WDPN31 PGTW 191500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 01W (NOKAEN) WARNING 
NR 020//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.0N 127.0E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 375 NM EAST-NORTHEAST OF MANILA,
PHILIPPINES
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
DEPRESSION (TD) 01W WITH A STRUGGLING, PARTIALLY EXPOSED LOW-LEVEL
CIRCULATION CENTER (LLCC) AND DISSIPATING ISOLATED CONVECTIVE
STRUCTURES THROUGHOUT THE NORTHEAST QUADRANT. DRY AIR IS EVIDENT
THROUGHOUT THE WESTERN AND SOUTHERN SEMICIRCLES, VOIDING THE
REGIONS OF ANY SUPPORTIVE CONVECTIVE BANDING. THE ENVIRONMENT HAS
BECOME MARGINALLY UNFAVORABLE DUE TO PERSISTENT DRY AIR ENTRAINMENT
AND DECREASING UPPER-LEVEL OUTFLOW. THE INITIAL POSITION HAS BEEN
PLACED WITH MEDIUM CONFIDENCE BASED ON EXTRAPOLATION FROM A 190925Z
91 GHZ SSMIS MICROWAVE IMAGE AND ANIMATED EIR SATELLITE IMAGERY.
THE INITIAL INTENSITY HAS BEEN ASSESSED WITH MEDIUM CONFIDENCE
BASED ON SUBJECTIVE AGENCY DVORAK ESTIMATES ALIGNED AT T-NUMBER 1.5
(25 KTS) AND CIMSS OBJECTIVE INTENSITY ESTIMATES LISTED BELOW.

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

CURRENT STEERING MECHANISM: A WEAKENING SUBTROPICAL RIDGE (STR)
LOCATED DIRECTLY TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T1.5 - 25 KTS
   RCTP: T1.5 - 25 KTS
   KNES: T1.5 - 25 KTS
   CIMSS SATCON: 35 KTS AT 190925Z
   CIMSS ADT: 37 KTS AT 191130Z
   CIMSS AIDT: 35 KTS AT 191130Z
   CIMSS D-MINT: 30 KTS AT 190924Z
   CIMSS D-PRINT: 28 KTS AT 191230Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 10-15 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: WEAK POLEWARD

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 01W IS FORECASTED TO TRACK
EAST-NORTHEASTWARD OVER THE NEXT 12-24 HOURS, ALONG THE
NORTHWESTERN EXTENT OF A WEAKENING STR LOCATED DIRECTLY TO THE
EAST. THROUGH TAU 24, AN ADDITIONAL STR CENTERED OVER CAMBODIA AND
VIETNAM WILL CONTINUE TO BUILD EASTWARD, DRIVING THE REMAINING
VORTEX SOUTHWARD BY TAU 48 IN AN INCREASINGLY HOSTILE ENVIRONMENT.
REGARDING INTENSITY, TD 01W IS EXPECTED TO MAINTAIN INTENSITIES
NEAR 30 KTS OVER THE NEXT 36 HOURS, AS SEA SURFACE TEMPERATURES
REMAIN WARM (26-27 C) AND POLEWARD OUTFLOW ALOFT REMAINS
SUPPORTIVE. BETWEEN TAU 24 AND TAU 36, INCREASING DRY AIR
ENTRAINMENT AND VERTICAL WIND SHEAR INCREASING TO ABOVE 25 KTS WILL
FURTHER ERODE THE SURFACE CIRCULATION, WITH AN EXPECTED PHASE
TOWARD COMPLETE DISSIPATION OVER WATER BY TAU 48 WITHIN THE
PHILIPPINE SEA.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE REMAINS IN FAIR
AGREEMENT THROUGHOUT THE NEXT 24 HOURS, WITH ALL JTWC CONSENSUS
TRACK MEMBERS SHOWING A NORTHEASTWARD TRACK TOWARD THE EVENTUAL
TURN SOUTHWARD AFTER TAU 24. FOLLOWING TAU 24, JTWC TRACK CONSENSUS
MEMBERS DIVERGE SIGNIFICANTLY, AS THE PRIMARY STEERING MECHANISM
SHIFTS TO THE STR LOCATED DIRECTLY TO THE WEST. DUE TO THE
UNCERTAINTY WITH THE SHALLOW VORTEX BEING DRIVEN BY AN EASTWARD
BUILDING STR, THE JTWC TRACK FORECAST HAS BEEN LAID WITH LOW 
CONFIDENCE AND ALIGNED CLOSELY WITH THE MULTI-MODEL TRACK CONSENSUS. 
REGARDING INTENSITY, ALL JTWC INTENSITY SOLUTIONS ILLUSTRATE SUSTAINED 
INTENSITIES BETWEEN 30-35 KTS OVER THE NEXT 36 HOURS, WITH EXPECTED 
WEAKENING THEREAFTER UNTIL THE END OF THE FORECAST PERIOD. THEREFORE, 
THE JTWC INTENSITY FORECAST HAS BEEN ASSESSED WITH MEDIUM CONFIDENCE 
AND ALIGNED CLOSELY TO THE JTWC MULTI-MODEL INTENSITY CONSENSUS.

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