WDPN31 PGTW 271500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 26W (NALGAE) 
WARNING NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.1N 130.1E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 552 NM EAST-SOUTHEAST OF MANILA,
      PHILIPPINES
   MOVEMENT PAST 6 HOURS: WESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
UPPER-LEVEL ANALYSIS USING THE 271200Z UW-CIMSS UPPER-LEVEL WINDS 
CHART, UPPER DIVERGENCE CHART AND ANIMATED WATER VAPOR IMAGERY 
CONTINUE TO INDICATE THAT THE TUTT IS POSITIONED OVER THE NORTHERN 
SEMICIRCLE OF THE SYSTEM WITH CONVERGENCE ALOFT. WHILE THIS IS 
HINDERING CONVECTIVE DEVELOPMENT OVER THE NORTHERN SEMICIRCLE, STRONG 
EQUATORWARD OUTFLOW OVER THE SOUTHERN SEMICIRCLE IS CONTINUING TO 
FUEL EXTENSIVE, INTENSE DEEP CONVECTION. ANIMATED ENHANCED INFRARED 
SATELLITE IMAGERY DEPICTS STRONG MID-LEVEL TURNING; HOWEVER, THE LOW-
LEVEL CIRCULATION CENTER (LLCC) REMAINS BROAD AND VERY DIFFICULT TO 
PINPOINT. A 271233Z AMSU-B 89GHZ MICROWAVE IMAGE REVEALS CURVED 
CONVECTIVE BANDING OVER THE SOUTHERN SEMICIRCLE WITH A POORLY DEFINED 
LLCC AND FRAGMENTED CORE CONVECTION. THE INITIAL POSITION IS PLACED 
WITH LOW CONFIDENCE BASED ON EXTRAPOLATION FROM A 270911Z SMOS 
WINDSPEED IMAGE, WHICH SHOWS A BROAD CENTER (WIND MINIMUM) WITH A 
SWATH OF 25-30 KNOT WINDS WRAPPING AROUND THE SOUTHERN, EASTERN AND 
NORTHERN QUADRANTS. ALTHOUGH THIS IMAGE SHOWS ISOLATED PATCHES OF 35 
KNOT WINDS, THE INITIAL INTENSITY REMAINS ASSESSED AT 30 KTS BASED ON 
THE AGENCY DVORAK ESTIMATES WITH MEDIUM CONFIDENCE.

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: T2.0 - 30 KTS
   CIMSS ADT: 33 KTS AT 271140Z

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: NUMERICAL GUIDANCE IS IN FAIR AGREEMENT THROUGH TAU 
72 WITH A 95NM SPREAD IN SOLUTIONS AT TAU 48 AND A 150NM SPREAD IN 
SOLUTIONS AT TAU 72. AFTER TAU 72, THERE IS A BIFURCATION IN THE 
GUIDANCE WITH ECMWF, EEMN AND NAVGEM SHOWING A MORE WESTWARD TRACK 
TOWARD HONG KONG WITH AN EVENTUAL STALL AND RAPID WEAKENING SOUTHWEST 
OF TAIWAN AS THE SYSTEM INTERACTS WITH A NORTHEAST SURGE EVENT. THE 
REMAINDER OF THE DETERMINISTIC GUIDANCE SHOWS A SLOW RECURVATURE 
TRACK WEST AND NORTHWEST OF LUZON THEN A SLOW NORTHEASTWARD TRACK. 
THE 270600Z ECMWF (EPS) ENSEMBLE SHOWS A BIFURCATION SCENARIO WITH 
THE FIRST CLUSTER OF SOLUTIONS RECURVING THE SYSTEM NORTHEASTWARD 
TOWARD TAIWAN AND THE SECOND CLUSTER TRACKING THE SYSTEM WEST-
NORTHWESTWARD TO NORTHWESTWARD TOWARD SOUTHERN CHINA. INTENSITY 
GUIDANCE IS NOW IN BETTER AGREEMENT WITH A 65-85 KNOT RANGE OF PEAK 
INTENSITIES. HWRF NOW HAS A MORE REALISTIC PEAK OF 75 KNOTS WITH A 
TRACK OVER LUZON. THE 270600Z 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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