WDPN31 PGTW 251500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 26W (BUALOI) WARNING NR 
009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.0N 126.8E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 373 NM EAST-SOUTHEAST OF MANILA,
PHILIPPINES
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 15 KTS
   SIGNIFICANT WAVE HEIGHT: 22 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
STORM 26W (BUALOI) WITH AN EXPANSIVE CENTRAL DENSE OVERCAST
OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC) AND CLOUD TOPS
MEASURING -90 C IN MULTIPLE AREAS OF THE OVERSHOOTING TOPS. A
251044Z GMI 89 GHZ MICROWAVE IMAGE REVEALED THE LOW-LEVEL CLOUDS
TIGHTLY WRAPPING INTO THE NORTHERN PORTION OF THE CIRCULATION AND A
VIGOROUS BURST OF DEEP CONVECTION JUST TO THE SOUTH OF THE ASSESSED
CENTER. ENVIRONMENTAL ANALYSIS CONTINUES TO INDICATE THAT 26W IS IN
A MARGINALLY FAVORABLE ENVIRONMENT CHARACTERIZED BY MODERATE
OUTFLOW ALOFT, MODERATE TO HIGH (20-25 KTS) EAST-NORTHEASTERLY
VERTICAL WIND SHEAR, AND WARM (29-30 C) SEA SURFACE TEMPERATURES.
THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON
EXTRAPOLATION FROM THE MENTIONED GMI MICROWAVE IMAGE. THE INITIAL
INTENSITY OF 55 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE
AGENCY DVORAK AND OBJECTIVE INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A DEEP-LAYERED
SUBTROPICAL RIDGE (STR) CENTERED TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T4.5 - 77 KTS
   RCTP: T3.5 - 55 KTS
   KNES: T4.0 - 65 KTS
   CIMSS SATCON: 53 KTS AT 251210Z
   CIMSS ADT: 57 KTS AT 251210Z
   CIMSS AIDT: 57 KTS AT 251210Z
   CIMSS D-MINT: 57 KTS AT 251043Z
   CIMSS D-PRINT: 53 KTS AT 251210Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 20-25 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: 26W IS FORECAST TO TRACK WEST-NORTHWESTWARD,
ALONG THE SOUTHERN PERIPHERY OF THE LARGE SUBTROPICAL RIDGE TO THE
NORTH THROUGH TAU 48. AN INITIAL LANDFALL ALONG NORTHEASTERN SAMAR
IS EXPECTED WITHIN THE NEXT 6 HOURS. AFTER TAU 48, 26W IS FORECAST
TO TURN SLIGHTLY MORE NORTHWESTWARD AS IT TRACKS ALONG THE
SOUTHWESTERN EXTENT OF THE RIDGE. A SECOND LANDFALL IS CURRENTLY
FORECAST TO OCCUR JUST AFTER TAU 72, NORTH OF VINH. REGARDING
INTENSITY, 26W IS FORECAST TO SLIGHTLY WEAKEN THROUGH TAU 12 DUE TO
THE EASTERLY VERTICAL WIND SHEAR AND TOPOGRAPHIC INTERACTION WITH
THE VISAYAS ISLANDS. THE RELATIVELY LOW ELEVATION AND CONTINUED
SUPPLY OF WARM SEA WATER WILL ALLOW 26W TO STAY AROUND 50 KTS AS IT
TRAVERSES THROUGH THE ISLANDS. AFTER EMERGING WITHIN THE SOUTH
CHINA SEA, THE ENVIRONMENT WILL IMPROVE WITH LOWER VERTICAL WIND
SHEAR, CAUSING 26W TO INTENSIFY AS IT APPROACHES THE GULF OF
TONKIN. THE ENVIRONMENT WITHIN THE GULF OF TONKIN IS EXPECTED TO BE
HIGHLY FAVORABLE, PARTICULARLY IN REGARD TO THE VERY WARM SEA
SURFACE TEMPERATURES. AS A RESULT, THE SYSTEM IS EXPECTED TO PEAK
NEAR TAU 72, SOUTHWEST OF HAINAN. 

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT, WITH THE EXCEPTION OF JGSM, WHICH IS QUITE A BIT FURTHER
NORTH THROUGHOUT THE FORECAST PERIOD THAN THE REMAINDER OF GUIDANCE
IS. WITHOUT JGSM THERE IS A 125 NM CROSS-TRACK SPREAD AT TAU 72.
THE JTWC TRACK FORECAST IS PLACED SLIGHTLY SOUTH OF THE MULTI-MODEL
CONSENSUS WITH OVERALL MEDIUM CONFIDENCE. INTENSITY GUIDANCE IS IN
GOOD AGREEMENT ON INTENSIFICATION AFTER TAU 24 WITH PEAK
INTENSITIES RANGING FROM 65-90 KTS AT TAU 72. HAFS-A AND COAMPS-TC
ARE ON THE LOWER SIDE WHILE GFS IS ON THE MOST AGGRESSIVE. THE JTWC
INTENSITY FORECAST IS HEDGED A BIT CLOSER TO THE HAFS-A GUIDANCE
WITH MEDIUM CONFIDENCE.

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