WDPN31 PGTW 270900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 26W (NALGAE) 
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.2N 130.0E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 545 NM EAST-SOUTHEAST OF MANILA,
      PHILIPPINES
   MOVEMENT PAST 6 HOURS: WESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
UPPER-LEVEL ANALYSIS INDICATES A COMPLEX PATTERN WITH A POINT
SOURCE POSITIONED SOUTH OF THE CENTER PROVIDING STRONG EQUATORWARD
OUTFLOW AND WEAK POLEWARD VENTING INTO THE TUTT TO THE NORTHEAST.
HOWEVER, THE TUTT EXTENDS SOUTHWESTWARD OVER THE NORTHERN AND
NORTHWESTERN QUADRANTS OF THE SYSTEM, WHICH IS HAMPERING CONVECTIVE
DEVELOPMENT OVER THE NORTHERN SEMICIRCLE. CONSEQUENTLY, ANIMATED
MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A BROAD, PARTIALLY
EXPOSED LOW-LEVEL CIRCULATION WITH A POORLY DEFINED CENTER WITH
MULTIPLE MESOVORTICES ROTATING ABOUT A CENTROID AND LIMITED
CONVECTIVE BANDING OVER THE SOUTHERN SEMICIRCLE. THE INITIAL
POSITION IS PLACED WITH LOW CONFIDENCE BASED ON EXTRAPOLATION FROM
A 270442Z AMSR2 WINDSPEED IMAGE SHOWING AN ELONGATED CENTER (WIND
MINIMUM) AND A 270130Z ASCAT-B PARTIAL IMAGE, WHICH SHOWS AN
ELONGATED CIRCULATION ORIENTED EAST-WEST ALONG 12N. A 270705Z GMI
89GHZ COLOR COMPOSITE MICROWAVE IMAGE REVEALS A POORLY-DEFINED,
BROAD LOW-LEVEL CIRCULATION CENTER WITH DEEP CONVECTIVE BANDING
WITHIN THE STRONG CONVERGENT LOW-LEVEL FLOW ALONG THE SOUTHERN AND
SOUTHEASTERN PERIPHERIES. THE INITIAL INTENSITY OF 30 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON RECENT ASCAT DATA, AMSR2
WINDSPEED DATA AS WELL AS THE SUBJECTIVE AND OBJECTIVE DVORAK
ESTIMATES WHICH RANGE FROM 25 TO 31 KNOTS.

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

CURRENT STEERING MECHANISM: LOW- TO MID-LEVEL SUBTROPICAL RIDGE
(STR) POSITIONED TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   KNES: T1.5 - 25 KTS
   CIMSS ADT: 31 KTS AT 270540Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 0-5 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   INITIAL INTENSITY: MEDIUM
   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: TD 26W IS STRUGGLING TO CONSOLIDATE DUE TO A
MARGINALLY FAVORABLE ENVIRONMENT, HOWEVER, THE TUTT IS FORECAST TO
WEAKEN WITH EXPANDING POLEWARD OUTFLOW INTO THE WESTERLIES TO THE
NORTH DEVELOPING WITHIN THE NEXT 24 HOURS. THIS SHOULD ALLOW THE
SYSTEM TO CONSOLIDATE AND INTENSIFY AT A FASTER RATE TO A PEAK OF
75 KNOTS BY TAU 48 NEAR LANDFALL OVER EASTERN LUZON. TD 26W WILL
WEAKEN SIGNIFICANTLY OVER THE PHILIPPINES BUT IS EXPECTED TO
RE-INTENSIFY AS IT RECURVES POLEWARD AND TRACKS AWAY FROM LUZON
AFTER TAU 96. A DYNAMIC 500MB SHORTWAVE TROUGH IS FORECAST TO
PROPAGATE OVER EASTERN CHINA AFTER TAU 84, WHICH SHOULD BREAK THE
STR DOWN AND ALLOW THE SYSTEM TO TRACK SLOWLY POLEWARD.      

MODEL DISCUSSION: THE BULK OF THE DETERMINISTIC MODEL GUIDANCE
SUPPORTS A SLOW RECURVATURE TRACK WEST AND NORTHWEST OF LUZON THEN
A SLOW TRACK TOWARD TAIWAN OVER THE NEXT FIVE DAYS. ECMWF IS THE
SOLE OUTLIER AND INDICATES A MORE WESTWARD TRACK OVER SOUTHERN
LUZON WITH SLOWER INTENSIFICATION THEN A NORTHWESTWARD TRACK TOWARD
HONG KONG (THE EXTENDED TRACK BEYOND FIVE DAYS INDICATES AN
EVENTUAL STALL AND RAPID WEAKENING SOUTHWEST OF HONG KONG AS THE 
SYSTEM INTERACTS WITH A NORTHEAST SURGE EVENT). THE 270000Z ECMWF 
(EPS) ENSEMBLE SHOWS A BIFURCATION SCENARIO WITH THE FIRST CLUSTER OF
SOLUTIONS RECURVING THE SYSTEM NORTHEASTWARD TOWARD TAIWAN AND THE
SECOND CLUSTER SIMILAR TO THE DETERMINISTIC MODEL SOLUTION. THERE
IS A LARGE SPREAD IN INTENSITY GUIDANCE WITH HWRF PEAKING AT 120
KNOTS AT TAU 72, HOWEVER, HWRF RECURVES THE SYSTEM EAST OF LUZON SO
IS NOT IMPACTED BY LAND INTERACTION. THE 270000Z COAMPS-TC ENSEMBLE
INDICATES A 20 TO 30 PERCENT PROBABILITY FOR RAPID INTENSIFICATION
IN THE 24 TO 48 HOUR PERIOD. DUE TO THE MARGINALLY FAVORABLE
CONDITIONS AND BROAD NATURE OF THE SYSTEM CURRENTLY, THIS IS
UNLIKELY BUT THE JTWC INTENSITY FORECAST STILL ANTICIPATES MODERATE
INTENSIFICATION BEFORE LANDFALL. DUE TO THE LARGE SPREAD IN
DETERMINISTIC AND PROBABILISTIC GUIDANCE IN THE EXTENDED PERIOD AND
POSSIBLE INTERACTION WITH THE NORTHEAST SURGE EVENT, THERE IS LOW
CONFIDENCE IN THE 72-120 HOUR JTWC FORECAST TRACK AND INTENSITY
FORECAST.        

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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