WDPN31 PGTW 280900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 26W (NALGAE)      
WARNING NR 006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.5N 126.7E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 356 NM EAST-SOUTHEAST OF MANILA,
      PHILIPPINES
   MOVEMENT PAST 6 HOURS: WESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A
CONSOLIDATING SYSTEM WITH IMPROVED CONVECTIVE BANDING AND CORE
CONVECTION. DESPITE THE IMPROVED OVERALL STRUCTURE EVIDENT IN MSI
AND INCREASED CONFIDENCE IN THE INITIAL POSITION, A 280531Z ATMS
88.2GHZ MICROWAVE IMAGE REVEALS A BROAD LOW-LEVEL CIRCULATION
CENTER WITH DEEP CONVECTIVE BANDING OVER THE SOUTHERN SEMICIRCLE
WRAPPING INTO THE NORTHEAST QUADRANT. AS FORECAST WELL BY THE
GLOBAL MODELS, THE TUTT, WHICH HAD BEEN PRESENT OVER THE
NORTHWESTERN QUADRANT, HAS SHIFTED NORTH AND WEAKENED ALLOWING
UPPER-LEVEL OUTFLOW TO IMPROVE OVER THE PAST 12 HOURS. THE INITIAL
INTENSITY OF 40 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON AN
AVERAGE OF THE DVORAK ESTIMATES AND THE CIMSS ADT ESTIMATE.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.5 - 35 KTS
   KNES: T2.5 - 35 KTS
   CIMSS SATCON: 44 KTS AT 280440Z
   CIMSS ADT: 39 KTS AT 280540Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL
   OTHER FACTORS: INTERACTION WITH LAND

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 26W IS FORECAST TO TRACK WEST-NORTHWESTWARD
THROUGH TAU 36 ALONG THE SOUTHERN PERIPHERY OF THE STR. THE SYSTEM
WILL SLOWLY INTENSIFY THROUGH TAU 24 AS IT SKIRTS THE SOUTHEASTERN
COAST OF LUZON WITH A PEAK INTENSITY OF 55 KNOTS EXPECTED AT TAU 24
THEN A SLIGHT WEAKENING TREND AS THE SYSTEM TRACKS ACROSS THE
MANILA REGION. AFTER TAU 36, THE SYSTEM WILL REEMERGE OVER THE
SOUTH CHINA SEA AND TRACK POLEWARD ALONG THE WESTERN PERIPHERY OF
THE STR TOWARD A BREAK IN THE STR. THIS BREAK IS ASSOCIATED WITH A
SERIES OF WEAK SHORTWAVE TROUGHS, WHICH ARE FORECAST TO QUICKLY
PROPAGATE OVER EASTERN CHINA WITHIN A ZONAL FLOW PATTERN. THE
SHORTWAVE TROUGHS ARE NOT STRONG AND LACK THE DYNAMICS TO INDUCE A
TYPICAL RECURVATURE SCENARIO. THE DEVELOPMENT OF A FRESH NORTHEAST
SURGE OVER THE EAST CHINA SEA BY TAU 96 WITH STRONG NORTH-
NORTHEASTERLY WINDS CHANNELING THROUGH THE TAIWAN STRAIT AND
EAST OF TAIWAN WILL FURTHER COMPLICATE THE SITUATION AND IS
EXPECTED TO CAUSE TS 26W TO SLOW SIGNIFICANTLY SOUTH TO SOUTHWEST
OF TAIWAN WITH POTENTIAL FOR A QUASI-STATIONARY TRACK MOTION. TS
26W WILL LIKELY BEGIN TO WEAKEN AS IT ENCOUNTERS THE MORE STABLE
AIR ASSOCIATED WITH THE SURGE EVENT.        

MODEL DISCUSSION: DETERMINISTIC AND PROBABILISTIC MODEL GUIDANCE
CONTINUE TO SHOW A BIFURCATION, HOWEVER, THE MORE ACCURATE GLOBAL
MODELS (ECMWF, EEMN, GFS, AEMN) NOW SUPPORT THE JTWC FORECAST TRACK
PHILOSOPHY AND THE LARGE MAJORITY OF THE ECMWF (EPS) AND GFS (GEFS)
ENSEMBLE SOLUTIONS SHOW A QUASI-STATIONARY OR SLOW WESTWARD TURN
TOWARD SOUTHERN CHINA. THE SOLUTIONS THAT DO RECURVE THE SYSTEM
NORTHEASTWARD GENERALLY REFLECT A WEAKENING AND DISSIPATION
SCENARIO NEAR OR EAST OF TAIWAN. INTENSITY GUIDANCE IS IN FAIR
AGREEMENT WITH A PEAK INTENSITY (PRE-LANDFALL) RANGING FROM 45 TO
60 KNOTS, AND A REINTENSIFICATION PHASE OVER THE SOUTH CHINA SEA TO
A PEAK OF 50-63 KNOTS.           

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