WDPN31 PGTW 301500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 26W (NALGAE) WARNING 
NR 015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.0N 117.7E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 193 NM WEST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: EASTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 22 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY STILL DEPICTS A
RATHER BROAD SYSTEM WITH FLARING CONVECTION CONFINED TO THE WESTERN
AND SOUTHWESTERN PERIPHERY OF THE SYSTEM. HOWEVER, THERE ARE EARLY
SIGNS THE SYSTEM IS IMPROVING AND BECOMING MORE CONSOLIDATED, WITH
CONVECTIVE BURSTS AND CLOUD TOPS TEMPERATURES OF (-70C), BEGINNING
TO WRAP AROUND THE LOW LEVEL CIRCULATION CENTER (LLCC). A 301024Z
SSMIS 91 GHZ MICROWAVE IMAGE REVEALS FORMATIVE CONVECTIVE BANDING
IN THE NORTHWEST AND SOUTHWESTERN QUADRANTS OF THE LOW LEVEL
CIRCULATION (LLC). THE INITIAL POSITION IS PLACED WITH MEDIUM
CONFIDENCE BASED ON ANIMATED EIR, AND THE PGTW FIX POSITION ALONG
WITH THE SSMIS MICROWAVE IMAGE. THE INITIAL INTENSITY OF 45 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE PGTW, RJTD DVORAK
INTENSITY ESTIMATES ALONG WITH A COMBINATION OF OBJECTIVE DVORAK
INTENSITY ESTIMATES. ENVIRONMENTAL CONDITIONS ARE GENERALLY
FAVORABLE, CHARACTERIZED BY LOW (5-10 KNOTS) WARM (29-30C) SSTS AND
FAVORABLE POLEWARD AND EQUATORWARD OUTFLOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: DEEP-LAYER STR CENTERED TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.5 - 35 KTS
   CIMSS SATCON: 45 KTS AT 300545Z
   CIMSS ADT: 37 KTS AT 301140Z

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: 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: TROPICAL STORM 26W (NALGAE) HAS MAINTAINED AN
INTENSITY OF 45 KNOTS AND HAS BEEN SLOW TO DEVELOP DUE TO THE
OVERALL BROAD CONVECTIVE STRUCTURE AND A LACK OF A SYMMETRICAL
CORE, HOWEVER THE CURRENT CONVECTIVE STRUCTURE SHOWS EARLY SIGNS OF
IMPROVEMENT. OVER THE PAST SIX HOURS THE SYSTEM HAS SLOWED DOWN TO
A QUASI-STATIONARY MOTION AND HAS TURNED SLIGHTLY TOWARD THE
NORTHEAST. OVER THE NEXT 24 HOURS, TS 26W IS EXPECTED TO TRACK
NORTH-NORTHWEST, WHILE INCREASING ITS FORWARD TRACK SPEED DUE AN
APPROACHING MID-LATITUDE TROUGH TO THE NORTH WHICH WILL INDUCE A
WEAKNESS IN THE WESTERN SIDE OF THE DEEP-LAYER STR TO THE EAST.
ADDITIONALLY, THE SYSTEM IS EXPECTED TO SLOWLY RECONSOLIDATE, AS AN
UPPER-LEVEL POINT SOURCE ALOFT IS ANTICIPATED TO DEVELOP ALOFT
ALONG WITH THE POSSIBILITY OF INCREASED POLEWARD OUTFLOW. THESE
IMPROVED ENVIRONMENTAL FACTORS WILL ALLOW FOR STEADY
INTENSIFICATION TO A PEAK OF 60-65 KNOTS BY TAU 48. HOWEVER, BY TAU
72, THE SYSTEM WILL BE IMPACTED BY COOLING SSTS, INCREASING
VERTICAL WIND SHEAR, ALONG WITH DRY AIR ENTRAINMENT WHICH WILL LEAD
TO A STEADY WEAKENING TREND THROUGH TAU 120. FURTHERMORE, THE
STEERING PATTERN EVOLVES, AS THE STR TO THE EAST BUILDS WESTWARD,
ALONG WITH LOWER-LEVEL FLOW OUT OF THE NORTH-NORTHEAST WHICH WILL
THEN STEER THE SYSTEM SHARPLY TO THE NORTHWEST AND THEN
WEST-NORTHWEST THROUGH TAU 120.

MODEL DISCUSSION: THE JTWC TRACK FORECAST REMAINS CONSISTENT WITH
THE PREVIOUS FORECAST, AND LIES CLOSE TO THE MULTI-MODEL CONSENSUS
MEAN THROUGH THE FORECAST PERIOD WITH MEDIUM CONFIDENCE. NUMERICAL
MODEL TRACK GUIDANCE REMAINS IN FAIR AGREEMENT, WITH THE PRIMARY
OUTLIERS BEING HWRF, COMAPS-TC (NAVGEM), AND JGSM ON THE WESTERN
EDGE OF THE AIDS ENVELOPE, AND GALWEM ON THE EASTERN EDGE. THE
REMAINDER OF THE TRACKERS ARE TIGHTLY GROUPED IN AN ENVELOPE WHICH
GRADUALLY EXPANDS TO 115NM AT TAU 72. THEREAFTER, THE MODEL TRACK
GUIDANCE DIVERGES SIGNIFICANTLY BY TAU 120. BOTH THE ECMWF ENSEMBLE
(EPS) AND GFS ENSEMBLE (GEFS) MEAN SOLUTIONS SUPPORT THE JTWC
TRACK FORECAST. THE INTENSITY GUIDANCE IS IN FAIR AGREEMENT, WITH
THE GFS REPRESENTING THE HIGH END OF THE SPECTRUM WITH A PEAK OF
60-65 KNOTS, WHILE CTCI, COTI AND DECAY SHIPS REPRESENTING THE LOW
END OF INTENSITY GUIDANCE. THE JTWC INTENSITY FORECAST IS PLACED
WITH MEDIUM CONFIDENCE AND LIES CLOSE TO ABOVE THE CONSENSUS MEAN
THROUGH TAU 36 AND CLOSER TO THE GFS SOLUTION THROUGH TAU 120.

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