140Z
   CIMSS AIDT: 31 KTS AT 011140Z
   CIMSS D-MINT: 25 KTS AT 010926Z
   CIMSS D-PRINT: 30 KTS AT 011140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: LOW
   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: 27W IS FORECAST TO TRACK WEST-NORTHWESTWARD,
UNDER THE INFLUENCE OF THE BUILDING SUBTROPICAL RIDGE TO THE NORTH
THROUGHOUT THE ENTIRE FORECAST PERIOD. AN INITIAL LANDFALL IS
CURRENTLY FORECAST TO OCCUR NEAR TAU 36, ALONG THE SOUTHEASTERN
PORTION OF THE CAGAYAN PROVINCE. A SECOND LANDFALL IS THEN FORECAST
TO OCCUR JUST BEFORE TAU 96, NEAR THE LEIZHOU PENINSULA. REGARDING
INTENSITY, 27W IS FORECAST TO INTENSIFY OVER THE NEXT 36 HOURS TO 
AROUND 55 KTS IN RESPONSE TO A FAVORABLE ENVIRONMENT WITH LOW SHEAR 
AND WARM SEA SURFACE TEMPERATURES. AFTER TAU 12, THE POLEWARD OUTFLOW 
CHANNEL IS EXPECTED TO IMPROVE, WHICH COULD POTENTIALLY SPUR A BOUT 
OF RAPID INTENSIFICATION AS THE SYSTEM APPROACHES THE COAST OF LUZON. 
A BRIEF PERIOD OF STAGNATION IN THE INTENSITY TREND IS EXPECTED AS 
THE SYSTEM TRACKS ALONG NORTHERN LUZON. ANOTHER PERIOD OF 
INTENSIFICATION IS FORECAST AS 27W TRAVERSES THROUGH THE SOUTH CHINA 
SEA DUE TO THE HIGHLY FAVORABLE ENVIRONMENT IN THE AREA. A PEAK 
INTENSITY WILL LIKELY OCCUR NEAR TAU 84, WHICH IS NOT CAPTURED BY THE 
FORECAST DUE TO TEMPORAL RESTRICTIONS. AFTER MAKING LANDFALL IN 
SOUTHERN CHINA, TERRAIN INTERACTION WILL RAPIDLY DETERIORATE THE 
VORTEX.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN VERY GOOD
AGREEMENT THROUGH TAU 96. AT TAU 36, NEAR THE TIME OF LANDFALL IN
LUZON, THERE IS AN 80 NM CROSS-TRACK SPREAD (50 NM WITHOUT NAVGEM).
AT TAU 96, NEAR THE TIME OF THE SECOND LANDFALL EVENT, THERE IS A
115 NM CROSS-TRACK SPREAD. AFTER TAU 96, MODELS BEGIN TO DIVERGE
DUE TO THE RAPIDLY WEAKENING VORTEX. THE JTWC TRACK FORECAST IS
PLACED CLOSE TO THE MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE
THROUGH TAU 72 AND MEDIUM CONFIDENCE THEREAFTER. INTENSITY HAS MORE
UNCERTAINTY WITH MANY RAPID INTENSIFICATION AIDS CONTINUING TO
TRIGGER THROUGH THE FIRST 36 HOURS OF THE FORECAST PERIOD. PEAK
INTENSITIES AT TAU 84 RANGE FROM 60 KTS (GFS) TO 105 KTS (COAMPS-TC). 
THE JTWC INTENSITY FORECAST IS PLACED JUST UNDER THE RAPID 
INTENSIFICATION AIDS THROUGH TAU 36 AND THEN NEAR THE CONSENSUS 
THROUGH TAU 120 WITH OVERALL LOW CONFIDENCE.

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